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.

Graphical AbstractA series of layered chromium vanadates ACrV2O7 (A=Na, K, Rb, Cs) have been synthesized by direct solid state reactions and ion-exchange routes. The interlayer alkali-metal cations were testified ion-exchangeable by some smaller monovalent cations.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► The entire family of ACrV2O7 (A=Na, K, Rb, Cs) have been prepared via solid-state reactions and ion-exchange routes. ► CsCrV2O7 and a metastable phase of NaCrV2O7 (ie-NaCrV2O7) were synthesized for the first time. ► Structural characterization, spectra features and physical property measurements were carried out contrastively. ► Alkali-metal cations in the layered structure were testified to be ion-exchangeable with smaller monovalent ions.