Purpose of the work is to discuss some theoretical aspects of the diffusion of hydrogen atoms in the crystal
lattice of BCC metals at low temperatures using the methods of statistical thermodynamics. The values of
the statistical model calculations of H diffusion coefficients in α-Fe, V, Ta, Nb, K are in good agreement
with the experimental data. The statistical model can also explain deviations from the Arrhenius equation
at temperatures 300-100 K in α-Fe, V, Nb and K. It was suggested that thermally activated fast tunnelling
transition of hydrogen atoms through the potential barrier at a temperature below 300 K provides an
almost free movement of H atoms in the α-Fe and V lattice at these temperatures. The results show that
quantum-statistical effects play a decisive role in the H diffusion in BCC metals at low temperatures. Using
the statistical model allows for the prediction of the diffusion coefficient for H in BCC metals at low
temperatures, where it’s necessary to consider quantum effects.
Study Some Parameters of Electrical Discharge in N2 and CO2 Without and With ...IOSRJECE
:We study the breakdown voltage under low pressure for N2, CO2 gases of with a magnetic field to the electrode of iron and aluminum with diameter (8.8cm) cm and distance separation between them is (3cm). by using Passion curve, we measur less effort collapsed, and we notice that less effort is linked to the collapse of a function held cities and when the magnetic field will be reduced to shed breakdown voltage. Since the breakdown voltage for CO2 is greater than breakdown voltage N2. Through curved Passion was calculated (훾) and when to shed the magnetic field will increase in value
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
Microstructural and Dielectric Characterization of Sr doped Ba(Fe0.5Ta0.5)O3 ...theijes
Solid state reaction method was used to synthesize Ba1-xSrx(Fe0.5Ta0.5)O3 ceramic(x=0, 0.1, 0.2, 0.3, 0.4 and 0.5). The raw materials of making Sr doped Ba(Fe0.5Ta0.5)O3 were BaCO3, SrCO3, Fe2O3, Ta2O5 (purity better than 99%). Pellet and ring shaped samples prepared from each composition were sintered at 1400 and 1450ºC for 5 hour. The phase formation of Ba1-xSrx(Fe0.5Ta0.5)O3 was checked using X-ray diffraction (XRD) technique and observed a cubic perovskite crystal structure in space group Pm3m (221). Microstructure of the individual compound was examined by the field emission scanning electron micrograph (FESEM). Grain size was found to be varied with Sr content. The lattice parameter decreased with increasing Sr content. Dielectric spectroscopy was applied to investigate the electrical properties of BSFT at room temperature and in a frequency range of 100Hz–100 MHz. An analysis of the dielectric constant εʹ and loss tangent tan with frequency was performed assuming a distribution of relaxation times. The low frequency dielectric dispersion corresponds to the DC electrical conductivity.
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
Research Inventy : International Journal of Engineering and Scienceresearchinventy
Research Inventy : International Journal of Engineering and Science is published by the group of young academic and industrial researchers with 12 Issues per year. It is an online as well as print version open access journal that provides rapid publication (monthly) of articles in all areas of the subject such as: civil, mechanical, chemical, electronic and computer engineering as well as production and information technology. The Journal welcomes the submission of manuscripts that meet the general criteria of significance and scientific excellence. Papers will be published by rapid process within 20 days after acceptance and peer review process takes only 7 days. All articles published in Research Inventy will be peer-reviewed.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Study the effect of Mn2+ ions on the ac electrical properties of some iron do...IJRES Journal
Oxide glasses doped with transition metal ions are of high interest because of their variant applications in both science and technology fields. However, the normal melt quench method have used to prepared some iron doped phosphate glasses according the following molecular formula: (65-x) mol% P2O5 - 20 mol% Na2O - 15 mol% Fe2O3 - x mol% MnO, Where x= 0, 5,10, 20, 25. The room temperature Mössbauer Effect ME Spectra used to characterized the glassy state homogeneity of these glasses. ME spectra show, for all glasses, no magnetic field participate which mean good glassy state formation. The ac electrical transport properties were also measured, as function of temperature up to 500k. It was found that the ac conductivity increased with the gradual increase of Mn2+ cations, while the electrical activation energy decreased.
Study Some Parameters of Electrical Discharge in N2 and CO2 Without and With ...IOSRJECE
:We study the breakdown voltage under low pressure for N2, CO2 gases of with a magnetic field to the electrode of iron and aluminum with diameter (8.8cm) cm and distance separation between them is (3cm). by using Passion curve, we measur less effort collapsed, and we notice that less effort is linked to the collapse of a function held cities and when the magnetic field will be reduced to shed breakdown voltage. Since the breakdown voltage for CO2 is greater than breakdown voltage N2. Through curved Passion was calculated (훾) and when to shed the magnetic field will increase in value
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
Microstructural and Dielectric Characterization of Sr doped Ba(Fe0.5Ta0.5)O3 ...theijes
Solid state reaction method was used to synthesize Ba1-xSrx(Fe0.5Ta0.5)O3 ceramic(x=0, 0.1, 0.2, 0.3, 0.4 and 0.5). The raw materials of making Sr doped Ba(Fe0.5Ta0.5)O3 were BaCO3, SrCO3, Fe2O3, Ta2O5 (purity better than 99%). Pellet and ring shaped samples prepared from each composition were sintered at 1400 and 1450ºC for 5 hour. The phase formation of Ba1-xSrx(Fe0.5Ta0.5)O3 was checked using X-ray diffraction (XRD) technique and observed a cubic perovskite crystal structure in space group Pm3m (221). Microstructure of the individual compound was examined by the field emission scanning electron micrograph (FESEM). Grain size was found to be varied with Sr content. The lattice parameter decreased with increasing Sr content. Dielectric spectroscopy was applied to investigate the electrical properties of BSFT at room temperature and in a frequency range of 100Hz–100 MHz. An analysis of the dielectric constant εʹ and loss tangent tan with frequency was performed assuming a distribution of relaxation times. The low frequency dielectric dispersion corresponds to the DC electrical conductivity.
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
Research Inventy : International Journal of Engineering and Scienceresearchinventy
Research Inventy : International Journal of Engineering and Science is published by the group of young academic and industrial researchers with 12 Issues per year. It is an online as well as print version open access journal that provides rapid publication (monthly) of articles in all areas of the subject such as: civil, mechanical, chemical, electronic and computer engineering as well as production and information technology. The Journal welcomes the submission of manuscripts that meet the general criteria of significance and scientific excellence. Papers will be published by rapid process within 20 days after acceptance and peer review process takes only 7 days. All articles published in Research Inventy will be peer-reviewed.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Study the effect of Mn2+ ions on the ac electrical properties of some iron do...IJRES Journal
Oxide glasses doped with transition metal ions are of high interest because of their variant applications in both science and technology fields. However, the normal melt quench method have used to prepared some iron doped phosphate glasses according the following molecular formula: (65-x) mol% P2O5 - 20 mol% Na2O - 15 mol% Fe2O3 - x mol% MnO, Where x= 0, 5,10, 20, 25. The room temperature Mössbauer Effect ME Spectra used to characterized the glassy state homogeneity of these glasses. ME spectra show, for all glasses, no magnetic field participate which mean good glassy state formation. The ac electrical transport properties were also measured, as function of temperature up to 500k. It was found that the ac conductivity increased with the gradual increase of Mn2+ cations, while the electrical activation energy decreased.
