Synthesis, formation and characterisation of MgNb2O6 powder in a columbite-like phase

A modified mixed oxide synthetic route has been developed for the synthesis of the columbite-like phase of magnesium niobate, MgNb2O6, (MN). Magnesium carbonate hydroxide pentahydrate was employed as a source of magnesium, wi th the formation of columbite phase investigated as a function of calcinati on temperature and dwell time by XRD and DTA. The particle size distributio n of the calcined powder was determined by laser diffraction, with the morp hology, phase composition and crystal structure determined via SLM, TEM and EDX techniques. If has been found that the Mg4Nb2O9 phase tends to form to gether with the columbite-type ;phase MgNb2O6, although a single columbite- like phase of MgNbzO6 was obtained for a calcination temperature of 1150 de grees C with a dwell-time of 4h. (C) 1999 Elsevier Science Limited. All rig hts reserved.