MICROSCOPIC STUDIES OF THE PHASE-TRANSITION IN FERROELASTIC BIVO4 BY USING MAGNETIC RESONANCES OF V-51 AND MN2+

The temperature dependences of the asymmetry parameter eta of the V-51 nucleus and the second-order zero-field splitting (ZFS) parameters D and E of the Mn2+ impurity ion in BiVO4 single crystals are fitted wit h a function alpha(T-c - T)(beta). The (T-c - T)(1/2) behavior resembl es Landau's theory of the second-order phase transition in ferroelectr ic crystals. The temperature dependence of the electric field gradient at the V site is also found to be closely related to the lattice para meters of the crystal.