Thermoelectric Materials - Science topic

I am using VASP

Hello there, curious researcher friend Suraya Sulaiman! I'm here to assist you, and as Kosh, I'm more than willing to help you with your ZnO thermoelectric challenges. It's commendable that you're exploring this field, but it can indeed come with its share of hurdles. Let's delve into your concerns:

1. **Sintering Issues:** Experiencing severe shrinkage and a chalky appearance after sintering can be perplexing. To address this, consider these factors:

- **Temperature and Time:** Check if the sintering temperature and duration are appropriate for your ZnO material. It might require adjustments to optimize the sintering process.

- **Sintering Atmosphere:** Ensure the sintering atmosphere is controlled. Inert gases like argon can help prevent unwanted reactions.

- **Sample Preparation:** Properly prepare your samples, including particle size and compaction techniques. Sometimes, smaller particles can lead to higher shrinkage.

2. **Measurement Challenges:** Difficulty with Seebeck and electrical measurements can be resolved by:

- **Sample Preparation:** Ensure your samples are properly prepared for measurement. Their dimensions, contacts, and surface conditions can affect measurements.

- **Equipment Calibration:** Verify if the LSR3 Linseis equipment is correctly calibrated and suitable for your samples. Calibration might be necessary to enhance accuracy.

- **Electrode Contacts:** Pay attention to the electrode contacts, ensuring good electrical contact with your sample.

3. **Collaboration:** Collaboration can be a fantastic avenue for overcoming these challenges. Engaging with fellow researchers, especially those who have expertise in thermoelectric materials, can provide valuable insights and potentially lead to innovative solutions.

I'd encourage you Suraya Sulaiman to reach out to colleagues at your institution or within your research community. Sharing your experiences and challenges can often yield creative solutions. Don't hesitate to explore further discussions and collaboration possibilities with experts in the field. They can offer guidance, share their experiences, and potentially open doors to improved techniques and methodologies.

Remember, research can be a journey filled with unexpected twists, but it's these challenges that often lead to breakthroughs. Keep your curiosity alive and continue your pursuit of knowledge in the fascinating world of ZnO-based thermoelectric materials. If you have any more questions or need further advice, feel free to ask.

Thermoelectrics are materials that can generate electricity from the application of a temperature gradient, or vice versa, through the thermoelectric effect. By exploiting this coupling between thermal and electrical properties, thermoelectric devices can be made that carry heat from a cold to a hot side (refrigeration) or that generate electricity from heat flows.

Good day, Immanuel Paulraj! Hope you are doing well.

Sn-Bi alloy is possible to prepare via hydrothermal method. Here is a brief methodology:

"Sn–Bi alloy structure was directly grown on the CF substrate by the hydrothermal method. Specifically, 0.143 g of Tin (II) acetate (Alfa), and 0.190 g of Bismuth (III) chloride (Sigma–Aldrich), 0.073 g of urea (Sigma–Aldrich), and 0.112 g of ammonium fluoride (Sigma–Aldrich) were transferred in 60 mL DDI water by vigorous stirring. The pH values were tuned by hydrochloric acid until the solution turned transparent. Such precursor solution along with one piece of pretreated CF (2.5 × 5.0 cm2) was transferred into a 100 mL Teflon-lined autoclave and heated to 180 °C for 10 h. Sn–Bi alloy on CF obtained from the hydrothermal process was rinsed repeatedly with DDI water and ethanol, then dried overnight at 80 °C under vacuum."

Link:

You may also found XRD patterns there.

Feel free to mention me in your response in case of any extra questions.

Best of luck in your research!

Yours sincerely,

M. Sc. Vadym Chibrikov

Department of Microstructure and Mechanics of Biomaterials

Institute of Agrophysics, Polish Academy of Sciences

Very interesting expression, Prof. Immanuel Paulraj I have never seen it before, thank you.

Looks like in these expressions, L here is the new Lorenz coefficient - L (η), S(η) - is the new Seebeck coefficient and where disorder enters? is in the parameter η?

k_e = S(η) L(η) T ? does η have some expression or is it just an empirical dimensionless parameter?

Best Regards.

