Reactivity of Ammonium Chloride/Mercuric Chloride Mixtures with Monel Containers. The New Compounds (NH4) 2(NH3)x[Ni(NH3)2Cl4] and (NH4)5Cl2[CuCl2][CuCl4]

We describe the synthesis and structural characterization of two new double perovskites, ALaFeVO6 (A=Ca, Sr), where Fe3 +/V4+ are partially ordered at the octahedral sites. The small charge difference between Fe3+/V4+ precludes the formation of a long-range ordered double-perovskite structure even on prolonged annealing at 1000°C. Electrical conductivity and magnetic susceptibility measurements show that both phases are weakly ferrimagnetic semiconductors where dis-ordered Fe3+–O–V4+ pairs persist even up to ~350 K.