Na_2O-Al_2O_3-P_2O_5系统玻璃中的[Al-O-P]~-基团

本文报道Na_2O-Al_2O_3-P_7O_5系统玻璃中[Al-O-P]~-基团的Raman谱。我们把高频峰有规律地移向低波数归结为由[Al-O-P]~-基团构成的玻璃网络聚合度下降造成。     

Na2O-K2O-Al2O3三元系固体结构研究

制备了xNa₂O-(1-x)K₂O-Al₂O₃(x=0.33, 0.50, 0.66, 1)三元系固体,实验利用拉曼光谱技术获得了xNa₂O-(1-x)K₂O-Al₂O₃三元系固体的常温拉曼光谱和升温拉曼光谱,使用CASTEP软件优化晶体结构和计算拉曼光谱,获得了xNa₂O-(1-x)K₂O-Al₂O₃三元系样品的常温拉曼光谱,结果表明低波数区(100～400 cm^-1)的拉曼特征峰为Na—O键的振动。中波数区(400～700 cm^-1)的拉曼特征峰为铝氧四面体中桥氧键的振动。高波数区(700～1 000 cm^-1)的拉曼特征峰为Al-O_nb的振动。对三元系样品的拉曼特征峰进行有效归属。获得了0.5Na₂O-0.5K<...     

Nd3+掺杂B2O3-Nb2O5-BaO-La2O3玻璃光谱性质的研究

 用高温熔融法制备了Nd³⁺(物质的量分数2％）掺杂40B₂O₃-(15-χ)Nb₂O₅-45BaO-χLa₂O₃玻璃，测量了样品的吸收光谱、发射光谱和差热分析（DTA）曲线。根据Nd3+光学跃起矩阵的特点，应用Judd-Ofelt理论，从吸收光谱获得了Nd³⁺光学跃起的强度参数。并计算了Nd³⁺离子的自发辐射跃迁几率、总自发辐射几率、荧光分支比、辐射能级寿命和受激发射截面。结果表明：该体系玻璃中，随着Nb₂O₅ 含量的增加和La₂O₃₂增大，说明材料的对称性降低；而Ω₆减小，说明Nd-O键的共价性和键强增强；受激发射截面减小。DTA实验表明，随着Nb₂O₅含量的增加，材料的热稳定性提高。     

Ce3+掺杂SiO2-Al2O3-Gd2O3玻璃的闪烁性能

通常, Ce离子掺杂的低密度玻璃有较高的发光效率, 而高密度的Ce离子掺杂玻璃其发光效率很低. 为了解释这一现象, 采用高温熔融法获得了SiO₂-Al₂O₃-Gd₂O₃三元系统的玻璃形成区, 并在还原气氛下制备了Ce³⁺掺杂SiO₂-Al₂O₃-Gd₂O₃以及SiO₂-Al₂O₃-Gd₂O₃-Ln₂O₃ (Ln=Y, La, Lu)闪烁玻璃, 研究了其光谱和闪烁性能. 测试结果显示: 随着Gd₂O₃含量增加, 玻璃紫外截止波长发生红移, 荧光强度降低, 衰减时间缩短; 加入Lu₂O₃, La₂O₃, Y₂O₃后, 紫外截止波长发生红移, 荧光强度降低, 衰减时间变短; 当Gd₂O₃超过10% mol时, X射线荧光积分光产额从相当于锗酸铋 晶体的61%降低到13%. 荧光强度降低、衰减时间缩短的原因是随着玻璃的紫外截止波长红移玻璃的能带宽度变窄, 使得Ce³⁺离子的d电子轨道开始接近玻璃的导带, Ce³⁺离子受辐射后跃迁到d电子轨道的电子会通过导带与玻璃中的空穴复合, 产生电荷迁移猝灭效应.     

