The field of nonlinear optics became practically a reality after the invention of laser. High performance electro-optic switching elements for telecommunication and optical information processing are based on materials with high nonlinear optical (NLO) properties. Single crystals of nonlinear optical material Llysine sulphate (LLS) are grown by slow evaporation technique. The crystal structure and lattice parameters are determined for the grown crystal by single X-ray diffraction studies. The wide transparency range of the crystals in the visible region of the electromagnetic spectrum is identified by the UV-Vis-NIR technique. The mechanical property of the grown crystal is determined by Vicker’s microhardness test. It is observed from the microhardness studies of the grown crystals that the hardness increases with increase in load. Meyer’s index n is calculated which proves that the material belongs to soft material category. The dielectric constant and dielectric loss are calculated by varying the frequencies at room temperature. The emission of green light on passing the Nd: YAG laser confirms the second harmonic generation (SHG) property of the crystals .The SHG efficiency of the crystals are found to be better than that of Potassium Di hydrogen Phosphate (KDP)
This is a power point presentation of project work on preparing Zinc oxide thin films by using SILAR technique and CBD technique and studying its characteristics.
Synthesis and characterization of pure zinc oxide nanoparticles and nickel do...eSAT Journals
Abstract In this paper, Zinc oxide nanoparticles are synthesized by simple wet chemical precipitation method. Zinc nitrate and sodium hydroxide are used as the starting materials.Zinc oxide nanoparticles are formed at a very low temperature of the order of 800C. Nickel doped zinc oxide nanoparticles are synthesized in two steps. In first step precipitate is obtained by reduction of mixture of zinc nitrate, ferric nitrate and starch by sodium hydroxide solution while in second step the given precipitate is thermally decomposed at high temperature of the order of 4000C. The crystallinity of the synthesized nanoparticles is then confirmed by X ray diffraction spectroscopy (XRD).The elemental composition of the powder is detected by Energy Dispersive X ray spectroscopy (EDAX). The morphology of the powder is investigated by Scanning Electron Microscopy (SEM). Magnetic characterization of nickel doped zinc oxide nanoparticles is done by Squid Magnetometer. Low temperature magnetization behavior revealed ferromagnetic behavior of sample. Key Words: Zinc oxide nanoparticles, Nickel doped ZnO, Antibacterial activity, Squid magnetometer, SEM
This is a power point presentation of project work on preparing Zinc oxide thin films by using SILAR technique and CBD technique and studying its characteristics.
Synthesis and characterization of pure zinc oxide nanoparticles and nickel do...eSAT Journals
Abstract In this paper, Zinc oxide nanoparticles are synthesized by simple wet chemical precipitation method. Zinc nitrate and sodium hydroxide are used as the starting materials.Zinc oxide nanoparticles are formed at a very low temperature of the order of 800C. Nickel doped zinc oxide nanoparticles are synthesized in two steps. In first step precipitate is obtained by reduction of mixture of zinc nitrate, ferric nitrate and starch by sodium hydroxide solution while in second step the given precipitate is thermally decomposed at high temperature of the order of 4000C. The crystallinity of the synthesized nanoparticles is then confirmed by X ray diffraction spectroscopy (XRD).The elemental composition of the powder is detected by Energy Dispersive X ray spectroscopy (EDAX). The morphology of the powder is investigated by Scanning Electron Microscopy (SEM). Magnetic characterization of nickel doped zinc oxide nanoparticles is done by Squid Magnetometer. Low temperature magnetization behavior revealed ferromagnetic behavior of sample. Key Words: Zinc oxide nanoparticles, Nickel doped ZnO, Antibacterial activity, Squid magnetometer, SEM
Synthesis and characterization of zno thin films deposited by chemical bath t...eSAT Journals
Abstract ZnO thin films have been deposited on silica glass substrate using the chemical bath deposition technique. The precursors used were zinc chloride and aqueous ammonia. The solution was stirred continuously with the help of a magnetic stirrer at a bath temperature of 70 oC and a deposition time of 70 minutes. The elemental composition and the surface morphology were studied using energy dispersive and scanning electron microscopy. The band gap was 2.72, 2.66, 2.60 eV for as-deposited, annealed at 200 oC and 300 oC respectively. There was a red shift in the band gap energy as the annealing temperature was increased. This might be due to an improvement in the crystallinity of the ZnO thin films. Index Terms: Zinc oxide, chemical bath, band gap, annealing
Dye Sensitized Solar Cells Incorporated with Tio2 -ZnO NanoparticlesScientific Review SR
We demonstrated an improvement in efficiency of Dye sensitized solar cells (DSSCs) decorated with
zinc oxide (ZnO) nanoparticles (NPs) through successive ionic layer adsorption and reaction (SILAR). A series of
ZnO with different SILAR cycles were synthesized on TiO
2 that has been pre-grown on fluorine tin oxide (FTO)
glass slides. The performance of DSSCs containing ZnO NPs was significantly affected. The photovoltaic (PV)
performance decreased with increasing number of SILAR cycles from two SILAR cycles to four SILAR cycles,
the best performance was achieved using the anodes prepared with two SILAR cycles. The best cell shows a
conversion efficiency (η) of 0.0064 %. The cell exhibits ~ 2.13 improvement over the performance (0.0030 %) of
bare FTO-based device. The related PV performance enhancement mechanism is discussed
Synthesis, Characterization of ZnS nanoparticles by Coprecipitation method us...IOSR Journals
ZnS nanoparticles are prepared by coprecipitation method using various capping agents like PVP (polyvinylpyrrolidone), PVA (polyvinylalcohol) and PEG-4000 (polyethyleneglycol). These are characterized by UV-Visible spectra, X-ray diffraction (XRD) studies, Fourier Transform Infra-red spectra (FTIR) and Transmission electron microscopy (TEM). UV-Visible absorption spectra are used to find the optical band gap and the values obtained have been found to be in the range of 3.80-4.00eV. The particle size of nanoparticles calculated from XRD pattern has been in the range of 2-4 nm. It is also observed that the particle size of nanoparticle is affected by the nature of capping agent. Photo catalytic degradation of xylenol orange (XO) by the nanoparticles shows that these act as photo catalysts under sunlight irradiation. The XO dye was degraded more than 87.24, 83.42 and 73.05% in the presence of PEG-4000, PVA and PVP capped ZnS nanoparticles in 120, 150 and 180 min. respectively. The kinetics of catalyzed by synthesized ZnS nanoparticles with XO dye follows pseudo-first order kinetics with reasonable apparent rate constants.
