On the orientation relationships in phase transformation of CaTiO3

Electron Backscattering Diffraction (EBSD) is a well-known technique which is primarily used to analyse the microstructural features in metallic materials, including the orientation relationship between microstructural constituents. However, its versatility has not yet been critically utilized to establish crystallographic relationships involved in phase transformation of ceramics. In view of the significance of transformation twinning in ceramics on mechanical properties, the representative orientation relationships in twinned grains of CaTiO3 is investigated using EBSD. It is observed that the matrix/twin pairs of CaTiO3 have misorientation angles at 87 degrees, 90 degrees and 98 degrees. The misorientations associated with the boundaries between twin/twin pairs formed by different twinning orientation relationships are noted at 90 degrees, 91 degrees, 92 degrees and 98 degrees. On the basis of the orientation relationships, the crystallography of cubic to orthorhombic and tetragonal to orthorhombic phase transformations in CaTiO3 is explored. The most favorable orientation relationships pertaining to such a phase transformation are (001)(0)[100](0)parallel to(03 (1) over bar)(c)[(3) over bar 13](c) between parent cubic and daughter orthorhombic phases and (001)(0)[100](0)parallel to(1 (1) over bar(2) over bar)(t)[(8) over bar(2) over bar(3) over bar](t) between parent tetragonal and daughter orthorhombic phases of CaTiO3.