A study of the mechanochemical synthesis of NaNbO3

We have studied the mechanochemical synthesis of NaNbO3, prepared from a powder mixture of Na2CO3 and Nb2O5. The formation of NaNbO3 during milling was followed using thermal analysis and X-ray diffraction. According to the thermogravimetric analysis, after 20 and 40 h of milling there was still some residual carbonate, while the X-ray diffraction shows NaNbO3 as the major crystalline phase present in the mixture. Based on the quantitative XRD phase analysis, the residual reactants were amorphous and as such undetectable with the X-ray diffraction. Furthermore, an X-ray line-broadening analysis was used to determine the NaNbO3 crystallite size and the microstrain. A decrease in the NaNbO3 crystallite size coupled with an increase in the amount of microstrains was found from 10 to 40 h of mechanochemical treatment. Finally, the TEM analysis confirmed the NaNbO3 crystallite size determined by the X-ray line-broadening analysis.