Structural and luminescence properties of LaAlO_3:Sm~(3+) nanophosphors synthesized via hydrothermal method

摘要

A sequence of orange-red light emitting LaAlO3: Sm3+ nanophosphors were prepared via hydrothermal technique. The phase identification, morphological studies, vibrational bands and photoluminescence characteristics of these nanophosphors were investigated. The X-ray diffraction proved that the nanophosphors crystallized in a single-phased rhombohedral crystal structure, the crystallite sizes were evaluated by Debye-Scherrer's relation and Williamson-Hall method and were detected in the range of 30-42 nm. Under the excitation at 407 nm, the photoluminescence peaks were noticed at 566, 600, 647 and 712 nm and were corresponding to (4)G(5/2) -> H-6(5/2), (4)G(5/2) -> H-6(7/2), (4)G(5/2) -> H-6(9/2) and (4)G(5/2) -> H-6(11/2) distinctive 4f-4f electronic transitions of Sm 3+ ion, respectively and the most intense emission peak noticed at 600 nm. The luminescence intensity increased with an addition of Sm3+ concentration up to 6 mol% and then decreased for 8 mol% due to concentration quenching effect. The luminescence decay from (4)G(5/2) level of Sm3+ ions for all the prepared samples were measured and a strong dependence lifetime on the Sm3+ ion concentration was observed. The calculated CIE coordinate values indicate the orange-red emission from the Sm3+ : LaAlO3 nanophosphors. All these results indicate that the present Sm3+ : LaAlO3 nanophosphors might be suitable for orange-red light emission for near-ultraviolet excited white light emitting diode applications.