After calcining, the calcined powder was investigated by Fourier transform infrared spectroscopy(Spectrum GX spectrometer, Perkin-Elmer) measured in the range from 400 to 4000 cm1, raman spectroscopy (DXR smart Raman, Thermo scientific) measured in the range from 100 to 1000 cm1 and X-ray diffraction (X'Pert MPD, Philips) measured in the range of 2θ¼10–701, using CuKα radiation to explore the optimum calcination conditions and phases formed for the formation of Ca4Nb2O9 powder. Particle sizes and powder morphology were characterized via scanning electron microscope (JSM-6335F, JEOL).