Efficient red‐emitting phosphor of Eu3+‐activated (Na0.5Gd1.5)(TiSb)O7 derived via cation‐substitutions in Gd‐Pyrochlore

Abstract

AbstractRare‐earth (RE) titanate pyrochlore with perovskite‐layered structure is a well‐known engineering material in applied in many field. In this work, a red‐emitting phosphor of Gd2−xNaxTi2−2xSb2xO7:Eu3+ (x = 0‐0.5) was developed via cation substitutions of (Sb5+→Ti4+) and (Na+→Gd3+) in Gd2Ti2O7. The motivation is based on the fact that the introduction of cation‐disorders has been regarded to be an effective approach for improving the luminescent efficiency and thermal stability of RE‐activated materials. All the samples were synthesized via facile solid‐state reaction method. The morphology properties were measured via SEM and EDS measurements. The structural Rietveld refinement was performed to investigate the microstructure in pyrochlore lattices. The luminescence properties of Gd2−xNaxTi2−2xSb2xO7:0.15Eu3+ (x = 0‐0.5) has a strict dependence on the cation substitution levels. The band energy of Gd2Ti2O7 is 2.9 eV with a direct transition nature. The incorporation of Sb5+ and Na+ in the lattices moves the optical absorption to a longer wavelength. The cation disorder results in significant improvements of luminescence intensity, excitation efficiency in the blue region, longer emission lifetime and thermal stability.