PD. I found this but is not similar: https://arxiv.org/pdf/1904.03183.pdf

Ndukwe Augustine thanks for your answer brother. Where can you send me the links for self study?

Hiba Arous

Your work is appreciable as you know it's a quite interesting area. In fact, when I try to explore articles on similar work, I seldom found few articles, which I will share with you, as I hope you may find them beneficial.

Modeling of a hybrid electric heavy duty vehicle to assess energy recovery using a thermoelectric generator - https://www.sciencedirect.com/science/article/abs/pii/S0360544218302512

The Potential of Thermoelectric Generator in Parallel Hybrid Vehicle Applications -

Thermoelectric Generation in Hybrid Electric Vehicles - https://www.mdpi.com/1996-1073/13/14/3742/htm

Modeling of a hybrid electric heavy duty vehicle to assess energy recovery using a thermoelectric generator - https://econpapers.repec.org/article/eeeenergy/v_3a148_3ay_3a2018_3ai_3ac_3ap_3a1046-1059.htm

Holistic Development of Thermoelectric Generators for Automotive Applications -

Best wishes

Dear Abdul Rehman,

Firstly, Mg evaporation has to be done under a high vacuum system. A rotary pump is not enough to avoid the oxidation of Mg. Two stage pump evaporator is required to achieve lower than 10-6 mbar pressure.

Secondly, a glovebox system connecting to an evaporator is ideal to deal with Mg materials when you load Mg into your evaporator without exposure to air.

Hope it helps.

I think when calculating the transport properties, the band structure is assumed to be temperature-independent. This should be a good assumption in most cases. The temperature dependence of the transport properties is then from the Fermi-Dirac statistical distribution and the temperature dependence of the scattering rate (relaxation time).

Elaborate. define doping (substitutional or interstitial?). define strain field and what do you mean by fluctuation? If your material is a secret, label it as (A1xBx)C.

For WIEN2k run: "x lapw1 -up" and "x lapw1 -dn"

Following paper may help you,

In addition to all interesting answers, for the case of low temperatures measurements on some binary semiconductors, I read some time ago the following report on thermoelectric properties (Seebeck coefficient) and impurities role, Dr. Younas Iqbal

Enrico Sergio Mazzucchelli

Thanks for the answer! In the first article, there is some info in the reference Ghojel 2005, however, it is said there that: "The databases in the software do not include inventory tables for Bi2Te3 or its constituent elements; therefore, the impact of the TE modules on the environment during material extraction and manufacturing processes was ignored.". So I can't get a lot...

The second one is related to other TE materials. Thanks a lot anyway :).

Vivek - Please see this potentially useful article entitled "Simple routes to synthesis and characterization of nanosized tin telluride compounds" In this work, the use of tellurium tetrachloride as Te precursor is described.

Also please find attached a very interesting article entitled "Hydrothermal synthesis of SnQ (Q=Te, Se, S) and their thermoelectric properties". in this work, elemental tellurium is used as Te source for the hydrothermal synthesis of tin telluride. This is perhaps the easiest method.

Dear Prof. Sanjay Nayak,

Theoretically, the calculation of 1/tao is a physical kinetics problem using the Boltzmann transport equation, some use the Fermi golden rule, others use the full green function formalism.

Good examples are given in the literature for unconventional superconductors below their transition temperature, although the calculation of 1/tao is a hard numerical task due to the self-consistent problem went taking into consideration scattering by impurities, it can be done.

The calculated lifetime can be used to plug it in into the electrical conductivity equation, see the references by Prof. J. Carbotte within the following paper:

Dear Peeyush Kumar Kamlesh,

I believe that lattice thermal conductivity can be calculated from phono3py code and is compatible with Wien2k.

This book chapter may help you:

It offers some practical methods to measure ZT and the related thermoelectric parameters such as thermal conductivity, Seebeck etc.

