Novel microwave initiated solid-state metathesis synthesis and characterization of lanthanide phosphates and vanadates, LMO4 (L = Y, La and M = V, P)

A novel solid-state metathesis (SSM) approach represented by the reaction (LCl3 + Na3VO4 -> LVO4 + NaCl) (L = Y, La) is proposed to synthesize technologically important rare-earth phosphates and vanadates. The SSM reaction, driven in the forward direction is facilitated by the formation of high lattice energy by-product like NaCl. The structural, thermal, optical, and chemical properties of synthesized powders are determined by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), differential scanning calorimetry (DSC), and diffused reflectance (DR) spectra in the UV-vis range. The direct band gap of the synthesized materials was found out to be similar to 3.5 eV for LaVO4, YVO4, YPO4 and similar to 2.6 eV for LaPO4. (C) 2007 Elsevier Masson SAS. All rights reserved.