Combustion derived single phase Y 4 Al 2 O 9 :Tb 3+ nanophosphor: crystal chemistry and optical analysis for solid state lighting applications.

Cool green light emanating monoclinic Y 4- x Al 2 O 9 : x Tb 3+ ( x = 1-5 mol%) nanophosphors have been fabricated through gel-combustion method. X-ray diffraction and transmission electron-microscopy data have been utilized to assess their structural and microstructural characteristics, including cell parameters and crystallite size. Uneven aggregation of nanoparticles in the nano-scale with distinctive porosity can be seen in the TEM micrograph. Kubelka-Munk model imitative diffuse reflectance spectra and an optical band gap of 5.67 eV for the Y 3.97 Al 2 O 9 :0.03Tb 3+ nanophosphor revealed high optical quality in the samples, which were thought to be non-conducting. The emission (PL) and excitation (PLE) spectra as well as lifetime measurements have been used to determine the luminescence characteristics of the synthesized nanophosphors. The emission spectra show two color i.e. blue color due to 5 D 3 → 7 F J ( J = 4 and 5) transitions and green color due to 5 D 4 → 7 F J ( J = 3, 4, 5 and 6) transitions. The most dominant transition ( 5 D 4 → 7 F 5 ) at 548 nm was responsible for the greenish color in focused nanocrystalline samples. Calculated colorimetric characteristics such as CIE, and CCT along with color purity of the synthesized nanocrystalline materials make them the best candidate for the solid-state lighting (SSL).