氟化钙污泥制备高性能上转换发光微晶玻璃的研究

半导体行业产生的氟化钙(CaF₂)污泥量大且含有絮凝剂等杂质，资源化利用难度大，现阶段主要处理方式为填埋。本文提出了将CaF₂污泥回收制备上转换发光微晶玻璃的资源化技术。将SiO₂、稀土Er₂O₃和Yb₂O₃引入到CaF₂污泥中，通过高温固相熔融法制备了一系列上转换发光微晶玻璃。采用X射线衍射、扫描电镜、荧光光谱等表征手段研究了不同含量CaF₂污泥和不同晶化温度对所得上转换发光微晶玻璃的结构、形貌、上转换发光峰位置、强度和荧光寿命等的作用规律。所得CaF₂基上转换发光微晶玻璃在980 nm激光激发下，能够发射出绿光(523和539 nm)和红光(655 nm)。原料质量配比为84.5%CaF₂污泥-10%SiO₂-0.5%Er₂O₃-5%Yb₂O₃     

掺稀土氟化物玻璃上转换发光材料发展概况

和传统的氧化物玻璃相比,氟化物玻璃具有声子能量低的特点,因此无辐射跃迁几率小,上转换量子效率高,使得掺稀土离子的氟化物玻璃具有高的发光效率.且稀土离子的能级在氟化物玻璃中具有较长的寿命,形成更多的介稳能级,有丰富的激光跃迁.利用稀土离子在氟化物光纤中的上转换特性,可以获得性能优良的光纤激光器.本文简述了掺稀土氟化物玻璃上转换激光材料的发光机理和研究进展.     

微晶玻璃新材料

本文简介了几种近年来新开发的微晶玻璃新材料,如高强度、高韧性微晶玻璃,表面高压缩增强微晶玻璃,纤维增强微晶玻璃复合材料,氟云母微晶玻璃柔性无机膜,发光透明微晶玻璃,核废料固化用微晶玻璃,生体修补用微晶玻璃及微晶玻璃建筑材料等.     

光敏微晶玻璃新材料

本文介绍光微晶玻璃新材料制备方法、产品性能、用途及应用意义。     

仿软玉的微晶玻璃

阐述了软玉特征与仿软玉的要求,介绍了仿软玉微晶玻璃成分与工艺,最后提出了仿软玉微晶玻璃研究方向。     

蓝绿光上转换荧光输出的稀土掺杂玻璃研究进展

上转换光纤激光器由于在医疗、生命科学等领域应用逐步加强,近年来受到了广泛的重视.本文简要回顾了上转换发光的发展历程,归纳了能够实现蓝绿光输出的稀土离子的种类,详细阐述了近年来具有蓝绿光输出的上转换发光的不同基质玻璃(氟化物玻璃、硫化物玻璃、碲酸盐玻璃、锗酸盐玻璃、铋酸盐玻璃、卤氧化物玻璃)的研究进展,最后,对稀土离子掺杂的玻璃上转换发光的研究动向进行了展望.     

锂云母微晶玻璃中的晶相与显微结构演变

采用DTA,XRD,SEM,TEM研究了MgO-Al2O3-SiO2-Li2O-R2O-F(R＝Na,K)玻璃系统晶化过程中的晶相与显微结构演变.结果表明,基础玻璃的分相自650℃开始;700℃以下,初期云母相出现;750℃β-锂辉石开始形成;850～950℃之间,随着Mg2+,K+,F-的扩散进入,β-锂辉石与玻璃相产生交代反应,以过渡相形式转变成云母类固溶体;在950℃以上;β-锂辉石不断转化为锂云母固溶体,云母晶体尺寸长大明显.     

Chlorapatite Glass-Ceramics

Apatite glass-ceramics are attractive for medical and dental applications, and fluorapatite glass-ceramics based on aluminosilicate glasses have been extensively studied. This study is the first study of chlorapatite glass-ceramics based on calcium chloride-containing Q² bioactive phosphosilicate glasses. The crystallization behavior of oxychloride glasses is examined and compared with mixed oxychloride/fluoride and oxyfluoride glasses. The glass transition temperature decreased for all three series with increasing halogen content. On increasing the halogen content, there was an increasing tendency of the glasses to crystallize. The halogen-free glass surface crystallized to pseudowollastonite and an apatite. On incorporating a halide, the glasses exhibited largely bulk crystallization to a haloapatite. In the case of chloride, the glasses crystallized to chlorapatite. This is the first time to our knowledge that chlorapatite has been shown to crystallize from a glass. Chlorapatite is very attractive for medical applications because it converts to hydroxyapatite the mineral phase of tooth and bone on immersion in water.     

