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Li5La3Ta2O12:Mn4+ (LLTO:Mn4+) phosphors are prepared in air via high‐temperature solid‐state method and investigated for their crystal structures and luminescence properties. LLTO:Mn4+ phosphor under excitation at 314 nm shows deep‐red emission peaking at 714 nm due to the 2E→4A2 transition of Mn4+ ion. The excitation bands in the range 220 ‐ 570 nm are attributed to the Mn4+ ‐ O2‐ charge‐transfer band and the 4A2g→4T1g, 2T2g, and 4T2g transitions of Mn4+, respectively. The optimal Mn4+ ion concentration is ~0.4 mol%. The concentration quenching mechanism in LLTO:Mn4+ phosphor is electric dipole‐dipole interaction. The luminous mechanism and temperature quenching phenomenon are explained by the Tanabe‐Sugano energy level diagram and the configurational coordinate diagram of Mn4+ in the octahedron, respectively. The experimental results indicate that LLTO:Mn4+ phosphor has a potential application prospect as candidate of deep‐red component in light‐emitting diode (LED) lighting. [ABSTRACT FROM AUTHOR]

Ca [1−3x/2] TiO 3 :xSm 3+ (0 ≤ x ≤ 5 mol%), Ca 0.955 TiO 3 :0.03Sm 3+ + 10 mol% H 3 BO 3 , Ca 0.94 TiO 3 :0.03Sm 3+ , 0.03Na + phosphors are synthesized by high temperature solid–state reaction method in air. All samples are pure phase CaTiO 3 . Two strong excitation bands within the range 400–435 nm and 455–510 nm are observed, which are nicely match with widely applied near-UV (400–430 nm) and blue (460–500 nm) LED chips. The strongest emission band peaking at ∼603 nm is assigned to the 4 G 5/2 → 6 H 7/2 transition of Sm 3+ ion. The optimal Sm 3+ doping concentration is ∼3 mol%. Fluorescent lifetimes of Ca 0.955 TiO 3 :0.03Sm 3+ phosphor with excitation 408, 467, and 481 nm are ∼0.809 m, 0.792 m, and 0.8 m, respectively. The PL intensity of Ca 0.955 TiO 3 :0.03Sm 3+ phosphor is enhanced 5–7 times after Na + ion is codoped as charge compensator and H 3 BO 3 is added as flux, and their CIE chromaticity coordinate is ∼ (0.5792, 0.4199). The experiment results are helpful to improve luminescence properties of other Sm 3+ -doped phosphors and study novel phosphors. [ABSTRACT FROM AUTHOR]

Li 2 Mg 3 SnO 6 :Mn 4+ deep red phosphor is synthesized by high-temperature solid-state reaction method in air. With excitation 330 and 480 nm, the emission band peaking at ∼670 nm within the range 600–790 nm is observed owing to the 2 E → 4 A 2 transition of Mn 4+ ion. Excitation bands peaking at ∼330, 395, and 480 nm in the range of 220–600 nm indicate that Li 2 Mg 3 SnO 6 :Mn 4+ phosphor can be effectively excited by (near) ultraviolet and blue light-emitting diode chips. The optimal Mn 4+ ion concentration is ∼0.4 mol%. Fluorescence lifetime and quantum efficiency of Li 2 Mg 3 SnO 6 :0.4%Mn 4+ phosphor with excitation 330 nm are ∼266.67 μs and 36.3%, respectively. The luminous mechanism is explained by the Tanabe-Sugano energy level diagram of Mn 4+ in the octahedron. [ABSTRACT FROM AUTHOR]