Elastic properties of potassium borate glass in a wide composition range studied by Brillouin scattering

Abstract

The elastic properties of potassium borate glass, xK2O. (100 - x) B2O3, where x is the molar composition of K 2O in mol%, have been investigated by Brillouin scattering spectroscopy over a wide composition range of 2≤x≤42mol%. From the observed values of longitudinal sound velocity, the elastic constant has been determined and compared with that of lithium borate glass. The sound velocity increases with increasing x below x = 30; however, for a further increase in x, it decreases owing to the softening caused by the formation and increase in the number of nonbridging oxygen atoms. The absorption coefficient also increases markedly above x = 30 owing to the scattering of acoustic waves by nonbridging oxygen atoms. The temperature dependences of both sound velocity and absorption coefficient of 14K2O.86B2O3 show a markedly change at approximately the glass transition temperature Tg of 395°C. © 2009 The Japan Society of Applied Physics.