Neue Verbindungen mit Granatstruktur. IV. Arsenate des Typs {Na3}[M2III](As3)O12

The preparation and thermal behaviour of two garnets of the type {Na₃}M^III₂]·(As₃)O₁₂ (M^III = Cr, Fe) are described. Both compounds undergo a reversible conversion into a high-temperature phase which, for the case of M^III = Ga, is found as the sole structure type. There is no mixed-crystal formation between {Y₃}Fe₂](Fe₃)O₁₂ and {Na₃}Fe₂] · (As₃)O₁₂ Preliminary investigations were performed on the possible mixed-crystal formation between the Ga compound and the Cr and Fe garnet structure, respectively.