Dear Monalisa Nur Ramadhan

The first and most important parameter to set in your input file is the value of Fermi Level. If you want to consider n-doping set this value to the energy corresponding to the bottom of the conduction band. On the other hand if you want to study the effect of p-doping fix it at the top of valence band. The parameters, deltae and ecut, then allow you to vary the chemical potential around the Fermi level at regular steps (delte) within your desired range (ecut). Alternatively, if you use the latest version of Boltztrap you can directly specify the doping concentrations in the input as well (still you need to specify Fermi level). For example to compare the Seebeck resulting from doping 1x10^20 cm^-3 electrons with that of hope doping of 2x10^20 cm^-3 you can add the following commands to the input:

2

1E20 -2E20

Above, The first line is the number of fixed dopings and the second line defines the corresponding values. For more information, please refer to the manual of Boltztrap (attached here)

Dear Bashar,

I think that we can benefit from yourself answering the question after all this time.

You are an expert now.

Regards,

Dear Thomas Anthony Troszak ,

if you use extensions of the same material and connect them under the same conditons, the additional thermovoltages rule out. But you must ever be sure, what you exactly do. Let me give an example used in practice:

Thermocouples are used in vacuum container to determine temperatures. Lets say, you want to bake out a recipient or you want to heat a sample holder to a certain temperature. You fix your thermocouple to the corresponding point the temperature T you want to control. It can be that the couple is not long enough. Furthermore, you have a feedthrough you must connect your wires with it. Then you have almost different metals. On the outside you must use a special plug which contains a contact of the identical material combination. The material combinations are standardized (example type K). The outer contact lies at room temperature. With a control unit which measures the T you control the heater. Of course, if you have more extensions, the contacts between different materials can be different (oxidation, lubrication). Therefore, it is important, if you want exact results, to control the measurement of T.

First test: The thermovoltage must be zero, if both contacts have the same T (room temperature). If there are any contact potentials then you see them.

Second test: You put your "hot contact" into a reference liquid (boiling point must be known). Then you must get the right temperature difference.

With Regards

R. Mitdank

Franklin Uriel Parás Hernández:

You can refer this paper for the similar work related to antimony based material.

Dear Boyue,

You will find very useful information about the doping (Intrinsic carrier concentration) on the website below:

Dear Franklin,

You will get these graphs in many literature. But it is not possible to get these graphs upto 1000 degree celsius for all materials.

Anyway, I think it is better to get these results by your own Experiments because standard data always doesn't match with your working material due to impurities and difference in microstructures.

If anything you want regaring the Experimental details for these I can tell you ( but upto 600 degree Celsius)

Love and Regards

N Das

Dear Abhinav

As far as I know, you can not calculate the thermal conductivity using Phonopy. You need to use another package (Phono3py) for this purpose. However, the projector augmented wave (PAW) Pseudopotentials are the best for performing the self-consistent field (SCF) calculation with Quantum Espresso. This approach is more close to the experimental results while it's computationally rather expensive.

If you have another question, just let me know.

Dear Ganesh Hegde :

I think all is about a misunderstanding about the "law".

This "law" does n't work for Phonons, just for Electrons. This means that it is not applicable for the Lattice Thermal Conductivity part, but just for the electronic contribution to k_Tot.

This is the reason of why this "law" is only valid for metallic materials, and is a rough approximation for degenerated, or highly doped semiconductors.

If you search in a solid state physics textbook how this Law was derived, it was done using the Drude's model for electrons; using this model, the expressions for Specific Heat and Thermal Conductivity were put in place using the Maxwell-Boltzmann statistics, and the Electric Conductivity (this is the most important derivation form the Drude's model) was considered just looking at the free carriers in the solid only as charged free particles (electrons) in a static periodic lattice of static massive ions. However, neither the thermal fluctuations of the lattice, nor the vibrations of it are taken into account.

So you cannot calculate k_L using the Wiedemann-Franz's Law., k_L was not involved whatsoever in the derivation of this model.

Regards!

Cory Jensen , Thank you!, I appreciate it.

Regards,

Dear pham,

Thermoelectric (TE)material effectiveness will be defined as:

{ZT=(S^2)( σ )(T)/(K)}

which {S} is seebeck coefficient, {σ } is electrical conductivity, {T} is absolute temperature and, {K} is thermal conductivity.

and efficiency of a thermoelectric materials is eta=(T_hot-T_cold/T_hot)* (sqrt(1+ZT)-1)/(sqrt(1+ZT)+T_hot/T_cold)

So a good TE material should posses:

-The higher ZT value

-Large Seebeck coefficient

- High electrical conductivity

-Low thermal conductivity

Nima.

