In this study, we investigate the photoluminescence （PL） properties of γ and θ-alumina nanoparticles synthesized by the chemical wet method followed by annealing. The obtained experimental results indicate the pre...In this study, we investigate the photoluminescence （PL） properties of γ and θ-alumina nanoparticles synthesized by the chemical wet method followed by annealing. The obtained experimental results indicate the presence of some favorable near ultraviolet （NUV）-orange luminescent centers for usage in various luminescence applications, such as oxygen vacancies （F, F＋, F2＋, and F2 centers）, OH related defects, cation interstitial centers, and some new luminescence bands attributed to trapped-hole centers or donor-acceptor centers. The energy states of each defect are discussed in detail. The defects mentioned could alter the electronic structure by producing some energy states in the band gap that result in the optical absorption in the middle ultraviolet （MUV） region. Spectra show that photoionazation of F and F2 centers plays a crucial role in providing either free electrons for the conduction band, or the photoconversions of aggregated oxygen va- cancies into each other, or mobile electrons for electrons-holes recombination process by the Shockley-Read-Hall （SRH） mechanism.展开更多
Our calculations demonstrate that the concentration of neutral oxygen vacancies can affect the geometrical structrue,electronic structure, and optical properties of α-quartz. Moreover, the distribution of the neutral...Our calculations demonstrate that the concentration of neutral oxygen vacancies can affect the geometrical structrue,electronic structure, and optical properties of α-quartz. Moreover, the distribution of the neutral oxygen divacancy can also exert some influence on the properties of α-quartz. The dissimilarity and similarities are presented in the corresponding density of state（DOS） and absorption spectrum. In addition, when a higher defect concentration is involved in α-quartz,the influence of E1 center on the geometry of α-quartz becomes more significant. However, the introduction of an E1 center barely results in any improvement compared with the influence produced by the corresponding neutral defect.展开更多
基金Iran’s Nanotechnology initiative council for their financial support
文摘In this study, we investigate the photoluminescence （PL） properties of γ and θ-alumina nanoparticles synthesized by the chemical wet method followed by annealing. The obtained experimental results indicate the presence of some favorable near ultraviolet （NUV）-orange luminescent centers for usage in various luminescence applications, such as oxygen vacancies （F, F＋, F2＋, and F2 centers）, OH related defects, cation interstitial centers, and some new luminescence bands attributed to trapped-hole centers or donor-acceptor centers. The energy states of each defect are discussed in detail. The defects mentioned could alter the electronic structure by producing some energy states in the band gap that result in the optical absorption in the middle ultraviolet （MUV） region. Spectra show that photoionazation of F and F2 centers plays a crucial role in providing either free electrons for the conduction band, or the photoconversions of aggregated oxygen va- cancies into each other, or mobile electrons for electrons-holes recombination process by the Shockley-Read-Hall （SRH） mechanism.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11176020 and 11374217)the Doctoral Program of Higher Education of China(Grant No.20100181110080)
文摘Our calculations demonstrate that the concentration of neutral oxygen vacancies can affect the geometrical structrue,electronic structure, and optical properties of α-quartz. Moreover, the distribution of the neutral oxygen divacancy can also exert some influence on the properties of α-quartz. The dissimilarity and similarities are presented in the corresponding density of state（DOS） and absorption spectrum. In addition, when a higher defect concentration is involved in α-quartz,the influence of E1 center on the geometry of α-quartz becomes more significant. However, the introduction of an E1 center barely results in any improvement compared with the influence produced by the corresponding neutral defect.
