SYNTHESIS, STRUCTURE, AND MAGNETISM OF BAVO2.8 - A NEW PEROVSKITE-RELATED VANADATE WITH V-III V-IV ORDERING/

A new barium vanadium oxide, BaVO2.8, was prepared from BaO and VO2 in an evacuated silica ampule at 1100 degrees C for 10 h with excess Zr getter. The compound consists of interleaving perovskite layers (two c orner-sharing VO6 octahedra) and BaNiO3 type layers (three face-sharin g VO6 octahedra) along the c-axis. Curie-Weiss magnetic behavior was o bserved with mu(eff) = 1.96 mu(B). The structural and magnetic data re veal ordering of V-III and V-IV cations at the corner-sharing and face -sharing octahedral holes, respectively. Qualitative molecular orbital analysis indicates M-M bonding in the face sharing [V3O12](12-) fragm ents with net 1/2 bond orders per V-V interaction (d(v-v) = 2.62 Angst rom). Crystallographic data: hexagonal space group <P(3)over bar>m1; a = 5.7685(2) Angstrom, c = 11.876(1) Angstrom, V = 342.22(4) Angstrom( 3), Z = 5, and d(calc) = 5.65 g/cm(3). The final R factors (Rietveld p rofile analysis) are R = 9.37% and R(wp) = 10.34%.