OPTICAL BEHAVIOUR OF SYNTHESIZED ZNO NANOTABLETS AND ITS TRANSFORMED NANORODS...antjjournal
We are reporting the preparation of ZnO nanotablets at relatively low temperature (1500C) using zinc acetate [Zn(Ac)2], NaOH, cetyltrimethylammonium bromide (CTAB) by solvothermal method. By adjusting
the molar ratio of the reactants we obtained nanorods and we also obtained the variation of the dimension
of the nanorods using hydrazine hydrate as capping reagent. The prepared samples were morphologically
recognized as well crystallized. The average diameter of the ZnO nanotablets were ranging from 500 to 600 nm and the average thickness of the nanotablets were ranging from 85 to 90 nm. The length of ZnO nanorods were ranging from 300 to several micrometers and breadth of the ZnO nanorods were ranging from 80 to 160 nm. The optical properties of the prepared materials have also been studied with the exhibition of its interesting behavior.
Nanoparticles are solid colloidal particles ranging in size from 10 to 1000 nm.
Nanoparticles are made of a macromolecular material which can be of synthetic or natural origin.
Synthesis and characterization of ZnO nanoparticles via aqueous solution, sol...iosrjce
ZnO nanoparticles were synthesized by aqueous solution method, sol-gel method and hydrothermal
method.The synthesized particles were characterized by XRD ,SEM ,EDX and UV .The X-ray diffraction studies
reveals that the synthesized ZnO nanoparticles have wurtzite structure and the particle size varies from 13 to 18
nm. Scanning Electron Microscopic investigation reveals that the surface morphology of ZnO nanoparticle is
spherical in hydrothermal process and varies to flower like arrangement in aqueous solution and sol-gel
process. The UV-Visible spectrum of the nanoparticles shows a blue shift compared to that of the bulk sample.
Different types of methods can be used for the preparation of Magnetic Nanoparticles, their advantages and disadvantages and applications of the materials in various fields are given in the presentation
Improvement Structural and Optical Properties of ZnO/ PVA Nanocompositesiosrjce
IOSR Journal of Applied Physics (IOSR-JAP) is a double blind peer reviewed International Journal that provides rapid publication (within a month) of articles in all areas of physics and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in applied physics. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
Solar cell absorber Kesterite- type Cu2ZnSnS4 (CZTS) thin films have been prepared by Chemical Bath Deposition (CBD). UV–vis absorption spectra measurement indicated that the band gap of as-synthesized CZTS was about1.68 eV, which was near the optimum value for photovoltaic solar conversion in a single-band-gap device. The polycrystalline CZTS thin films with kieserite crystal structure have been obtained by XRD. The average of crystalline size of CZTS is 27 nm
Synthesis and characterization of zno thin films deposited by chemical bath t...eSAT Journals
Abstract ZnO thin films have been deposited on silica glass substrate using the chemical bath deposition technique. The precursors used were zinc chloride and aqueous ammonia. The solution was stirred continuously with the help of a magnetic stirrer at a bath temperature of 70 oC and a deposition time of 70 minutes. The elemental composition and the surface morphology were studied using energy dispersive and scanning electron microscopy. The band gap was 2.72, 2.66, 2.60 eV for as-deposited, annealed at 200 oC and 300 oC respectively. There was a red shift in the band gap energy as the annealing temperature was increased. This might be due to an improvement in the crystallinity of the ZnO thin films. Index Terms: Zinc oxide, chemical bath, band gap, annealing
Dye Sensitized Solar Cells Incorporated with Tio2 -ZnO NanoparticlesScientific Review SR
We demonstrated an improvement in efficiency of Dye sensitized solar cells (DSSCs) decorated with
zinc oxide (ZnO) nanoparticles (NPs) through successive ionic layer adsorption and reaction (SILAR). A series of
ZnO with different SILAR cycles were synthesized on TiO
2 that has been pre-grown on fluorine tin oxide (FTO)
glass slides. The performance of DSSCs containing ZnO NPs was significantly affected. The photovoltaic (PV)
performance decreased with increasing number of SILAR cycles from two SILAR cycles to four SILAR cycles,
the best performance was achieved using the anodes prepared with two SILAR cycles. The best cell shows a
conversion efficiency (η) of 0.0064 %. The cell exhibits ~ 2.13 improvement over the performance (0.0030 %) of
bare FTO-based device. The related PV performance enhancement mechanism is discussed
Synthesis, Characterization of ZnS nanoparticles by Coprecipitation method us...IOSR Journals
ZnS nanoparticles are prepared by coprecipitation method using various capping agents like PVP (polyvinylpyrrolidone), PVA (polyvinylalcohol) and PEG-4000 (polyethyleneglycol). These are characterized by UV-Visible spectra, X-ray diffraction (XRD) studies, Fourier Transform Infra-red spectra (FTIR) and Transmission electron microscopy (TEM). UV-Visible absorption spectra are used to find the optical band gap and the values obtained have been found to be in the range of 3.80-4.00eV. The particle size of nanoparticles calculated from XRD pattern has been in the range of 2-4 nm. It is also observed that the particle size of nanoparticle is affected by the nature of capping agent. Photo catalytic degradation of xylenol orange (XO) by the nanoparticles shows that these act as photo catalysts under sunlight irradiation. The XO dye was degraded more than 87.24, 83.42 and 73.05% in the presence of PEG-4000, PVA and PVP capped ZnS nanoparticles in 120, 150 and 180 min. respectively. The kinetics of catalyzed by synthesized ZnS nanoparticles with XO dye follows pseudo-first order kinetics with reasonable apparent rate constants.