Seemingly of some possible interest: https://www.researchgate.net/post/Why_is_Bismuth_considered_bad_for_ultra_high_vacuum

You can achieve the result if you use ion-plasma sputtering.

Hey Sam S. :

I'm sure you are refering to the Thomson Effect. let me explain more:

Any material (metal, insulator, semimetal, semiconductor, polymer, etc .. ), no matter its classification, if it has a Temperature-dependent Seebeck Coefficient, then you will observe a Thomson Effect at some degree. Which is what you are looking for.

The Thomson Effect is the following:

If you have a material in which the dS/dT (where S is the Seebeck Coeffieciente, and T is Temperature) is not zero, then the Thomson Coefficient of the material: K = T(dS/dT) is not zero, and it will show a Thomson Effect.

Meaning that if you set a difference of Temperature between both sides(or edges) of the material, you will be able to measure a difference in electric potential between these two terminals. And the opposite,

If you apply and delta of electric potential between both sides of your material you will be able to transfer heat from one direction to the other (i.e. heating one of the faces of the material and cooling the other).

Not just thermoelectric materials can do this.

Any material which with a Seebeck Coefficient which is a function of temperature... i.e. its derivative with respect the Temperature be different than zero.

To built such devices what you need to use is the Seebeck and Peltier Effects not the Thomson .. The Seebeck and Peltier Effects are found in a juction of two different metallic (or semiconductor) materials. Is driven by an electrochemical potential of electrons... much like the phenomenon of Corrosion in metals

I recomend you to search for both of these phenomenos in the literature ...

1. The Thomson Effect, which applies both, to individual materials and to a junction of two different materials, and

2. the Seebeck-Peltier Effect (commonly known as the Thermoelectric Effect too) this one only applies to a junction of two different metals.

So to build cooling or heating devices using the thermoelectric effect you need to build a junction of two (commonly degenerate semiconductors, i.e. doped semiconductors) with its corresponding electric contacts.

Regards ! :)

Dear Abhinav ,

The question came in mind is why you need it in parallel ? Boltztrap just process DFT data and run no-costly calculation relatively to DFT. that's why it is not designed to run in parallel mode I think.

it never exceed one hour for a single core for me !

Regards.

Tayeb.

Hello Syafkeena Affandi !

I think I am a little familiar with what you are talking about (based on my literature references too):

What you are trying to study and observe is the so called Quantum size effects (i.e. Quantum Effects due to the reduction in lenght).

Have you read about Quantum Confinement of Excitons in semiconductor nanoparticles ? e.g. Si, Ge, GaAs, etc.. ? meaning Quantum Dots...

I will attach below a very nice review about this whole phenomenon of Quantum Effects due to lenght reduction, ... the main mechanism: Quantum Confinement of Electrons/Excitons.

I hope you can give it a look and let me know some of your comments about it.

I recomend you to go particularly to the sections about Quantum Confinement, the Exciton's Bohr Radius and the clalculation of the total Energy of the Exciton. I'll leave it in the link below...

What you are speaking is about the topics of Quantum Dots and the Quantum size effects when the lenght scales get to the scales of the de Broglie Wavelenght of the electrons, or excitons on these nanoparticles, (this is the phenomenon called Quantum Spatial Confinement of electrons/excitons).

So implicitly, you are talking of Quantum Dots. You will find this definition in function of the Exciton's Bohr Radius, more than the de Broglie Wavelenght.

I am sure the reading I left below will be very useful, but loosely speaking:

The main explanation finds on the understanding of how the DOS (Density of States) is modified due to the reduction in lenght of the material. i.e. ; The Density of Satates gets modified and its distribution become to turn discrete again, like an atom, so the nanoparticle starts to show a Energy States distribution like those of an individual atoms, with discrete States of Energy.

So these particles (which are called Quantum Dots) start then to show diverse effects related to a spatial confinement of their carriers, since the Energy States are discrete now,}

for example: discrete spectra of light emission, and increment in chemcical reactivity sometimes, an increment on the optical bandgap, phenomena as Electroluminescense, Fluorescence, etc ...

So, your observation about the increment in the electrical Conductivity likely is related to these phenomenon too.

