Diffusionless reactions of electron exchange in oxide crystals with garnet structure

Principles of crystallochemical and thermodynamic analyses, suitable for any multiple-sublattice crystals and allowing one to calculate the quantity, valence and distribution of cations with regard to their magnetic state in nonstoichiometric multicomponent garnets, are formulated. It is shown that diamagnetic garnets (M1M22) [M22+] (V35+)O12 (M1 -Cu, Ag, K, Tl; M2 - Ca2+, Pb2+; M2+ - Mg,Zn,Cd) become weak magnetics as a result of thermochemical treatment at pO2<pO2eq. A new type of diffusion-free electron exchange reactions which are inevitable in all crystallographic structures, containing non-equivalent lattice points and produced by variable valence ions, is revealed. Effective ion radii are calculated (the shannon system)