Effects of milling method and calcination condition on phase and morphology characteristics of Mg4Nb2O9 powders

Magnesium niobate, Mg4Nb2O9, powders has been synthesized by a solid-state reaction. Both conventional ball- and rapid vibro-milling have been investigated as milling methods, with the formation of the Mg4Nb2O9 phase investigated as a function of calcination conditions by DTA and XRD. The particle size distribution of the calcined powders was determined by laser diffraction technique, while morphology, crystal structure and phase composition were determined via a combination of SEM, TEM and EDX techniques. The type of milling method together with the designed calcination condition was found to show a considerable effect on the phase and morphology evolution of the calcined Mg4Nb2O9 powders. It is seen that optimization of calcination conditions can lead to a single-phase Mg4Nb2O9 in both milling methods. However, the formation temperature and dwell time for single-phase Mg4Nb2O9 powders were lower with the rapid vibro-milling technique.