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Infrared-to-green upconversion luminescence and mechanism of Ho3+, Nd3+ and Yb3+ ions in oxyfluoride glass ceramics 下载免费PDF全文
New oxyfluoride glasses and glass ceramics co-doped with Nd^{3+}, Yb^{3+} and Ho^{3+} were prepared. The upconversion of infrared radiation into green fluorescence has been studied for Nd^{3+}, Yb^{3+} and Ho^{3+} in the transparent oxyfluoride glass ceramics. At room temperature very strong green upconversion luminescence due to the Ho^{3+}: ({}^5F_4, {}^5S_2)→{}^5I_8 transition under 800 nm excitation was observed in the glass ceramics. The intensity of the green upconversion luminescence in a 1mol% YbF_3-containing glass ceramic was found to be about 120 times stronger than that in the precursor oxyfluoride glass. The reason for the highly efficient Ho^{3+} upconversion luminescence in the oxyfluoride glass ceramics is discussed. The upconversion mechanism is also investigated. 相似文献
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利用高温固相法制备了Tm3+/Yb3+共掺杂的氟氧化物玻璃和玻璃陶瓷材料,在980 nm的激光激发下,样品发射出明亮的蓝色上转换荧光。通过对玻璃和玻璃陶瓷样品的对比,发现Tm3+离子和Yb3+离子之间存在着Tm3+(3H4)→Yb3+(2F5/2)的反向能量传输通道,并且与晶场有较强的依赖关系。分析了在玻璃和玻璃陶瓷中蓝色上转换发光过程,随着敏化剂Yb3+浓度的增加,在玻璃中正向和反向能量传递的竞争作用使得Tm3+离子在Yb3+离子的最佳浓度时上转换发光最强;而在玻璃陶瓷中, Tm3+离子的上转换发光始终随着Yb3+离子的浓度增加而增强。 相似文献
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In this work, we investigate the thermal entanglement for interacting spin systems , by varying the parameters of temperature T, direction and magnetic field B.
PACS numbers: 03.67.Mn, 03.65.Ud, 05.30.Cd, 73.43.Nq 相似文献
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通过熔融法以及热处理,制备了Ce~(3+)掺杂含Li Lu F_4纳米晶的透明氟氧微晶玻璃。XRD结果表明,玻璃中析出的晶相为Li Lu F_4,其晶粒大小随热处理温度的升高和时间的延长而变大。在330 nm紫外光激发下,Ce~(3+)掺杂的氟氧玻璃和Li Lu F4微晶玻璃的发射为一峰值波长为370 nm的宽带光谱。微晶玻璃的发光强度显著高于未经过热处理的基础玻璃,并且随着热处理温度的升高及时间的延长,微晶玻璃的发光逐渐增强。微晶玻璃的370 nm发射的荧光寿命均长于基础玻璃的。 相似文献
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We report the constraints of $H_0$ obtained from Wilkinson Microwave Anisotropy Probe (WMAP) 9-year data combined with the latest baryonic acoustic oscillations (BAO) measurements. We use the BAO measurements from 6dF Galaxy Survey (6dFGS), the SDSS DR7 main galaxies sample (MGS), the BOSS DR12 galaxies, and the eBOSS DR14 quasars. Adding the recent BAO measurements to the cosmic microwave background (CMB) data from WMAP, we constrain cosmological parameters $\Omega_m=0.298\pm0.005$, $H_0=68.36^{+0.53}_{-0.52} {\rm km}\cdot {\rm s}^{-1}\cdot {\rm Mpc}^{-1}$, $\sigma_8=0.8170^{+0.0159}_{-0.0175}$ in a spatially flat $\Lambda$ cold dark matter ($\Lambda$CDM) model, and $\Omega_m=0.302\pm0.008$, $H_0=67.63\pm1.30 {\rm km}\cdot{\rm s}^{-1}\cdot {\rm Mpc}^{-1}$, $\sigma_8=0.7988^{+0.0345}_{-0.0338}$ in a spatially flat $w$CDM model, respectively. Our measured $H_0$ results prefer a value lower than 70 ${\rm km}\cdot {\rm s}^{-1}\cdot{\rm Mpc}^{-1}$, consistent with the recent data on CMB constraints from Planck (2018), but in $3.1$ and $3.5\sigma$ tension with local measurements of SH0ES (2018) in $\Lambda$CDM and $w$CDM framework, respectively. Our results indicate that there is a systematic tension on the Hubble constant between SH0ES and the combination of CMB and BAO datasets. 相似文献
