Formation of zircon-type DyCrO4 and its magnetic properties

The formation mechanism of hydrolytic sol-gel synthesized DyCrO₄ with a complexing agent in acidic and basic mediums is thoroughly studied. The role of complexing agents and pH on phase formation temperature is also intensively investigated. The formation temperature for DyCrO₄ is ～500 °C in the absence and presence of complexing agents such as oxalic acid and ethylenediaminetetraacetic acid (EDTA) at pH 10. When critic acid is used, the DyCrO₄ forms with Cr₂O₃ impurity. The crystallite size in the presence of a complexing agent in the basic medium is ～55 nm which is small as compared to only ammonia solution. The various reaction modes lead to tetragonal zircon-type DyCrO₄ at ～500 °C, transforming into orthorhombic perovskite DyCrO₃ at 800 °C. The magnetization curve shows the ferromagnetic behavior of DyCrO₄ below transition temperature T_c ～21 K. This low T_c makes nanocrystalline DyCrO₄ a potential material for cryogenic applications.