The prediction of lattice constants in orthorhombic perovskites

The correlation between ionic radii and the lattice constants of orthorhombic perovskites is examined and new empirical formulae for the relationship are derived. As for cubic/pseudocubic perovskites, the lattice constants are largely a function of A-X and B-X bond lengths rather than ionic charge. The average absolute relative error in the predicted a, b, and c lattice constants so derived is expected to be about 0.616%, 1.089%, and 0.714%, respectively; therefore, these formulae are in better agreement with experimental data than those derived by earlier researchers.