铒铝硼硅酸盐玻璃的析晶

通过对Er2O3-A12O3-B2O3-SiO2玻璃样品的析晶热处理,使稀土玻璃结构与晶体联系起来研究,能在一定程度上揭示稀土玻璃的结构形式。对铒铝硼硅酸盐玻璃进行了差热分析,确定其析晶热处理温度;然后对铒铝硼硅酸盐玻璃热处理后的晶相及其微观形态进行了系统地研究,发现该玻璃样品受热析晶后析出的全部为ErBO3相,且呈层状排列。这表明在受热时玻璃发生了分相,Er^3 较多地在富硼相中偏聚而析出,富硅相则保持玻璃态。而玻璃本身也可能具有微不均匀性,存在富硼和富硅两种网络结构,而Er^3 则主要分布在偏硼酸盐结构的富硼环境中,这使得其析出时容易形成层状结构。     

铒硼硅酸盐玻璃形成性能的研究

用新的玻璃形成区研究方法探索了铒硼硅酸盐玻璃的形成区范围,研究了A12O3含量和Er2O3含量对玻璃形成区的影响和相应的玻璃形成区图。结果表明：当A12O3含量从15％增加到20％时玻璃形成区相应增大,Er2O3含量从20％增加到30％时玻璃形成区缩小。同时利用热分析结果所得到的玻璃析晶倾向参数β值,讨论了铒硼硅酸盐玻璃的形成能力,发现含有Er2O3的铝硼硅酸盐玻璃的玻璃形成能力比较弱,但在一定的组成范围内随着Er2O3含量的增加,铒硼硅酸盐玻璃的形成能力也会有所提高。另外,在铒硼硅酸盐玻璃系统中加入A12O3,可以加强玻璃的网络结构,从而能够提高玻璃的形成能力。     

新型掺铒钆硼硅酸盐玻璃的制备和光学性质的研究

用高温熔融法制备了成分为Gd2O3,SiO2,B2O3和Na2O的新型玻璃体系,探索了该玻璃体系的成玻范围,发现该系统在B2O3:20%以上,SiO2:0～50%,Gd2O3:0～30%的范围内均可形成完全透明的玻璃.在Gd2O3:30%,B2O3:60%和SiO2:60%,B2O3:30%两个组分附近时玻璃轻微失透.除此以外,在其他组分实验上没有得到玻璃.根据差热分析的数据,计算得到的玻璃析晶倾向参数β在0.32～1.76之间,说明含10%Gd2O3的钆硼硅酸盐玻璃具有较强的形成能力;利用McCumber理论计算出样品的吸收和受激发射截面,并从玻璃1.5 μm的吸收光谱出发拟合出了J-O参数,进而计算了Er3 离子各相关能级的理论振子强度、实验振子强度和自发辐射速率等参数.同时,用Er3 离子1.5 μm发射光谱的半高全宽与其峰值发射截面的乘积值对含10%Gd2O3钆硼硅酸盐玻璃1.5μm发射的增益带宽作出了表征,结果表明,含10%Gd2O3玻璃体系的FWHM×σepeak值均大于已有报道的硅酸盐、磷酸盐和锗酸盐玻璃,其中最大值和氧氟硅酸盐玻璃的相差不多.     

铈掺杂高密度硼硅酸盐玻璃光谱性质研究

实验制备了一种密度为5.2 g.cm-3的高密度铈离子掺杂硼硅酸盐闪烁玻璃,该玻璃具有较高的析晶稳定性。测试了该闪烁玻璃的激发和发射光谱,其峰值波长分别对应于325和385 nm,斯托克斯位移为60 nm。当氧化铈掺杂浓度小于1%(质量分数)时,325 nm激发下的发射光谱强度随浓度的增加而提高,而掺杂浓度的进一步提高,由于三价态铈离子的自吸收等吸收猝灭效应导致380 nm的发射强度出现严重降低。掺杂1%(质量分数)的玻璃样品经245Gy的伽马射线辐照后,其可见波段的透过率并未出现明显降低,说明该玻璃具有较好的耐辐照性能。     