OPTICAL BEHAVIOUR OF SYNTHESIZED ZNO NANOTABLETS AND ITS TRANSFORMED NANORODS...antjjournal
We are reporting the preparation of ZnO nanotablets at relatively low temperature (1500C) using zinc acetate [Zn(Ac)2], NaOH, cetyltrimethylammonium bromide (CTAB) by solvothermal method. By adjusting
the molar ratio of the reactants we obtained nanorods and we also obtained the variation of the dimension
of the nanorods using hydrazine hydrate as capping reagent. The prepared samples were morphologically
recognized as well crystallized. The average diameter of the ZnO nanotablets were ranging from 500 to 600 nm and the average thickness of the nanotablets were ranging from 85 to 90 nm. The length of ZnO nanorods were ranging from 300 to several micrometers and breadth of the ZnO nanorods were ranging from 80 to 160 nm. The optical properties of the prepared materials have also been studied with the exhibition of its interesting behavior.
Nanoparticles are solid colloidal particles ranging in size from 10 to 1000 nm.
Nanoparticles are made of a macromolecular material which can be of synthetic or natural origin.
Synthesis and characterization of ZnO nanoparticles via aqueous solution, sol...iosrjce
ZnO nanoparticles were synthesized by aqueous solution method, sol-gel method and hydrothermal
method.The synthesized particles were characterized by XRD ,SEM ,EDX and UV .The X-ray diffraction studies
reveals that the synthesized ZnO nanoparticles have wurtzite structure and the particle size varies from 13 to 18
nm. Scanning Electron Microscopic investigation reveals that the surface morphology of ZnO nanoparticle is
spherical in hydrothermal process and varies to flower like arrangement in aqueous solution and sol-gel
process. The UV-Visible spectrum of the nanoparticles shows a blue shift compared to that of the bulk sample.
Different types of methods can be used for the preparation of Magnetic Nanoparticles, their advantages and disadvantages and applications of the materials in various fields are given in the presentation
Improvement Structural and Optical Properties of ZnO/ PVA Nanocompositesiosrjce
IOSR Journal of Applied Physics (IOSR-JAP) is a double blind peer reviewed International Journal that provides rapid publication (within a month) of articles in all areas of physics and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in applied physics. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
Solar cell absorber Kesterite- type Cu2ZnSnS4 (CZTS) thin films have been prepared by Chemical Bath Deposition (CBD). UV–vis absorption spectra measurement indicated that the band gap of as-synthesized CZTS was about1.68 eV, which was near the optimum value for photovoltaic solar conversion in a single-band-gap device. The polycrystalline CZTS thin films with kieserite crystal structure have been obtained by XRD. The average of crystalline size of CZTS is 27 nm
Growth and Analysis of Urea Thiourea Sodium Sulphate CrystalIOSR Journals
Urea Thiourea Sodium sulphate (UTNS) crystal have been grown from aqueous solution by slow
evaporation technique at room temperature. The crystal structure was confirmed by powder XRD technique and
it reveals that UTNS crystal belongs to orthorhombic system. Microstructure and compositions of the grown
single crystal UTNS was carried out by SEM with EDS. The molecular structures present in the crystal were
identified by recording the FTIR spectrum. Optical property was established by UV-Visible spectrum and the
mechanical strength of the grown crystal was estimated by the Vicker’s microhardness test.
Study of Optical Property of Gel Grown Mercuric Iodate CrystalsIOSR Journals
Mercuric Iodate Crystals were grown by a simple gel technique using diffusion method. The optimum growth conditions were established for the growth of these crystals by changing various parameters such as pH of the gel solution, gel concentration, gel setting time, concentrations of reactants etc. The grown Mercuric Iodate crystals were spherical in shape. These crystals were opaque. The crystals were characterized using UV-VIS Specrophotometrry.
