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101.
Transparent Er3+-doped bulk nanocrystallized (size of nanocrystals: ∼40 nm) glasses of 15K2O·15Nb2O5·70TeO2·0.5Er2O3 and 10BaO·10Gd2O3·80TeO2·0.5Er2O3 are prepared, and the Judd-Ofelt parameters, (t=2, 4, 6), of Er3+ are evaluated from optical absorption spectra. The change in the molar polarizability due to the nanocrystallization is small in both samples, but a clear decrease in the mean atomic volume due to the nanocrystallization, i.e. more close atom packing, is observed. In both systems, a large decrease is observed in the parameter due to the nanocrystallization, indicating that the degree of the site symmetry of Er3+ ions in nanocrystallized glasses is much higher than that in the precursor glasses. The decrease in the and parameters due to the crystallization is small, suggesting that the covalency of Er3+-O bonds in nanocrystals is not so different from that in the precursor glasses.  相似文献   
102.
Addressed here are polarization optics for extreme-ultraviolet and soft X-ray wavelengths, especially as relevant to laser cavities. It is pointed out that the whisper-gallery mirrors studied by Vinogradov can serve as weak polarizers and, more importantly, as birefringent elements. The application of multilayer technology to polarizing mirrors and beamsplitters is also considered. It is shown that multilayer beamsplitters can function both as reflective and transmissive polarizers. Their behavior is surprising in some cases, with the same polarization being preferred in both reflection and transmission. Three polarizing cavity schemes are proposed, each incorporating a polarizing beamsplitter as its output coupler. Cavity optimization issues are discussed.  相似文献   
103.
We present an overview of the recent studies on the properties of the potential energy surface for a simple model of water. We emphasize the relations between PES properties and dynamics in supercooled states for the model and discuss possible future application of the PES studies. Received 13 March 2002  相似文献   
104.
After classifying amorphous materials according to their topology, we review a recently proposed theory of pressure amorphization (PA) that arises from some degree of displacive disorder while retaining a crystalline topology. That theory is based on the notion that one or more branches of the phonon spectrum become soft and flat with increasing pressure and is illustrated by a simple model that possesses the range of features displayed by many of the materials which undergo PA with displacive disorder. We report the results of Langevin simulations of the simple model which show how the probability of amorphization increases with the number of unit cells in the system and support our theory. We comment on how to generalize the model for the study of real systems. Received 29 march 2002  相似文献   
105.
Optical absorption, thermoluminescence, infrared spectra and differential thermal analysis of three different tellurite glass systems viz., ZnF2-As2O3-TeO2, ZnF2-Bi2O3-TeO2 and ZnF2-P2O5-TeO2 containing 0.4% of Cr2O3, have been investigated. Results have been analysed in the light of different oxidation states of chromium ion and the most suitable host for lasing Cr3+ ions has been identified and reported.  相似文献   
106.
城市生活垃圾流化床焚烧时PCDD/Fs排放特性的研究   总被引:7,自引:0,他引:7  
城市生活垃圾焚烧处理已逐渐在我国推广应用.垃圾焚烧所产生的二恶英污染问题日益被人们所关注,浙江大学基于我国城市生活垃圾的特点(高水份、多组份、低热值等),成功开发了异重流化床焚烧技术并应用于一座 150 t/d垃圾流化床焚烧锅炉.木文首先介绍了二恶英的分析方法,其次在小型流化床上进行了PCDD/Fs的生成机理试验、在此基础上,对150t/d垃圾焚烧炉烟气中二恶英排放进行了分析,实验结果将指导焚烧炉优化运行并为进一步研究打下坚实基础。  相似文献   
107.
108.
Molecular dynamics simulation of binary glass 52Li2O-48P2O5 and ternary glasses 45Li2O-42P2O5-13LiCl and 39Li2O-36P2O5-25LiCl was undertaken to study the effects of the addition of LiCl to the binary phosphate glass. The results show that addition of LiCl in the glass creates more non-bridging oxygens and reduces P-O-P chain lengths and branches in these chains, leading to a weakening of the glass matrix and consequent lowering of Tg. Interchain linkages mediated by Li in the binary structure diminish, and consequently better channels are created for Li+ movement, enhancing the ionic conductivity σ. Structure parameters also indicate the absence of LiCl clusters in the glass matrix.  相似文献   
109.
110.
Two-dimensional crystal curved lines consisting of the nonlinear optical SmxBi1−xBO3 phase are fabricated at the surface of 8Sm2O3·37Bi2O3·55B2O3 glass by continuous wave Nd:YAG laser (wavelength: 1064 nm) irradiation (samarium atom heat processing) with a power of ∼0.9 W and a laser scanning speed of 5 μm/s. The curved lines with bending angles of 0-90° or with sine-shapes are written by just changing the laser scanning direction. The polarized micro-Raman scattering spectra for the line after bending are the same as those for the line before bending, indicating that the crystal plane of SmxBi1−xBO3 crystals to the crystal growth direction might be maintained even after the change in the laser scanning direction. It is found from laser scanning microscope observations that the crystal lines at the surface are swelled out smoothly, giving a height of about 10 μm.  相似文献   
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