Ultrasonic study on germanium-rich binary V_2O_5-Ge_O_2glass: Signature of isopaustic character

摘要

Study of the composition and temperature dependence of the acoustic properties of glasses is a valuable aid for preparing new glass materials. Such study may lead to the preparation of isopaustic glass, i.e. glass having a zero temperature coefficient of sound velocity. Isopaustic glasses may be composed of two component glasses with positive and negative temperature coefficients competing against each other. Search for such glasses is important because isopaxistic glasses find application in many acoustic devices such as acoustic delay lines, fitters and ultrasonic wave guides etc., for which acoustic properties are required to have maximum thermal stability in the temperature range of its application. It is known that tetrahedrally bonded glasses like SiO2, GeO2, BeF2 etc. show a minimum [1-3] when the acoustic velocity is plotted against temperature, and at room temperature they have a positive temperature coefficient of the sound velocity, whereas in some other glasses [1-3] having planar structure like B2O3, AS2S3 etc. it remains negative throughout the range from extremely low to high temperatures. For some multicomponent glasses it seems possible to achieve isopausticity by suitably choosing the composition of the system. In a previous communication [4] the velocity and attenuation of ultrasonic waves in V2O5-GeO2 glasses were investigated for different compositions of the binary system at different temperatures ranging from 80 to 300 K.