Study of crystal structure and unique photoluminescence properties of Eu_(2-x)Fe_xO_3 (x = 0 - 0.5) orthoferrites

摘要

A series of Europium orthoferrites, Eu_(2-x)Fe_xO_3 (x = 0 - 0.5) are successfully prepared by employing solid state reaction technique. The structural analysis through powder X-Ray diffraction technique reveals the multiphase formation of all the prepared compounds. Further, the unit cell visualization of all the prepared compounds confirms the change of crystal structure from cubic to orthorhombic phase. The crystal structure analysis confirms the typical framework of Eu - Fe - O chains with unprecedented ratio of Eu~(3+) and Fe~(3+) ions. The optical properties of prepared compounds are investigated using photoluminescence (PL) analysis. Upon excitation at 495 nm wavelength, the emission spectrum of prepared compounds exhibits a broad band in the range of 500-70nm with maximum intensity peak at 548 nm (Blue - 2.26eV). Hence, the substitution of Fe~(3+) ion yields with intrinsic blue photoluminescence (~5D_0 → ~7F_0) of Eu~(3+) and is easily shielded by the substitution of Fe~(3+) which may be due to the closer conduction band gap of Eu~(3+) (2.26 eV) with Fe~(3+) (2.67 eV). The schematic energy level diagram for Fe~(3+) in the Eu~(3+) host matrix has been proposed for the better understanding of photoluminescence processes. The variation of intensity of PL peak between 500 and 700 nm for the substitution of Fe in the range of x = 0 - 0.5 yields with interesting optical properties for exploring new phosphor materials for optoelectronic device fabrications.