Enhancement of Structure, Tc and Irreversibility Line in High Tc Superconduct...IJERA Editor
AC susceptibility (ac= ’+ i‖) and X ray diffraction (XRD) are very useful for characterizing high Tc superconductors. We report here on the preparation, X-ray diffraction with Rietveld refinement, resistivity , AC magnetic susceptibility measurements and effect of heat treatments in (Y1-xNdx)SrBaCu3O6+z. Each sample was subject to two types of heat treatment: oxygen annealing [O] and argon annealing followed by oxygen annealing [AO]. For each x, the [AO] heat treatment increases the orthorhombicity ε = (b-a)/(b+a) (for 0≤x<1),>0.2), the distance d[Cu(1)-(Sr/Ba)] (for x<0.25)>0.25; increase in cationic and chain oxygen ordering; psh and in-phase purity for the [AO] samples may account for the observed data.
Influence of the alkyl chain length of alkyltriazoles on the corrosion inhibi...Al Baha University
Abstract. Steel is an important material and has been widely used in today's industrial production. Using organic
corrosion inhibitors is an effective means to prevent steel from corrosion. Generally, the molecular structures of
inhibitors can have a major impact on their corrosion inhibition efficiency. In this work, the influence of alkyl chain
length of three alkyltriazoles on the corrosion inhibition of iron has been investigated by density functional based tight
binding (DFTB) approach. Several typical descriptors such as frontier molecular orbital, adsorption energy, density of
states have been discussed in detail. Our findings will contribute to the understanding of the inhibition mechanism and
the designing of novel corrosion inhibitors.
Influence of Interface Thermal Resistance on Relaxation Dynamics of Metal-Die...A Behzadmehr
Nanocomposite materials, including noble metal nanoparticles embedded in a dielectric host medium, are interesting because of their optical properties linked to surface plasmon resonance phenomena. For studding of nonlinear optical properties and/or energy transfer process, these materials may be excited by ultrashort pulse laser with a temporal width varying from some femtoseconds to some hundreds of picoseconds. Following of absorption of light energy by metal-dielectric nanocomposite material, metal nanoparticles are heated. Then, the thermal energy is transferred to the host medium through particle-dielectric interface. On the one hand, nonlinear optical properties of such materials depend on their thermal responses to laser pulse, and on the other hand different parameters, such as pulse laser and medium thermodynamic characterizes, govern on the thermal responses of medium to laser pulse. Here, influence of thermal resistance at particle-surrounding medium interface on thermal response of such material under ultrashort pulse laser excitation is investigated. For this, we used three temperature model based on energy exchange between different bodies of medium. The results show that the interface thermal resistance plays a crucial role on nanoparticle cooling dynamics, so that the relaxation characterized time increases by increasing of interface thermal resistance.
Electron Diffusion and Phonon Drag Thermopower in Silicon NanowiresAI Publications
The field of thermoelectric research has undergone a renaissance and boom in the fast two decades, largely fueled by the prospect of engineering electronic and phononic properties in nanostructures, among which semiconductor nanowires (NWs) have served both as an important platform to investigate fundamental thermoelectric transport phenomena and as a promising route for high thermoelectric performance for device applications. In this report we theoretical studied the carrier diffusion and phonon-drag contribution to thermoelectric performance of silicon nanowires and compared with the existing experimental data. We observed a good agreement between theoretical data and experimental observations in the overall temperature range from 50 – 350 K. Electron diffusion thermopower is found to be dominant mechanism in the low temperature range and shows linear dependence with temperature.
On the Unification of Physic and the Elimination of Unbound Quantitiesijrap
This paper supports Descartes' idea of a constant quantity of motion, modernized by Leibniz. Unlike Leibniz, the paper emphasizes that the idea is not realized by forms of energy, but by energy itself. It remains constant regardless of the form, type, or speed of motion, even that of light. Through force, energy is only transformed. Here it is proved that force is its derivative. It exists even at rest, representing the object's minimal energy state. With speed, we achieve its multiplication up to the maximum energy state, from which a maximum force is derived from the object. From this point, corresponding to Planck's Length, we find the value of the force wherever we want. Achieving this removes the differences between various natural forces. The new idea eliminates infinite magnitudes. The process allows the laws to transition from simple to complex forms and vice versa, through differentiation-integration. For this paper, this means achieving the Unification Theory.
Gravity Also Redshifts Light – the Missing Phenomenon That Could Resolve Most...ijrap
In this paper I discover that gravity also redshifts light like the velocity of its source does. When light travels towards a supermassive object, its waves (or photons) undergo continuous stretching, thereby shifting towards lower frequencies. Gravity redshifts light irrespective of whether its source is in motion or static with respect to its observer. An equation is derived for gravitational redshift, and a formula for combined redshift is presented by considering both the velocity, and gravity redshifts. Also explained is how frequencies of electromagnetic spectrum continuously downgrade as a light beam of mix frequencies passes towards a black hole. Further, a clear methodology is provided to figure out whether expansion of the universe is accelerating or decelerating, or alternatively, the universe is contracting.
More Related Content
Similar to SOME THEORETICAL ASPECTS OF HYDROGEN DIFFUSION IN BCC METALS AT LOW TEMPERATURES
Enhancement of Structure, Tc and Irreversibility Line in High Tc Superconduct...IJERA Editor
AC susceptibility (ac= ’+ i‖) and X ray diffraction (XRD) are very useful for characterizing high Tc superconductors. We report here on the preparation, X-ray diffraction with Rietveld refinement, resistivity , AC magnetic susceptibility measurements and effect of heat treatments in (Y1-xNdx)SrBaCu3O6+z. Each sample was subject to two types of heat treatment: oxygen annealing [O] and argon annealing followed by oxygen annealing [AO]. For each x, the [AO] heat treatment increases the orthorhombicity ε = (b-a)/(b+a) (for 0≤x<1),>0.2), the distance d[Cu(1)-(Sr/Ba)] (for x<0.25)>0.25; increase in cationic and chain oxygen ordering; psh and in-phase purity for the [AO] samples may account for the observed data.
Influence of the alkyl chain length of alkyltriazoles on the corrosion inhibi...Al Baha University
Abstract. Steel is an important material and has been widely used in today's industrial production. Using organic
corrosion inhibitors is an effective means to prevent steel from corrosion. Generally, the molecular structures of
inhibitors can have a major impact on their corrosion inhibition efficiency. In this work, the influence of alkyl chain
length of three alkyltriazoles on the corrosion inhibition of iron has been investigated by density functional based tight
binding (DFTB) approach. Several typical descriptors such as frontier molecular orbital, adsorption energy, density of
states have been discussed in detail. Our findings will contribute to the understanding of the inhibition mechanism and
the designing of novel corrosion inhibitors.
