Nucleation and growth kinetics of the tetragonal to orthorhombic transition in YBa2Cu3O7minus;part;

摘要

The nucleation and growth geometry of the tetragonal to orthorhombic transformation in YBa2Cu3Oxis determined to be grainhyphen;boundary nucleation after saturation. In this geometry the orthorhombic phase rapidly nucleates along the grain boundaries, then propagates into the grains as a planar front governed by the much slower volume diffusion of oxygen. This conclusion is reached by fitting the volume fraction of the superconducting, and hence orthorhombic, phase as a function of annealing time at 400thinsp;deg;C to the Avrami relation. The volume fraction of the superconducting phase is obtained using magnetization versus field data.