Synthesis of hexagonal YMnO3 from precursor obtained by the glycine–nitrate process

Abstract

A new synthesis route for obtaining a single-phase hexagonal YMnO3 was developed, based on the annealing of the amorphous precursor powder obtained by the glycine–nitrate combustion method. The process was monitored by XRD as well as by magnetic and heat capacity measurements. The analysis of these data shows that precursor powder undergoes a gradual phase transformation that depends on the annealing temperature. The metastable orthorhombic YMnO3 phase is the first to appear at temperatures below 700°C, while a mixture of ortho- and hexa-phases was found to exist within the 700–900°C range. An almost complete conversion to hexa-phase occurs at 900–1000°C, but to obtain the pure, well crystallized h-YMnO3 phase an annealing temperature of 1300°C was necessary. The synthesis method applied in this work has been proved to be more convenient for obtaining single-phase h-YMnO3 than by a solid state reaction. In addition, it is capable of producing sample free of parasitic phases that are often present in specimens obtained by other synthesis methods.