Influence of Interface Thermal Resistance on Relaxation Dynamics of Metal-Die...A Behzadmehr
Nanocomposite materials, including noble metal nanoparticles embedded in a dielectric host medium, are interesting because of their optical properties linked to surface plasmon resonance phenomena. For studding of nonlinear optical properties and/or energy transfer process, these materials may be excited by ultrashort pulse laser with a temporal width varying from some femtoseconds to some hundreds of picoseconds. Following of absorption of light energy by metal-dielectric nanocomposite material, metal nanoparticles are heated. Then, the thermal energy is transferred to the host medium through particle-dielectric interface. On the one hand, nonlinear optical properties of such materials depend on their thermal responses to laser pulse, and on the other hand different parameters, such as pulse laser and medium thermodynamic characterizes, govern on the thermal responses of medium to laser pulse. Here, influence of thermal resistance at particle-surrounding medium interface on thermal response of such material under ultrashort pulse laser excitation is investigated. For this, we used three temperature model based on energy exchange between different bodies of medium. The results show that the interface thermal resistance plays a crucial role on nanoparticle cooling dynamics, so that the relaxation characterized time increases by increasing of interface thermal resistance.
Electron Diffusion and Phonon Drag Thermopower in Silicon NanowiresAI Publications
The field of thermoelectric research has undergone a renaissance and boom in the fast two decades, largely fueled by the prospect of engineering electronic and phononic properties in nanostructures, among which semiconductor nanowires (NWs) have served both as an important platform to investigate fundamental thermoelectric transport phenomena and as a promising route for high thermoelectric performance for device applications. In this report we theoretical studied the carrier diffusion and phonon-drag contribution to thermoelectric performance of silicon nanowires and compared with the existing experimental data. We observed a good agreement between theoretical data and experimental observations in the overall temperature range from 50 – 350 K. Electron diffusion thermopower is found to be dominant mechanism in the low temperature range and shows linear dependence with temperature.
On the Unification of Physic and the Elimination of Unbound Quantitiesijrap
This paper supports Descartes' idea of a constant quantity of motion, modernized by Leibniz. Unlike Leibniz, the paper emphasizes that the idea is not realized by forms of energy, but by energy itself. It remains constant regardless of the form, type, or speed of motion, even that of light. Through force, energy is only transformed. Here it is proved that force is its derivative. It exists even at rest, representing the object's minimal energy state. With speed, we achieve its multiplication up to the maximum energy state, from which a maximum force is derived from the object. From this point, corresponding to Planck's Length, we find the value of the force wherever we want. Achieving this removes the differences between various natural forces. The new idea eliminates infinite magnitudes. The process allows the laws to transition from simple to complex forms and vice versa, through differentiation-integration. For this paper, this means achieving the Unification Theory.
Gravity Also Redshifts Light – the Missing Phenomenon That Could Resolve Most...ijrap
In this paper I discover that gravity also redshifts light like the velocity of its source does. When light travels towards a supermassive object, its waves (or photons) undergo continuous stretching, thereby shifting towards lower frequencies. Gravity redshifts light irrespective of whether its source is in motion or static with respect to its observer. An equation is derived for gravitational redshift, and a formula for combined redshift is presented by considering both the velocity, and gravity redshifts. Also explained is how frequencies of electromagnetic spectrum continuously downgrade as a light beam of mix frequencies passes towards a black hole. Further, a clear methodology is provided to figure out whether expansion of the universe is accelerating or decelerating, or alternatively, the universe is contracting.
In this paper I present a new theory that explains as to when and how dark energy is created as mass is destroyed. The theory extends Einstein’s mass energy equation to a more generic form in order to make it work even in high gravity conditions. It also explains why dark energy is created. Further, it is proved Einstein’s mass energy equation holds good only when the destroyed mass has no supermassive object in its close vicinity. The relationship between dark energy and dark matter is unveiled. An extended mathematical form of Einstein’s mass energy equation is derived, based on which the conditions leading to dark energy creation are explained. Three new physical parameters called dark energy discriminant, dark energy radius and dark energy boundary are introduced to facilitate easy understanding of the theory. It is explained in detail that an extremely superdense object has two dark energy boundaries, outer and inner. Mass destroyed only between these two boundaries creates dark energy. Dark energy space, the space between the two aforementioned boundaries, shrouds visible matter in obscurity from optical and electromagnetic telescopes. This theory identifies Gargantuan as a superdense black hole currently creating fresh dark energy, which could be the subject of interest for the astronomical research community having access to sophisticated telescopes, and working on dark energy. It also upholds dark energy and denies the existence of dark matter. Dark matter is nothing but the well-known visible matter positioned in dark energy space. An important relationship is derived between a photon’s frequency and its distance from a black hole to demonstrate the effect of gravity on light. Another important fact revealed by this theory is gravity stretches out light, thereby causing redshift, which is unaccounted in the computation of velocities of outer galaxies. Whether the universe is undergoing accelerated or decelerated expansion, or accelerated contraction can precisely be determined only after accounting for the redshift caused by gravity
International Journal on Soft Computing, Artificial Intelligence and Applicat...ijrap
International Journal on Soft Computing, Artificial Intelligence and Applications (IJSCAI)
is an open access peer-reviewed journal that provides an excellent international forum for sharing
knowledge and results in theory, methodology and applications of Artificial Intelligence, Soft
Computing. The Journal looks for significant contributions to all major fields of the Artificial
Intelligence, Soft Computing in theoretical and practical aspects. The aim of the Journal is to
provide a platform to the researchers and practitioners from both academia as well as industry to
meet and share cutting-edge development in the field.
Authors are solicited to contribute to the journal by submitting articles that illustrate research
results, projects, surveying works and industrial experiences that describe significant advances in
the areas of Database management systems.
MASSIVE PHOTON HYPOTHESIS OPENS DOORS TO NEW FIELDS OF RESEARCHijrap
Mass, an inherent property of matter, is calculated directly for the photon particle from the very classical
principles of the kinetic theory of gases. It is not an end result with no perspective nor other outcome.
Quite the opposite, a single ponderable tiny photon frees the mind of old ways of thinking and opens up
new paths to a broad field of investigation where the very large can then be described and explained by the
very small. This reality of a non-zero mass suddenly shows up in the interpretation of many experiments
which become clear and simple to comprehend. Besides, that same key particle has the potential to unlock
and solve some long lasting major observational issues or enigmas. All this converges upon its
acknowledgement and acceptance.
PHENOMENOLOGICAL METHOD REGARDING A THIRD THEORY OF PHYSICS “THE EVENT:THE TH...ijrap
The quest for a third theory uniting macro-cosmos (relativity) and micro-cosmos (quantum mechanics) has coexisted with the denial of feminine/subjective polarity to masculine/objective. The dismissal of electromagnetism as the tension of opposites in quest of inner/outer unity is sourced in the denial of the feminine qualia -- the negative force field attributed to dark energy/dark matter. However, a conversion philosophy sourced in the hieros gamos and signified by the Mobius strip has formulated an integral consciousness methodology producing quantum objects by means of embracing the shadow haunting contemporary physics. This Self-reflecting process integrating subject/object comprises an ontology of kairos as the “quantum leap.” An interdisciplinary quest to create a phenomenological narrative is disclosed via a holistic apparatus of hermeneutics manifesting image/text of a contemporary grail journey. Reflected in this Third space is the sacred reality of autonomous number unifying polarities of feminine/subjective (quality) and objective/masculine (quantity) as new measurement apparatus for the quantum wave collapse.