Ga2O3组分对Tm3+掺杂GeO2-Ga2O3-Li2O-BaO-La2O3玻璃的光谱性能影响

制备了Tm³⁺(8.0mol%)掺杂(77-x)GeO₂-xGa₂O₃-8Li₂O-10BaO-5La₂O₃(x=4,8,12,16)系列玻璃.系统地研究了Ga₂O₃从4mol%变化到16mol%时,玻璃的光谱性质与热学性质的变化规律.差热分析表明,随着Ga₂O₃含量的增加,锗酸盐玻璃的热稳定性增加.运用Judd-Ofelt(J_O)理论计算得到了Tm³⁺在不同Ga₂O₃含量的GeO₂-Ga₂O₃-Li₂O-BaO-La₂O₃玻璃中的J-O强度参数(Ω₂,Ω₄,Ω₆)及Tm³⁺各激发能级的自发跃迁概率、荧光分支比以及辐射寿命等光谱参量.在808nm激光二极管的激发下,测试并分析了Ga₂O₃对Tm³⁺荧光光谱特性的影响.随着Ga₂O₃从4mol%增加到16mol%,Tm³⁺在1.8μm处的荧光强度呈现先减弱后增强的特性.当Ga₂O₃含量大约在12mol%时,Tm³⁺在1.8μm处的荧光强度最弱,受激发射截面达到最小.还初步讨论了Ga₂O₃对玻璃结构与光谱参数的影响规律. 关键词： 3+掺杂锗酸盐玻璃')" href="#">Tm³⁺掺杂锗酸盐玻璃 光谱性能 Judd-Ofelt参数 热稳定性     

Er3+掺杂的Bi2O3-B2O3-SiO2玻璃的光谱性质

测试了Bi₂O₃-B₂O₃-SiO₂玻璃中的Er³⁺离子的吸收光谱、发射光谱、⁴I_13/2的荧光寿命、拉曼光谱,及OH^-的傅里叶红外吸收光谱。应用Judd-Ofelt理论计算了该玻璃中的Er³⁺离子的J-O参数、振子强度、⁴I_13/2能级的寿命,从而利用测得的⁴I_13/2的荧光寿命得出了⁴I_13/2能级的量子效率(15%)。由于较低量子效率可能与OH^-有关,所以计算了玻璃中的OH^-浓度,发现其浓度较高(1.66×10¹⁹cm^-1,相当于Er³⁺浓度的3倍)。应用McCumber理论和四能级模型计算了Er³⁺离子的受激发射截面和荧光发射光谱的半峰全宽,结果与通过吸收光谱计算所得基本吻合。根据透射率和折射率的关系计算了折射率,发现和测量值相差很大,说明有较大的散射,通过拉曼光谱和显微镜测试,认为是玻璃中的微小气泡造成的。     

光学碱度对Tb3+掺杂Bi2O3-B2O3玻璃发光性能的影响

采用熔融法制备了Tb³⁺掺杂的Bi₂O₃-B₂O₃系统玻璃,使用激发、发射及拉曼光谱分析了光学碱度与玻璃结构及发光性能的关系,同时绘制了Tb³⁺、Bi³⁺和Bi²⁺的能级图。研究结果表明：Tb³⁺掺杂的Bi₂O₃-B₂O₃玻璃由[BO₃]、[BiO₃]、[BO₄]及[BiO₆]共同组成,且随着光学碱度由0.63增加到0.93,玻璃的结构逐渐疏松。高的光学碱度使部分Bi³⁺变为Bi²⁺,发出571 nm（²P_3/2（2）→²P_1/2）的光,Bi³⁺→Tb³⁺的能量降低。在光学碱度及Tb³⁺、Bi³⁺和Bi²⁺离子的共同作用下,随着光学碱度的提高,玻璃的发光颜色由黄绿色变为白色。     

Magnetic and structural properties of CaO–SiO2–P2O5–Na2O–Fe2O3 glass ceramics

Magnetic properties of glass ceramics derived from glasses with composition 41CaO·(52−x)SiO₂·4P₂O₅·xFe₂O₃·3Na₂O (2?x?10 mol% iron oxide (Fe₂O₃)) are reported. Structural investigation revealed the presence of nanocrystalline magnetite phase in the heat-treated samples containing x?2 mol% Fe₂O₃. Magnetic hysteresis cycles of the glass-ceramic samples were obtained with a maximum applied field of ±20 kOe as well as a low field of ±500 Oe, in order to evaluate the potential of these glass ceramics for hyperthermia treatment of cancer. Samples with x>2 mol% of iron oxide exhibited magnetic behavior similar to soft magnetic materials with low coercivity. The evolution of magnetic properties in these samples as a function of iron oxide molar concentration is correlated with the amount and crystallite size of magnetite phase present in them.     

