Elastic and nonlinear acoustic properties and thermal expansion of rare-earth metaphosphate glasses

Abstract The thermal expansions and the ultrasonic wave velocities and attenuations of (Sm2O3)0.234(P2O5)0.776 and (La2O3)0.222 (P2O5)0.778 and mixed (La2O3)x (Sm2O3)y(P2O5)0.75 (where x + y = 0.25) metaphosphate glasses have been measured as functions of temperature. The change in the ultrasonic wave velocity induced by application of hydrostatic pressure up to 0.16 GPa has also been measured at selected temperatures between room temperature and 375 K. The experimental results provide the temperature dependences of the adiabatic elastic stiffnesses C11 and C44 and related elastic properties and provide the hydrostatic-pressure derivatives (∂C 11/∂P)P=0 and (∂C 44/∂P)p=0 of the elastic stiffnesses and (∂B S/∂P)P=0 of the bulk modulus. The results obtained for C IJ and (∂C IJ/∂P)P=0 are used to determine the long-wavelength acoustic-mode Gruneisen parameters; these quantify the vibrational anharmonicity, which is essential information for developing the acoustic mode contribution to the thermal expansion o...