3rd International Conference on Integrating Technology in Education (ITE 2022)ijrap
3rd International Conference on Integrating Technology in Education (ITE 2022) This forum also aims to provide a platform for exchanging ideas in new emerging trends that needs more focus and exposure and will attempt to publish proposals that strengthen our goals.
A SPECIAL RELATIONSHIP BETWEEN MATTER, ENERGY, INFORMATION, AND CONSCIOUSNESSijrap
This paper discusses the advantages of describing the universe, or nature, in terms of information and consciousness. Some problems encountered by theoretical physicists in the quest for the theory of everything stem from the limitations of trying to understand everything in terms of matter and energy only. However, if everything, including matter, energy, life, and mental processes, is described in terms of information and consciousness, much progress can be made in the search for the ultimate theory of the universe. As brilliant and successful as physics and chemistry have been over the last two centuries, it is important that nature is not viewed solely in terms of matter and energy. Two additional components are needed to unlock her secrets. While extensive writing exists that describes the connection between matter and energy and their physical basis, little work has been done to learn the special relationship between matter, energy, information, and consciousness.
This paper discusses the advantages of describing the universe, or nature, in terms of information and consciousness. Some problems encountered by theoretical physicists in the quest for the theory of everything stem from the limitations of trying to understand everything in terms of matter and energy only. However, if everything, including matter, energy, life, and mental processes, is described in terms of information and consciousness, much progress can be made in the search for the ultimate theory of the universe. As brilliant and successful as physics and chemistry have been over the last two centuries, it is important that nature is not viewed solely in terms of matter and energy. Two additional components are needed to unlock her secrets. While extensive writing exists that describes the connection between matter and energy and their physical basis, little work has been done to learn the special relationship between matter, energy, information, and
consciousness.
THE CONCEPT OF SPACE AND TIME: AN AFRICAN PERSPECTIVEijrap
Understanding the concept of space and time is critical, essential, and fundamental in searching for theall-encompassing theory or the theory of everything (ToE). Some physicists argue that time exists, whileothers posit that time is only a social or mental construct. The author presents an African thought systemon space and time conception, focusing on the African (Bantu) view of space and time. The author arguesthat before the advent of the Western linear view of space and time, Africans had their own visionregarding these two concepts. Their conception of time appears to be holistic, highly philosophical, non-linear, and thought-provoking. The author hopes that exploring these two concepts from an African perspective will provide a new and more in-depth insight into reality's nature. A scientific investigation of space and time from an African-centered perspective is a worthy and necessary endeavor in the quest forthe ToE
Learning to Pronounce as Measuring Cross Lingual Joint Orthography Phonology ...ijrap
Machine learning models allow us to compare languages by showing how hard a task in each language might be to learn and perform well on. Following this line of investigation, we explore what makes a language “hard to pronounce” by modelling the task of grapheme-to-phoneme (g2p) transliteration. By training a character-level transformer model on this task across 22 languages and measuring the model’s proficiency against its grapheme and phoneme inventories, we show that certain characteristics emerge that separate easier and harder languages with respect to learning to pronounce. Namely the complexity of a language's pronunciation from its orthography is due to the expressive or simplicity of its grapheme-to phoneme mapping. Further discussion illustrates how future studies should consider relative data sparsity per language to design fairer cross-lingual comparison tasks.
THE CONCEPT OF SPACE AND TIME: AN AFRICAN PERSPECTIVEijrap
Understanding the concept of space and time is critical, essential, and fundamental in searching for the all-encompassing theory or the theory of everything (ToE). Some physicists argue that time exists, while others posit that time is only a social or mental construct. The author presents an African thought system on space and time conception, focusing on the African (Bantu) view of space and time. The author argues
that before the advent of the Western linear view of space and time, Africans had their own vision
regarding these two concepts. Their conception of time appears to be holistic, highly philosophical, nonlinear, and thought-provoking. The author hopes that exploring these two concepts from an African
perspective will provide a new and more in-depth insight into reality's nature. A scientific investigation of space and time from an African-centered perspective is a worthy and necessary endeavor in the quest for the ToE.
International Journal of Recent advances in Physics (IJRAP)ijrap
International Journal of Recent advances in Physics (IJRAP) is a peer-reviewed, open access journal, addresses the impacts and challenges of Physics. The journal documents practical and theoretical results which make a fundamental contribution for the development of Physics.
The Concept of Space and Time: An African Perspectiveijrap
Understanding the concept of space and time is critical, essential, and fundamental in searching for the all-encompassing theory or the theory of everything (ToE). Some physicists argue that time exists, while others posit that time is only a social or mental construct. The author presents an African thought system on space and time conception, focusing on the African (Bantu) view of space and time. The author argues that before the advent of the Western linear view of space and time, Africans had their own vision regarding these two concepts. Their conception of time appears to be holistic, highly philosophical, nonlinear, and thought-provoking. The author hopes that exploring these two concepts from an African perspective will provide a new and more in-depth insight into reality's nature. A scientific investigation of space and time from an African-centered perspective is a worthy and necessary endeavor in the quest for the ToE.
The majority of physicists take it for granted that the universe is made up of matter. In turn, matter is composed of atoms; atoms are made up of particles such as electrons, protons, neutrons, etc. Also, protons
and neutrons are composed of quarks, etc. Furthermore, that everything in nature is governed by the known laws of physics and chemistry. The author only partially shares this view. He argues that many phenomena in the universe may depend on rules or factors as yet incorporated by the physical sciences.
The last few years have led him to reflect on the many unsolved physics problems, such as the quest for the theory of everything (ToE), the arrow of time, the interpretation of quantum mechanics, the fine-tuned
universe, etc. to mention just a few. The author posits that a field carries information, performs various mathematical and computational operations, and behaves as an intelligent entity embedded with consciousness.
Call For Papers - International Journal of Recent advances in Physics (IJRAP)ijrap
International Journal of Recent advances in Physics (IJRAP) is a peer-reviewed, open access journal, addresses the impacts and challenges of Physics. The journal documents practical and theoretical results which make a fundamental contribution for the development of Physics.
Call For Papers - International Journal of Recent advances in Physics (IJRAP)ijrap
International Journal of Recent advances in Physics (IJRAP) is a peer-reviewed, open access journal, addresses the impacts and challenges of Physics. The journal documents practical and theoretical results which make a fundamental contribution for the development of Physics.
Call For Papers - International Journal of Recent advances in Physics (IJRAP)ijrap
International Journal of Recent advances in Physics (IJRAP) is a peer-reviewed, open access journal, addresses the impacts and challenges of Physics. The journal documents practical and theoretical results which make a fundamental contribution for the development of Physics.
