Spectroscopy analysis and optical transition property of GdNbTiO₆: Eu³⁺, Sm³⁺ phosphor

Red-emitting GdNbTiO₆ phosphors, single-doped and co-doped with Eu³⁺ and Sm³⁺, were synthesized by solid-state method at 1400°C for 4 h. The crystal structure and downshifting luminescence performance of GdNbTiO₆: Eu³⁺, Sm³⁺ phosphors were studied. The energy transfer behaviour between Sm³⁺ and Eu³⁺ was investigated and the effect of Sm³⁺ doping on the downshifting luminescence and optical transition properties of Eu³⁺ was discussed based on the photoluminescence spectra and the framework of Judd–Ofelt theory. The addition of Sm³⁺ extends the excitation wavelength range of Eu³⁺ in the near ultra-violet light region and significantly enhances the emission intensity under 408 nm excitation, while no obvious changes on the optical transition parameters of Eu³⁺ was found. In addition, as Sm³⁺ doping concentration is increasing, the colour coordinates of the phosphor under different wavelength excitations always remained in the orange–red light region. These results indicated that Eu³⁺, Sm³⁺ co-doped samples with stable colour-rendering performance have wide-application prospects in the field of high-quality solid-state lighting.