In mineral science, there are several analytical instruments used for various purpose, viz…
Scanning electron microscopy
X-ray diffraction
Transmission electron microscopy
X-ray fluorescence
Flame atomic absorption spectroscopy
Electron microprobe analysis
Secondary ion mass spectrometry
Atomic force microscopy
Study of highly broadening Photonic band gaps extension in one-dimensional Me...IOSR Journals
In this paper, we show theoretically that the reflectance spectra of one dimensional multilayer metal-organic periodic structure (1D MOPS) can be enhanced due to the addition of the organic constituents. We have used simple transfer matrix method to calculate the absorption, transmittance and reflectance of the 1D MOPS systems. The organic component like N,N’-bis-(1-naphthyl)-N,N’diphenyl-1; 1biphenyl-4; 4diamine (NPB) absorbs the light in ultra-violet, visible and infrared electromagnetic region and the structure with Ag-metal also having the tendency to absorb the light by the plasmaonic action and their refractive can be calculated from Drude equation. The reflectance spectra of multilayer 1D MOPS containing a variable number periodic of Ag/N,N’-bis-(1-naphthyl)-N,N’diphenyl-1; 1biphenyl-4; 4diamine (NPB) structure are calculated taking optical constant of NPB and Ag. The optical band gap and reflectance spectra of 1D MOPS of the considered structure is obtained in the visible and near infrared regions either with the variation of the metal layer thickness or thickness of the organic layer. From the results under investigation through TMM, tunability in the optical band gap was observed either change in thickness of the other layer 1/ or 2 or the angle of the incident. Due to optical absorption of the light in the different region of electromagnetic spectrum due to either N,N’-bis-(1-naphthyl)-N,N’diphenyl-1; 1biphenyl-4; 4diamine (NPB) or silver metal, the optical band gap of 1DMOPS shows the shift of band edges of λL and λR from ultra-violet to visible and the infrared with change the optical constant.
Calculation of Optical Properties of Nano ParticlePHYSICS 5535- .docxRAHUL126667
Calculation of Optical Properties of Nano Particle
PHYSICS 5535- Optical Properties Matter-Spring 2017
Raznah Yami
Outline
1. Introduction: this part gives a precise overview of the whole paper. It begins by illustrating a brief introduction and importance of Nano Particles and the theoretical approaches used for their calculation.
2. Main idea: this section provides a step-by-step in-depth analysis of recently developed theories the calculation of optical properties of nanoparticles. It also provides calculation and equations employed these approaches.
2.1 Optical Properties of Nanoparticles: this section talks about the basics principles and governing the optical behavior of Nano particles and provides in-depth knowledge of different phenomena observed while dealing with optical properties of Nano particles.
2.2 Mie-Theory: the research provides exhaustive information the study optical properties of nanoparticles using Mie theory. This research focuses on Mie theory for the calculation of optical properties of Nano particle according to which we can calculate the place of surface Plasmon resonance in optical spectra of metallic spherical nanoparticle.
2.3 Discrete Dipole Approximation method: this section enumerates sufficient information about the calculation of absorption and scattering efficiencies and optical resonance wavelengths for three commonly used classes of nanoparticles: gold Nano spheres, silica-gold Nano shells, and gold Nano rods and we examine the magneto-optical scattering from nanometer-scale structures using a discrete dipole approximation.
3. Conclusion: This section provides a summary of the most important points, which presents an overview of the practical application and calculation methods of optical properties of Nano particles talking about core principles, which therefore explain the behavior exhibited by nanoparticles.
List of figures:
Figure 1: Localized surface Plasmon resonance ,resulting from the collective oscillations of delocalized electrons in response to an external electric field
Figure 2: Absorption spectra of semiconductor nanoparticles of different diameter. Right-nanoparticles suspended in solution.
Figure 3: Comparison of absorbance along increasing wavelength between Nano GaAs (7-15 nm) and Bulk GaAs showing an apparent blue shift
Figure 4: Showing the effect of blue shift because of quantum confinement as the wavelength shifts from 1100 nm to 2000 nm when we move from particle size of 9nm to parcile size of 3 nm.
Figure 5: Emission spectra of several sizes of (Cdse) Zns core-shell quantum dots.
Figure 6: The optical spectra and transmission electron micrographs for the particles in vials 1–5 are also shown. Scale bars in micrographs are all 100 nm
Figure7: Shows the effect of varying relative core and shell thickness of gold Nano Shells, there is an apparent blue shift as the frequency increases
References:
1. . P. S. Per ...
Effects of Different Parameters in Enhancing the Efficiency of Plasmonic Thin...IJAMSE Journal
Efficiency of thin film solar cells are less comparing to thick film solar cells which can be enhanced by utilizing the metal nanoparticles near their localized Plasmon resonance. In this paper, we have reviewed the Plasmon resonance of metallic nanoparticles and its application in solar cell technology. Beside this, we have also reviewed about different parameters which dominate the nanoparticles to increase optical absorption. Thus a cost-effective model has been proposed.
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.
SOME THEORETICAL ASPECTS OF HYDROGEN DIFFUSION IN BCC METALS AT LOW TEMPERATURESijrap
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.
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
Richard's aventures in two entangled wonderlandsRichard Gill
Since the loophole-free Bell experiments of 2020 and the Nobel prizes in physics of 2022, critics of Bell's work have retreated to the fortress of super-determinism. Now, super-determinism is a derogatory word - it just means "determinism". Palmer, Hance and Hossenfelder argue that quantum mechanics and determinism are not incompatible, using a sophisticated mathematical construction based on a subtle thinning of allowed states and measurements in quantum mechanics, such that what is left appears to make Bell's argument fail, without altering the empirical predictions of quantum mechanics. I think however that it is a smoke screen, and the slogan "lost in math" comes to my mind. I will discuss some other recent disproofs of Bell's theorem using the language of causality based on causal graphs. Causal thinking is also central to law and justice. I will mention surprising connections to my work on serial killer nurse cases, in particular the Dutch case of Lucia de Berk and the current UK case of Lucy Letby.
