debye temperature उदाहरण वाक्य
उदाहरण वाक्य
- At low temperatures ( T is far less than Debye temperature ), the relaxation time is determined by scattering of fixed impurities, defects, sample boundaries, etc . and is roughly constant.
- Umklapp scattering requires production of a phonon beyond the Brillouin zone boundary; because of the high Debye temperature of diamond and graphite, the peak in the thermal conductivity of these materials is near 100 K, significantly higher than for most other materials.
- However, as shown below, kT _ D is roughly equal to the phonon energy of the minimum wavelength mode, and so we can interpret the Debye temperature as the temperature at which the highest-frequency mode ( and hence every mode ) is excited.
- In the low temperature limit, the limitations of the Debye model mentioned above do not apply, and it gives a correct relationship between ( phononic ) heat capacity, temperature, the elastic coefficients, and the volume per atom ( the latter quantities being contained in the Debye temperature ).
- Both are usually found by fitting the models to the experimental data . ( The Debye temperature can theoretically be calculated from the speed of sound and crystal dimensions . ) Because the two methods approach the problem from different directions and different geometries, Einstein and Debye scales are "'not "'the same, that is to say
- For scattering from acoustic phonons, for temperatures well above Debye temperature, the estimated cross section ? ph is determined from the square of the average vibrational amplitude of a phonon to be proportional to T . The scattering from charged defects ( ionized donors or acceptors ) leads to the cross section { \ Sigma } _ { def } \ propto { \ left \ langle v \ right \ rangle } ^ {-4 }.
- where \ rho ( 0 ) is the residual resistivity due to defect scattering, A is a constant that depends on the velocity of electrons at the Fermi surface, the Debye radius and the number density of electrons in the metal . \ Theta _ R is the Debye temperature as obtained from resistivity measurements and matches very closely with the values of Debye temperature obtained from specific heat measurements . n is an integer that depends upon the nature of interaction:
- where \ rho ( 0 ) is the residual resistivity due to defect scattering, A is a constant that depends on the velocity of electrons at the Fermi surface, the Debye radius and the number density of electrons in the metal . \ Theta _ R is the Debye temperature as obtained from resistivity measurements and matches very closely with the values of Debye temperature obtained from specific heat measurements . n is an integer that depends upon the nature of interaction:
- where ?M?is the mean atomic weight of the atoms in the primitive cell, " V a " = 1 / " n " is the average volume per atom, " T D, " " is the high-temperature Debye temperature, " T " is the temperature, " N " o is the number of atoms in the primitive cell, and ?? 2 G ?is the mode-averaged square of the Gr�neisen constant or parameter at high temperatures.