THE EFFECT OF POROSITY ON ELASTIC-MODULI OF YBA2CU3O7-DELTA HIGH T-C SUPERCONDUCTORS

Abstract

The ultrasonic velocity measurements of a series of YBa2Cu3O7-delta samples having different porosities, have been undertaken by the Pulse Transmission Technique. Using the experimental values of Young's moduli, the void-free elastic moduli of all the samples have been arrived at theoretically by assuming that the shape of the pores is spherical. For this purpose, different types of equations viz. linear, non-linear, exponential and power types have been used. Later the computed Values have been compared with the polycrystalline Young's modulus value obtained by Voigt-Reuss-Hill (VRH) scheme using the single crystalline elastic stiffness constants available in the literature. It has been concluded that the Young's modulus values obtained by the power equations are more accurate in predicting the void-free state of moduli of Y-Ba-Cu-O samples of present investigation, when compared with those obtained by other types of equations.