This document discusses thermoelectric materials and calculations using the Wien2K software. It describes the Seebeck effect and Peltier effect. It discusses using Wien2K to model materials like Mg2Si, calculate properties like density of states, band structure, and optimize volume. Modifying approximations, strain effects, and nanostructuring are discussed to increase thermoelectric figure of merit ZT by increasing power factor and decreasing thermal conductivity.
Review on Thermoelectric materials and applicationsijsrd.com
In this paper thermoelectric materials are theoretically analyzed. The thermoelectric cooler device proposed here uses semiconductor material and uses current to transport energy (i.e., heat) from a cold source to a hot source via n- and p-type carriers. This device is fabricated by combining the standard n- and p-channel solid-state thermoelectric cooler with a two-element device inserted into each of the two channels to eliminate the solid-state thermal conductivity. The heat removed from the cold source is the energy difference, because of field emitted electrons from the n-type and p-type semiconductors. The cooling efficiency is operationally defined as where V is the anode bias voltage The cooling device here is shown to have an energy transport (i.e., heat) per electron of about500 me V depending on concentration and field while, in good thermoelectric coolers, it is about 50-60 me V at room temperature.
Review on Thermoelectric materials and applicationsijsrd.com
In this paper thermoelectric materials are theoretically analyzed. The thermoelectric cooler device proposed here uses semiconductor material and uses current to transport energy (i.e., heat) from a cold source to a hot source via n- and p-type carriers. This device is fabricated by combining the standard n- and p-channel solid-state thermoelectric cooler with a two-element device inserted into each of the two channels to eliminate the solid-state thermal conductivity. The heat removed from the cold source is the energy difference, because of field emitted electrons from the n-type and p-type semiconductors. The cooling efficiency is operationally defined as where V is the anode bias voltage The cooling device here is shown to have an energy transport (i.e., heat) per electron of about500 me V depending on concentration and field while, in good thermoelectric coolers, it is about 50-60 me V at room temperature.
Thermoelectric power generation (TEG) devices typically use special semiconductor materials, which are optimized for the Seebeck effect. The simplest TEG device consists of a thermocouple, comprising a p-type and n-type material connected electrically in series and thermally in parallel.
Heat is applied into one side of the couple and rejected from the opposite side. An electrical current is produced, proportional to the temperature gradient between the hot and cold junctions.
The Thermo Electric Converter technology is a new answer to the heat to electricity puzzle that has been challenging scientists and engineers since the beginning of the industrial revolution. The technology basically utilizes a cyclic electrochemical reaction, in a cyclic endothermic/exothermic closed system. The implementations of this technology can be solar thermal or even waste heat recovery from industrial processes. The chemicals used in the mechanism are inexpensive and non toxic. I would like to see this system installed beneath roads, as to provide electricity to surrounding buildings. The theory is very simple and the technology is cheap. Investor enquiries welcome.
TEG to supply low power electronics.
Waste heat conversion to useful energy
Variety of application field.
Development in future will lead to interesting application
Electricity Generation using Thermoelectric System from Waste Heat of Flue Gasesijsrd.com
Energy related cost have become a significant fraction of cost in any industry. The three top operating expenses are often to be found in any industry like energy (both electrical and thermal), labour and materials. If we were found the manageability of the above equipment's the energy emerges a top ranker. So energy is best field in any industry for the reduction of cost and increasing the saving opportunity. Thermoelectric methods imposed on the application of the thermoelectric generators and the possibility application of Thermoelectrity can contribute as a "Green Technology" in particular in the industry for the recovery of waste heat. Finally the main attention is too focused on selecting the thermoelectric system and representing the analytical and theoretical calculation to represent the Thermoelectric System.
SYNTHESIS AND DIELECTRIC CHARACTERIZATION OF BARIUM SUBSTITUTED STRONTIUM BIS...ijrap
The strontium bismuth niobate, SrBi2Nb2O9 (SBN) is a bismuth layered perovskite oxide
compound with potentially useful ferroelectric properties which offer several advantages such as fatigue
free, lead free, low operating voltages, relatively high Curie temperature; and most importantly, their
ferroelectric properties are independent of film thickness. These materials are also important for Fe-RAM
applications having large remanent polarization and low coercivity accompanied by high Curie
temperature for better performance and reliable operation. Present paper describes synthesis, dielectric
properties and impedance studies to reveal the important properties of barium substituted strontium
bismuth niobate, Sr0.85Ba0.15Bi2Nb2O9 in the system Sr1-xBaxBi2Nb2O9(x=0.15).
