Diluted solid solutions of ’3d’ (chromium) and ’4f’ (neodymium and cerium) elements in the K2NiF4-type 1/1 perovskite rock salt intergrowth structure of mixed aluminates were investigated in order to get evidence of mutual influence phenomena. Crystal chemical data obtained for the solid solution Y1-xNdxCaCryAl1-yO4 (x ? 0.1; y ? 0.1) point to the existence of an Nd(III)-O-Cr(III) coupling in the bridge bonds which connect the perovskite and rock salt slabs. A non-statistical distribution of Nd(III) is very likely to occur in the rock salt slabs. A magnetochemical characterization brings the proof of a partial reduction of Ce(IV) to Ce(III) in the composition Y0.9Ce0.1CaAlO4, as in Y0.8Ce0.1Ca1.1AlO4 the only (IV) valence state is found. The simultaneous presence of Ce(IV) and Ce(III) is confirmed by the results of structure calculations, in terms of a splitting of the Ce-O distances in the rock salt slabs. ? 1997 Elsevier Science S.A.