(May 29th, 2024) Advancements in Intravital Microscopy- Insights for Preclini...Scintica Instrumentation
Intravital microscopy (IVM) is a powerful tool utilized to study cellular behavior over time and space in vivo. Much of our understanding of cell biology has been accomplished using various in vitro and ex vivo methods; however, these studies do not necessarily reflect the natural dynamics of biological processes. Unlike traditional cell culture or fixed tissue imaging, IVM allows for the ultra-fast high-resolution imaging of cellular processes over time and space and were studied in its natural environment. Real-time visualization of biological processes in the context of an intact organism helps maintain physiological relevance and provide insights into the progression of disease, response to treatments or developmental processes.
In this webinar we give an overview of advanced applications of the IVM system in preclinical research. IVIM technology is a provider of all-in-one intravital microscopy systems and solutions optimized for in vivo imaging of live animal models at sub-micron resolution. The system’s unique features and user-friendly software enables researchers to probe fast dynamic biological processes such as immune cell tracking, cell-cell interaction as well as vascularization and tumor metastasis with exceptional detail. This webinar will also give an overview of IVM being utilized in drug development, offering a view into the intricate interaction between drugs/nanoparticles and tissues in vivo and allows for the evaluation of therapeutic intervention in a variety of tissues and organs. This interdisciplinary collaboration continues to drive the advancements of novel therapeutic strategies.
Professional air quality monitoring systems provide immediate, on-site data for analysis, compliance, and decision-making.
Monitor common gases, weather parameters, particulates.
This pdf is about the Schizophrenia.
For more details visit on YouTube; @SELF-EXPLANATORY;
https://www.youtube.com/channel/UCAiarMZDNhe1A3Rnpr_WkzA/videos
Thanks...!
Introduction:
RNA interference (RNAi) or Post-Transcriptional Gene Silencing (PTGS) is an important biological process for modulating eukaryotic gene expression.
It is highly conserved process of posttranscriptional gene silencing by which double stranded RNA (dsRNA) causes sequence-specific degradation of mRNA sequences.
dsRNA-induced gene silencing (RNAi) is reported in a wide range of eukaryotes ranging from worms, insects, mammals and plants.
This process mediates resistance to both endogenous parasitic and exogenous pathogenic nucleic acids, and regulates the expression of protein-coding genes.
What are small ncRNAs?
micro RNA (miRNA)
short interfering RNA (siRNA)
Properties of small non-coding RNA:
Involved in silencing mRNA transcripts.
Called “small” because they are usually only about 21-24 nucleotides long.
Synthesized by first cutting up longer precursor sequences (like the 61nt one that Lee discovered).
Silence an mRNA by base pairing with some sequence on the mRNA.
Discovery of siRNA?
The first small RNA:
In 1993 Rosalind Lee (Victor Ambros lab) was studying a non- coding gene in C. elegans, lin-4, that was involved in silencing of another gene, lin-14, at the appropriate time in the
development of the worm C. elegans.
Two small transcripts of lin-4 (22nt and 61nt) were found to be complementary to a sequence in the 3' UTR of lin-14.
Because lin-4 encoded no protein, she deduced that it must be these transcripts that are causing the silencing by RNA-RNA interactions.
Types of RNAi ( non coding RNA)
MiRNA
Length (23-25 nt)
Trans acting
Binds with target MRNA in mismatch
Translation inhibition
Si RNA
Length 21 nt.
Cis acting
Bind with target Mrna in perfect complementary sequence
Piwi-RNA
Length ; 25 to 36 nt.
Expressed in Germ Cells
Regulates trnasposomes activity
MECHANISM OF RNAI:
First the double-stranded RNA teams up with a protein complex named Dicer, which cuts the long RNA into short pieces.
Then another protein complex called RISC (RNA-induced silencing complex) discards one of the two RNA strands.
The RISC-docked, single-stranded RNA then pairs with the homologous mRNA and destroys it.
THE RISC COMPLEX:
RISC is large(>500kD) RNA multi- protein Binding complex which triggers MRNA degradation in response to MRNA
Unwinding of double stranded Si RNA by ATP independent Helicase
Active component of RISC is Ago proteins( ENDONUCLEASE) which cleave target MRNA.
DICER: endonuclease (RNase Family III)
Argonaute: Central Component of the RNA-Induced Silencing Complex (RISC)
One strand of the dsRNA produced by Dicer is retained in the RISC complex in association with Argonaute
ARGONAUTE PROTEIN :
1.PAZ(PIWI/Argonaute/ Zwille)- Recognition of target MRNA
2.PIWI (p-element induced wimpy Testis)- breaks Phosphodiester bond of mRNA.)RNAse H activity.
MiRNA:
The Double-stranded RNAs are naturally produced in eukaryotic cells during development, and they have a key role in regulating gene expression .