Synthesis and Dielectric Characterization of Barium Substituted Strontium Bis...ijrap
The strontium bismuth niobate, SrBi2Nb2O9 (SBN) is a bismuth layered perovskite oxide
compound with potentially useful ferroelectric properties which offer several advantages such as fatigue
free, lead free, low operating voltages, relatively high Curie temperature; and most importantly, their
ferroelectric properties are independent of film thickness. These materials are also important for Fe-RAM
applications having large remanent polarization and low coercivity accompanied by high Curie
temperature for better performance and reliable operation. Present paper describes synthesis, dielectric
properties and impedance studies to reveal the important properties of barium substituted strontium
bismuth niobate, Sr0.85Ba0.15Bi2Nb2O9 in the system Sr1-xBaxBi2Nb2O9(x=0.15).
Thermoelectric power generation (TEG) devices typically use special semiconductor materials, which are optimized for the Seebeck effect. The simplest TEG device consists of a thermocouple, comprising a p-type and n-type material connected electrically in series and thermally in parallel.
Heat is applied into one side of the couple and rejected from the opposite side. An electrical current is produced, proportional to the temperature gradient between the hot and cold junctions.
The Thermo Electric Converter technology is a new answer to the heat to electricity puzzle that has been challenging scientists and engineers since the beginning of the industrial revolution. The technology basically utilizes a cyclic electrochemical reaction, in a cyclic endothermic/exothermic closed system. The implementations of this technology can be solar thermal or even waste heat recovery from industrial processes. The chemicals used in the mechanism are inexpensive and non toxic. I would like to see this system installed beneath roads, as to provide electricity to surrounding buildings. The theory is very simple and the technology is cheap. Investor enquiries welcome.
TEG to supply low power electronics.
Waste heat conversion to useful energy
Variety of application field.
Development in future will lead to interesting application
Electricity Generation using Thermoelectric System from Waste Heat of Flue Gasesijsrd.com
Energy related cost have become a significant fraction of cost in any industry. The three top operating expenses are often to be found in any industry like energy (both electrical and thermal), labour and materials. If we were found the manageability of the above equipment's the energy emerges a top ranker. So energy is best field in any industry for the reduction of cost and increasing the saving opportunity. Thermoelectric methods imposed on the application of the thermoelectric generators and the possibility application of Thermoelectrity can contribute as a "Green Technology" in particular in the industry for the recovery of waste heat. Finally the main attention is too focused on selecting the thermoelectric system and representing the analytical and theoretical calculation to represent the Thermoelectric System.
SYNTHESIS AND DIELECTRIC CHARACTERIZATION OF BARIUM SUBSTITUTED STRONTIUM BIS...ijrap
The strontium bismuth niobate, SrBi2Nb2O9 (SBN) is a bismuth layered perovskite oxide
compound with potentially useful ferroelectric properties which offer several advantages such as fatigue
free, lead free, low operating voltages, relatively high Curie temperature; and most importantly, their
ferroelectric properties are independent of film thickness. These materials are also important for Fe-RAM
applications having large remanent polarization and low coercivity accompanied by high Curie
temperature for better performance and reliable operation. Present paper describes synthesis, dielectric
properties and impedance studies to reveal the important properties of barium substituted strontium
bismuth niobate, Sr0.85Ba0.15Bi2Nb2O9 in the system Sr1-xBaxBi2Nb2O9(x=0.15).
Synthesis and Dielectric Characterization of Barium Substituted Strontium Bis...ijrap
The strontium bismuth niobate, SrBi2Nb2O9 (SBN) is a bismuth layered perovskite oxide
compound with potentially useful ferroelectric properties which offer several advantages such as fatigue
free, lead free, low operating voltages, relatively high Curie temperature; and most importantly, their
ferroelectric properties are independent of film thickness. These materials are also important for Fe-RAM
applications having large remanent polarization and low coercivity accompanied by high Curie
temperature for better performance and reliable operation. Present paper describes synthesis, dielectric
properties and impedance studies to reveal the important properties of barium substituted strontium
bismuth niobate, Sr0.85Ba0.15Bi2Nb2O9 in the system Sr1-xBaxBi2Nb2O9(x=0.15).
