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

Abstract

The mechanical behavior, sound velocities and Debye temperature of beryllium-selenide (BeSe) semiconductor under pressure up to 50 GPa have been estimated using the structural parameters and elastic constants of Fanjie Kong and Gang Jiang (Physica B 404 (2009) 3935-3940). The Pugh ratio, the directional dependence of elastic wave velocity, the longitudinal, transverse and average sound velocities, and the Debye temperature are successfully predicted and analyzed in comparison with the available theoretical data. The analysis of the Pugh ratio indicates that this compound is prone to brittle behavior. Our obtained results of the longitudinal, transverse and average sound velocities at high pressure indicate that these of Kong and Jiang (Physica B 404 (2009) 3935-3940) are not correctly predicted.

Bulk modulus of CaO under high pressure up to 65 GPa

“…The Debye temperature θD is an important thermodynamical quantity describing various physical properties of solids that are related to lattice vibrations [6,8,26]. Debye temperature θD represents highest mode of vibration of the crystal, during phonon vibrations [27], it is usually calculated from the elastic constants Cij [28][29][30][31][32]. To estimate the Debye temperature θD of cubic rock-salt CaO compound, we use the experiential structural parameters and elastic constants measured at normal conditions [3].…”

“…The values of the lattice parameter and the elastic constants Cij used here are: a = 4.8115 Å, C11 = 219.4 GPa, C12 = 58.1 GPa, and C44 = 80 GPa, respectively [3]. For materials with cubic zincblende (B3) and cubic rock-salt (B1) structures, the Debye temperature θD can be obtained from the following simplified formula: θD ≈ 595.467 (vm/a) [31], where vm is the average sound velocity (given in km/s) and a is the lattice parameter (expressed in Å). For aggregate polycrystalline solids, the mean value of the acoustic wave speed vm is given as follows [28][29][30][31]:…”

“…Where vlis the longitudinal wave velocity and vt is the transverse elastic wave velocity, respectively. In general both the longitudinal vl wave speed increases with increasing pressure [31]. They can be calculated from the elastic moduli as follows;…”

Debye temperature of CaO under high pressure up to 65.2 GPa

“…The knowledge of the sound velocity can play in important role in material science [30]. For polycrystalline materials, the mean value of the acoustic wave speed vm is related to the longitudinal vl and transverse vt elastic wave velocities as follow: vm = ((1/3)(2vt -3 + vl -3 )) -1/3 [31][32][33]. The longitudinal wave speed vl as well as the transverse wave speed vt can be calculated from the elastic moduli (B, G) and the mass density ρ using these expressions: vl = ((3B+ 4G)/3ρ) 1/2 , and vt = (G/ρ) 1/2 [5], [31][32][33].…”

“…They found also that both the elastic constants C11 and C12 increase with rising pressure, while both the elastic constant C44 and the Zener anisotropy factor A decrease with increasing pressure. Daoud [7] has studied the sound velocities and Debye temperature of BeSe material under high pressure up to 50 GPa, while several other works [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26] have focalized on the investigation of structural, mechanical, thermal, electronic and optical properties of I-VII, II-VI, III-V and some other materials using different approaches. The intent of this paper is to present and investigate the effect of high pressure up to 65.2 GPa on the bulk modulus, aggregate shear modulus, elastic wave velocities, and Debye temperature of CaO material using only the experimental data reported by Speziale et al [6].…”