Investigation on cation distribution and luminescence in spinel phase gamma-Ga3-deltaO4 : Sm nanostructures using X-ray absorption spectroscopy

Title
Investigation on cation distribution and luminescence in spinel phase gamma-Ga3-deltaO4 : Sm nanostructures using X-ray absorption spectroscopy
Authors
채근화원성옥Aditya SharmaMAYORA VARSHNEYHyun-Joon Shin
Keywords
nanoparticle; XANES; EXAFS; XRD; Photoluminescence; nanostructures
Issue Date
2017-11
Publisher
RSC advances
Citation
VOL 7, NO 83-52554
Abstract
In this study, spectroscopic investigations are employed to quantify the Ga distribution over the tetrahedral/octahedral sites and to assimilate the luminescence properties in the barely reported γ-Ga2.67O4  :  Sm nanoparticles. O K-edge XANES are convincing the decreased electron density in the outermost hybrid orbits of O 2p and Ga 4p, and the movement of p electrons to the inner hybrid orbits with s character under the distorted oxygen environment of γ-Ga2.67O4  Sm nanoparticles. The Ga K/L-edge XANES and Sm L3/M5,4-edge XANES results have confirmed Ga3+ and Sm3+ ions, respectively, in the γ-Ga2.67O4  Sm nanoparticles. Quantitative determination of the cation distribution is performed by applying Ga K-edge XANES data analysis, which is further substantiated by an EXAFS data simulation, and conveys a Ga-O4 tetrahedra/Ga-O6 octahedra ratio (Ga(t)/Ga(o)) of ∼0.9, ∼1.4, ∼1.5 and ∼1.6 for the β-Ga2O3, γ-Ga2.67O4, γ-Ga2.67O4  5Sm and γ-Ga2.67O4  10Sm samples, respectively, which signify the Sm doping induced deformation of Ga-O6 octahedra via the formation of oxygen defects. Multiple luminescence centres, facilitated by the Ga-O6 octahedra distortion, O vacancies and Sm3+ ions, have helped in a significant enhancement of the emission characteristics. Our spectroscopy investigations, with the help of XANES and EXAFS, may open new opportunities to the mechanistic understanding of metal-O polyhedra alteration induced fruition of physical/chemical properties in the less explored meta stable phases of other complex oxides.
URI
http://pubs.kist.re.kr/handle/201004/66600
ISSN
2046-2069
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KIST Publication > Article
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