A new polymorph of ZrW2O8 prepared using nonhydrolytic sol-gel chemistry

A new polymorph of ZrW2O8, structurally related to trigonal ZrMo2O8, has ben prepared at low temperatures using nonhydrolytic sol-gel chemistry. Its identity was established by powder C-ray diffraction, energy dispersive X-ray analysis, and extended X-ray absorption fine structure (EXAFS). This material is denser than the previously reported cubic and orthorhombic forms of ZrW2O8 and decomposes into the binary oxides on prolonged heating at 700 C. An EXAFS investigation of the crystallization of ZrW2O8 gels, prepared by nonhydrolytic methods, suggests that the coordination environments of the cations in the heat-treated gels evolve toward those found in the new form of ZrW2O8 prior to the crystallization of this product