Call For Papers - International Journal of Recent advances in Physics (IJRAP)ijrap
International Journal of Recent advances in Physics (IJRAP) is a peer-reviewed, open access journal, addresses the impacts and challenges of Physics. The journal documents practical and theoretical results which make a fundamental contribution for the development of Physics
The majority of physicists take it for granted that the universe is made up of matter. In turn, matter is
composed of atoms; atoms are made up of particles such as electrons, protons, neutrons, etc. Also, protons
and neutrons are composed of quarks, etc. Furthermore, that everything in nature is governed by the
known laws of physics and chemistry. The author only partially shares this view. He argues that many
phenomena in the universe may depend on rules or factors as yet incorporated by the physical sciences.
The last few years have led him to reflect on the many unsolved physics problems, such as the quest for the
theory of everything (ToE), the arrow of time, the interpretation of quantum mechanics, the fine-tuned
universe, etc. to mention just a few. The author posits that a field carries information, performs various
mathematical and computational operations, and behaves as an intelligent entity embedded with
consciousness.
Democratizing Fuzzing at Scale by Abhishek Aryaabh.arya
Presented at NUS: Fuzzing and Software Security Summer School 2024
This keynote talks about the democratization of fuzzing at scale, highlighting the collaboration between open source communities, academia, and industry to advance the field of fuzzing. It delves into the history of fuzzing, the development of scalable fuzzing platforms, and the empowerment of community-driven research. The talk will further discuss recent advancements leveraging AI/ML and offer insights into the future evolution of the fuzzing landscape.
About
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
• Remote control: Parallel or serial interface.
• Compatible with MAFI CCR system.
• Compatible with IDM8000 CCR.
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
• Easy in configuration using DIP switches.
Technical Specifications
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
Key Features
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Immunizing Image Classifiers Against Localized Adversary Attacksgerogepatton
This paper addresses the vulnerability of deep learning models, particularly convolutional neural networks
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adversary training.
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Courier management system project report.pdfKamal Acharya
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This document will discuss each of the underlying technologies to create and implement an e- commerce website.
SOME THEORETICAL ASPECTS OF HYDROGEN DIFFUSION IN BCC METALS AT LOW TEMPERATURES
1. International Journal of Recent advances in Physics (IJRAP) Vol.12, No.1/2, May 2023
DOI:10.14810/ijrap.2023.12202 13
SOME THEORETICAL ASPECTS OF HYDROGEN
DIFFUSION IN BCC METALS AT LOW
TEMPERATURES
Serhii Bobyr, Joakim Odqvist
KTH Royal Institute of Technology, Department of Materials Science and Engineering,
Brinellvägen 23, SE-100 44, Stockholm, Sweden
ABSTRACT
Purpose of the work is to discuss some theoretical aspects of the diffusion of hydrogen atoms in the crystal
lattice of BCC metals at low temperatures using the methods of statistical thermodynamics. The values of
the statistical model calculations of H diffusion coefficients in α-Fe, V, Ta, Nb, K are in good agreement
with the experimental data. The statistical model can also explain deviations from the Arrhenius equation
at temperatures 300-100 K in α-Fe, V, Nb and K. It was suggested that thermally activated fast tunnelling
transition of hydrogen atoms through the potential barrier at a temperature below 300 K provides an
almost free movement of H atoms in the α-Fe and V lattice at these temperatures. The results show that
quantum-statistical effects play a decisive role in the H diffusion in BCC metals at low temperatures. Using
the statistical model allows for the prediction of the diffusion coefficient for H in BCC metals at low
temperatures, where it’s necessary to consider quantum effects.
KEYWORDS
Hydrogen diffusion; BCC metals; Statistical model; Pre-exponential factor; Low temperature; Quantum-
statistical effects
1. INTRODUCTION
The diffusion of hydrogen, H, in metals has been the subject of intense study in recent decades.
This is due to the practical interest in using the metal-hydrogen system for several technological
applications [1, 2]. Diffusion of H in Fe and other metals is very important as it leads to
engineering problems associated with hydrogen embrittlement and degradation of high strength
steels, reactor materials, etc. [3–6].
Hydrogen atoms have an extremely high diffusion mobility in solid metals it is almost the same
as in liquids [7–9]. This high diffusion mobility is thought to be the result of a very low activation
energy due to the quantum nature of hydrogen [9].
In metal lattices, depending on the type of lattice and temperature, hydrogen can occupy two
types of interstitial sites: octahedral and tetrahedral [7–9, 12]. Even in a pure metal, transitions
between interstitials of different types are possible, which entails the ambiguity of the activation
energy of hydrogen diffusion [10–13].
Also, it should be considered that the equilibrium distance between the metal and hydrogen atoms
is much less than between metal atoms [12]. It should be noted that other factors may also lead to
deviations from the Arrhenius law, in particular, the possibility of diffusion jumps of different
lengths and the effect of crystal lattice defects [12, 13].
2. International Journal of Recent advances in Physics (IJRAP) Vol.12, No.1/2, May 2023
14
First principles calculations and classical approaches such as molecular mechanics have been
used to study hydrogen diffusion in the case of body-centred cubic, BCC, Fe in several papers
[14-21].
It is assumed that modern ab initio modelling will provide a good description of the diffusion
parameters in Fe-H systems. However, as far as we know, there is no systematic derivation of the
diffusion coefficients in which quantum-statistical effects are considered in a wide temperature
range [13, 22]. The providing of such investigations is important for understanding the possible
mechanisms of hydrogen diffusion in metals.
The purpose of this work is to discuss some theoretical aspects of the diffusion of hydrogen
atoms in the crystal lattice of BCC metals at low temperatures using the methods of statistical
thermodynamics.
2. THEORETICAL METHOD
In the classical limit and using the random-walk model of interstitial diffusion in a BCC lattice,
D0 in the Arrhenius expression for the diffusion parameter D = D0exp (-Ea/RT) can be
represented as [21]:
3
2
1
0 3
1
6
N
j j
N
j j
n
D
(1)
where, n is a geometrical factor for the number of equivalent jump paths, Δ is the jump length,
and νj and νj
+
are the real normal mode frequencies at the initial state and the transition state,
respectively.
Close to the room temperature it is necessary to account for quantum correlations to the diffusion
barrier i.e. the discreteness of H vibrational modes in the metal lattice [21].
Kehr presented another description of H diffusion, assumed, that the lattice vibrations are the
same minimum energy and saddle-point configurations. For BCC metals at room temperature the
limit of hνH >> kBT, where νH is the frequency of the localized H vibrational modes. In this limit
the pre-exponential factor can be represented as [Ref. 21]:
2
0 exp
6
B
B
k T
n E ZPE
D
h k T
(2)
Where ΔE is the energy difference between the saddle point and minimum energy configuration
on the potential energy surface, ΔZPE is the difference in zero-point energies. Thus, the
exponential term (ΔE+ΔZPE) in Eq. 2 is a ZPE-corrected diffusion barrier. Moreover, we can see
that the pre-exponential factor in Eq. 2 is temperature dependent to the first degree.
In [14] it is proposed to use statistical model expressions for the pre-exponential coefficient. This
approach, based on the first principles of statistical thermodynamics, makes it possible to
adequately consider the statistical distribution of impurity atoms according to their energy.
