Phase evolution and magnetic properties of Dy₃Fe_5+xO_12−x nanocrystalline powders: A choice of fuel approach

Garnet based Dy₃Fe₅O₁₂ nanostructured materials have gained considerable attention in recent years due to their potential technological applications. Garnet type structured Dy₃Fe_5+xO_12−x nanocrystalline powders were synthesized via propellant chemistry route. Single and mixed-fuel approaches were employed in the solution combustion process. Annealing the combusted powders at 1000 °C for 6 h resulted in nanocrystalline powders which are about 95% by weight garnet type and 5% orthorhombic DyFeO₃. This was confirmed from powder X-ray diffraction studies through Rietveld analysis. The solution combustion mechanisms involved in the formation of Dy₃Fe_5+xO_12−x nanocrystalline powders are briefly discussed. Scanning electron microscopy and energy dispersive X-ray spectroscopy studies revealed that the choice of fuel approach in the synthesis process affected the morphology and elemental composition. Raman spectroscopic studies revealed the existence of two magnon and two phonon scattering peaks rarely observed for garnet based Dy₃Fe₅O₁₂. The synthesized Dy₃Fe_5+xO_12−x nanocrystalline powders displayed ferromagnetic behavior. The saturation and remanent magnetization varied between 2.67-8.29 and 1.08–2.64 emu/g respectively, while the corecivities were in the order of few hundreds oersteds, characteristic of a soft ferromagnetic material. It is suggested that Dy₃Fe_5+xO_12−x nanocrystalline powders with different magnetic properties could be tailored for different requirements.