Study on Thermal Hysteresis of Elastic Modulus in Granular Y-Ba-Cu-O and Bi-Sr-Ca-Cu-O

Abstract

A large thermal hysteresis ( > 100 K) of elastic modulus was measured for coarse grained Y-Ba-Cu-O and Bi-Sr-Ca-Cu-O. Whereas, only a small thermal hysteresis (2--3 K) near the velocity minima at 240 K, and 150 K was observed in Bi 2 Sr 2 CaCu 2 0 8 single crystal, which were found to be associated with phaselike transitions (PLT). The investigations of isothermal recovery of modulus for coarse grained YBCO and BSCCO disclose that the large thermal hysteresis may be attributed to the defects of pore size generated in the interconnecting region between grains as a result of PLT of weak first order but covering a wide temperature range. The mechanism of a large thermal hysteresis for coarse grained samples has been discussed in detail.