Crystal structure and photoluminescent analysis of bright orange-red emanating Sm 3+ -doped Ca 9 Bi(VO 4 ) 7 nanophosphor for WLEDs

A bright orange-red emanating Ca 9 Bi 1− x (VO 4 ) 7 : x Sm 3+ ( x = 0.05–0.5) nanophosphor crystalline series has been synthesized for the first time through solution combustion route. X-ray diffraction pattern of Ca 9 Bi 0.80 Sm 0.20 (VO 4 ) 7 was analyzed and processed using Rietveld Refinement. The nanophosphors synthesized were found to crystallize in trigonal crystal lattice with R3c (161) space group. The morphological behavior of prepared nanophosphors was studied by means of transmission electron microscopy (TEM). The photoluminescence nature of the nanophosphors corresponds to bright orange emission due to near-ultraviolet (NUV) excitation at 405 nm followed by 4 G 5/2 → 6 H 7/2 radiative relaxation. The chromaticity coordinates ( x = 0.5504, y = 0.4484) are in harmony with the intense orange-red emission. The decay curves been well fitted in 1st-order exponential decay function indicate that a single type of crystallographic site is occupied by the dopant-Sm 3+ ions in host lattice. Auzel’s model was implemented to investigate into rates of nonradiative relaxation (302.008 s −1 ), radiative lifetime (0.76 ms), and quantum efficiency (81%) values. The crystalline and optical behavior of the synthesized orange-red emitting nanophosphors promote their usage in near UV-based WLEDS.