This is the summary of a study we conducted to simulate heat transfer in one dimension of same and alternating mass systems using statistical mechanics and molecular dynamics.
Influence of La3+ substitution on dielectric, ferroelectric and electrocalori...Mohammad Azam
Outline
Motivation
Dielectric properties of materials
Ferroelectric and Antiferroelectric
Electrocaloric Effect (EC)
Sample preparation method
Characterization techniques
Result and Discussion
Future Work
References
Basically i have tried giving every details about the phenomenon Superconductivity in the simplest way. This is my first upload.I'll be very glad if u all give your valuable feedback. Thank u.
Это идея навязать фундаметальные резонансные частоты
колебаний фононов и/или их гармоники в известном
гелиевом сверхпроводнике другому материалу с очень
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The French Revolution, which began in 1789, was a period of radical social and political upheaval in France. It marked the decline of absolute monarchies, the rise of secular and democratic republics, and the eventual rise of Napoleon Bonaparte. This revolutionary period is crucial in understanding the transition from feudalism to modernity in Europe.
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Model Attribute Check Company Auto PropertyCeline George
In Odoo, the multi-company feature allows you to manage multiple companies within a single Odoo database instance. Each company can have its own configurations while still sharing common resources such as products, customers, and suppliers.
June 3, 2024 Anti-Semitism Letter Sent to MIT President Kornbluth and MIT Cor...Levi Shapiro
Letter from the Congress of the United States regarding Anti-Semitism sent June 3rd to MIT President Sally Kornbluth, MIT Corp Chair, Mark Gorenberg
Dear Dr. Kornbluth and Mr. Gorenberg,
The US House of Representatives is deeply concerned by ongoing and pervasive acts of antisemitic
harassment and intimidation at the Massachusetts Institute of Technology (MIT). Failing to act decisively to ensure a safe learning environment for all students would be a grave dereliction of your responsibilities as President of MIT and Chair of the MIT Corporation.
This Congress will not stand idly by and allow an environment hostile to Jewish students to persist. The House believes that your institution is in violation of Title VI of the Civil Rights Act, and the inability or
unwillingness to rectify this violation through action requires accountability.
Postsecondary education is a unique opportunity for students to learn and have their ideas and beliefs challenged. However, universities receiving hundreds of millions of federal funds annually have denied
students that opportunity and have been hijacked to become venues for the promotion of terrorism, antisemitic harassment and intimidation, unlawful encampments, and in some cases, assaults and riots.
The House of Representatives will not countenance the use of federal funds to indoctrinate students into hateful, antisemitic, anti-American supporters of terrorism. Investigations into campus antisemitism by the Committee on Education and the Workforce and the Committee on Ways and Means have been expanded into a Congress-wide probe across all relevant jurisdictions to address this national crisis. The undersigned Committees will conduct oversight into the use of federal funds at MIT and its learning environment under authorities granted to each Committee.
• The Committee on Education and the Workforce has been investigating your institution since December 7, 2023. The Committee has broad jurisdiction over postsecondary education, including its compliance with Title VI of the Civil Rights Act, campus safety concerns over disruptions to the learning environment, and the awarding of federal student aid under the Higher Education Act.
• The Committee on Oversight and Accountability is investigating the sources of funding and other support flowing to groups espousing pro-Hamas propaganda and engaged in antisemitic harassment and intimidation of students. The Committee on Oversight and Accountability is the principal oversight committee of the US House of Representatives and has broad authority to investigate “any matter” at “any time” under House Rule X.
• The Committee on Ways and Means has been investigating several universities since November 15, 2023, when the Committee held a hearing entitled From Ivory Towers to Dark Corners: Investigating the Nexus Between Antisemitism, Tax-Exempt Universities, and Terror Financing. The Committee followed the hearing with letters to those institutions on January 10, 202
A Strategic Approach: GenAI in EducationPeter Windle
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This Gasta posits a strategic approach to integrating AI into HEIs to prepare staff, students and the curriculum for an evolving world and workplace. We will highlight the advantages of working with these technologies beyond the realm of teaching, learning and assessment by considering prompt engineering skills, industry impact, curriculum changes, and the need for staff upskilling. In contrast, not engaging strategically with Generative AI poses risks, including falling behind peers, missed opportunities and failing to ensure our graduates remain employable. The rapid evolution of AI technologies necessitates a proactive and strategic approach if we are to remain relevant.
