Novel La3GaGe5O16 : Mn4+ based deep red phosphor: a potential color converter for warm white light

Abstract

New non-rare-earth red phosphor La₃GaGe₅O₁₆ : Mn⁴⁺ was prepared successfully via the traditional solid state reaction method. In this paper, we reported this red phosphor La₃GaGe₅O₁₆ : Mn⁴⁺ as a promising red converter for warm white light under excitation at UV or blue light. The phase and microstructure of this red phosphor were characterized with aids of the XRD and SEM; the luminescent performance was investigated by the diffuse reflection spectra, photoluminescence (PL) spectra, and temperature-dependent PL/decay measurements. The excitation band of La₃GaGe₅O₁₆ : Mn⁴⁺ phosphor covers a broad spectral region from 250 nm to 500 nm, which match well with the commercial near-UV and blue LEDs and can give intense bright red emission. The crystal field strength (D_q) and the Racah parameters (B and C) are calculated to evaluate the nephelauxetic effect of Mn⁴⁺ suffering from the La₃GaGe₅O₁₆ host. The concentration quenching of Mn⁴⁺ in La₃GaGe₅O₁₆ : Mn⁴⁺ occurs at a low content of 0.25% due to the dipole–dipole interaction in this work. We gained insight into the temperature-dependent relative emission intensity of La₃GaGe₅O₁₆ : 0.25% Mn⁴⁺ phosphor, and we also reported the luminescence quenching temperature and the activation energy for thermal quenching (ΔE). In future, WLEDs will be made when this red phosphor was applied to the package of a UV/blue LED chip and YAG : Ce.