Synthesis for fine perovskite-type materials using precursor prepared by metal nitrates solution mixed with organic solvent

Abstract

For the preparation of precursors for fine perovskite-type (0.05 mol) materials, the metal nitrates were completely dissolved in a water solution (total 100 ml) with organic solvent of ethylene glycol (EG), diethylene glycol (DEG), or glycerin (GL), and then dried at 120 °C. In the case of a La–Fe precursor without organic solvent, LaFeO 3 was not the main phase for the calcined materials even at 1000 °C. However, the LaFeO 3 single phase was obtained by mixing a small amount of organic solvent EG (≥10 ml), DEG(≥5 ml), and GL(≥5 ml) into the solution. In the case of EG, clear XRD peaks of the LaFeO 3 single phase were obtained by calcination even at 350 °C. A higher calcination temperature for the formation of the LaFeO 3 phase was needed with an increase in the amount of the mixed organic solvent. The oxygen in these organic molecules would act to coordinate to the metal ions instead of nitric acid ions to form a quasi-polymer containing metal ions in a random position, because the nitrogen elemental ratio in the precursor decreased with the amount of added organic solvent. The elemental distribution of La and Fe was highly homogeneous for the decomposed sample. The La 1− X Sr X MnO 3 system was also examined by this method using GL. A single perovskite-type phase formed even for calcination at 700 °C.