Earliest Galaxies in the JADES Origins Field: Luminosity Function and Cosmic ...Sérgio Sacani
We characterize the earliest galaxy population in the JADES Origins Field (JOF), the deepest
imaging field observed with JWST. We make use of the ancillary Hubble optical images (5 filters
spanning 0.4−0.9µm) and novel JWST images with 14 filters spanning 0.8−5µm, including 7 mediumband filters, and reaching total exposure times of up to 46 hours per filter. We combine all our data
at > 2.3µm to construct an ultradeep image, reaching as deep as ≈ 31.4 AB mag in the stack and
30.3-31.0 AB mag (5σ, r = 0.1” circular aperture) in individual filters. We measure photometric
redshifts and use robust selection criteria to identify a sample of eight galaxy candidates at redshifts
z = 11.5 − 15. These objects show compact half-light radii of R1/2 ∼ 50 − 200pc, stellar masses of
M⋆ ∼ 107−108M⊙, and star-formation rates of SFR ∼ 0.1−1 M⊙ yr−1
. Our search finds no candidates
at 15 < z < 20, placing upper limits at these redshifts. We develop a forward modeling approach to
infer the properties of the evolving luminosity function without binning in redshift or luminosity that
marginalizes over the photometric redshift uncertainty of our candidate galaxies and incorporates the
impact of non-detections. We find a z = 12 luminosity function in good agreement with prior results,
and that the luminosity function normalization and UV luminosity density decline by a factor of ∼ 2.5
from z = 12 to z = 14. We discuss the possible implications of our results in the context of theoretical
models for evolution of the dark matter halo mass function.
THE IMPORTANCE OF MARTIAN ATMOSPHERE SAMPLE RETURN.Sérgio Sacani
The return of a sample of near-surface atmosphere from Mars would facilitate answers to several first-order science questions surrounding the formation and evolution of the planet. One of the important aspects of terrestrial planet formation in general is the role that primary atmospheres played in influencing the chemistry and structure of the planets and their antecedents. Studies of the martian atmosphere can be used to investigate the role of a primary atmosphere in its history. Atmosphere samples would also inform our understanding of the near-surface chemistry of the planet, and ultimately the prospects for life. High-precision isotopic analyses of constituent gases are needed to address these questions, requiring that the analyses are made on returned samples rather than in situ.
Optical and Dielectric Studies on Semiorganic Nonlinear Optical Crystal by Solution Growth Technique
1. International Journal of Recent advances in Physics (IJRAP) Vol.3, No.1, February 2014
1
OPTICAL AND DIELECTRIC STUDIES ON
SEMIORGANIC NONLINEAR OPTICAL CRYSTAL
BY SOLUTION GROWTH TECHNIQUE
Suresh Sagadevan1
* , Priya Murugasen2
1
Department of Physics, Sree Sastha Institute of Engineering and Technology,
Chembarambakkam, Chennai-600 123, India
2
Department of Physics, Saveetha Engineering College, Chennai, India
ABSTRACT
The field of nonlinear optics became practically a reality after the invention of laser. High performance
electro-optic switching elements for telecommunication and optical information processing are based on
materials with high nonlinear optical (NLO) properties. Single crystals of nonlinear optical material L-
lysine sulphate (LLS) are grown by slow evaporation technique. The crystal structure and lattice
parameters are determined for the grown crystal by single X-ray diffraction studies. The wide transparency
range of the crystals in the visible region of the electromagnetic spectrum is identified by the UV-Vis-NIR
technique. The mechanical property of the grown crystal is determined by Vicker’s microhardness test. It is
observed from the microhardness studies of the grown crystals that the hardness increases with increase in
load. Meyer’s index n is calculated which proves that the material belongs to soft material category. The
dielectric constant and dielectric loss are calculated by varying the frequencies at room temperature. The
emission of green light on passing the Nd: YAG laser confirms the second harmonic generation (SHG)
property of the crystals .The SHG efficiency of the crystals are found to be better than that of Potassium Di
hydrogen Phosphate (KDP)
Keywords:
Single crystal, NLO, Single crystal XRD, Microhardness, Dielectric constant and Dielectric loss.
1 INTRODUCTION
Crystal growth is an important area of science and technology, especially in the field of
photonics. The single crystals with advanced properties play a significant role in the growth of
modern scientific world of advanced technology. Crystal growth is a significant field of materials
science, which involves controlled phase transformation. In the current decades, there has been a
growing interest in crystal growth process, particularly in view of the development of materials
for technological applications [1]. Materials can be classified as single crystals, poly crystals and
amorphous materials depending upon the arrangement of constituent molecules, atoms or ions. If
the surroundings of an atom are exactly the same as the surroundings of every similar atom then
that crystal is said to be ideal. The real crystals are finite and they contain defects. The single
2. International Journal of Recent advances in Physics (IJRAP) Vol.3, No.1, February 2014
2
crystals are solids in the most uniform condition that forms the basis for most of the applications
of crystals. The uniformity of single crystals can allow the transmission of electromagnetic
waves, without scattering. There are many methods for growing crystals and mainly dictated by
the characteristics of the material and its size [2]. The semi-organic crystals attract great attention
in the field of nonlinear optics due to their optical nonlinearity, chemical flexibility, thermal
stability and excellent transmittance in the UV–visible region [3, 4]. The semi-organic crystals
possess properties such as high damage threshold, wide transparency region and high nonlinear
coefficient which have various applications and they need NLO require single crystals in the bulk
form. This is achieved with the crystals, which exhibit wide transparency, large and bulky crystal
morphologies. The contribution from the delocalized π - electrons belonging to the organic ligand
results in wide optical transmittance and high nonlinear electro -optic coefficients. L – Lysine
sulphate is a semiorganic NLO material possessing large value of hyperpolarizability. The LLS
possesses good stability and do not show any hygroscopic effect for a long time. It has been found
that there is a network of hydrogen bonds in crystal that stabilizes its structure. From the optical
assessment, LLS is a promising new nonlinear-optical crystal for frequency up conversion in the
UV region of high-power laser sources.
