Site selective and enhanced luminescence of SrGe4O9:Mn4+ red phosphor via Ti4+ or Sn4+ codoped

Highlights: • Sn⁴⁺/Ti⁴⁺ enhanced emission intensity of SrGe₄O₉:Mn⁴⁺ phosphor by 22%/13% due to the changed corrdination environment. • Sn⁴⁺ may be substituted the Ge1 site but Ti⁴⁺ replaced the Ge2 site Sn⁴⁺/Ti⁴⁺ co-doped SrGe₄O₉:Mn⁴⁺ deep red phosphors were synthesized via high temperature solid state method. The structure, morphology and photoluminescence properties were investigated by XRD, SEM and fluorescent spectrometer. The obtained samples exhibit strong deep red emission located at 660 nm under 430 nm excitation. The optimum concentration of Mn⁴⁺ was about 1.2 mol% and concentration quenching mechanism was related to d-d interaction. Co-doping of Ti⁴⁺ (Sn⁴⁺) enhanced emission intensity of SrGe₄O₉ by 22% (13%) due to the changed coordination environment of Mn⁴⁺ and efficient energy transfer between Ti⁴⁺ (Sn⁴⁺) and Mn⁴⁺. Sn⁴⁺ may be substituted the Ge1 site and Ti⁴⁺ replaced the Ge2 site. The fabricated LED showed a white light with chromaticity coordinates (0.3429, 0.2941). The results indicated that site selective occurred and SrGe₄O₉:Mn⁴⁺, Ti⁴⁺ (Sn⁴⁺) have potential to supplementary red light and package white LEDs.