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采用高温熔融法和热处理工艺制作了含有GdF3纳米晶的氧氟微晶玻璃。在386 nm激发下,Dy3+掺杂氧氟微晶玻璃的发光强度明显增强,且蓝光对黄光的发光强度比逐渐增大,表明Dy3+已进入到GdF3纳米晶中。在980 nm激光器泵浦下,Er3+,Yb3+共掺氧氟微晶玻璃的上转换发光随着热处理温度的升高明显增强,Er3+的上转换发光出现明显的Stark分裂现象,这亦说明Er3+已进入到GdF3纳米晶相中。通过研究上转换发光强度与泵浦功率的关系,确定绿光上转换发光为双光子过程。 相似文献
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Accurate theoretical evaluation of strain energy of all-carboatomic ring (cyclo[2n]carbon), boron nitride ring,and cyclic polyacetylene 下载免费PDF全文
Cyclocarbon fully consists of sp-hybridized carbon atoms, which shows quite unusual electronic and geometric structures compared to common molecules. In this work, we systematically studied strain energy (SE) of cyclocarbons of different sizes using regression analysis method based on electronic energies evaluated at the very accurate DLPNO-CCSD(T)/cc-pVTZ theoretical level. In addition, ring strain of two systems closely related to cyclocarbon, boron nitride (BN) ring, and cyclic polyacetylene (c-PA), is also explored. Very ideal relationships between SE and number of repeat units ($n)$ are built for cyclo[2$n$]carbon, B$_{n}$N$_{n}$, and [2$n$]c-PA as ${\rm SE} = 555.0\cdot n^{-1}$, 145.1$\cdot n^{-1}$, and 629.8$\cdot n^{-1}$ kcal$\cdot $mol$^{-1}$, respectively, and the underlying reasons of the difference and similarity in their SEs are discussed from electronic structure perspective. In addition, force constant of harmonic potential of C-C-C angles in cyclocarbon is derived based on SE values, the result is found to be 56.23 kcal$\cdot $mol$^{-1}\cdot $rad$^{-2}$. The possibility of constructing homodesmotic reactions to calculate SEs of cyclocarbons is also explored in this work, although this method is far less rigorous than the regression analysis method, its result is qualitatively correct and has the advantage of much lower computational cost. In addition, comparisons show that $\omega $B97XD/def2-TZVP is a good inexpensive alternative to the DLPNO-CCSD(T)/cc-pVTZ for evaluating energies used in deriving SE, while the popular and very cheap B3LYP/6-31G(d) level should be used with caution for systems with global electron conjugation such as c-PA. 相似文献
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The European Physical Journal E - We synthesized and characterized the colloidal suspensions of $\mathrm{FeO}\cdot\mathrm{Fe}_{(2-x)}\mathrm{Nd}_{x} \mathrm{O_{3}}$ nanoparticles with x = 0.00,... 相似文献
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The Eu 2+ /Tb 3+ /Sm 3+ co-doped oxyfluoride glass ceramics containing Ba2LaF7 nanocrystals are prepared in the reducing atmosphere.The X-ray difiraction results show that Eu 2+ ,Tb 3+ and Sm 3+ ions are enriched into the precipitated Ba2LaF7 nanophase after the annealing process.It deduces efficient energy transfers from Eu 2+ to Tb 3+ and Sm 3+ and intenses warm white luminescence of the glass ceramics. Comparing with the glass,the luminescence quantum yield of the glass ceramics is also enlarged by about 3 times.This demonstrates the potential white light-emitting diode application of the glass ceramics produced in this letter. 相似文献
