Structural and luminescence property evaluation of Sm3+ activated orange light emitting Li7La3Zr2O12 phosphors

Samarium (Sm) activated Li7La3Zr2O12 (LLZO) phosphors were synthesized by solid state reaction method. Crystal structure of Sm3+ doped LLZO was investigated using X-ray diffraction and Raman spectroscopy analysis. From Raman spectra, the presence of characteristic Raman peak at 110 cm−1 confirms the formation of LLZO. The Raman peaks present at 345 cm−1 and 125 cm−1 correspond to T2g Raman mode of vibration and Eg mode of vibration, respectively. The optical energy band gap values of synthesised phosphors obtained from UV–vis spectroscopy for pure and Sm3+ doped LLZO were calculated to be 4.140 eV and 3.972 eV, respectively. Microstructure and selected area diffraction (SAED) pattern of phosphor was observed by High Resolution Transmission Emission Electron Microscope. Using an excitation wave length of 209 nm, blue emission was observed for pure LLZO and the chromaticity coordinate was found to be at (x = 0.1636, y = 0.0123). Sm3+ doped phosphors showed orange light emission under 408 nm excitation due to transition of 4G5/2-6H7/2, as observed from the Commission Internationale de l’Eclairage (CIE) chromatic coordinate graph. The maximum intensity of emission was observed in 0.5 % Sm3+ doped LLZO with the calculated color purity and correlated color temperature of 85.9 % and 2229 k, respectively.