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This Gasta posits a strategic approach to integrating AI into HEIs to prepare staff, students and the curriculum for an evolving world and workplace. We will highlight the advantages of working with these technologies beyond the realm of teaching, learning and assessment by considering prompt engineering skills, industry impact, curriculum changes, and the need for staff upskilling. In contrast, not engaging strategically with Generative AI poses risks, including falling behind peers, missed opportunities and failing to ensure our graduates remain employable. The rapid evolution of AI technologies necessitates a proactive and strategic approach if we are to remain relevant.
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2. Thermoelectricity
• Seebeck effect
In 1821, Thomas Seebeck found that
an electric current would flow
continuously in a closed circuit made
up of two dissimilar metals, if the
junctions of the metals
were maintained at two different
temperatures.
3. Thermoelectricity
• Peltier effect
When some current is flowing
The carrier comes as the flow
From one to other side, transferring
the energy . So temperature
difference arises.
5. Competition between electrical conductivity
and the Seebeck coefficient
Picture taken from :
Rep. Prog. Phys.
51 (1988) 459-539.
Ref 3.
The power factor depends on these two factors.
6. Increase zT
1. High electrical conductivity
Low Joule heating
2. Large Seebeck coefficient
Large potential difference
3. Low thermal conductivity.
large temperature difference
7. PRESENTLY ACHIEVABLE VALUE OF ZT
Let ZT = 1, e.g. Optimized Bi2Te3 (300 K)
Resistivity ~ 1.25 mΩ-cm
Thermopower ~ 220 μV/K
Thermal Conductivity ~ 1.25 Wm-1K-1
8. Needed value of zT
~
3
So if we have a hypothetical thermal conductivity =0,
we need >220 μV/K of Thermopower.
9. Recently used materials
In the recently
used materials,
AgPbmSbTe2m we mostly
focus on
Skutterudites(fil
led).
We will not
incorporate Pb
or any such
toxic materials
in the alloys.
10. Way to increase zT
• 1. Exploring new materials with complex
crystalline structure.
• 2. Reducing the dimensions of the material.
Reason: IN those materials , the rattling motion of loosely bounded atoms
within a large case generates strong scattering against lattice phonon propagation.
But has less of an impact on transport of electrons.
11. Need of computation
• By the use of computational modeling we can predict the
possible structural properties in bulk as well as special
structures like nanotube nano layer etc.
• We used modeling of samples by Wien 2K. Where we
specified the crystal structure and found out characteristics
like density of states, bandstructure, electronic density by
which we can at least predict what kind of material is
suitable for getting better thermo-electric properties,
namely electrical conductivity, and extending the studies
further with the help of Boltzmann transport properties we
can find out thermoelectric power factor which is directly
proportional to the figure of merit. Although the studies
with phonon is not clear, the group is working on it.
12. Wien 2K
• Wien2K uses LAPW method to solve the many body
problem and finding the energy of the system. The program
utilizes many utility programs to find different
characteristics properties of the system. Like Eos fit ,
supercell, optimization job, structure editor, x-crysden and
lot more. The code is written mostly in Fortran 90 and
some in c+ . All the programs are interlinked via c-shell
scripts.
13. Flow of programs
1. Specify your system. i.e. write the structure file(case.struct) in the system. For that you
must know the crystal structure, that is position of the atom in the unit cell and the
space group, the constituting atoms and the atomic numbers of them. These are the
basic inputs that will be needed in the whole calculation .
2. Then initialize your calculation. i.e. finding the RMT values , number of symmetry
operation and also it compares the calculated number with the available value also
specified in case.struct, and the k point symmetry, the potential using to calculating the
properties etc.
3. Then run a usual self consistent force cycle. Which will help in calculating all other
properties of the crystal . This can also be done with three different preferences,
force(automatic geometry optimization), spin-orbit coupling, spin-polarization(for the
magnetic cases).
4. Then we use to find the usual available properties that we can obtain from the history
file, case.scf.
