用相图原理研究玻璃结构和性质 (Ⅱ)核磁共振谱研究锂硼硅、镉硼锗和锂硼碲玻璃结构

本文在以前工作的基础上,用电子计算机计算了Li_2O-B_2O_3-SiO_2,CdO-B_2O_3-GeO_2和Li_2O一B_2O_3-TeO_2三元玻璃系统的NMR数据(N_(BO_4)),和实验结果相比较,根据相图原理,提出了一种新的玻璃结构模型,即相图模型.作者认为:玻璃和晶体具有相似的结构,多成分玻璃则是由相图中最邻近的同成分熔融化合物组成的混合物,且各化合物的量可按“杠杆原理”计算,即相图模型.对于未知相图的三元系统,在相图模型的基础上,作者作了一些简单的假设并进行修正.     

GeS2-In2S3硫系玻璃的物化性质与晶化行为研究

认识玻璃组成-性能-结构之间关系是玻璃科学中经久不衰的研究课题之一. 在制得(100-x) GeS₂-xIn₂S₃ (x=10, 15, 20, 25或30 mol%) 系列玻璃和玻璃陶瓷样品的基础上, 利用可见-近红外透过光谱, DSC, XRD和Raman光谱等测试技术表征了随组份变化的光学带隙, 玻璃转变温度以及晶化行为等, 并结合GeS₂-Ga₂S₃玻璃研究结果探讨了Ga, In 元素及其形成的网络结构对玻璃性质的影响.研究发现, 在硫系玻璃中In比Ga对光学带隙和玻璃转变温度等性质的影响要大. 它们所形成玻璃的晶化行为也截然不同, 但与其各自的材料相图有着密切的联系. 利用偏振拉曼光谱获得玻璃网络中的基本结构单元信息.最后, 结合材料相图, 玻璃随组成变化的物化性质和晶化行为以及基本网络结构单元的认识, 探讨了玻璃的化学拓扑与网络拓扑之间的联系, 为今后研究提供一种新的研究思路.     

TiO2对磷酸钙玻璃结构影响的Raman光谱研究

利用Raman光谱、X射线衍射(XRD)和热分析(DSC)技术研究了包容TiO2的磷酸钙玻璃的结构特点.结果表明,TiO2添加量小于3 mol%时,与磷酸钙形成均质玻璃.添加量为6～12 mol%时,玻璃基体中生成了Ca2P2O7和CaTi4(PO4)6品相.随着TiO2的加入,玻璃体系中发生了偏磷酸盐向焦磷酸盐和正磷酸盐的结构转变.TiO2添加量小于3 mol%时,加入TiO2增强了玻璃结构的内聚力,使得玻璃转变温度逐渐提高,玻璃的热稳定性增强.     

稀土掺杂硼铝硅酸盐玻璃结构的NMR研究

在Sm₂O₃掺杂BaO-B₂O₃-Al₂O_3-SiO_2-Sm₂O₃(BBASS)玻璃系统的形成性能研究的基础上,借助MAS NMR以及差热测试(DTA)技术,研究了玻璃的结构特点以及玻璃组成、热处理条件等因素对玻璃结构的影响. 研究表明,在未掺稀土的BBAS玻璃结构中,硼氧多面体主要以[BO₃]、[BO₄]存在,铝氧多面体主要以[AlO₄]、[AlO₅]、[AlO₆]存在;随着BBAS中BaO含量的增加,硼氧三角体[BO₃]逐渐向[BO₄]转变,原先[AlO₄]、[AlO₅]、[AlO₆]共存的铝氧多面体结构逐渐转变为大量[AlO₄]和少量[AlO₅]共存的结构;稀土Sm³⁺具有较强的积聚作用,其能促使玻璃结构中的硼氧多面体形成巨大的网络结构;热处理对玻璃结构中硼氧多面体和铝氧多面体的配位结构影响不大.     

