Deep-red-emitting SrLa2Sc2O7:Mn4+ phosphor: Synthesis and photoluminescence properties

Novel deep-red-emitting SrLa2Sc2O7:Mn4+ phosphors with different Mn4+ contents are successfully synthesized in air by the conventional high-temperature solid-state reaction method. The crystal structure, morphology, phase purity, luminescence properties, concentration quenching, decay lifetimes, and temperature dependent emission spectra are systematically investigated and analyzed. SrLa2Sc2O7:Mn4+ phosphor presents broad excitation band with different excitation peaks from 220 nm to 620 nm owing to the O2− - Mn4+ charge transfer and 4A2 → (4T1, 2T2, and 2T2) transitions of Mn4+ ion and shows intense deep-red emission peaking at 704 nm in the range of 650–800 nm because of the 2E → 4A2 transition of Mn4+ ion. The optimal Mn4+ concentration in SrLa2Sc2O7:Mn4+ phosphor is ∼0.6 mol%. The chromaticity coordinates of the SrLa2Sc2O7:0.6%Mn4+ phosphor are (x = 0.732, y = 0.268), locating in deep-red region. The mechanism of concentration quenching is inferred to be dipole-dipole interaction. The luminous mechanism, concentration quenching, and temperature quenching are explained by using the Tanabe–Sugano diagram and configurational coordinate diagram of the Mn4+ ion in SrLa2Sc2O7:Mn4+ phosphor. The experimental results on SrLa2Sc2O7:Mn4+ phosphor can offer the helps for the development of other Mn4+ doped deep-red-emitting phosphor.