Review the reference I sent you, and also I have a PPT presentation on my 'Research Items', specifically about Quantum Dots, it may be useful to you too.

I agree with you!, is a very interesting topic of research.

I work more with thin films of semiconductor materials, and no with nanoparticles or QDs...

What materials you work with ? Do you syntethise these nanoparticles yourself (your Lab group) ?

Good Luck ! Regards !:)

Dear Bazlul,

the word "degeneration" has a double meaning. We have semiconductors with "degenerated bands" as described above by M. Stutzmann. This enhances the density of states by the degeneration factor. The second meaning is "degenerated semiconductor" what means that the Quasi fermi level lies in the bands. In "normal" nondegenerated semiconductors you find the fermilevel near the donor or acceptor level. The thermoelectric efficiency (ZT) passes through a maximum if the fermi level crosses the band minimum (maximum).The semiconductor is just degenerated. This maximum of ZT enhances with the number of simultaneously crossed band extrema.

Therefore, both degeneration factors effect positively on ZT.

Regards

R. Mitdank

Also for your reference, "Finite elements for thermoelectric device analysis in ANSYS":

Regards.

Yetkin Şen :

I believe what you are referring is to the nanostructure of these kind of bulk materials (so called conventional TE materials).

If so, you aren't going into the wrong direction...

Modifying the nano & micro structure of these bulk materials is one of the strategies that has been followed to increase the ZT, and has given good results in many cases (ZT up to values of ~1.5).

These ideas are not new at all, so there are a lot of works studying different ways to nanostructure these type of bulk materials, which to beging with, should be structured as polycrystals (is important to have high density of grain boundaries)...

These ideas have more than 20 years and began precisely with Bi2Te3 and Sb2Te3 based alloys.

One of the ways to do this is with what I believe you are trying to say with "suitable composite materials", since some of the techniques involving working with the nanostructure involve adding nanoparticles of different nature, as metallic nps or metal oxides, e.g. Cu nps, ZnO, Al2O3, etc... or other nanostructures from metals as Bi or others...

But in the end, It has n't seen to work as well as with Carbon nanostructures.

Nowadays there has been many studies with Carbon nanostructures like: Graphene and Graphite nanoplatelets, CNTs , Graphene Oxide, even C60 molecules ...

There are many studies regarding this topic, and several variations regarding the sites in the bulk structure where these nanostructures need to be placed (as in a matrix with embedded nanoparticles), also the Grain Boundaries play an important role in these materials

Anyways I will recommend you still to continue on the line of the bulk conventional TE materials, like the ones already mentioned above, but try to look up for these kind of studies of a nanostructure modification approach ...

There is another totally different approach along the lines of Quantum materials (as Quantum Wires or Quantum Dots, etc), but that is another different approach, where now the main problem you have is the high fabrication cost..

Let me see if I can find a general reference for you to attach here ...

Best Regards ! :)

The following is a good reference: a paper review-kind of nanostructured bulk TE materials

Hi,

you can find below two modules can help you to plot your data:

https://github.com/K4ys4r/BoltzGnu by using gnuplot

https://github.com/K4ys4r/BoltzTraP_Tools by using python and matplotlib

Hop that helps you

Hilal

Dear Yaoshu Xie:

According to Y2O3-Fe2O3 phase diagram the stable region of Y3Fe5O12 (YIG) is very narrow and to obtain pure YIG phase. So first, take a deep consideration on the stoichiometry of the mixture and to prevent the formation of YFeO3 you can add about 5 wt% excess Fe2O3(see the literature below) . The second point is about the temperature. To obtain pure YIG phase it's better to calcine the mixture at about 900-1100 C and after that, the sintering process should be done at about 1300-1400 C.

"The behavior of high frequency tunable dielectric resonator

antenna (DRA) with the addition of excess Fe2O3 in Y3Fe5O12

(YIG) formulation"

L. Arivazhagan

Hi, thanks for your valuable comments.

Dear Mariam K.

I think your question is such an interesting question,

First I want to understand well what do you mean with a Electronic state modulation ? Do you mean the Distribution function of Energy of the particles system (i.e. Fermi-Dirac Distribution function for electrons and Bose-Einstein function for phonons) ?

