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

Abstract

• Synthesis of cubic blue light emitting pure LLZO and orange light emitting LLZO: xSm 3+ (x=0.1, 0.3, 0.5, 0.7 and 0.9 M.W%) phosphors by solid state reaction method. • The optical energy band gap values of synthesised phosphors for pure and Sm 3+ doped LLZO were calculated to be 4.140 eV and 3.972 eV, respectively. • The strongest PL emission band observed at 602 nm was assigned to 4 G 5/2 → 6 H 7/2 transition in orange region under the ultraviolet excitation wavelength of 408 nm. • The blue and orange light emission was confirmed by CIE chromaticity X, Y coordinates. • Color purity and CCT value of 0.5 MW% Sm 3+ doped LLZO phosphor was 85.9% and 2227 K, respectively. Samarium (Sm) activated Li 7 La 3 Zr 2 O 12 (LLZO) phosphors were synthesized by solid state reaction method. Crystal structure of Sm 3+ 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 T 2g Raman mode of vibration and E g mode of vibration, respectively. The optical energy band gap values of synthesised phosphors obtained from UV-Vis spectroscopy for pure and Sm 3+ 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). Sm 3+ doped phosphors showed orange light emission under 408 nm excitation due to transition of 4 G 5/2 - 6 H 7/2. as observed from the Commission Internationale de l’Eclairage (CIE) chromatic coordinate graph. The maximum intensity of emission was observed in 0.5% Sm 3+ doped LLZO with the calculated color purity and correlated color temperature of 85.9% and 2229k, respectively.