125 resultados para NA2O-B2O3-P2O5
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Early glasses (about 1066 BC-220 AD) unearthed from Xinjiang of China were chemically characterized by using PIXE and ICP-AES. It was found that these glasses were basically attributed to PbO-BaO-SiO2 system, K2O-SiO2 system, Na2O-CaO-SiO2 system and Na2O-CaO-PbO-SiO2 system. The results from the cluster analysis showed that some glasses had basically similar recipe and technology. The PbO-BaO-SiO2 glass and the K2O-SiO2 glass were thought to come from the central area and the south of ancient China, respectively. The part of the Na2O-CaO-SiO2 glass (including the Na2O-CaO-PbO-SiO2 glass) might be imported from Mesopotamia, while the other part might be locally produced. (c) 2005 Elsevier B.V. All rights reserved.
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The earliest Chinese ancient glasses before the West Han Dynasty (200 BC) from different regions are studied. The glass samples were unearthed from Hunan, Hubei, Yunnan, Sichuan, Guizhou, Guangdong and Xinjiang of China. The chemical composition of these glasses samples is analyzed by proton induced X-ray emission (PIXE) technique, energy dispersive X-ray fluorescence (EDXRF) method and inductively coupled plasma atomic emission spectrometry (ICP-AES). It is shown that the glass chemical compositions belong to barium-lead silicate BaO-PbO-SiO2, potash soda lime silicate K2O (Na2O)-CaO-SiO2 (K2O/Na2O > 1), soda potash lime silicate Na2O (K2O)-CaO-SiO2 (K2O/Na2O < 1) and potash silicate K2O-SiO2 glass systems, respectively. The origins of the earliest Chinese ancient glasses are discussed from the archaeological and historical points of view. These four types of Chinese ancient glasses were all made in Chinese territory using local raw materials. The glass preparation technology was related to the Chinese ancient bronze metallurgy and proto-porcelain glaze technology. The glass technology relationship between the East and the West is analyzed at the same time.
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结合外束质子激发X荧光(proton induced X-ray emission,PIXE)和能量色散X射线荧光(energy dispersive X-ray emission,EDXRF)分析技术,对中国新疆、湖北、四川、广东出土的古代镶嵌玻璃珠的化学成分进行了检测.结果表明:新疆拜城克孜尔墓地出土的西周-春秋时期镶嵌玻璃珠为CaO-MgO-SiO2玻璃,战国时期中国境内的PbO-BaO-SiO2和Na2O-CaO-SiO2镶嵌玻璃珠是同时存在的.本文亦对相关问题进行了一些讨论,并提出了部分今后的工
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对化学成分体系的确定是中国古代玻璃研究中很重要的一个方面,为此,用外束质子激发X荧光技术(PIXE)、电感耦合等离子体原子发射光谱分析(ICP-AES)等方法,对新疆、湖北、河南和重庆等地区出土的一批战国时期的玻璃珠(包含镶嵌玻璃珠)、玻璃璧样品进行了检测。结果表明,战国时期中国境内同时存在PbO-BaO-siO2、K2O-SiO2、Na2O-CaO-SiO2三种硅酸盐玻璃,分布的地域范围从中国的新疆东部一直到长江、黄河流域,以及南方的四川、贵州等地区。中国古代的PbO-BaO-SiO2和K2O-SiO玻
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采用改进的外束质子激发x射线荧光、电感耦合等离子体原子发射光谱分析等技术,对广西合浦地区出土的一批汉代古玻璃样品的化学成分和结构特性等进行了检测。结果表明:两汉时期,合浦地区的古代玻璃存在K2O—SiO2、PbO-BaO-SiO2、PbO—SiO2、Na2O-K2O-PbO-SiO2、(Na2O)K2O-CaO—SiO2等多种类型,但绝大多数为K2O—SiO2玻璃。表面风化可引起K2O-SiO2玻璃表面K2O等助熔剂的流失和富硅层的形成。综合化学成分以及器型特征,认为我国汉代K2O—SiO2玻璃制造技术可
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研究了西汉(公元前200年)以前不同地区的最早的中国古代玻璃.古玻璃样品出土于新疆维吾尔自治区、湖北省、湖南省、四川省、云南省、广东省和贵州省等地.用质子激发X光荧光技术、能量分散X光荧光技术和电感耦合等离子发射光谱等方法测定了玻璃的化学成分.这些古玻璃样品的化学成分属于以下玻璃系统:Na2O(K2O)-CaO—SiO2(K2O:Na2O〈1),K2O(Na2O)-CaO—SiO2(K2O:Na2O〉1),K2O—SiO2和BaO—PbO—SiO2.从考古和历史学观点讨论了这些最早的中国古代玻璃的起源,指
