Chemical wise, the Debye model is explained in the reference (http://pubs.acs.org/doi/abs/10.1021/ic501013x) :
I know that it is important to obtain low temperature heat capacity (C) with high −ΔSm values. However, my question is , what is the advantage of obtaining a material with high Debye temperature.
Generally, the larger the Debye temperature ΘD, the harder the material. Also for insulators where the low-temperature specific heat is determined by phonon excitations, the larger the ΘD, the smaller the low-temperature specific heat; for these materials kBΘD takes over the role of the Fermi energy εF in metals as the physically relevant low-temperature energy scale.
Thank you very much. Please can you tell me what is the expected application for a such high temperature, Also, if there is a review with examples of debye temperature measured for polymeric and discrete molecules.
You are welcome Murad.
The Debye temperature is not one that one measures with a thermometer, but is a parameter in the Debye model. For details, I refer you to Chapter 23 of the book Solid State Physics, by Aschroft and Mermin. As for experiments, I refer you to two relevant pages whose links at attach below.
http://polymerdatabase.com/polymer%20physics/EinsteinFunction.html
http://polymerdatabase.com/polymer%20physics/CpPS.html
Consult the references herein.
http://polymerdatabase.com/polymer%20physics/EinsteinFunction.html
http://polymerdatabase.com/polymer%20physics/CpPS.html
"a molecule" can not have Debye temp. 'cause DT is a term related to the solid state. i.e. MANY molecules (order 10^23, Arrhenius constant). DT designates maximum phonone energy that are able traverse through the solid. The larger DT the harder the material. Dependent from particular needs DT could be required high or low. Molecular materials generally demonstrate low DT, so usually it is required to increase DT to make more robust material for applications etc
Dear Andrey Alex, I respectfully disagree with you. If you consider the relevant literature (you could for instance consult the references that I have cited earlier on this page), you will find abundant use of the term 'Debye temperature', although admittedly the Debye model was originally conceived for macroscopic solids. A molecule, no matter how small, has vibrational modes and a free energy associated with these modes. One can calculate (and measure) for instance the heat capacity associated with these modes and parametrise it in terms of one or more Debye temperatures, exactly as in the case of macroscopic solids.
Dears,
What I mean is the measurement found in http://pubs.acs.org/doi/abs/10.1021/ic501013x
I have similar system and I obtained a debye temperature = 343 K and a survey showed that it is the highest reported system for inorganic complexes.
Dear Murad, the main question on this page reads "What is the importance of finding a molecule with high debye temperature?", which I believe I have already answered. It is not clear to me what question is contained in your latest response. Could you please elaborate?
As I have indicated earlier -- in three separate responses (also with reference to the appropriate chapter in the book by Ashcroft and Mermin), the Debye temperature features in the expression for the specific heat as the temperature scale characterising the variation of the specific heat as arising from the contribution of the vibrational modes of the system, as function of temperature T. From this (since in three-dimensional systems to leading order the last-mentioned specific heat varies like (T/ΘD)3), one infers that the larger the ΘD, the harder the material. In fact, for insulators (where the low-temperature specific heat is dominated by the vibrational modes -- electronic excitations in these systems have an exponentially small contribution to the specific heat at low-temperatures) the melting temperature proves to be invariably of the same order of magnitude as the Debye temperature.
I think you will have to make a literature search on the Debye temperatures and mechanical properties of a set of systems that are similar to your system and see whether you can draw a clear conclusion with regard to a correlation between the Debye temperature and the elastic properties of these systems. I think experimentalists working in the area of atomic force microscopy know a great deal about the mechanical properties of molecules, large and small.
Thank you prof faird very much. I guess your last comment is a good answer to what I want to understand. It was a helpful.
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