Luminescence properties of near-UV excitable yellow-orange light emitting warm CaSrAl2SiO7:Sm3+ phosphors

Single-phase CaSrAl₂SiO₇:Sm³⁺ phosphors were synthesized by traditional high temperature solid state reaction method. Formation of samples and phase analysis were confirmed by X-ray diffraction technique. Morphology was done by field emission scanning electron microscopy and elemental compositions were confirmed by energy dispersive X-ray analysis. Present phosphors have tetragonal crystallography with space group P$\overline{\mathrm{4}}$2₁m. Average crystallite size was calculated by using Scherrer and Williamson-Hall method. Photoluminescence study of CaSrAl₂SiO₇:Sm³⁺ phosphor was investigated. Under different excitation wavelengths, PL spectra consist of four emission bands at 564, 570, 601 and 650 nm. The emission bands located at 564 and 570 nm are associated with the transition ⁴G_5/2 → ⁶H_5/2 while emission bands at 601 and 650 nm are due to ⁴G_5/2 → ⁶H_7/2 and ⁴G_5/2 → ⁶H_9/2, respectively. Intense emission was obtained when phosphor was excited under 404 nm wavelength. Non-radiative energy transfer process involved in concentration quenching, was also discussed. CIE coordinate is found in yellow-orange region, hence CaSrAl₂SiO₇:Sm³⁺ phosphors emit yellow-orange light when efficiently excited by near UV (～400 nm) LED chip. Color purity and CCT of the phosphor were determined; CCT suggests that present phosphor is a good candidate as a warm yellow-orange color emitting phosphor. Effect of different heating rates and different UV exposure time on the TL glow curve of the phosphor was investigated. Activation energies and kinetic parameters for different traps were calculated by using peak shape method. TL emission spectrum was also recorded. Present article explains all the possible mechanisms associated with luminescence process in CaSrAl₂SiO₇:Sm³⁺ phosphors.