稀土掺杂硼铝硅酸盐玻璃结构的NMR研究

在Sm2O3掺杂BaO-B2O3-Al2O3-SiO2-Sm2O3(BBASS)玻璃系统的形成性能的研究基础上,借助MAS NMR以及差热测试技术,研究了玻璃的结构特点以及玻璃组成、热处理条件等因素对玻璃结构的影响。研究表明,在未掺稀土的BBAS玻璃结构中,硼氧多面体主要以[BO3]、[BO4]存在,铝氧多面体主要以[AlO4]、[AlO5]、[AlO6]存在;随着BBAS中BaO含量的增加,硼氧三角体[BO3]逐渐向[BO4]转变,铝氧多面体中的[AlO5]、[AlO6]结构单元逐渐向[AlO4]转变;稀土Sm3+具有较强迫积聚作用,能促使玻璃结构中的硼氧多面体形成巨大的网络结构;热处理对玻璃结构中硼氧多面体和铝氧多面体的配位结构影响不大。     

CaO-SiO2绿光玻璃陶瓷荧光体的沉积组织结构对发光性质的影响

采用半熔化-淬冷的一步法制备了一种新型的硅酸钙绿光玻璃陶瓷,通过变化在1 550℃的保温时间,研究了玻璃陶瓷中沉积的微观结构对发光性质的影响.延长保温时间,玻璃陶瓷中沉积的发光晶体β-Ca SiO4:Eu2+和发光玻璃相的比例趋于减少,导致样品发射光谱红移,透明度增加.本论文同时分析了SiO2晶粒在玻璃基体中的沉积现象...     

玻璃-熔盐离子交换对玻璃结构的影响

本文根据含锂硼硅酸盐玻璃系统在熔融钠盐中进行离子交换后而获得的自聚焦透镜的数值孔径变化规律,对照玻璃组成与结构的关系,提出了该玻璃的结构模型及其结构的变化规律.     

溶胶-凝胶法制备的GeO2-SiO2凝胶玻璃的红光发射

以3三氯锗丙酸和正硅酸乙酯为原料采用溶胶凝胶法制备了GeO2SiO2凝胶玻璃.室温下以532nm激光(Nd:YAG)激发GeO2SiO2凝胶玻璃有一强的发光峰,这种发光有两个发光带,其峰位分别在575nm和624nm.该发光现象是由镶嵌在GeO2SiO2凝胶玻璃中GeO2纳米颗粒产生的.利用吸收光谱和TEM对GeO2SiO2凝胶玻璃进行了表征,结果发现随着Ge含量的增加凝胶玻璃中GeO2纳米颗粒的尺寸越来越大,吸收边向低能边移动.X射线衍射和电子衍射确定GeO2SiO2凝胶玻璃中GeO2颗粒的结构为非晶结 关键词： GeO2-SiO2凝胶玻璃 溶胶-凝胶法 红光发射     

用相图原理研究玻璃结构和性质(Ⅲ) 核磁共振谱研究钠硼钒、钾硼磷、钾硼铝和钠硼镁玻璃结构

本文运用相图模型方法,通过电子计算机计算了Na_2O-B_2O_3-V_2O_5,K_2O-B_2O_3-P_2O_5,K_2O-B_2O_3-Al_2O_3和Na_2O-B_2O_3-MgO三元系统玻璃的NMR数据,比较了实验值和计算得出的硼四配位分数(N4),得到了满意的结果。     

稀土掺杂P2O5-Al2O3-BaO玻璃的制备及其结构研究

稀土掺杂磷酸盐玻璃具有优异的光学和光谱特性,在激光介质、有色滤光材料等领域中有着重要的应用。在P2O5_Al2O3_BaO_Sm2O3(PABS)玻璃形成能力研究的基础上,借助MAS NMR、红外光谱等分析手段,研究了玻璃的结构、玻璃组成与热处理等对玻璃结构的影响。结果表明:不同组成PAB(S)玻璃的31P MAS NMR谱在-20ppm~-25ppm范围内均存在单一的特征信号峰,对应于磷氧多面体[PO4]的Q2型结构;在18ppm、-12ppm和-36ppm处27Al的MAS NMR谱的三个特征信号峰分别对应于27Al的[AlO5][、AlO6]、[AlO6]配位结构,稀土离子的掺入以及热处理均使得[AlO6]向[AlO5]转变;玻璃的网络结构主要由Q2型[PO4]、[AlO5]和[AlO6]构成,并P_O_P、P_O_Al的形式相连接。玻璃在1383 cm-1处出现的吸收峰可能是玻璃结构中形成了P_O_Sm键所致。     