钠硼硅酸盐玻璃分相及浸析的NMR研究

用多种ＮＭＲ方法，包括＾２９Ｓｉ、＾２３Ｎａ，＾１１Ｂ ＭａＳ及＾２９Ｓｉ ＣＰ／ＭＡＳ ＮＭＲ，研究了一定组成的ａ２Ｏ－Ｂ２Ｏ３－ＳｉＯ２三元体系玻璃在不同温度下分相处理２４小时及用酸浸析处理后的结构变化。结果表明，在低于分相上界临界温度的范围内，存在着一个温度转折点，低于这一温度时，受动力学因素影响，分相未达平衡态，温度愈低，距平衡态愈过，分相愈下完全。超过这一温度，分相可达平衡态，受热力学控     

不同Pr2O3含量硼铝硅酸盐玻璃析晶性能研究

采用高温熔融法制备了不同Pr2O3掺量的SiO2-B2O3-Al2O3-BaO玻璃,利用DTA,XRD,TEM以及IR等手段研究了稀土氧化物掺入量对玻璃热稳定性、析晶行为、玻璃结构的影响。结果表明：当稀土掺入量逐渐增加时,玻璃的热稳定性递减;在高于Tx的温度下进行热处理,玻璃析晶产物逐渐由PrAl2.03（B4O10）O0.54向PrBO3转变;Pr^3＋填充在[SiO4],[BO4]和[BO3]等结构单元组成的混合网络的空隙之中,网络中间离子Al^3＋随稀土氧化物的增加,发生从网络变性离子向网络形成离子的转变。     

ICP-AES法测定硼硅酸盐玻璃中的常量及微量元素

应用电感耦合等离子体原子发射光谱(ICP-AES)法,对硼硅酸盐玻璃中的常量元素Si、Ca、Al、B及微量元素Fe、Ti、Mg进行测定。在优化的工作条件下,各元素的检出限:SiO20.026μg/mL,Ca0.0002μg/mL,Al0.028μg/mL,B0.005μg/mL,Mg0.0002μg/mL,Fe0.006μg/mL,Ti0.005μg/mL。样品测定结果的相对标准偏差(n=6)在0.02%~1.47%之间,加入标准溶液的回收率为93.0%~103.2%。采用该方法对硼硅酸盐玻璃标准样品进行测定,测定值与标准值一致。     

稀土掺杂硼铝硅酸盐玻璃结构的NMR研究

采用魔角核磁共振（MAS NMR）研究了稀土掺杂B2O3-Al2O3-SiO2玻璃的结构及其组成和热处理等因素对玻璃结构的影响。研究发现，在B2O3-Al2O3-SiO2玻璃结构中，硼的配位主要是三角体[BO3]和[BO4]，铝的配位主要是[AlO4]，[AlO5]和少量的[AlO6]。随着B2O3-Al2O3-SiO2玻璃中BaO含量的增加，[BO3]逐渐向[BO4]转变，[AlO5]和[AlO5]也转变为[AlO4]。此外，由于稀土离子比钡离子更高的离子场强，其能够积聚硼氧结构使得其形成了巨大的网络结构。随着稀土掺量的增加，玻璃结构中的硅氧配位逐渐以Q4（3T）为主。热处理对玻璃结构中的硼氧和铝氧配位影响很小。     

硼硅酸盐生物玻璃表面多层结构的形成机理

描述了硼硅酸盐生物活性玻璃在体外含磷溶液中的转变过程,并采用XRD、SEM和EDS对反应产物的微观结构、形貌和成分进行了分析。结果显示,产物为多层结构,由羟基磷灰石和无定型SiO₂层交替排列而成。此外,提出了一个定性模型来解释层状结构的形成机制。研究证实,反应动力学及反应产物的微观结构主要取决于生物活性玻璃的成分和含磷溶液的浓度。     

Er^3＋掺杂硼硅酸盐玻璃的近红外发射特性研究

利用高温熔融法合成了掺Er^3 硼硅酸盐玻璃。测量了样品的吸收光谱，由J-0理论得到了强度参数Ωλ(λ＝2，4，6)及一些相关参数；用970nm光激发测量了10-300K之间的近红外发射光谱。利用McCumber理论拟合得到了1．53μm发射的受激发射截面，并与测量得到的发射光谱线形符合较好。由受激发射截面和发射光谱得到的半高全宽分别为59和56nm。利用能级简化模型讨论了样品的红外变温发射光谱，提出了增大1．53μm发射带宽的途径。     

Devitrification of Fluoroindate Glasses

Most fluoride glasses are likely to devitrify when heated for some time between the glass transition and melting temperatures. The crystallization kinetics of some fluoroindate glasses were studied by isothermal and non-isothermal methods using differential scanning calorimetry. The heating rate α varied between 1 and 10 K min^?1. The value of Avrami’s exponent n lay between 1 and 2.5, corresponding to a diffusion-controlled growth of crystals. The apparent activation energy for crystallization, E, varied from 45 to 50 kcal mol^?1. These values of n and E are low by comparison with those of other fluoride glasses, which suggests high stability against devitrification.     

