Novel Sm3+-doped La3Ga5MO14 (M = Si or Ge) phosphors for indoor illumination: effects of M cations on photoluminescence

Abstract

A series of La_3(1−x)Ga₅MO₁₄:xSm³⁺ (M = Si or Ge) orange-red phosphors with high color purity, low correlated color temperature, and good thermal stability were successfully synthesized via a high-temperature solid-phase technique. The phase structure and morphology of La₃Ga₅SiO₁₄(LGSi):xSm³⁺ and La₃Ga₅GeO₁₄(LGGe):xSm³⁺ were investigated. Sm³⁺-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 Si⁴⁺ and Ge⁴⁺ on luminescence performance was discussed. The internal quantum efficiencies of LGSi:0.03Sm³⁺ and LGGe:0.02Sm³⁺ 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:0.02Sm³⁺ 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.