HYDROTHERMAL SYNTHESIS AND CHARACTERIZATION OF A NOVEL MIXED-VALENCE OXIDE, HXV2ZR2O9-CENTER-DOT-H2O, X=0.43

A novel complex oxide with V(IV,V) mixed valence, HxV2Zr2O9 . H2O, has been hydrothermally synthesized in a V2O5-ZrO2-H2O system at 240 degr ees C for 5 days; NaF was used as a mineralizer. The product crystalli zes in a monoclinic system with cell parameters a = 0.940(4) nm, b = 1 .156(8) nm, c = 0.636(3) nm, beta = 104.1(7)degrees, and V = 0.671(2) nm(3). The vanadium in the product appears in mixed valence IV and V, which was evidenced by electron paramagnetic resonance analysis, Therm ogravimetric analysis showed that the product dehydrated and underwent phase transformations in air and N-2 in the temperature range 500 sim ilar to 600 degrees C. (C) 1997 Academic Press.