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制备了用于离子交换法制备光波导器件的掺铒碲-钨-钠玻璃基质。应用扎得-奥菲而特(Judd—Ofelt)理论计算了玻璃样品的三个强度参量,由强度参量计算了Er^3+离子的自发跃迁几率、荧光分支比等光谱参量;应用麦克库玻(McCumber)理论,计算了Er^3+离子在1.5μm的受激发射截面,荧光测试发现Er^3+离子的荧光半峰全宽可达65nm。比较了Er^3+离子在不同玻璃基质中的光谱特性。结果表明,Er^3+离子在碲-钨-钠玻璃中具有较高的受激发射截面和较宽的荧光半峰全宽,可以用于宽带光波导器件的制备。
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分析了掺Er^3+碲酸盐玻璃的热力学稳定性能,研究了掺Er^3+碲酸盐玻璃的吸收和荧光光谱性质;应用Judd-Ofelt理论计算了碲酸盐玻璃中Er^3+离子的强度参数Ω(Ω2=4.79×10^-20cm^2,Ω4=1.52×10^-20cm^2,Ω6=0.66×10^-20cm^2),计算了离子的自发跃迁几率,荧光分支比;应用McCumber理论计算了Er^3+的受激发射截面(σe=10.40×10^-21cm^2)、Er^3+离子^4I13/2→^4I15/2发射谱的荧光半高宽(FWHM=65.5nm)
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The doped Eu3+ ions can be partly reduced to Eu2+ in a series of MO-B2O3: Eu (M=Ba, Sr, Ca) glasses synthesized in air atmosphere, but not in the 12CaO-7Al(2)O(3): Eu glass. The different redox-behavior of Eu ions in these two glass systems is attributed to the different host optical basicity. It is found that a lower valence state of Eu2+ is more favorable in acidic glasses, which have lower optical basicities. A notion of the critical value of optical basicity is introduced empirically, which can be used as a guide for the selection of glass composition suitable to incorporate Eu2+ for luminescence. (C) 2006 Elsevier B.V. All rights reserved.
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The Er3+/Yb3+ co-doped glasses with compositions of xBi(2)O(3)-(65-x)P2O5-4Yb(2)O(3)-11Al(2)O(3)-5BaO-15Na(2)O (where x = 0, 2.5, 5, 7.5 and 10 mol%) were prepared using the normal melt quench technique. The optical absorption spectra of the glasses were recorded in the wavelength range 300-1700 nm. The effect of Bi2O3 content on the thermal stability and absorption spectra of glasses was investigated. In addition, the Judd-Ofelt parameters and oscillator strengths were calculated by employing Judd-Ofelt theory. It was observed that the positions of the fundamental absorption edge and cut-off wavelength shifted towards red as the content of Bi2O3 increased. However, there were no red shifts found both in the peak wavelength and in the center of mass wavelength of all absorption bands with Bi2O3 content increasing. The results of Judd-Ofelt theory analysis showed that Judd-Ofelt parameters Omega(t), (t = 2, 4, 6) changed sharply when Bi2O3 concentration exceeded 5 mol%. The variation trends of experimental oscillator strength were similar with those of Judd-Ofelt parameters as function of Bi2O3 concentrations. Moreover, differential scanning calorimetry experiments showed that the increases of Bi2O3 content weakened the network structure and then lowered the thermal stability of the glasses. The spontaneous emission probability A(rad), branching ratio beta and the radiative lifetime tau(rad) were also calculated and analyzed. The stimulated emission cross-section of Er3+ was calculated according to the McCumber theory. It was found that the stimulated emission cross-section of Er3+ was monotonically increases with Bi2O3 content increasing. (C) 2006 Elsevier B.V. All rights reserved.
