Abstract
Unit cell dimensions and oxygen contents of Ba2YCu3O7-y were determined at room temperature for two kinds of specimens with different oxygen contents as functions of annealing temperatures. Unit cell dimensions of ordered orthorhombic phases increase linearly with decreasing oxygen content regardless of the phase transition temperature which is about 570°C. This is evidence for existence of intrinsic phase transition caused by ordering of oxygen atoms. It has been found that oxygen content 7-y equals -5.454c+70.512 where c is c cell dimensions in angstroms.