In this case the diffusion coefficient for impurity atoms in metals is equal to [14]:
3. International Journal of Recent advances in Physics (IJRAP) Vol.12, No.1/2, May 2023
15
0
2 2
-W /kT
3
2
e
mk T d
D
h
, W0 = U – μ0. (3)
U is the potential barrier height of the diffusion process,
μ0 is the chemical potential of impurity atoms,
and pre-exponential factor after transformations is [14]:
N
h
d
T
k
m
N
D a
e
3
2
2
2
0
2
, (4)
where d – distance between two nearest identical position sites of impurity particles;
N is the Avogadro number (mol-1
);
k (kB) – Boltzmann constant;
h – Planck constant;
Ne is the atomic number of the diffusive impurity atoms (1 for H);
ma is the atomic mass unit (H).
ρ is the metal density.
Expression (4) of the developed statistical model significantly differs from the expressions used
in simple molecular dynamics [14 - 21]. The interplanar distance d enters this expression to the
first degree. But this formula assumes the dependence of D0 on the square of the atomic number
of the diffusing element and the square of the temperature.
If we compare expression (4) with the classical equation for the diffusion coefficient [11]:
D = KΔ2
ν, (5)
where Δ is the jump length of an atom during diffusion,
ν is the jump frequency, K – constant (usually 1/6),
and in Eq. (5) we put d = Δ, then for the jump frequency we can express:
0
2 2 2
-W /kT
3
2
e
e a
N m k T
KN h
. (6)
Eqs. (4) and (6) can be used in molecular dynamics for calculation of diffusion parameters.
In the developed statistical model (SM) pre-exponential factor (D0) of hydrogen can be calculate
by [14]:
2 2
0 0.114 /
D T m s
, (7)
where Δ is in meters, ρ is in kg/m3
.
4. International Journal of Recent advances in Physics (IJRAP) Vol.12, No.1/2, May 2023
16
3. RESULTS
3.1. The Hydrogen Diffusion in A-Iron
Fig. 1 shows the two types of interstitial sites in the BCC lattice, octahedral O (a) and tetrahedral
T (b). By using the experimental lattice parameter of BCC Fe the “radius” of the T-sites and O-
sites were found to be 0.36 Ǻ and 0.19 Ǻ respectively. H has a covalent radius of 0.37 Ǻ, and it
has been suggested, that H fit better in T-sites, than in O-sites [22]. This simple assumption has
been confirmed by DFT calculations [13, 21].
Let’s consider the movement of a hydrogen atom between tetrahedral sites; the most probable
trajectory for the migration of a hydrogen atom from one T-site into the nearest-neighbor T-site is
via a S-site how (Fig. 1, c). In [21] it was found that H does not utilize a straight – line trajectory,
but rather hops from one T-site to a nearby T-site by a curved path distorted towards an O-site.
The S-site is set like a saddle point along the minimum energy path (MEP) for direct hopping of a
H atom between two neighboring T-site [13]. The length of a single jump of a H atom from S-site
is more than one fourth of a lattice parameter. But at temperatures below 300 K, the migration of
a hydrogen atom from one T-site into the other T-site via an O-site becomes possible due to
changed potential barrier [13].
Fig. 1. Positions of O-sites (a) and T-sites (b) of the BCC lattice.
The S-sites are the saddle point along the MEP [13, 21] for direct hopping of a H atom between
two neighboring T-sites (paths 1-2 and 3-4 respectively) (c).
In several experimental studies, the Ea values were practically estimated by the slope of the lnD
versus 1/T plot between 290 K and 1000 K [23-25]. Typical Ea values range from 0.035 eV to
0.142 eV and D0 from 3.35×10-8
m2
s-1
to 2.2×10-7
m2
s-1
for H diffusion in BCC Fe, as compiled
from ten research groups for temperatures as low as 233 K [23].
It was shown in [13] that the diffusion of hydrogen in α-iron deviates from the Arrhenius
equation, which is an additional indication of the dependence of diffusion coefficients on
5. International Journal of Recent advances in Physics (IJRAP) Vol.12, No.1/2, May 2023
17
temperature. In [13] the centroid path-integral molecular dynamics method (CMD) was used to
change free energy profiles for H migration at various temperatures [see Fig. 5 in Ref. 13].
According to these data, at temperatures below 300 K, hydrogen diffusion can occur both through
S-sites and O-sites with similar potential barrier values. We used this important theoretical result
in the present work.
The results of the molecular dynamics and SM calculations are compared with the experimental
data found in [11, 13, 24, 25], see Figure 2, Table 1.
We can see that the present SM approach is valid for predicting the values of the diffusion
coefficients below the temperature of 300 K. For the calculations we used the potential by
Kimizuka, Mori and Ogata [13]. Estimated D values show a good agreement with classical MD
results, see Fig 2.
SM calculations with temperature-dependent potentials (TDP) by Kimizuka et al have given a
plausible description of H diffusion in Fe below 300 K and show a good agreement for the
temperature 500 K. This result shows the necessity of considering the increase of the potential
barrier at high temperatures.
Table 1. Calculated values for an activation energy (Ea) and a pre-exponential factor (D0) and of H
diffusivity in α-Fe for the temperatures below 300 K, together with experimental values.
Diffusion
parameters
Ea
(eV)
D0×10−8
(m2
/s)
D×10−8
(m2
/s)
T= 293 K
D×10−8
(m2
/s)
T= 250 K
D×10−8
(m2
/s)
T= 100 K
Calc. (MD)
(Ref. 13)
0.037 3.23 0.80 0.62 0.053
Calc. (CMD)
(Ref. 13)
TDP**
0.075*
3.23 0.83 0.70 0.45
Calc. (SM) TDP** 3.68* 0.31 0.20 0.05
Calc. (SM) 0.0
0.03*
2.61* 0.89 0.65 0.105
Expt. (Ref. 11) 0.044 4.15 0.1-1.0 0.06 -
Expt. (Ref. 24)
(290 -1040 K)
0.040 4.20 0.87 - -
Expt. (Ref. 25)
(290 -1040 K)
0.035 3.35 0.81 - -
*
At 500 K. ** temperature-dependent potentials by Kimizuka et al.
6. International Journal of Recent advances in Physics (IJRAP) Vol.12, No.1/2, May 2023
18
Fig 2. Diffusion coefficients of H in α-Fe in the temperature range 100-500 K.
The solid triangles and open squares represent the CMD and classical MD results for the potential
used by Kimizuka, Mori and Ogata, respectively [13]. The crosses represent the classical MD
results for the potential of Wen et al. [13]. The stars represent the SM results for a potential of
0.037 eV. The oval symbols represent the SM results for temperature-dependent potentials (TDP)
by Kimizuka, Mori and Ogata [13]. Diamonds represent the SM results with a potential equal
zero. Black and colored circles show experimental results on hydrogen diffusion from [11] and
[13] respectively.