Eu2+掺杂P2O5-BaO-Na2O-K2O与Na2O-TeO2-ZnO系统玻璃的制备与光谱性质

用高温熔融法,把Eu₂O₃掺入到P₂O₅-BaO-Na₂O-K₂O与Na₂O-TeO₂-ZnO系统玻璃中。测定了玻璃的荧光光谱与激发光谱。结果表明,Eu离子在P₂O₅-BaO-Na₂O-K₂O玻璃中呈现出Eu³⁺态。然而在Na₂O-TeO₂-ZnO系统玻璃中,尽管在空气气氛下,大部分的Eu离子在玻璃中以二价的状态存在。从玻璃的结构及化学组分解释了产生Eu²⁺的原因。在磷酸盐玻璃配料中加入适量的硅粉(Si)作还原剂,能有效地把玻璃中的极大部分Eu³⁺还原成Eu²⁺,获得含Eu²⁺的优质透明磷酸盐玻璃。     

Li_2O-(LiCl)_2-B_2O_3-Al_2O_3系玻璃的红外光谱

本工作系统地测量和分析了Li_O-(LiCl)_2-B_2O_3-Al_2O_3系玻璃的红外光谱,据此研究了玻璃中硼的配位数和硼酸盐结构基团随组成的变化以及Al~(3+)和Cl~-离子在结构中所起的作用,并对光谱中某些吸收峰机理作了定性探讨。     

掺Er3+钆硼硅酸盐玻璃及玻璃陶瓷的红外发光特性和热稳定性

报道了一种新型可作为掺铒光纤放大器(EDFA)基质材料的Er³⁺掺杂B₂O₃-SiO₂-Gd₂O₃-Na₂O(BSGN)体系玻璃及其玻璃陶瓷。对材料中铒的⁴I_13/2→⁴I_15/2跃迁的1.5μm发射光谱、吸收光谱、时间分辨光谱及寿命进行了测量和分析,讨论了热处理对玻璃材料带宽和寿命的影响。结果表明,铒掺杂玻璃1.5μm发射的带宽和J-O参数Ω₆都随B₂O₃含量的增加而增加,寿命随B₂O₃含量的增加而减小。经过热处理后得到的玻璃陶瓷比具有相同组分的玻璃具有更高的1.5μm发射效率。同时,差热分析的数据表明,该玻璃体系具有极好的热稳定性。     

Inelastic light scattering in strontium borate glasses in the systemxSrO.(1−x)B2O3 and (SrCl2) y .[xSrO.(1−y−x)B2O3]1−y

Raman spectra of strontium borate binary glasses in the systemxSrO.(1-x)B₂O₃ forx=0.20, 0.25, 0.30, 0.35, 0.40, and 0.50 and ternary glasses in the system (SrCl₂) _y .[xSrO.(1−y−x)B₂O₃]_1−y fory=0.10, 0.20, 0.30 and 0.40 andx=0.20 and 0.35, are reported. Raman spectra of the glasses show experimental evidence of glass network modifying nature of SrO in borate matrix. SrO causes a change of boron atom coordination number from 3 to 4 resulting in the complex structural groupings comprising of BO₄ and BO₃ units. Strontium cations are not easily accommodated in the glass structure and tend to break up the network at high concentration (x) of SrO, causing non-bridging oxygens. The effect of temperature variation of binary glasses has also been studied. The introduction of SrCl₂ to the binary stronium borate glass causes a large change in intensity of low frequency Raman scattering whereas there is no change in the vibrational dynamics in the high frequency region. The temperature reduced Raman spectra represents true vibrational density of states. Martin-Brenig model developed for the low frequency region has been discussed to obtain the structural correlation range in the glass.     

氟锆酸盐光纤玻璃中的析晶和分相现象

氟化物光纤玻璃中的夹杂物,分相颗粒和微晶颗粒等缺陷,造成光纤的散射损失,影响了实际制备工作.本文利用大视场光学显微镜,X射线衍射,透射电子显微镜和差热分析,研究了ZBLA氟化物玻璃中的分相和析晶现象,观察到了以成核生长机理进行的分相颗粒,析晶颗粒的成分是β-BaF_2·ZrF_4和α-BaF_2·2ZrF_4,通过DTA分析确定了这些相的析晶活化能.     