Hence, in the present investigation, report the single X-ray diffraction, optical, mechanical,
dielectric and SHG characterization of the L-lysine sulphate single crystal for NLO applications.
Single crystal X-ray diffraction analysis confirmed the lattice parameters and crystal structure of
the grown crystals. Microhardness studies of the crystal have been determined using Vicker’s
indentation test. Dielectric constant and dielectric loss studies were carried out at room
temperature. The SHG test proves that the LLS crystal was one of the potential nonlinear optical
materials.
2 EXPERIMENTAL PROCEDURE
Slow evaporation of L-Iysine and sulphuric acid taken in equimolar ratio in aqueous solution was
used to grow single crystals of L-lysine sulphate. The solution was stirred continuously and the
solution was filtered. The solution is kept undisturbed at room temperature. Defect free tiny seed
crystals with good transparency formed due to spontaneous nucleation was selected and
suspended in the mother solution. This solution which was allowed to evaporate at room
temperature yields large size single transparent crystals due to collection of monomers at the seed
crystal sites from the mother solution. Crystals of LLS were harvested by slow evaporation
technique in a period of 30 days.
3 RESULTS AND DISCUSSIONS
3.1 Single Crystal X-ray diffraction Analysis
Single crystal X-ray diffraction provides detailed information about the molecular structure,
atomic co-ordinates, band lengths, band angles, unit cell dimensions, molecular orientation and
packing of molecules in single crystals which is a non-destructive analytical technique. ENRAF
NONIUS CAD4 automatic X-ray diffractometer was used to identify the cell parameters. The
crystals belongs to orthorhombic system and the lattice parameters were calculated to be a =
5.73Å, b = 11.54 Å, c = 16.58 Å, α = β = γ = 90o
with noncentrosymmetric space group P212121.
3. International Journal of Recent advances in Physics (IJRAP) Vol.3, No.1, February 2014
3
3.2 UV-VIS-NIR Spectral Analysis
The absorption of UV and visible light involves promotion of the electron in the σ and π orbital
to higher states, the UV-VIS-NIR spectrum gives information about the structure of the molecules
in the crystals. The optical absorption spectrum of LLS crystal shown in Fig.1 was recorded
between 200 and 1200 nm. The crystal exhibits excellent transmission in the entire visible region.
The lower cutoff wavelength is 240 nm. Single crystals are mainly used in optical applications as
optical transmittance windows. For the realization of SHG output in the range of (200nm-400nm),
the transparency lower cut off (200 nm-400 nm) is very important.
This transparent nature of the crystals in the visible region is the property which makes the
material important for NLO applications. The bandgap of the crystal (Eg) was estimated from the
following relation
max
3
10
243
.
1
×
=
g
E (1)
Where λmax is the maximum wavelength. This was found to be 5.17 eV, which is typical property
of the dielectric materials.
This high value of bandgap shows the crystal possesses dielectric behavior to induce polarization
when powerful radiation is incident on the material. The suitability of the grown crystals for
photonic and optical applications is confirmed by the absence of absorption bands in the visible
region. The large energy bandgap also confirms that the defect concentration in the grown crystal
is very low.
Fig.1 Absorption spectrum of LLS crystal
4. International Journal of Recent advances in Physics (IJRAP) Vol.3, No.1, February 2014
4
3.3 Refractive index measurements
Finely polished crystals of the as grown L-lysine sulphate (LLS) were used for refractive index
measurements. The crystals which were cleaved and placed on a rotating mount at an angle
varying from 0 to 90 degrees. The He-Ne laser of wavelength 632.8 nm was used as the source.
Brewster’s angle (θp) for LLS was measured to be 58.4 degrees. The refractive index has been
calculated using the following relation
n = tan θp (2)
where θp is the polarizing angle and it is found to be 1.625.
3.4 Microhardness Studies
The resistance offered by a material to the motion of dislocation, deformation or damage under an
applied stress is measured by the hardness of the crystal. During the making of NLO crystals
mechanical stress is applied on the crystal while cutting and polishing. So it is necessary to know
the mechanical stress the crystals can withstand without any crack. The ratio of the applied load
to the projected area indentation gives the hardness. To find the surface hardness of the grown
L-lysine sulphate microhardness was measured for a load of 5-50 gms using SHIMADZU HMV –
2000 microhardness tester with diamond pyramid indenter attached to an optical microscope.
Several indentations were made on the sample with a dwell time of 10 seconds for the accuracy
of the obtained results. The Vickers hardness number (Hv) was calculated using the standard
formula,
2
2
/
8544
.
1 mm
kg
d
P
Hv
=
(3)
where P is the applied load and d is the mean diagonal length of the indentation. The increase of
the hardness with load up to 50g is represented in Fig.2 which proves the use of grown crystals
in which can withstand thermal local stresses. The Mayer’s index number was calculated from
Mayer’s law, which relates the load and the indentation diagonal length as
n
d
k
P 1
= (4)
where ‘n’ is called Mayer’s index or work hardening index. In order to find work hardening index
(n), a graph is plotted with log P against log d which gives a straight line. From the slope of the
line, the Mayer’s index number was found to be 3.65. According to Onitisch, if the value of n is
greater than 2, the microhardness will increase with increase of load. From the hardness study,
the grown LLS crystal is found to be relatively soft material.