We also performed calculations using Eq. (7) with zero potential. In doing so, we account for the
fact, as was done in [13], that at low temperatures H migration along not only the S-sites but also
O-sites becomes possible. For comparison we estimated D values based on SM approximation by
Eq. (7) in the temperature range 100 – 293 K; the obtained values of D show a good agreement
with experimental and CMD calculated data, see Table 1. At a temperature of 500 K the
calculated value is more than the experimental values, which also indicates the necessity of
considering the increase in the potential barrier at this temperature. As shown in our calculations,
for full agreement with experimental values the calculated value for an activation energy Ea must
be 0.0022 eV at 293 K and 0.03 eV at 500 K. Last value is close to the potential of Kimizuka et
al. and corresponds to their approach with temperature-dependent potentials [13].
Our approach based on first principles of statistical thermodynamics makes it possible to
coherently describe the temperature dependence of the diffusion coefficient H in α-Fe for
temperatures below 500 K. However, experimental data on the diffusion of hydrogen in α-Fe at
low temperatures near 100 K are clearly insufficient. Further experimental studies of this process
followed by a theoretical description are therefore of high interest.
3.2. Hydrogen Diffusion in BCC Low Temperatures
In [27] it was found that H in BCC metals, V, Nb and Ta, had a preference to occupy T-sites, but
O-sites in FCC-Pd, which could be correlated qualitatively with protonic electrostatic potential in
pure bulk metals.
7. International Journal of Recent advances in Physics (IJRAP) Vol.12, No.1/2, May 2023
19
Despite a significant number of experimental studies of hydrogen diffusion in metals (see e.g.
[26–35]), there are very few reliable data, especially on the hydrogen distribution at temperatures
below room temperature. Experimental data on quantum diffusion of hydrogen have been
obtained for Nb and Ta [28, 29] and in Na and K for deuterium [30, 31].
Theory of hydrogen diffusion in metals has been developed by various models, namely: the small
polaron model of Flynn and Stoneham [34, 36, 37], semiclassical transition state theory [37],
Feynman path-integral molecular dynamics model [13, 38], density functional theory (DFT) [35,
38] centroid and ring polymer molecular dynamics, [39], statistical thermodynamics [40, 41], and
others. In quantum theories of diffusion, the interpretation of bends on the D(T) dependences in
Ta and Nb [34, 35] was successful. Ab initio DFT calculations of diffusion activation energies for
both migration mechanisms were performed, which showed excellent agreement with
experimental data for H in Nb and Ta [40].
Experimental results on the temperature dependencies of the diffusion coefficients D(T) for
deuterium in K were presented in [26]. At temperatures from 250 to 120 K, the mechanism of
above-barrier motions of atoms dominates in the process of mass transfer, while below 120 K,
this is the tunneling mechanism.
In work [41] was presented the statistical model of H diffusion in FCC metals at a high
temperature (900 – 2000 K). This thermodynamics model makes it possible to explain the high
values of the pre-exponential factor of H diffusion coefficients (~10–7
m2
s–1
− 10–6
m2
s–1
) in FCC
metals (γ-Fe, Ni, Pd, Al, Ag) at high temperature due to the coefficient T2
in the diffusion
equations.
In the present work we propose and develop a statistical model for describing of H diffusion in
BCC metals at low temperatures. The values of a pre-exponential factor for Nb, Ta, V were found
from first principles, see Eq. 7.
The calculated activation energy, pre-exponential factor and experimental values from the [11]
and [26] are presented in Table 2 and in the Fig. 3.
Table 2. Calculated values for an activation energy (Ea), pre-exponential factor (D0) and H diffusivity D in
the considered metals at the temperature below 300 K, together with data from [11] and [26].
Metals K (De)* Ta Nb V
Temperature K 100 200 200 300 200 300 200 300
Calc. (Ref. 11)
Ea (eV)
0.0024 0.16 0.04 0.14 0.068 0.106 0.045 0.045
Calc. (Ref. 11)
D0 10-8
(m2
s–1
)
3.28
×10-8
1.24
×10-4
0.02 4.4 0.9 5.0 0.31 0.31
Expt. (Ref. 11)
D 10-8
(m2
/s)
2.0×
10-8
1.0×
10-5
0.002 0.02 0.17 0.8 1.7 4.0
Calc. (SM)
D0 10-8
(m2
/s)
0.31
×10-4
1.25
×10-4
0.005 4.0 2.2 5.0 1,76 4.37
Calc. (SM)
Ea (eV)
0.135 0.016 0.077 0.044 0.0023
*Deuterium diffusion in K at the data in [26].
8. International Journal of Recent advances in Physics (IJRAP) Vol.12, No.1/2, May 2023
20
The SM calculations results show a good agreement with experimental data, especially in case of
H diffusion in Nb and V (Fig. 3). The statistical model allows for the prediction of the diffusion
coefficients for H in Nb and V at low temperatures. For Ta, as in the classical description, we
had to use two diffusion SM equations with different activation energies, which indicates a
change in the diffusion parameters of H in Ta near the Debye temperature.
Fig. 3. Temperature dependences of diffusion coefficient for H in Nb, Ta, V and deuterium De in K.
Circles demonstrate experimental results on hydrogen diffusion [11] and deuterium diffusion in
K [26]. The star symbols and lines represent the SM results.
The calculated values of the SM-preexponential factor (D0) for H diffusion in Nb, Ta, V at the
high temperature is in good agreement with the known data (Table 3). But the calculated values
of an activation energy are significantly different from those accepted in [11] values, especially in
case of H diffusion in V. This value 0.0023 eV is almost equal to the calculated value of an
activation energy of deuterium diffusion in K at a temperature below 100 K - 0.0024 eV. Such
low activation energy values indicate quantum mechanism of deuterium diffusion in K and H
diffusion in V.
4. DISCUSSION
As was found in [26] for the systems Nb–H, Ta–H, and K–D, the bend temperatures Tb are 250,
229, and 120 K and Debye temperatures 260, 225, and 100 K, respectively.
Using the statistical model, we will discuss this issue of relating the quantum mechanical motion
of hydrogen in metals to the Debye temperature of these metals. Let's present the calculation data
of Table 2 in activation energy Ea of H diffusion in BCC metals versus – temperature diagram
indicating the Debye temperature of these metals and scale of energy Eh=kBT. This energy makes
it possible to estimate the average energy of a hydrogen atom at a certain temperature (Fig. 4).
From the above data, there is an inverse relationship between the activation energy Ea of H in
BCC metals and the Debye temperature of these metals. The higher the Debye temperature for a
metal, the lower the energy barrier that hydrogen needs to overcome at a temperature of 300 K.
9. International Journal of Recent advances in Physics (IJRAP) Vol.12, No.1/2, May 2023
21
Similar results were obtained earlier in a different form in [26]. The mechanism of this
connection requires a separate theoretical study.
Fig. 4. Correlation of diffusion activation energy Ea of Н in BCC metals at the 300 K with energy Eh and
the Debye temperature points of these metals.
The black squares and diamonds symbols represent the SM results and the classical results for
activation energy respectively and the Debye temperature points of BCC metals on the
temperature scale. For α-Fe, potential by Kimizuka et al. was used.