Eu3+掺杂Bi2O3-PbO-B2O3-ZnO玻璃光谱性质

用高温融熔法制备了Eu³⁺掺杂浓度为1%的(60-x)Bi₂O₃xPbO30B₂O₃10ZnO(x=0,10,30,摩尔分数)玻璃.测定了玻璃的差热分析曲线、吸收光谱、声子边带谱、发射光谱与激发光谱.由发射光谱与稀土Eu³⁺离子光学跃迁矩阵元的特点,计算了Eu³⁺光学跃迁的J-O参数Ω₂与Ω₄.结果显示强度参数Ω₂随着PbO量的增加而略减少,表明材料的对称性略增加,Eu—O键强减弱,共价性降低.PbO组分的增加,使玻璃的结晶起始温度与软化温度差降低,导致玻璃的热温度性变差.随着PbO的增加,电-声子耦合减弱.     

Na3GdSi2O7:Tb3+荧光粉发光特性及Gd3+→Tb3+之间的能量传递

采用高温固相法合成了Na3Gd1-xTbxSi2O7(x=0.01,0.02,0.04,0.06,0.08,0.1)系列荧光粉。研究了荧光粉的真空紫外-可见发光光谱和荧光寿命,讨论了Tb3+在扭曲八面体结构(标示为Gd(1)3+)和正三棱柱构型(标示为Gd(2)3+)两种格位中的最低5d轨道能级。同时研究了Gd3+→Tb3+之间无辐射能量传递速率K和无辐射能量传递效率η。研究结果表明:Tb3+在Gd(1)3+格位中的最低允许跃迁和禁戒跃迁的5d轨道能级分别位于235 nm和280 nm,在Gd(2)3+格位中的最低允许跃迁和禁戒跃迁的5d轨道能级分别位于224nm和256 nm。随着Tb3+浓度的增加,能量传递效率及速率显著增大,说明在Na3Gd1-xTbxSi2O7中存在有效的Gd3+-Tb3+能量传递。     

Li2O-(LiCl)2-B2O3-Al2O3系统玻璃的Raman光谱研究

我们用Raman光谱研究了Li₂O(LiCl)₂B₂O₃-Al₂O₃系玻璃的结构,着重研究了Al₂O₃的影响。对于Li₂O-B₂O₃系玻璃,Li₂O含量增加使玻璃中存在的BO₃三角体转变为BO₄四面体, 关键词：     

Li2O-(LiCl)2-B2O3-Al2O3系统玻璃的声学性质

本工作测量了Li₂O-(LiCl)₂-B₂O₃-Al₂O₃系统玻璃的密度、超声速,计算了玻璃的绝热压缩系数,从声学性质分析了玻璃骨架结构随组成的变化,为研究玻璃的离子导电性提供了方法和分析的依据。 关键词：     

xNa2O·yB2O3玻璃的融熔态结构

本文应用变温核磁共振技术研究了xNa₂O·yB₂O₃二元玻璃体系的融熔态结构。结果表明,R≤0.5的熔体中存在两种较为稳定的结构:在730—780℃温度区域形成了B原子间以双桥氧连接的网状结构;在880—920℃温度区域形成了B原子间含三桥氧的链状结构。当R>0.5时熔体中只存在第一种结构。 关键词：     

Fabrication of ZnO/Al2O3 core-shell nanostructures and crystalline Al2O3 nanotube

We have demonstrated the crystalline ZnO-Al₂O₃ core-shell nanowire structure by atomic layer deposition (ALD) at a temperature 100 °C. The core-shell structure could have potential applications in the fabrication of ZnO field effect transistor. After dissolving the ZnO core, shape defined, rigid and robust crystalline Al₂O₃ shelled nanostructures have been fabricated. Nanowire ZnO nanostructures have been replicated by alumina shell. This is one of the most effective techniques for producing core-shell or shell/hollowed nanostructures of any desired objects. The Al₂O₃ shelled nanostructures could have potential applications as space confined nanoreactors, drug delivery, nanofluidic channels and optical transmitting.     

Ag concentration dependent transport properties of LiF-MoO3-P2O5 glasses

LiF-MoO₃-P₂O₅ glasses mixed with different concentrations of Ag₂O (ranging from 0 to 1.0 mol%) was prepared. D.C. conductivity and dielectric properties over a range of temperature have been investigated. The analysis of the results of d.c. conductivity has indicated that T>θ_D/2, the small polaron hoping model seems to be fit and the conduction is adiabatic in nature. These results further indicated that there is a change over of conduction mechanism from electronic to ionic at about 0.4 mol% of Ag₂O. The low temperature part of a.c. conductivity is explained based on quantum mechanical tunneling model. The quantitative analysis of these results is further extended with the aid of the data on optical absorption, ESR and IR spectral studies.     

