Charge disorder effects in 3d transition metal oxide perovskites

The effects of the random electrostatic potential due to differences in formal charge between A site R3+ (lanthanide, Y), M2+ (Ca, Sr, Ba) and Th4+ cations have been investigated in ferromagnetic AMnO(3) and superconducting A(2)CuO(4) perovskites. Series of samples in which the mean A site charge and the mean and variance of the A cation radius distribution are held constant, but the A site charge variance increases, show no significant changes of the electronic (Curie or superconducting) transition temperatures. The effect of the A cation random potentials on electronic transitions in the 3d metal oxide perovskites are insignificant in comparison to the lattice effects from the differing cation sizes. (C) 2003 Elsevier Science (USA). All rights reserved.