When using the Arrhenius equation for diffusion calculations, the calculated values of the
activation energy of hydrogen are greater than the values of the statistical model, i.e. these
parameters are dependent on the experimental data processing model. The true values of the
energy barrier for hydrogen diffusion can be calculated from first principles [17, 18, 21, 37, 38].
The transition from the theoretical values of the energy barrier to the model values of the
activation energy is associated with considering additional influencing factors, primarily physical
parameters: - zero-point energy [21], decay of local deformation near the hydrogen atom [40],
temperature-dependent potentials [13], etc. The presentation of the results is greatly influenced
by the parameters of the diffusion models used for calculations - the Arrhenius equation itself
[10, 11], the Einstein formula of molecular dynamics [9, 20], the Kerr diffusion equation [21], the
operator expression of quantum statistical mechanics [40], and T2
-diffusion equation of statistical
thermodynamics [41].
In view of the foregoing, let us analyze the data presented in Fig. 4. At a temperature of 300 K,
Eh-energy has a value of ~0.026 eV, which is very close to the apparent values of the diffusion
activation energy of H determined from the Arrhenius equation in iron (0.037 eV) and vanadium
(0.044 eV). The ab initio determined value of the energy barrier at this temperature is U300 ≈ 0.05
eV for iron, according to the data of the work [13]. Thus, at a given ratio of Eh and U300, there are
all conditions for a thermally activated fast tunneling transition of hydrogen atoms through the
potential barrier of iron atoms at this temperature [13, 40, 42].
10. International Journal of Recent advances in Physics (IJRAP) Vol.12, No.1/2, May 2023
22
In the statistical model of diffusion, this situation becomes even more obvious, since the
calculated value is Ea = 0.0022 eV, which indicates an almost free movement of H atoms in the
iron lattice at this temperature. This can explain the very low solubility of H in α-Fe and the
extremely high diffusion mobility.
A similar situation occurs for the diffusion of hydrogen in vanadium, for which Ea = 0.0023 eV.
Therefore, we assume that the patterns of hydrogen diffusion in vanadium manifest themselves in
the same way as in iron. However, this assumption requires additional both experimental and
theoretical studies for its verification.
Other studied BCC metals have at room temperature a significant potential barrier for H
diffusion, which indicates its diffusion over the barrier.
As the diffusion temperature rises to 500 K, i.e. above the Debye temperature for iron in the
statistical model, it is necessary to use the energy value Ea = 0.03 eV is close to the CMD model
value (0.037 eV). At the same time, the value of the energy barrier is calculated from first
principles U500 ≈ 0.075 eV [13]. Considering the difference in zero-point energy (-0.046 eV) [21],
the ZPE-corrected diffusion barrier becomes equal to 0.029 eV corresponding to the value Ea in
the statistical model.
It can be assumed that above the Debye temperature the H vibrational modes become more than
the maximal frequency of Fe lattice vibrations; this decoupling and the increasing interaction of
H atoms with phonons leads to an increase in the potential barrier of H diffusion.
Other BCC metals – Nb, Ta and K also show an increasing potential of H diffusion above the
Debye temperature. Therefore, the question of transition from tunneling to over-barrier H
diffusion at a temperature close to the Debye temperature remains open for further research.
When the diffusion temperature drops below 300 K, the energy decreases, but the magnitude of
the potential barrier decreases accordingly, supporting the process of quantum diffusion of H and
an almost free movement of H atoms in the iron lattice. This indicates, different from [26], that
the quantum effects strongly control the mechanism of local diffusion of H in α-Fe at low
temperature [13]. We can assume the same patterns for diffusion of V and K at temperatures
below the Debye temperature.
For Nb and Ta, quantum-statistical effects manifest themselves in a change in the diffusion
mechanism near the Debye temperature in the presence of a significant energy barrier for
hydrogen diffusion behind the over barrier mechanism [34, 40].
5. CONCLUSIONS
It was shown that the most probable trajectory for the migration of a hydrogen atom from one T-
site into the nearest-neighbor T-site going on across a S-site is by a curved path distorted toward
the O-site. The length of a single jump of an H atom during S-site is more than one fourth of a
lattice parameter. But at temperatures below 300 K it is also possible with the migration of a
hydrogen atom from one T-site into the other T-site across an O-site due to temperature-
dependent potentials and changing (decreasing) diffusion path for H.
It was proposed to use the statistical model for a more accurate calculation of the hydrogen
diffusion in BCC metals at low temperatures. The calculations performed are compared with the
known experimental data on the diffusion of hydrogen atoms in α-Fe with a good agreement
between the results.
11. International Journal of Recent advances in Physics (IJRAP) Vol.12, No.1/2, May 2023
23
It was suggested using the SM model that thermally activated fast tunneling transition of
hydrogen atoms through the potential barrier at temperatures below 300 K provides an almost
free movement of H atoms in the iron lattice at these temperatures. We may also assume that the
patterns of hydrogen diffusion in vanadium manifest themselves in the same way as in iron.
Our approach makes it possible to coherently describe the temperature dependence of the
diffusion coefficient H in α-Fe at temperatures below 300 K. However, experimental data on the
diffusion of hydrogen in α-Fe at low temperatures are clearly insufficient. Further experimental
studies of this process followed by a theoretical description are expedient.
The results show that quantum-statistical effects play a decisive role in the H diffusion in BCC
metals at low temperatures. Using the statistical model allows for the prediction of the diffusion
coefficient for H in BCC metals at low temperatures, where it’s necessary to consider quantum
effects. Thus, the values of the SM pre-exponential factor of H diffusion in BCC metals are in
good agreement with the experimental data at room temperature.
Undoubtedly, this model does not consider many specific factors affecting the diffusion
parameters of atoms in a metal, such as the interaction of impurity atoms, the presence of
vacancies, influence of the Debye temperature, quantum tunneling at a cryogenic temperature,
etc. Further development of this model and quantum theories of diffusion will allow for
consideration of the influence of these factors.
ACKNOWLEDGEMENTS
This project was funded by the Swedish Foundation for Strategic Research (SSF), contract
UKR22-0070. We want to thank profs. Annika Borgenstam and Liubov Belova for supporting
this project and prof. Andrei Ruban for fruitful discussions and critical remarks.
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AUTHORS
DSc Serhii Bobyr is a Leading Researcher in Metal Physics and Materials science with
rich on hands experience in academic and commercial projects participation and
management with several developments patented and implemented in industrial
enterprises.
From 15.09.2022 is a Leading Researcher at КТН - Royal Institute of Technology,
Stockholm, Sweden
2016 – 2022 - Leading Researcher at Z.I. Nekrasov Iron & Steel Institute of the
National Academy of Science of Ukraine (ISI NASU).
2016 -Winner of the prize of the G.V. Kurdyumov name of the National Academy of Sciences of Ukraine.
2011 - DSc. Degree, 2005 - 2016 - Senior Researcher at ISI NASU.
Dr. Joakim Odqvist works as a professor at KTH Royal Institute of Technology,
Stockholm, Sweden. His research interests are phase transformations in metallic alloys
and computational materials design. In 2004 he was awarded a PhD degree in Materials
Science from KTH.