THEORETICAL CALCULATIONS OF ELASTIC PROPERTIES AND PHONON-DISPERSION OF SE-GE GLASS WITH VARIOUS CONCENTRATIONS OF GE

Citation
Rvg. Rao et R. Venkatesh, THEORETICAL CALCULATIONS OF ELASTIC PROPERTIES AND PHONON-DISPERSION OF SE-GE GLASS WITH VARIOUS CONCENTRATIONS OF GE, Indian Journal of Pure & Applied Physics, 34(5), 1996, pp. 310-315
Citations number
22
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Physics
ISSN journal
0019-5596
Volume
34
Issue
5
Year of publication
1996
Pages
310 - 315
Database
ISI
SICI code
0019-5596(1996)34:5<310:TCOEPA>2.0.ZU;2-F
Abstract
The acoustic Gruneisen constants gamma(g)(L) and gamma(g)(T) have been calculated through Schofield's (Sch) equations and Bhatia-Singh's (BS ) parameters for different concentrations of Ge in Se. The calculated results are in good agreement with experiment. The BS parameters have been used to calculate the phonon frequencies. The third order elastic constants (TOECs) have been calculated using Shiren's non-linear para meter, Thurston's equations and Rao-Venkatesh equation for this glass. The calculated TOECs have been: used to compute the pressure derivati ve of bulk modulus and is found to be in excellent agreement with expe riment. The Smith-DeLaunay-Nath equation has been used to derive the a bsorption band position. From Smith DeLaunay-Nath's equation a new equ ation is derived to evaluate the which is found to be slightly higher than gamma(g)(HT). The slight difference between calculated gamma(g)(e l) and gamma(g)(HT) may be due to the non-excitation of some vibration al frequencies at which the measurements have been made. The phonon fr equency heights both in the case of longitudinal omega(L)(k) and trans verse omega(T)(k) peaks, the TOECs, the absorption band position shows a sharp change and clearly demonstrate the formation of a new Species attributed to be GeSe4 at about 25 at.% of Ge. Experimentally the ela stic moduli also show the same trend. No changes could be observed in the case of acoustic Gruneisen constants and pressure variation of bul k modulus.