Crystal Structure of a Metastable Form of Indium Orthovanadate, InVO 4-I

Abstract

The compound InVO 4-I has been obtained with a good purity level from a chimie douce process. Using X-ray powder diffraction data, its crystal structure has been determined by analogy with isostructural compounds crystallizing with the so-called α-MnMoO 4 type structure. The crystal symmetry is monoclinic (space group C2/ m) and the unit cell parameters are a = 10.271(1) Å, b = 9.403(1) Å, c = 7.038(1) Å, and β = 105.08(1)°. The structure has been refined by the Rietveld method ( R F = 0.030 and R wp = 0.098 for 360 reflections). The structure is based on compact In 4O 16 groups of four edge-sharing InO 6 octahedra linked to each other by VO 4 tetrahedra. Each In 4O 16 cluster contains two In1O 6 and two other In2O 6 octahedra and the corresponding In1-O and In2-O mean distances are 2.14 and 2.17 Å. The mean value for the V-O bond length is 1.71 Å. Relationships with the stable indium vanadate and related phases are discussed.