The Non-Isothermal Devitrification of Potassium Germanate Glasses

The devitrification behaviour of the glasses K₂O·xGeO₂ with x=4, 7 or 8 was examined by means of differential thermal analysis (DTA), the Fourier transformation infrared (FTIR) transmittance spectra and X-ray diffraction (XRD). The glass transition temperatures were related to the molar ratio GeO₄/GeO₆. For the glass with x=4, metastable K₄Ge₉O₂₀> crystals are initially formed and then converted at higher temperatures into stable K₂Ge₄O₉ crystals. The glasses with x=7 or 8 both devitrify into K₂Ge₇O₁₅> crystals. The effects of the specific surface area of the samples on the devitrification mechanisms were established. Bulk nucleation predominates in the glass with x=4, while the glasses with x=7 or 8 crystallize from the surface. The activation energies for crystal growth were evaluated from the DTA curves. This revised version was published online in July 2006 with corrections to the Cover Date.     

钐对锰激活的硼硅锌存储玻璃的影响

使用高温固相法合成了钐锰共激活的硼硅锌玻璃. 利用热释光谱研究了钐的掺入对锰激活的硼硅锌玻璃的陷阱能级的影响, 发现钐的掺入使后者的缺陷向浅能级方向移动, 表现为锰激活的硼硅锌玻璃的余辉和存储性能的相应变化.     

Leach of Cesium and Barium from Sol-Gel Derived Zincborosilicate and Borosilicate Glasses

Borosilicate and zincborosilicate glass powders containing up to 20 wt.% of cesium and barium oxide were prepared by the sol-gel method and characterized by XRD and SEM. Monolithic samples of borosilicate and zinc borosilicate glasses were prepared by pressing and annealing the above powders. Leach rates of barium and cesium from the samples in water were measured as a function of time. Leach rates of cesium and barium from zincborosilicate were significantly lower than borosilicate glass, and barium showed higher leachability than cesium in all the prepared glasses.     

Devitrification Behavior of Calcium Phosphate Glasses Containing Al2O3 and SiO2 Additives

The effects of Al₂O₃ and SiO₂ additives on the crystallization of calcium phosphate glasses were studied. When the Al₂O₃ content was higher than 7 mol%, surface devitrification occurred in the glasses. However, for glasses with Al₂O₃ contents higher than 10 mol%, bulk devitrification predominanted. For the glasses with SiO₂, a surface devitrification mechanism predominanted. Non-isothermal DTA techniques were applied in order to establish the devitrification mechanism, and the kinetic parameters of crystal growth were obtained. The parameter m depends on the mechanism and morphology of devitrification of calcium phosphate, glass containing SiO₂ as additive, the values of m being lower than 1.2. These results indicate that the devitrification is controlled by the reaction at the glass-crystal interface, or occurs from surface nuclei. This revised version was published online in July 2006 with corrections to the Cover Date.     

Characterization of Tin Oxide Based Sol-Gel Coatings on Borosilicate Glasses by X-Ray Reflectivity

The X-ray reflectivity technique was applied in the study of tin oxide films deposited by sol-gel dip-coating on borosilicate glasses. The influence of the withdrawal speed and temperature of thermal treatment on the film structure was analyzed. We have compared the thermal evolution of the density and the shrinkage of the films with these properties measured for the monolithic xerogel by helium picnometry and thermomechanical analysis. In agreement with the Landau-Levich model, the layer thickness increases by increasing the withdrawal speed. Nevertheless, it decreases with the increase of the thermal treatment temperature, due to the densification process. The values of apparent density are smaller than the skeletal density, which shows that the films are porous. The comparison between the film and the monolith indicates that shrinkage during firing is anisotropic, occurring essentially perpendicular to the coating surface.