Sound velocities and thermal properties of BeX (X=S, Se and Te) alkaline-earth chalcogenides

Abstract

The sound velocities and some thermal properties of BeX (X=S, Se and Te) beryllium-chalcogenides large band gaps semiconductors have been estimated by employing some usual theoretical and emperical formulas. The lattice parameters and the elastic stiffness constants used here are taken from the literature. The longitudinal, transverse and average elastic wave velocities, the Debye temperature, the melting temperature, the thermal conductivity and the Grüneisen parameter are successfully predicted and analyzed in comparison with the available experimental and theoretical data. In general, our obtained results of these quantities agree well with the experimental and other theoretical data of the literature.

Sound velocities and Debye temperature of BeSe under high pressure up to 50 GPa

“…Using the previous numerical values of the elastic constants Cij and the crystal density g, the numerical values obtained of the sound velocities for major directions in BeSe semiconductor up to 50 GPa are reported in Table. 3. The obtained values at zeropressure are compared to the data obtained in our previous work [12]. To the best of our knowledge, there are no data available in the literature on the sound velocities for major directions in BeSe material at high pressure.…”

“…But, usually the thin films and bulk materials are used in the fabrication of the electronic and optoelectronic devices, so with consequence, the average values of different quantities are used. The average sound velocity (vm) is determined from the longitudinal (vl) and transverse (vt) wave velocities by using the following formula [12], [14]  …”

“…The longitudinal and transverse wave velocities may be calculated using the following expressions [12], [14]:…”

“…There are several empirical formulas related the Debye temperature θD and other physical quantities (elastic constants, thermal conductivity, sound velocity,…etc). For materials with cubic zincblende and cubic rock-salt structures, the Debye temperature θD can be obtained from the average sound velocity vm (given in km/s) and the lattice parameter a (given in Å) by means of the following simple formula [12], [14]:…”

“…The sound velocity, the thermal properties and other physical quantities under pressure and at equilibrium conditions of BeX (X=S, Se and Te) binary compounds [5][6][7][8][9][10][11][12] and ternary alloys [13] are the subject of several studies. In the present work, we have predicted the directional dependence of elastic wave velocity, the longitudinal, transverse and average sound velocities, and the Debye temperature up to 50 GPa of BeSe semiconductor.…”