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FSodium phosphate tellurite glasses in the system (NaPO3)(x)(TeO2)(1-x) were prepared and structurally characterized by thermal analysis, vibrational spectroscopy, X-ray photoelectron spectroscopy (XPS) and a variety of complementary solid-state nuclear magnetic resonance (NMR) techniques. Unlike the situation in other mixed-network-former glasses, the interaction between the two network formers tellurium oxide and phosphorus oxide produces no new structural units, and no sharing of the network modifier Na2O takes place. The glass structure can be regarded as a network of interlinked metaphosphate-type P(2) tetrahedral and TeO4/2 antiprismotic units. The combined interpretation of the O 1s XPS data and the P-31 solid-state NMR spectra presents clear quantitative evidence for a nonstatistical connectivity distribution. Rather the formation of homootomic P-O-P and Te-O-Te linkages is favored over mixed P-O-Te connectivities. As a consequence of this chemical segregation effect, the spatial sodium distribution is not random, as also indicated by a detailed analysis of P-31/No-23 rotational echo double-resonance (REDOR) experiments. ACHTUNGTRENUNG(TeO2)1 x were prepared and structurally characterized by thermal analysis,vibrat ional spectroscopy,X-ray photoelectron spectroscopy (XPS) and a variety of complementary solid-state nuclear magnetic resonance (NMR) techniques. Unlike the situation in other mixed-network-former glasses,the interaction between the two network formers tellurium oxide and phosphorus oxide produces no new structural units,and no sharing of the network modifier Na2O takes place. The glass structure can be regarded as a network of interlinked metaphosphate-type P(2) tetrahedral and TeO4/2 antiprismatic units. The combined interpretation of the O 1s XPS data and the 31P solid-state NMR spectra presents clear quantitative evidence for a nonstatistical connectivity distribution. Rather,the formation of homoatomic P O P and Te O Te linkages is favored over mixed P O Te connectivities. As a consequence of this chemical segregation effect,the spatial sodium distribution is not random,as also indicated by a detailed analysis of 31P/23Na rotational echo double-resonance (REDOR) experiments.
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The flattening and broadening effects of Ga
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We report on the energy transfer and frequency upconversion spectroscopic properties of Er3+-doped and Er3+/Yb3+-codoped TeO2-ZnO-Na2O-PbCl2 halide modified tellurite glasses upon excitation with 808 and 978 nm laser diode. Three intense emissions centered at around 529, 546 and 657 nm, alongwith a very weak blue emission at 4 10 nm have clearly been observed for the Er3+/Yb3+-codoped halide modified tellurite glasses upon excitation at 978 nm and the involved mechanisms are explained. The quadratic dependence of fluorescence on excitation laser power confirms the fact that the two-photon contribute to the infrared to green-red upconversion emissions. And the blue upconversion at 410 nm involved a sequential three-photon absorption process. (c) 2005 Elsevier Ltd. All rights reserved.
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(100 - x)TeO2 - xNb(2)O(5) (x=5-20) mobic tellurite glasses doped with 0.5 mol.% Er2O3 were synthesized, and their thermal, mechanical, and spectroscopic properties were measured and compared to the properties of the typical 75TeO(2)-20ZnO-5Na(2)O (TZN) tellurite glass. The refractive index (n(d)), density (p), and glass transition temperature (T-g) of bulk glasses increase with the Nb2O5 content. The Vickers microhardness (H-v) of bulk glass in niobic tellurite glasses also increases with the Nb2O5 content. The values (2.5-3.2 GPa) of H, in the niobic tellurite glasses are 47-88% larger than that (1.7 GPa) in TZN glass. The effect of Nb2O5 content on absorption spectra, the Judd-Ofelt parameters Omega(t) (t = 2, 4, 6), fluorescence spectra and the lifetimes of Er3+ :I-13/2 level were also investigated, and the stimulated emission crosssection was calculated from McCumber theory. With increasing Nb2O5 content in the glass composition, the Omega(t) (t = 2, 4, 6) parameters, fluorescence full width at half maximum (FWHM) Of I-13/2 of Er3+ increase, while the I-4(13/2) lifetimes of Er3+ decreases. Compared with TZN glass, the gain bandwidth properties of Er3+-doped TeO2-Nb2O5 glass is much larger than in tellurite glass based TeO2-ZnO-Na2O system, bismush-based glass, germanate, and silicate glasses, which indicates that TeO2-Nb2O5 glasses are better choice as a practical available host material for broadband Er3+-doped amplifier. (c) 2005 Elsevier B.V. All rights reserved.
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Er3+ doped aluminophosphate glasses with various Na2O/Li2O ratios were prepared at 1250 degrees C using a silica crucible to study mixed alkali effect (MAE). The effect of relative alkali content on glass transition temperature, crystallization temperature and thermal stability were investigated using differential scanning calorimetry (DSC). In addition, apparent activation energies for crystallization, E, were determined employing the Kissinger equation. The effect of Al2O3 content on the magnitude of MAE was also discussed. No mixed-alkali effect is observed on crystallization temperature. (c) 2006 Elsevier B.V. All rights reserved.