Radiative and non-radiative characteristics of Ca9Bi(PO4)7:Eu3+ nano-phosphor for solid state lighting devices

Highlights: • Ca₉Bi(PO₄)₇:Eu³⁺ phosphors are synthesized first time via solution combustion route. • Lattice parameters are determined for both the host and doped sample. • Lattice sites of Eu³⁺/Bi³⁺ and Judd-Ofelt parameters are obtained. • Quantum efficiency and peak stimulated emission cross-sections have been calculated. • Potential candidates for solid state lighting, display and laser devices. -- Abstract: Single-phased bright-red emitter Ca₉Bi_1–x(PO₄)₇:xEu³⁺ nanophosphor series was obtained by time-saving combustion-synthesis technique. The structural prototype for Ca₉Bi(PO₄)₇ and Ca₉Bi_0.40(PO₄)₇:0.60Eu³⁺ were obtained by using the Rietveld refinement method, revealing a trigonal crystal system of R3c(161) space group symmetry. The values of the band-gap for maximum-fluorescent-concentration and pure host were determined to be 4.23 and 4.30 eV, respectively. The critical distance for energy migration (12.35 Å) and Dexter's exchange-profiling held the dipole/dipole (d–d) interactions responsible for the quenching process observed after optimum composition. The refractive index of the pure host (2.22) and the photoluminescent (PL) emission spectra of Eu³⁺-doped samples were used to work out Judd-Ofelt intensity parameters. The detailed photo-luminescent analysis provided the value of quantum efficiency, non-radiative and total radiative transition-rate for Ca₉Bi_0.40(PO₄)₇:0.60Eu³⁺ phosphor. Furthermore, various optical results, including the very high value of stimulated emission-cross-section (10.64), claim Ca₉Bi_0.40(PO₄)₇:0.60Eu³⁺ system as a very much promising candidate for the laser and solid-state lighting (SSL) devices.