A 20-resolved hadox study of bati0³ linz crystals

X-ray intensities in reciprocal-lattice space can be measured with high resolution in two dimensions by improved high-angle double-crystal X-ray diffractometry (HADOX). The method has been applied to the cubic-to-tetragonal phase transition in BaTiCf Linz crystals grown by the method of top-seeded solution growth; the results are compared with those of previous experiments on butterfly crystals of BaTi0³. It is found that the two types of crystals behave in quantitatively different manners around the transition: the transition temperature, the temperature range of two-phase coexistence etc. are different. In both types of crystals, on the other hand, the lattice constant of the cubic phase shows a different temperature dependence when the tetragonal phase coexists, and the orientation of crystal grains shows anomalous behaviour. The results are discussed in terms of the effect of stresses.