Elastic constants of high temperature superconductor YBa₂Cu₃O_x

We calculate the defect-free elastic constants of high temperature ceramic superconductor YBa₂Cu₃O_x from measured elastic constants of bulk YBa₂Cu₃O_x which contains numerous microcracks and voids. Defect-free elastic constants represent long-wavelength acoustic phonons and relate to a variety of solid-state-phenomena such as Debye temperature, thermal expansivity and theoretical strength. By the use of the self-consistent method or the differential method, we eliminate the effect of random distribution of microcracks on the elastic constants of YBa₂Cu₃O_x. The scattered-plane-wave method is also used to eliminate the effect of voids and then obtain the defect-free elastic constants. Numerical calculations are carried out and the influence of the microcracks and the voids on the elastic constants of YBa₂Cu₃O_x is discussed in detail.