Synthesis and Photoluminescence Properties of Ba2GeO4:Mn4+ Novel Deep Red-emitting Phosphor

Novel deep red phosphor Ba2GeO4:Mn4+ is synthesized and investigated. Emission peaking at 667 nm with excitation 290 nm is observed within the range 610–720 nm due to the 2E → 4A2 transition of Mn4+ ion. The optimal Mn4+ concentration is ca. 0.6 mol %. Luminous mechanism is explained by Tanabe–Sugano energy diagram and configurational coordinate diagram of Mn4+ ion. Ba2GeO4:Mn4+ phosphor can be used as deep red phosphor candidate for red LEDs used in indoor plant cultivation.