Dual synthesis routes to dysprosium activated Y2Mo3O12 Phosphors: Structural and luminescence insights

Abstract

Conventional solid-state ceramic techniques and the solution combustion method were employed to synthesize Y_2-xDy_xMo₃O₁₂ compounds. X-ray diffraction studies of samples synthesized by both methods reveal diffuse spectra, indicating the presence of Y₂Mo₃O₁₂. 3H₂O phase. High-temperature (HT) X-ray diffraction of the optimum Dy³⁺ doped sample synthesized by both methods showed an orthorhombic Y₂Mo₃O₁₂ crystal structure, but with different space groups, which was subjected to Rietveld refinement. This structural variation in Y_2-xDy_xMo₃O₁₂ compounds, influenced by Dy³⁺ doping and synthesis route, was studied based on the vibrations of the MoO₄ tetrahedra in Y_2-xDy_xMo₃O₁₂ compounds using Raman and Infrared vibrational analyses. The relative intensity changes observed in the ${\nu }_1\left(A_1\right)$ and ${\nu }_3\left(F_2\right)$ stretching modes with increasing Dy³⁺ doping concentration in combustion synthesized Y_2-xDy_xMo₃O₁₂ compounds support the structural phase difference observations in diffraction studies. The diffuse reflection spectra of Y_2-xDy_xMo₃O₁₂ compounds synthesized by both methods showed absorption bands corresponding to the intra f-f transition of the Dy³⁺ ion. The band gap of solid-state synthesized Y_2-xDy_xMo₃O₁₂ samples exhibits a dependence on Dy³⁺ ion concentration, unlike combustion synthesized samples. Y_2-xDy_xMo₃O₁₂ phosphors synthesized by the combustion technique showed a more intense emission spectrum. The average lifetime of the yellow emission line in the optimum Dy³⁺ doped sample in Y₂Mo₃O₁₂ host was 113 $\mu$ s for the solid-state synthesized sample and 30 $\mu$ s for the combustion synthesized sample. The CIE and CCT values of Y_2-xDy_xMo₃O₁₂ phosphors synthesized by both methods demonstrated their suitability for warm white LED applications.