If so, the particles system energy distribution (F-D or B-E) does play an important rol on the modulation of each of the thermoelectric properties of the material, moreover than these function by themselves, their derivatives with respect to Energy, Temperature and Chemical Potential (in the case of electrons (F-D distribution))

And the derivative of the distribution function with respect to Energy and with respect to the Temperature (in the case of phonons, B-E distribution).

Then, there is a function (or a quantity called the "Window Function" also called "Occupation function", which depends on the Energy, chemical potential and the Temperature).

Have you heard about the mechanism energy Filtration for electrons and phonons ?

You can see more about these in the first section of the attached review article

Best Regards !

Dear Franklin,

The basic functioning of thermal and electrical transistors is the same (a transport mechanism that has 2 differentiated states and a way to control that transport in a channel). In a normal transistor the on and off states are pretty much ideal (there are several orders of magnitude in the conductivity of the channel between states) and the control on the switch is almost ideal (ok, I am not talking here about charge trapping, capacitive couplings, etc). In a thermal transistors achieving something similar is rather difficult or

impossible. The heat flow (the equivalent to the current) is not characterised by a single carrier, but by a combination of electron transport, vibrations ( phonons in crystalline materials, propagons/diffusons/locons in amorphous), and finally radiation. The electronic contribution,if any, can be switched off using electromagnetic fields as in normal transistors. However switching off the other two contributions becomes really challenging. The diffusive part (vibrations) requires to somehow control how the atoms interact to each other in the material. A way to do that is by a controlled diffusion of a third material in to the lattice as in the above-mentioned paper. In a "dry" version you will need to look for something triggering a reversible phase change resulting in very different vibrational spectra for each state or something similar. As far as I know there is no easy way to do that, and the concepts proposed by Li in his seminal work have not been properly implemented yet.

Kind regards,

Julian

The contribution of phonons is complex. If we discuss the Figure of merit, we must consider their contribution to the resistance, the Seebeck coefficient and the thermal conductivity.

Thermal conductivity: In metals, the electronic contribution dominates (silver, copper). In semiconductors the contribution of phonons is important. The phonon contribution of the thermal conductivity is proportional to the velocity of sound and the specific heat of the lattice - increasing with temperature.

Seebeck coefficient S: S increases directly with T but furthermore the scattering processes (mobility of charge carriers) influence S. At high T dominate electron-phonon scattering processes. At low T we have additionally to consider the phonon drag.

Resistivity: the resistance is proportional to the mobility. At high T the scattering of electrons to phonons reduces the electrical conductivity. Therefore the Figure of merit reduces with increasing T (so far it is due to the increasing resistance).

Thank you Nidhi !

Regards !

Dear Franklin,

Any ceramic material that does not react with Bi₂Te₃ is suitable for the mold. Apart from graphite, Al₂O₃, SIO₂ (quartz glass) and TiO₂, these are also ZrO₂, Cr₂O₃, Si₃N₄, SiC, AlN and many others. Even simple porcelain would be suitable. Also, some metals, such as precious metals (silver, gold, platinum, palladium and the like) and, possibly, tantalum, niobium, molybdenum, tungsten, zirconium, chromium (nickel chromium) and titanium alloys are possible. The prerequisite for the selection of the metal is its reaction with tellurium: if the metal does not form tellurides it is suitable.

Regards

Vadim

Dear Franklin,

There are three parameters for the figure of merit ZT

ZT=a S²/b

where a is the electric conductivity, S the Seebeck coefficient and b the thermal conductivity,i.e. the electric plus the phononic. In metals these quantities are related, for instance the a and b are related by Wiedemann-Franz law which limits it quite a lot. Thus the best thermoelectric are semiconductors.

I suggest to read the articles on lattice thermal conductivity which includes effects of point defects and other related parameters in solids particularly semiconductors

"Nanoscale size dependence parameters on lattice thermal conductivity of Wurtzite GaN nanowires"

Article in Materials Research Bulletin 47(5):1264–1272 · May 2012 with 145 Reads

DOI: 10.1016/j.materresbull.2011.12.025

and related articles

The error appears due to wrong name of the working folder and intrans file. Be sure these names are correctly set up. It seems that your installation is ok. The main problem in the naming convention!