Bismuth silicate glass containing heavy metal oxide as a promising radiation shielding material

Optical and FTIR spectroscopic measurements and electron paramagnetic resonance (EPR) properties have been utilized to investigate and characterize the given compositions of binary bismuth silicate glasses. In this work, it is aimed to study the possibility of using the prepared bismuth silicate glasses as a good shielding material for γ-rays in which adding bismuth oxide to silicate glasses causes distinguish increase in its density by an order of magnitude ranging from one to two more than mono divalent oxides. The good thermal stability and high density of the bismuth-based silicate glass encourage many studies to be undertaken to understand its radiation shielding efficiency. For this purpose a glass containing 20% bismuth oxide and 80% SiO₂ was prepared using the melting–annealing technique. In addition the effects of adding some alkali heavy metal oxides to this glass, such as PbO, BaO or SrO, were also studied. EPR measurements show that the prepared glasses have good stability when exposed to γ-irradiation. The changes in the FTIR spectra due to the presence of metal oxides were referred to the different housing positions and physical properties of the respective divalent Sr²⁺, Ba²⁺ and Pb²⁺ ions. Calculations of optical band gap energies were presented for some selected glasses from the UV data to support the probability of using these glasses as a gamma radiation shielding material. The results showed stability of both optical and magnetic spectra of the studied glasses toward gamma irradiation, which validates their irradiation shielding behavior and suitability as the radiation shielding candidate materials.     

The structure of AgI-Ag2O-V2O5 glasses

Structures of 10AgI-3Ag₂O-2V₂O₅, 3AgI-3Ag₂O---2V₂O₅ and 2AgI---2Ag₂O-V₂O₅ glasses have been investigated by neutron diffraction experiments. The characteristic features of observed structure factors S(Q) in 10AgI-3Ag₂O-2V₂O₅ glass is similar to those of other superionic conducting glasses and molten AgI. From the standpoint of the pair distribution functions, it is clarified that the Ag-I and I-I correlation strength and Ag---Ag correlation length increase with increasing AgI concentration. Observed results suggest that the local AgI structure accompanied by the re-arrangement of silver ions is formed with highly doped iodide ions.     

Synthesis and characterization of holmium oxide doped cadmium lead borate glasses

Holmium doped cadmium lead borate glasses were prepared from melting in appropriate proportions of a mixture of CdO, PbO₂, H₃BO₃ and (1–2 mol %) Ho₂O₃ in the temperature range of 800–850 °C. The density of glass samples was measured using Archimedes Principle. The infrared spectra of the glasses in the range of 400–4000 cm^?1 showed their structure systematically. No boroxol ring formation was observed in the structure of these glasses, but the conversion of 3-fold to 4-fold coordination of boron atoms in the structure of glasses was observed. The glass transition studies were done through differential scanning calorimetry. The optical analysis is done by using the Judd–Ofelt theory.     

Crystallization kinetics of Li2O-PbO-V2O5 glasses

Lead vanadate glasses of the system 5Li₂O−(45−x) PbO−(50+x) V₂O₅, with x=0, 5, 10, and 15 mol% have been prepared and studied by differential scanning calorimetry (DSC). The crystallization kinetics of the glasses were investigated under non-isothermal conditions applying the formal theory of transformations for heterogeneous nucleation to the experimental data obtained by DSC using continuous-heating techniques. In addition, from dependence of the glass-transition temperature (T_g) on the heating rate, the activation energy for the glass transition was derived. Similarly the activation energy of the crystallization process was determined and the crystallization mechanism was characterized. The results reveal the increase of the activation energy for glass transition which was attributed to the increase in the rigidity, the cross-link density and the packing density of these glasses. The phases into which the glass crystallizes have been identified by X-ray diffraction. Diffractograms of the transformed material indicate the presence of microcrystallites of Li_0.30V₂O₅, Li_0.67O₅V₂, LiV₆O₁₅, Li₄O₄Pb, and O₇Pb₂V₂ in a remaining amorphous matrix.