Gel-combustion synthesis, structural and optoelectronic analyses of Tb3+ activated LaSr2AlO5 nanophosphors: A green emitter for displays

A gel-combustion approach, utilizing urea as a fuel has been employed to generate highly green luminous LaSr2AlO5:Tb3+ nanophosphors. This experiment explored the crystal structure, chemical content, phase purity, morphology, band gap, photoluminescence characteristics and thermal quenching process of the synthesized materials. The tetragonal structure of the synthesized material which comprises the I4/mcm (140) space group is supported by the X-ray diffraction data. The agglomerated particles exhibited almost uniform morphology and crystallite diameters between 45 and 65 nm, supported by SEM and TEM analyses. The band gap of LaSr2AlO5 (5.97 eV) and optimum La0.97Sr2AlO5:3 mol % Tb3+ (5.61 eV) classify it as direct band gap material. The LaSr2AlO5:Tb3+ phosphors displayed a green emission peak at 543 nm (5D4→7F5 transition) after being stimulated at 252 nm. LaSr2AlO5:Tb3+ phosphor has an optimum doping concentration of x = 3 mol %. The average decay time of the excited state of all samples has been determined from the double exponential fitting results of the decay curves obtained from PL at 252 nm and 543 nm of excitation and emission wavelengths respectively. With activation energy of 0.1838 eV, this phosphor exhibits excellent temperature stability. The CIE coordinates show the presence of emitted light with high color purity in the green region of visible spectrum. All the results of present research endorse the applicability of LaSr2AlO5:Tb3+ nanophosphors as a green component for displays and other lighting applications.