Li6AlGd(BO3)4: Sm3+ phosphors for orange-red light sources

Abstract

A new class of Li6AlGd(BO3)4: Sm3+ phosphors were prepared via solid-state-reaction method and analyzed for orange-red light sources. The structure, morphology, distribution of particles, presence of various bonds responsible for optical properties, energy-transfer among the excited Sm3+ ions and decay properties were broadly studied. Most of the intense and sharp excitation transitions of Sm3+ in LAGBSmx phosphors appear in n-UV region and the emission spectra reveal 4G5/2 → 6H5/2, 7/2, 9/2, 11/2 transitions upon 408 nm n-UV wavelength excitation. The concentration was optimized to be 1.0 mol% for efficient orange-red emission. The CIE colour coordinates were obtained as (0.611, 0.388) for LAGBSmx phosphors with a negligible change with variation in concentration of Sm3+ ions. The decay profiles were well fitted to double-exponential function showing the occupation of Sm3+ in two different sites. The transfer of energy among the excited Sm3+ ions was possible through exchange interaction at higher concentrations. The emission of orange-red light shows its proficiency for solid-state lighting devices as well as red light source replacement in the design of white-LEDs.