Crystal structure and luminescence properties of thermally stable Sm³⁺-doped Sr₉In(PO₄)₇ orange-red phosphor

Abstract

A series of novel phosphate orange-red phosphor, Sr9In(PO4)7:xSm3+ (0.01 < x < 0.30), were successfully synthesized from high-temperature solid-state synthesis in this work. Their crystal structure has been analyzed by the Rietveld refinement, which shows Sr9In(PO4)7 consists of a monoclinic cell (C2/c), which also confirms the successful doping, preferential site occupancy and local ligand environment of Sm3+. Luminescence properties of the samples have been systematically investigated including excitation and emission spectra, quantum efficiency, concentration quenching, fluorescence decay and temperature-dependent luminescence properties. Photoluminescence spectra exhibited typical peaks, corresponding to 4G5/2 → 6HJ transitions of Sm3+ ions, where J = 5/2, 7/2, 9/2, and 11/2, respectively. Moreover, the concentration quenching result revealed that the optimal doping content of Sm3+ was 0.15 mol, and based on the Dexter theory, the energy transfer between Sm3+ ions was found in dipole-dipole interactions. The quantum yield of Sr9In(PO4)7:0.15Sm3+ phosphor was acceptable (58.5%). Most importantly, the emission intensity of Sr9In(PO4)7:0.15Sm3+ remains constant (>97%) below 150 °C and the configurational coordinate diagram analysis demonstrated excellent thermal stability of the Sr9In(PO4)7:Sm3+ phosphor, which is superior to that of the previously reported and commercially available phosphors. These results suggest that the Sr9In(PO4)7:Sm3+ phosphor is a promising orange-red phosphor materials for white light emitting diodes.

A novel Eu2+/Tb3+ co‐doped phosphor with pyroxene structure applied for cryogenic thermometric sensing

“…Figure 5H indicates the decay curves of CSMS:0.03Eu 2+ , yTb 3+ (y = 0.05, 0.08, and 0.10) phosphors measured at room temperature underneath 340 nm excitation to learn about the luminescence properties of co-doped samples. The curves can be properly outfitted through a secondorder exponential functions: 36,37 𝐼(𝑡) = 𝐴 1 exp…”

Using liquid phase precursor method to create a high-efficiency Ca₂SiO₄:Eu²⁺ green-emitting phosphor

“…The divalent europium loaded the alkaline earth silicate phosphor structure is of specific importance because the ion radii of alkaline are earth ions, including 0.112 nm of [Eu 2+ ] and [Sr 2+ ], 0.099 nm of [Ca 2+ ], and 0.134 nm of [Ba 2+ ], are equivalent to those of the divalent europium. Consequently, divalent europium is more stable and diffuses more freely into the lattice sites in an alkaline earth silicate host [4]- [6].…”

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