Microwave and conventional processing of niobium and manganese doped lanthanum germanate based apatites

Abstract

The paper reported calcination and sintering of apatites of compositions La9.5Ge5.5Nb0.5O26.5 and La9.5Ge5.5Mn0.5O26 using microwave energy for the first time from the precursor prepared by the mixed oxide method. The calcination was done conventionally under an identical condition to compare the results. The single phase of La9.5Ge5.5Nb0.5O26.5 and La9.5Ge5.5Mn0.5O26 could be obtained by microwave processing at temperature 1100 °C within 1 h. But the single phase of aptites could not be prepared by conventional heating under the identical conditions. The calcined powder obtained by microwave heating was sintered by microwave heating as well as conventional heating. The products obtained were characterized by XRD and SEM. It was observed that the microwave sintered products had higher density and uniform microstructure compared to the sintered products obtained by the conventional heating.