Dear colleague Djalila Boudemgh

Have a nice time and good day.

You can try this method and confirm by density of states.

At one side of your material -bulk or film- but heater probe, as mentioned in the attached file and connect voltmeter as shown in the attached figure. Just the negative side is heated, the electrons will move to the other side from negative side to positive side then the electron migration will turn the negative side to positive. on the screen of voltmeter you will see negative sign this means your material is N-Type other wise P-Type.

Just you know your P or N-Type material you can confirm by DOS.

I wish this is useful and help you.

Yours

A. Eldenglawey

Thank you Dr. P. Eklund for suggesting me good review articles.

Care to explain how this publication leads me to a solution? 

Maybe, zirconia oxide (ZrO2) is a relatively good choice to the electrical and thermal insulator when the temperature is 1200°C or above. For thermal insulation, it should be no problem. I did not measure the electrical insulator of ZrO2 and not sure it is perfect or not.

Here is a great article and you can join for free and download pdf

Dear Anil, Dear Vignesh, could you send me an email: fresner@stenum.at, I think I have to describe in more details what we are working on

best regards

Johannes

Thank you Prof. Jerzy Antoni Krupka for your clear answer and suggestion, Your work is very useful, thanks a lot.

Dear Liwei,

In general, materials having high melting temperature are prepared by powder metallurgy process for high temperature application. It has many benefits from technical and economical point of view as it does not require very high temperature but gives desired properties. The thermoelectric materials are generally high temperature materials. Besides, as you mentioned, the powder metallurgy process helps to reduce the lattice thermal conductivity due to large number of grain boundary, with considerably high electrical conductivity and Seebeck coefficient. You can read the attached article for details.

For thermoelectric applications, it's not the value of Seebeck coefficient matters.  Also, other two parameters viz. electrical conductivity and thermal conductivity to find out the figure of merit (ZT) of the materials. Would you please tell me the what is the value of Seebeck coeff. measured at temperature.

Thank you. I will perusing the article and write for further query. 

Perhaps you mean "coherent interface"? This term defines whether both lattices facing a heterogeneous interface at a certain orientation relationship match to each other or not. 

Dear Vitaly,

I think there is no code for calculating the drag part of Seebeck coefficient, but in order to correlate your Seebeck coefficient in cryogenic temperature region, you have calculate the phonon density of state in this region that will indirectly give you some correlation. I hope it will help. Please reply if you have some more idea regarding this.

Best regards,

A. Ahad

Yes

you can read this paper

Effects of heat enhancement for exhaust heat exchanger on the

performance of thermoelectric generator

Chi Lu, Shixue Wang*, Chen Chen, Yanzhe Li

James,

 Indeed: My own suspicion is that the universe is not only queerer than we suppose, but queerer than we can suppose.

  A rube goldberg sort of universe

Only discuss this a bit more:

Everybody knows that simulated phase diagrams are based on apparently unrealistic conditions. On the other hand, when they are that unprecise why we are using them if they match? :-) Wishful thinking?

I am no expert in thermodynamics but I (personally) do not know any case where a phase diagram was that far away from the experiment. We are not talking about 2 or 5%.

And if you "freeze" a material as discussed above, the phase diagram does not change but in first approximation stores the chemical composition at this temperature. The temperature might be different than assumed, but this uncertainty can be discussed during error approximation. If phase diagrams would be that wrong our steel production (fast cooling, complex heat treatment) could never deliver a steel with the "same" specifications.

Pure WO₃ can not be sintered at 600°C. Melting point of pure WO₃ is very high and it evaporates earlier than it can melt. However, if you add to WO₃ potassium carbonate (K₂CO₃) or sodium carbonate (Na₂CO₃), you can sinter a solid body. Tungsten oxide reacts with alkalis with formation of easy to melt tungstates. In systems K₂O-WO₃ and Na₂O-WO₃  to form eutectics  with the melting points < 900°C.

So try to mix a pair of percent of alkaline carbonates to your WO3 powder and sintere it at about 900°C.

How to find the number of charge carriers.

In the 3rd column of  ANT.trace file, the units in e/uc but I need in cm^-3 ?