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通过高温熔融法和后续热处理制得Tb~(3+)掺杂含SrF_2纳米晶的透明硅酸盐微晶玻璃。利用X射线衍射(XRD)、透射电子显微镜(TEM)、紫外可见透过光谱、荧光光谱、荧光寿命和X射线激发发光光谱(XEL)探讨了基础玻璃和微晶玻璃的结构和光谱特性。XRD结果表明,玻璃中析出晶体为SrF_2纳米晶,衍射峰随着热处理温度的升高和时间的延长而逐渐明显,晶粒也随热处理温度的升高和时间的延长越来越大。在376 nm紫外光和X射线激发下,与基础玻璃相比,微晶玻璃发光显著增强,且发光强度随热处理温度的升高和时间的延长而逐渐增强。 相似文献
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We have used spectral hole burning to measure the homogeneous linewidth of the (3)H(6)(1)- (3)F(3)(1) transition of Tm(3+) ions doped into oxyfluoride glass ceramics consisting of nanocrystals of LaF(3) in an aluminosilicate glass matrix. From the magnitude of the hole width in the nanocrystals and its dependence on temperature, we propose that excitation of tunneling modes in the adjacent glassy phase as well as of confined mechanical modes in the nanocrystals is responsible for the broadening. 相似文献
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通过低温选择激发玻璃陶瓷中的LaF3:Tm3+的1D2能级,成功地分开了两种局域环境中Tm3+离子的发射谱,使一些频率的发射谱仅来自于晶相,而另一些则仪来自于玻璃相.讨论了玻璃陶瓷中形成玻璃的氧化物和以晶相析出的氟化物之间的相互作用对两种局域环境中Tm3+离子的光学性能的影响.结果表明:晶粒较大时,氧化物玻璃对处于纳米晶体局域环境的稀土离子的影响减弱,纳米晶体对处于氧化物玻璃局域环境的稀土离子的影响增强;晶粒较小时,氧化物玻璃和晶粒接触面的增加会降低处于纳米晶体局域环境的稀土离子的发光效率,但纳米晶体对处于氧化物玻璃局域环境的稀土离子的影响减弱.晶粒越大,氧化物玻璃对处于纳米品体局域环境的稀土离子的发光影响越小,发光性能越好.玻璃基质中SiO2的含量能影响两种局域环境的Tm3+离子发光效率. 相似文献
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Botao Wu Shifeng Zhou Jinjun Ren Yanbo Qiao Danping Chen Congshan Zhu Jianrong Qiu 《Journal of Physics and Chemistry of Solids》2008,69(4):891-894
Transparent Ni2+-doped MgO–Al2O3–SiO2 glass ceramics without and with Ga2O3 were synthetized. The precipitation of spinel nanocrystals, which was identified as solid solutions in the glass ceramics, could be favored by Ga2O3 addition and their sizes were about 7.6 nm in diameter. The luminescent intensity of the Ni2+-doped glass ceramics was largely enhanced by Ga2O3 addition which could mainly be caused by increasing of Ni2+ in the octahedral sites and the reduction of the mean frequency of phonon density of states in the spinel nanocrystals of solid solutions. The full width at half maximum (FWHM) of emissions for the glass ceramics with different Ga2O3 content was all more than 200 nm. The emission lifetime increased with the Ga2O3 content and the longest lifetime is about 250 μs. The Ni2+-doped transparent glass ceramics with Ga2O3 addition have potential application as broadband optical amplifier and laser materials. 相似文献
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Giorgos S. Athanasiou Elżbieta Bereś-Pawlik Grzegorz Semczuk David Furniss Angela B. Seddon Trevor M. Benson 《Optical and Quantum Electronics》2013,45(9):961-967
A novel method for obtaining a multimode optical coupler in chalcogenide glass fibre is described. The fibres used had a large $\text{ Ge }_{17}\text{ As }_{18}\text{ Se }_{65}$ Ge 17 As 18 Se 65 core comprising about 74 % of the total cross-sectional area with an optical cladding of $\text{ Ge }_{17}\text{ As }_{18}\text{ Se }_{62}\text{ S }_{3}$ Ge 17 As 18 Se 62 S 3 . A single arc-shaped U-groove was formed in each of two silicate glass blocks. A length of fibre was embedded into each groove and glued in place. The centre of each fibre length was subsequently side-polished. Finally two such embedded fibres were glued together in close contact to form the coupler, whilst monitoring the coupling ratio at the output. 相似文献