Heat-induced changes in microstructure and magnetic properties of Co0.75Ni0.75[Fe(CN)6] · XH2O

Abstract

Polycrystalline Co0.75Ni0.75[Fe(CN)6] · XH2O was prepared by coprecipitation. The coprecipitated powder was annealed in vacuum at 80°C, 100°C, and 130°C. Variation of microstructural and magnetic properties with different annealed temperatures was studied by Fourier-transform infrared, X-ray diffraction, and magnetization measurements. The differences in magnetic phase transition temperature, coercivity, remanence, and effective magnetization were studied in detail. The magnetic contribution mainly results from FeIII–CN–CoII/NiII and FeIII–NC–CoII/NiII because FeII–CN–CoIII/NiII carries no net spin. After annealing at 130°C, the microstructures FeIII–CN–CoII/NiII and FeIII–NC–CoII/NiII convert to FeII–CN–CoIII/NiII. Differences in magnetic properties may be attributed to heat-induced microstructural changes.