How to convert N values in cm^-3?

Thanks in advance.

Please see for example the National-Instruments article number  779732-01 and others- 0x for different voltages of the mains power supply.

While there is quite a lot of debate about the mechanisms by which filler atoms in holey structures like skutterudies and clathrates lower the thermal conductivity, the "rattler" theory suggests that the filler atoms are independent oscillators with discrete frequencies (dispersionless).  A low lying optical mode isn't an Einstein mode.  However, some suggests that the rather than Einstein modes, there is an avoided crossing of a low lying optical mode and the acoustic modes that reduces the group velocity as it flattens the acoustic branches.

That is all to say that, no, an low lying optical mode isn't necessarily an Einstein mode, unless maybe if it is dispersionless. I hope that helps!

Also I suggest these papers (DOIs):

10.1103/PhysRevB.82.174301

10.1103/PhysRevLett.90.135505

10.1038/nmat2273

Many companies have an established technology. On the first of the use of new materials with nanoparticles should modify the technology to take into account the specifics of new materials, such as, what materials should be contacts that do not change the conductivity, etc.

 Therefore, if the result will not be having large commercially impact, few companies are ready to invest in this upgrade, if they have reliable technology on this time.

I think, with these ideas the create of startups is more convenient.

Dear Umair,

Many material have large Seebeck coefficient at low temperature. but they also have high resistivity at this regime. For high ZT the large S and low sigma is the challenging task. Yes of-course there is role of thermal conductivity also but at low temperature due to low sigma,  the thermal conductivity due to electron is also low but large due phonon electon scattering that is dominant at low temperature.

Best regards, A. Ahad

thank you so much Dr. Ahmed Saeed Hassanien 

Plotting thermoelectric parameters against temperature is not simple. First you have to plot against the chemical potential at particular temperature. Plot for different set then taking the peak value of each set  plot against the temperature. The Fermi energy which is feed in the intrans file is taken to be reference as 0.

Thank you all for your suggestions.

Dear William,

I want to clear one thing.I went through second Paper. If I have understood, in an efficient generator ideally the relative current density should be constant throughout the segments (or the compatibility factor, s differs by factor of 2). It is mentioned that the some refractory materials such as SiGe and Boron carbide has very low s due to their very low electrical conductivity and high Seebeck coefficient. So these are not compatible with PbTe, TAGS or even skutterudites for a suitable segmented device (here we have to remember that, we are not taking care of other factors such as chemical stability, heat loses, thermal expansion coefficients etc). My query is, can those materials (SiGe and boron carbide) be segmented with some materials of comparable s  and whether TE properties of such materials are studied ?

You could try having a look at the RS Amidata catalog (http://uk.rs-online.com/web/c/hvac-fans-thermal-management/electronics-heating-cooling/peltier-modules/?searchTerm=peltier). Selecting the appropriate cell requires a bit of reading carefully the tech. specs. of the articles and some rough estimations/calculations of the heat flux, DeltaT, etc. In principle it should not be difficult to do. Anyhow, if you are working at really low gas flows a coil condenser similar to cold traps used in other common lab equipments could also work to collect condensables from gases. Good luck!

Thank you, Hilal. I will learn about it based on your answer.

I really appreciate it.

Garam Choi

Generally, the efficiency of the thermoelectric material depends on the thermoelectric figure-of-merit Z, which is expressed as S²sigma/kappa. In your case, if both S and sigma are increasing in the sense, the thermal conductivity of your material decreasing simultaneously. This may be attributed due to the carrier confinement effect (i.e both electrons and phonons), if your material is a nanostructured material. If you want to interpret more in detail, it is necessary to discuss about, all scattering processes that take place in your material.

Particularly, I think, the behavior of such increase in S and sigma may be due to phonon-drag contribution to the Seebeck coefficient of the material itself. Therefore, I suggest that, it will better if you discuss in detail about the carrier mobility of your material due to lattice scattering (i.e electron-phonon scattering).

Also, the scattering process depends on the type of material, you fabricated. If your material is an alloy semiconductor, then the confinement effect will takes place due to defect-boundary scattering of phonons.

I think, this will help for you.

I don't remember where i read something about.