Novel Sm 3+ -doped La 3 Ga 5 MO 14 (M = Si or Ge) phosphors for indoor illumination: effects of M cations on photoluminescence

A series of La Ga MO : Sm (M = Si or Ge) orange-red phosphors with high color purity, low correlated color temperature, and good thermal stability were successfully synthesized a high-temperature solid-phase technique. The phase structure and morphology of La Ga SiO (LGSi): Sm and La Ga GeO (LGGe): Sm were investigated. Sm -doped LGSi and LGGe phosphors emitted orange-red light under an excitation of 403 nm, and the optimal doping concentrations were 3 mol% and 2 mol% with excellent color purities of 98.46% and 98.25%, respectively. The concentration quenching mechanism of both the samples was dominated by dipole-dipole interaction, and the effect of Si and Ge on luminescence performance was discussed. The internal quantum efficiencies of LGSi:0.03Sm and LGGe:0.02Sm were calculated to be 27.14% and 56.07%, respectively. The CIE and CCT values indicated that the luminescence of the prepared phosphors was in the orange-red region. Additionally, a white light-emitting diode (w-LED) was fabricated with LGGe:0.02Sm phosphors, which was capable of emitting bright and warm white light and exhibiting a high color rendering index (CRI) of 87.17 and an appropriate correlated color temperature (CCT) of 6108 K. These results indicated that the prepared phosphors with excellent luminescent performances have potential application in indoor illumination.