Praseodimum Zirconate: Phase Formation During Heat Treatmentand Electrochemicalbehavior

Abstract

Method has been described for the preparation of a complex oxide material of praseodym-ium zirconate using combustion synthesis with urea and nitrates of the corresponding metals. Dur-ing the work, a viscous homogeneous precursor was synthesized. In order to determine the charac-teristic temperatures of phase formation, the thermal behavior of the initial nitrates of praseodym-ium and zirconyl, as well as the obtained precursor, was investigated by methods of simultaneous thermal analysis combined with mass spectrometry of evolved gases. It was found that the formation and crystallization of the praseodymium zirconate phase occurs in the range of 360 -580 °С. The influence of the composition of the atmosphere on the thermal behavior of the precursor, as well as praseodymium and zirconyl nitrates, has been established. Thermal destruction of these sub-stances in an oxidizing atmosphere does not differ significantly from that in an inert atmosphere, but leads to a more rapid course of the formation of the oxide phase. During the thermal destruction of the precursor, the release of urea particles, nitrogen oxides, and carbon dioxide was detected by mass spectrometry. X-ray phase analysis of the sample annealed at 560 °Сfor 6 hshowed that the resulting material is completely single-phase and consists of praseodymium zirconate with a pyro-chlore structure type. The lattice parameter was a = 10.64754 Ǻ.The crystallinity value of the ob-tained powder was 65.1%. With a decrease in the time of heat treatment of the sample, its degree of crystallinity significantly decreases. Micrographs of the annealed sample show the presence of meso-and micropores in the microstructure of the material, formed as a result of thermal destruction of the precursor. The electrochemical behavior of the materialwas studied by cyclic voltammetry with different potential scan rates, and its specific capacity in a sodium sulfate so-lution was calculated.