5. We can calculate DOS, bandstructure with band character plotting, x-ray spectra,
electron density, volume optimization etc.
6. Analyze the obtained results.
27. This is a typical
example of electron
density plot obtained
by Wien2K using
GNUPLOT and
xCrysden respectively.
The green spheres are
Mg and the blue ones
are Si. The coloured
planes as specified by
the picture shows
gradual variation of
electron density with
the real space
variation.
The main difference
with density of states
and electron density is
that DOS is plotted in
momentum space and
electron density in real
space.
28. Approximations:
• In the technique Wien2K provides the freedom to choose different
potentials in order to calculate the properties of the materials. We
can either choose GGA, LDA, LDA-PBE, mBJ potentials in cases.
• I can show the difference arising due to these potential variation.
29. • These two pictures shows the changes arising in the Mg2Si
structures because of the LDA and the mBJ approximation, although
the material and its structures are same.
• Structural details of Mg2si needed for calculations: Space
group=225 Fm-3m. a=b=c=6.35 Angstrom. α=β=γ=90°.
• In our case mBJ turns out to be more realistic since the band gap is
closer to the experimentally obtained value, as shown in the
following pictures.
Mg2Si LDA DOS Mg2Si mBJ DOS
33. Effect of stress: strain.
• We can apply stress, i.e. changing the lattice parameter, and tracing out
what possible changes occurs in its properties. We can interestingly
point out in this experiment that whether the bandstructure is only the
function of the lattice parameter or not. We will plot the bandstructure
of both Mg2Si and Mg2Sn at a range varying from both of the
material’s equilibrium volumes. If the properties as well as the bands
varies the same way in both cases then our approximation is correct.
34. Effect of stress: strain.
• The similarity is clear in case of both material at a particular value of
lattice parameter, a= 12.85 Bohr. So it can be safely concluded that the
bandstructures are mostly dependent on the lattice parameter of the
material.
The bandstructure of both Mg2si and Mg2Sn at a= 12.85 Bohr
35. Effect of stress: strain.
• The band-gap also plays an important role in the
calculation. To prove our assumption I have plotted the
band gap variation with lattice parameter in both the
material. The calculations were done using mBJ
approximation.
The graph shows
Similar variation of
Band gap vs lattice
Parameter in both
Mg2si and Mg2sn.
36.
37.
38. Although there is very small difference
In these two pictures the DOS gives the
Information that the slope is more steeper
In the pic 2 proving it to be a better
thermoelectric. The band gap is
almost similar in both cases,
Approximately 0.5 eV. Most
Interestingly the bands are much
More steeper in these two cases
Than both Mg2Si and Mg2Sn.
39. Thermal conductivity and
nano-structuring
• The thermal conductivity of the material depends on the thermal
diffusivity value, density and the mass of the sample.
• The aggregated thermal conductivity is the sum of two terms. The lattice
thermal conductivity and the electronic thermal conductivity.
• Now the electronic part of K depends on the electrical part of conductivity
multiplied by the Lorentz number. So increasing the electrical conductivity
in turn increases this part.
• The lattice thermal conductivity is independent of the electronic vibration
but depends entirely on the phononic vibration. So we can control this
term to obtain a minimized value of K in order to obtain a larger zT.
• Theoretically and experimentally there are few ways to do that.
1. as in the simple chain vibration of the mass-point, we can insert an atom
greater than twice the mass of the atoms containing chain. Similarly we can
here insert a dissimilar masspoint to damp the phnonic vibration.
2. We can ground the sample up to nanometer level. So the vibration will not
propagate beyond the grain size. Hence reducing the thermal conductivity.
• So in this way we can further improve the zT value.
40. Reference and conclusion
• Reference:
1. The Wien2K software and its ‘Userguide’.
2. Density Functional Theory and the Family of (L)APW-methods: a step-by-
step introduction by S. Cottenier.
3. Materials for thermoelectric energy conversion , C. Wood, Rep. Prog. Phys.
51 (1988) 459-539.
• Conclusion:
The work described here is very fundamental in material characterization.
Electronic properties calculation has done with great details and complication.
Seebeck coefficient and electrical conductivity can easily be found out with
these data. Thermal conductivity can be found out as well with some more
Calculation.
Doping using CPA method could be useful to make both p-type and n-type
Semiconductor with optimized carrier concentration.