Noticeable red emission and Raman active modes in nanoscale gadolinium oxyfluoride (Gd₄O₃F₆) systems with Eu³⁺ inclusion

Abstract

Eu³⁺ doped gadolinium oxyfluoride (Gd₄O₃F₆, GOF) nanoscale systems have been synthesized following a modified Pechini method. While exhibiting a tetragonal crystal structure, the GOF nanosystem gave an average crystallite size (d) of ~21–26 nm. The Lotgering factor (L _F), which is a measure of orientation of crystallites along the preferred direction was found to vary between 0.22 and 0.48. In the photoluminescence spectra, ~595 and ~613 nm peaks were identified as magnetically driven (⁵ D ₀ → ⁷ F ₁) and electrically driven (⁵ D ₀ → ⁷ F ₂) transitions with latter (red emission) being strongly manifested with Eu³⁺ doping concentration and intrinsic defects. Moreover, several Raman active modes have been probed in the Raman spectra with low frequency peaks (<300 cm⁻¹) and moderate frequency peaks (~481 and 567  cm⁻¹) assigned to observable vibration of heavy atom Gd–Gd pairs and Gd–O groups, respectively. Apart from manifestation of phononic features, inclusion of Eu³⁺ in the host lattice would bring new insight on improving the red emission response prior to concentration quenching.