Enthalpies of formation of rare earth orthovanadates, REVO4

Rare earth orthovanadates, REVO4, having the zircon structure, form a series of materials interesting for magnetic, optical, sensor, and electronic applications. Enthalpies of formation of REVO4 compounds (RE=Sc, Y, Ce–Nd, Sm–Tm, Lu) were determined by oxide melt solution calorimetry in lead borate (2PbO·2B2O3) solvent at 1075 K. The enthalpies of formation from oxide components become more negative with increasing RE ionic radius. This trend is similar to that obtained for the rare earth phosphates.

Comparison of enthalpies of formation from oxides at 298 K for REVO4 [this work] and REPO4 compounds [S.V. Ushakov, K.B. Helean, A. Navrotsky, L.A. Boatner, J. Mater. Res. 16(9) (2001) 2623] vs. RE3+ ionic radius. Filled symbols indicate scheelite structure, open symbols zircon structure.Figure optionsDownload as PowerPoint slide