Syntheses and properties of a series of chromium vanadates ACrV2O7 (A=Na, K, Rb, Cs) with layered structure

A series of layered compounds ACrV2O7 (A=Na, K, Rb, Cs) were investigated by means of powder X-ray diffraction technique, thermal analysis and IR spectroscopy. As a new member in this family, the structure of CsCrV2O7 is confirmed by Rietveld refinement applying powder X-ray diffraction data. Isostructural NaCrV2O7 was obtained by ion-exchange reaction of KCrV2O7 in NaNO3 melt under 350 °C and was testified to be a metastable phase. These compounds crystallize in a monoclinic structure in the space group P2/c, and consist of planar CrV2O7− slabs interleaved by alkali-metal cations. ACrV2O7 (A=K, Rb, Cs) present decreasing melting points and characteristic vibration of V=O bond in IR spectra. Magnetic measurements reveal weak antiferromagnetic interactions between Cr3+ cations in the isolated chains.