5. International Journal of Recent advances in Physics (IJRAP) Vol.3, No.1, February 2014
5
Fig.2 Vickers microhardness of LLS crystal
Fig.3 Plot of log P vs log d
3.5 Dielectric Studies
Dielectric properties are related with the electric field distribution within solid materials. One of
the widely used parameters is the relative dielectric constant or relative permittivity and the
dielectric constant of a material gives an insight into the nature of bonding. The dielectric
property of the LLS crystals was studied at room temperature using HIOKI 3532 LCR
HITESTER in the frequency region 50Hz - 5MHz. The variation of dielectric constant with
frequency is shown by Fig.4. The dielectric constant is higher in the region from 50Hz - 5MHz
6. International Journal of Recent advances in Physics (IJRAP) Vol.3, No.1, February 2014
6
and gradually decreases with increase in frequency and continues upto 5MHz. After this, it
almost remains constant at all other higher frequencies. The presence of electronic, ionic, dipolar
and space charge polarizations in the material are the reasons for the high value of dielectric
constant at low frequency [5]. In accordance with Miller rule, the lower value of dielectric
constant at higher frequency is a suitable parameter for the enhancement of SHG coefficient [6].
Fig.5 shows the variation of dielectric loss with frequency. The crystal possesses enhanced optical
quality with lesser defects and this parameter plays a vital role for the fabrication of nonlinear
optical devices because of low dielectric loss with high frequency for the samples [7].
Fig.3 Variation of dielectric constant of LLS single crystal with frequency
Fig.4 Variation of dielectric loss of LLS single crystal as a function of frequency
7. International Journal of Recent advances in Physics (IJRAP) Vol.3, No.1, February 2014
7
3.6 NLO Test – Kurtz Powder SHG Method
The Kurtz powder technique is used to identify the materials with non-centrosymmetric crystal
structures and is the most widely used technique for confirming the SHG efficiency of NLO
materials. In order to confirm the NLO behavior of these material, powdered samples was
subjected to Kurtz and Perry powder technique. The NLO property of the sample was
tested using a Q-switched Nd: YAG laser beam of wavelength 1064nm and 10ns pulse width with
an input rate of 10Hz. The output of the grown crystal was measured as 8mV while the KDP gave
an SHG signal of 16mV for input beam energy of 6.5mJ/Pulse. The green radiation generated
confirms the second harmonic signal generated in the crystalline sample. The standard NLO
inorganic KDP was used as the reference material. The emission of green light (λ=532 nm) from
the LLS crystals confirmed their noncentrosymmetric crystal structure. The SHG efficiency is
decreased due to lower polarizing ability of the material.
4. CONCLUSION
L-lysine sulphate (LLS) single crystal was grown by slow evaporation technique. From the single
crystal XRD data obtained, it is proved that the crystals belong to orthorhombic structure and
non-centrosymmetric space group P212121. The presence of a wide transparency window lying
between 200 nm and 1200 nm with λmax =240 nm is represented by the UV spectrum. The
bandgap was estimated to be of 5.17 eV which is typical of dielectric material. The wide energy
band gap confirms that the defect concentration in the grown crystal is very low and large
transmittance in the visible region. The crystal possesses moderate mechanical stability which is
confirmed by the Vickers microhardness analysis. By Meyer’s law, the value of Meyer’s index n
estimated to be 3.65 indicates that the crystal belongs to soft material category and the dielectric
property studied at room temperature indicates that the dielectric constant and dielectric loss
decreases with the increase in frequency which is the normal behavior of nonlinear optical
materials. The low dielectric constant and dielectric loss of the crystal in the high frequency
region represent good optical quality. The nonlinear optical nature of the crystal was confirmed
by Kurtz-Perry powder technique. The transmission near the Nd:YAG laser fundamental (1064
nm) and second harmonic wavelength (532 nm) is reduced . This reduction contributes to the
resistance of the material to laser damage threshold. This transmission range of the crystal makes
it valuable for applications that require blue green light. High frequency shift and good NLO
property and other physicochemical properties make this material a good laser converter.
Acknowledgement
The author thanks the Management and Principal of Sree Sastha Institute of Engineering and
Technology, Chembarambakkam, Chennai-600123 for their continuous encouragement.
References
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[2] Buckley H.E. (4 May 1951). Crystal Growth, Wiley, New York
[3] Pricilla Jeyakumari, A., Ramajothi, J. and Dhanuskodi, S., Structural and microhardness studies of a
NLO material–bisthiourea cadmium chloride, J.Cryst.Growth, 2004, 269, 558-564.
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[4] Sun, H.Q., Yuan, D.R., Wang, X.Q., Cheng, X.F., Gong, C. R., Zhou, M., Xu, H.J., Wei, X.C., Luan,
C.N., Pan, D.Y., Li, Z.F. and Shi, X.Z., A novel metal-organic coordination complex crystal: tri-
allylthiourea zinc chloride (ATZC), Cryst.Res.Technol., 2005, 40, 882-886.
[5] Pan, J.S. and Zhang, X.W., Structure and dielectric behavior of Pb(Mg1/3Nb2/3)O3–
Pb(Ni1/3Nb2/3)O3–Pb(Zn1/3Nb2/3)O3–PbTiO3 ferroelectric ceramics near the morphotropic phase
boundary, Acta Mat., 2006, 54, 1343-1348.
[6] Von Hundelshausen, U., Electrooptic effect and dielectric properties of cadmium-mercury-
thiocyanate crystals, Physics Letters A, 1971, 34, 405-406.
[7] Balarew, C. and Duhlew, R., Application of the hard and soft acids and bases concept to explain
ligand coordination in double salt structures, J.Solid State Chem., 1984, 55, 1-6.