Low-temperature synthesis of potassium triniobate (KNb3O8) ceramic powder by a novel aqueous organic gel route

Abstract

Potassium triniobate (KNb3O8) ceramic powder has been synthesized by a novel aqueous organic gel route relatively at low calcination temperature above 700 °C. Initially, homogeneous K-Nb precursor gels were prepared using the starting materials K-EDTA and Nb-citrate complex. Afterward, the mixture in stoichiometric ratio of K, Nb, and citric acid produced a pale yellow viscous like gel from which precursor powder was obtained after prolonged heating at 80 °C. The X-ray diffraction patterns reveal the formation of nearly single crystalline phase of KNb3O8 powder calcinated from 750 to 800 °C. Furthermore, the particle size of KNb3O8 powder is also estimated in the nano range using XRD data by the Debye-Scherrer formula. The microstructure, compositional homogeneity, and EDS analysis were performed by scanning electron microscopy that confirmed the fine, almost homogeneous agglomerate microstructure of synthesized ceramics. Thermal analysis showed about 90.3% weight loss of the precursor powder which was mainly responsible for the decomposition of the organic and some other substances. FTIR analysis ensured characteristic absorption bands for the formation of KNb3O8 ceramic powder.