Li2O-2B2O3熔体的物性研究

系统测量了四硼酸锂(Li₂Ｏ-２Ｂ_２Ｏ_３)熔体的密度ρ、表面张力γ随着温度的变化规律，实验结果表明在1100K到1500K范围内Li₂Ｏ-２Ｂ_２Ｏ_３高温熔体的密度和表面张力随着温度的升高均线性减小.通过实验数据拟合得出熔体密度与温度关系为ρ(T)=2.574—4.89×１０^－４T，熔点处Li₂Ｏ-２Ｂ_２Ｏ关键词： 功能晶体 四硼酸锂 密度 表面张力     

EPR and magnetic properties of MgO-CaO-SiO2-P2O5-CaF2-Fe2O3 glass-ceramics

Glass-ceramics have been derived from 4.5MgO(45−x)CaO34SiO₂16P₂O₅0.5CaF₂xFe₂O₃ (x=5, 10, 15, 20 wt%) glasses by heat treatment. Room temperature electron paramagnetic resonance (EPR) spectra and temperature-dependent magnetic susceptibility (χ) of the glass-ceramics have been obtained. The EPR absorption line centered at g≈4.3 disappeared at higher concentrations of iron oxide. The intensity and line width of the EPR absorption line centered at g≈2.1 increased as the iron oxide concentration was increased. Temperature-dependent magnetization of samples with low iron oxide content revealed ferrimagnetic as well as paramagnetic contributions. Information about the structural changes involving iron ions, their valence state and the type of magnetic interactions between the Fe ions as a function of composition was obtained using EPR and χ studies.     

Optical and crystal-field analysis of Er ion in Y2O3-P2O5 thin films

Luminescence spectra of erbium ions doped in Y₂O₃-P₂O₅ thin films, with different P₂O₅ content (from 3% to 47%), were analysed with crystal-field Hamiltonian model with D_2d symmetry including J-mixing effect. The empirical crystal-field parameters (CFPs) obtained for the best fit of calculated to experimental energy levels allows us to confirm the well-established YPO₄ phase for 47% of P₂O₅. The CFPs are compared to those calculated for Ce³⁺, Nd³⁺ and Dy³⁺ in the YPO₄ host. This work is a continuation of our previous results for erbium-doped Y₂O₃ thin films.     

非晶锂离子导体P2O5-0.7Li2O-0.4LiCl-0.1Al2O3的离子导电性与结构研究

本文研究了非晶锂离子导体P₂O₅-0.7Li₂O-0.4LiCl-0.1Al₂O₃的60目、120目、200目粉末、粉末压片和整片非晶在60至380℃的离子电导率和激活能。发现颗粒度减小能使离子电导率提高四倍以上,但不影响激活能,它归因于同一非晶相的界面效应。各样品在380℃等温热处理76h内的离子电导率和X射线衍射研究表明:颗粒度越小,晶化就越容易。整片非晶比粉末压片不仅电导率提高两个数量级,激 关键词：     

Characteristics of sandwich-structured Al2O3/HfO2/Al2O3 gate dielectric films on ultra-thin silicon-on-insulator substrates

Sandwich-structure Al₂O₃/HfO₂/Al₂O₃ gate dielectric films were grown on ultra-thin silicon-on-insulator (SOI) substrates by vacuum electron beam evaporation (EB-PVD) method. AFM and TEM observations showed that the films remained amorphous even after post-annealing treatment at 950 °C with smooth surface and clean silicon interface. EDX- and XPS-analysis results revealed no silicate or silicide at the silicon interface. The equivalent oxide thickness was 3 nm and the dielectric constant was around 7.2, as determined by electrical measurements. A fixed charge density of 3 × 10¹⁰ cm⁻² and a leakage current of 5 × 10⁻⁷A/cm² at 2 V gate bias were achieved for Au/gate stack /Si/SiO₂/Si/Au MIS capacitors. Post-annealing treatment was found to effectively reduce trap density, but increase in annealing temperature did not made any significant difference in the electrical performance.