Nanophase Glass-Ceramics

Future applications for glass-ceramics are likely to capitalize on designed-in, highly specialized properties for the transmission, display, and storage of information. Glass-ceramics with microstructures comprised of uniformly dispersed crystals <100 nm in size offer promise for many potential new applications as well as provide unique attributes for many current products. This paper focuses on two types of nanocrystalline glass-ceramics: transparent glass-ceramics and tough, high-modulus glass-ceramics with precisely engineered surfaces. Transparent glass-ceramics are formed from certain aluminosilicate glasses capable of efficient crystal nucleation and slow growth. The key crystalline phases include β-quartz solid solutions, characterized by low-thermal-expansion behavior; spinel, with high hardness and elastic modulus; and mullite, which shows unique chromium-luminescence behavior.     

High-Strength Mica-Containing Glass-Ceramics

Glass-ceramics containing barium–mica in the system Ba_0.5 Mg₃ (Si₃AIO₁₀)F₂–2MgO · 2Al₂O₃· 5SiO₂–Ca₃ (PO₄)₂ are two to three times stronger than conventional mica-containing glass-ceramics. Moreover, the barium-mica glass-ceramics are easier to machine, as confirmed by a drilling test using conventional steel tools. Such mechanical properties are attributable to the microstructure of the barium–mica glass-ceramics. Very fine, interlocking mica crystals are precipitated in the glass, and a crack-deflection mechanism is observed by scanning electron microscopy.     

Transparent Magnetic Glass-Ceramics

Transparent magnetic glass-ceramics were produced by infiltrating nano-porous glass with nitrate salts and firing. The resultant glass-ceramics contained spinel ferrite nanocrystals that exhibited ferromagnetic and superparamagnetic behavior depending on composition and firing temperature. Transparency in the near infrared was obtained when oxidizing conditions were used to prevent Fe²⁺ formation, while the porous matrix ensured nano-sized crystallites to limit scattering losses. MnFe₂O₄ glass-ceramics treated at 1000°C offered the best combination of magnetic and optical properties with a saturation magnetization of 5.6 emu/g, a Verdet constant of 16.5°/cm, and losses below 3 dB/mm at 1550 nm.     

Monopyroxenic Basalt-Based Glass-Ceramics

Uniform, ultrafine, microcrystalline, hard, pyroxenic glass-ceramic materials have been obtained successfully from basalt rock; instead of adding nucleation catalysts, the FeO:Fe₂O₃, CaO:Na₂O, and CaO:MgO ratios have been rectified. This process has been accomplished by deliberately adding the smallest permissible amounts of oxidizers, limestone, dolomite, and soda ash (as additives) that are necessary to fulfill the monominerality requirements; these requirements affect the melting, workability, crystallization, and microstructure of the glass-ceramics. The melting temperature decreases as the ratios decrease (beyond certain limits); in addition, the workability, crystallization, and microstructure also improve as the ratios decrease. An almost-stable solid solution of augite or aegirine-augite composition is the only crystalline phase that is formed. The minimal FeO:Fe₂O₃ ratio and the likelihood of a greater affinity of the Na⁺ cation for the Fe³⁺ cation, rather than the Al³⁺ cation, may be responsible for increasing the stability and widening of the crystallization field of the complex aluminum-bearing pyroxene solid solution.     

Tribological Properties of Glass-Ceramics

Tribological properties of five glass-ceramics are reported. The materials were tested unlubricated against themselves. Testing was performed using a simulated inertial sample dynamometer. Sliding speeds were between 0.5 and 1.8 m /S with an applied load of 225 N. Average friction coefficients were in the range 0.07 to 0.5. The wear rate of a lithium aluminosilicate was 43 ×10–14 m3/N.m, in good agreemen2 with previous pin-on-disk results. Wear surfaces exhibited cracking, ploughing, delamination, and viscous flow or plastic deformation.     

Bioactivity of Zirconia-Toughened Glass-Ceramics

Bioactivity of zirconia-toughened glass-ceramic composites was evaluated by their surface reaction in simulated body fluid and the bonding strength to living bone. The composite containing 30 vol% zirconia showed high bioactivity, whereas that containing 50 vol% zirconia, extremely low. TEM observation indicated that Ca in the glass-ceramic particles reacted with the zirconia during sintering. It was found that the decrease in Ca in the particles degraded the bioactivity of the composite. In this study, the optimum composition was determined for high-strength and bioactive ceramic.     

Crystallization Mechanisms in Glass-Ceramics

Transmission electron microscopy, electron diffraction, and microprobe X-ray analysis were used to study crystallization of glasses in the systems Li₂O-SiO₂, BaO-SiO₂, and Li₂O-A1₂O₃-SO₂. The ternary system, with 4 mol% TiO₂ added to an Li₂O-Al₂O₃-4SiO₂ composition, crystallizes with a simple morphology of equiaxed grains of the β-quartz metastable phase which transforms at higher temperatures to the stable β-spodumene structure. The binary systems exhibit a more complex crystallization morphology dictated by crystal anisotropy, temperature, impurity content, and susceptibility either to intermediate-phase formation (BaO-SiO₂) or to liquid immiscibility (Li₂O-SiO₂). The initial crystal growth units formed in these systems are frequently two-phase branched morphologies many micrometers in diameter. They may be recrystallized to form polycrystalline glass-ceramics with submicrometer grain sizes.