Pure MgNb2O6 powders with high specific surface area and high crystallinity
have been successfully synthesized by the "Polymerized Complex (PC) Method
". A solution of water, citric acid, ethylene glycol and niobium and magnes
ium ions, was polymerized at 130 degrees C by the water elimination and was
calcined at 400 degrees C for 2 h. The precursor formed was calcined at te
mperatures from 700 degrees C to 1000 degrees C in air to obtain the columb
ite phase. Thermal analysis, Raman spectroscopy, x-ray diffraction, adsorpt
ion/desorption hysteresis and scanning electron microscopy were used to inv
estigate the polymer decomposition and the columbite phase evolution. No ev
idence for phase separation of crystalline MgCO3 and Nb2O5 in Raman spectra
and x-ray diffraction pattern as distinct intermediates were found, and th
e MgNb2O6 probably is formed through a single-step decomposition of oxycarb
onate intermediate, as other double oxide synthesized by the PC Method, as
indicated by the thermal decomposition of the precursor.