Temperature Dependence of Elastic Constants and the Velocity of Propagation of Ultrasonic Waves in High Permittivity Ceramics

Abstract

In order to work out the elastic constants and their temperature dependence of high-permittivity ceramics the velocity of propagation of ultrasonic waves were studied using the rotating method which measures the angles of total reflection of insident beam by rotating the specimen. From the results the velocities of transvers and longitudinal waves and thus the elastic constants may be worked out.The following measurements were carried out:(1) The velocities of longitudinal and transvers waves of the frequency of 5MC in Barium Titanate were measured at the temperatures between 10° and 140°C. From the values obtained the temperature dependency of Young's modulus, Poisson's ratio, Lamé's constant, bulk modulus, and compressibility were worked out. The measurements were extended to a binary system, BaTiO3-BaSnO3.(2) The same measurements were carried out with TiO2, CaTiO3, NiSnO3, CuZrO3, etc., with a result that the velocities in TiO2 and various titanates were in the range of 7000-9000m/sec.(3) The elastic constants of Barium Titanates showed the slight fluctuations according to the method of preparing the specimens, which probes that this simple method is accurate enough to detect such small differences.The present method seems to be very convenient for the measurement of elastic constants of other ceramic materials whose mechanical properties are important for practical use.