Analysis of dielectric and magnetic phase transitions in Yb(Fe0.5Cr0.5)O3 bulk perovskite

A comprehensive investigation of dielectric and magnetic phase transitions in Yb(Fe0.5Cr0.5)O-3 bulk ceramics has been presented. The co-existence of orthorhombic phase (Pbnm) along with minor hexagonal (P6(3)cm) phase is detected through Rietveld refinement technique, whereas the presence of Fe3+/Fe2+ and Cr3+/Cr2+ species is also encountered under XPS study. The dielectric broad-band spectroscopic study (5-500K) reveals that two dielectric transition peaks: (1) at 370K, first order ferroelectric transition for induced local non-centrosymmetry, and (2) at 462K, diffuse like relaxor transition because of formation of polar nano-regions and, Schottky barriers at sample-electrode interface, respectively. The complex impedance spectroscopic study exhibits the non-Debye type dielectric relaxation phenomena at lower temperatures, while at high temperatures, oxygen ion vacancies are found to contribute the conduction progression. Furthermore, dc-magnetization plot in FC-ZFC mode detects the strong interactions between Cr3+/Fe(3+)sublattices also with Yb3+ ions and Yb3+-Yb3+ ions. This results into an antiferromagnetic ordering at T-N similar to 271K for Cr3+-Cr3+/Fe3+-Fe3+ or Cr3+-Fe3+ spins followed by weak ferromagnetic ordering at 41K for the occurrence of progressive spin reorientation and further at 11.2K due to onset interactions of ferromagnetic Cr3+/Fe3+ sub-lattices with paramagnetic Yb3+ ions.