Synthesis and Crystal Structure of SrV4O9 in a Metastable State

In the SrO–VO2 phase diagram there exists no SrV4O9 phase corresponding to the CaV4O9 phase in the CaO–VO2 diagram and synthesis of SrV4O9 has not been reported so far. We are successful in hydrothermal synthesis of the synthesis of SrV4O9: hydrothermal treatment of SrCl2–NaVO3–(CH3)4NCl solutions above 300°C yielded light-green plate crystals identified as SrV4O9. Single-crystal X-ray diffractometry confirmed the CaV4O9-type structure consisting of V4O9 layers and interstitial Sr atoms: P4/n, a=8.379(2) ?, c=5.259(3) ?, and Z=2. The refinements based on 826 reflections with I>3(I) converged to R=0.039 and Rw=0.048. Temperature variation of magnetic susceptibility exhibits a low-dimensional feature of a broad maximum around 100 K, just like that of CaV4O9. Single crystals of CaV4O9 were similarly grown in the hydrothermal CaCl2–NaVO3–(CH3)4NCl system at 280°C and its single-crystal X-ray study was also made to compare with those of SrV4O9.