Impact of Eu3+ Ions on Physical and Optical Properties of Li2O-Na2O-B2O3 Glass

The lithium sodium borate glasses doped with Eu³⁺ ion are prepared using melt quenching technique, their structural and optical properties have been evaluated. The density of prepared glasses exhibits an inverse behavior to the molar volume ranging from 2.26 g/cm³ to 2.43 g/cm³ and 26.95 cm³ /mol to 26.20 cm³ /mol, respectively. The absence of sharp peaks in XRD patterns confirms the amorphous nature of the prepared glasses. The absorption spectra yield four transitions centered at 391 nm (⁷F₀→⁵L₆), 463 nm (⁷F₀→⁵D₂), 531 nm (⁷F₀→⁵D₁), and 582 nm (⁷F₀→⁵D₀). The most intense red luminescence is observed at 612 nm corresponding to ⁵D₀→⁷F₂ transition under 390 nm laser excitations.     

含氟CaO-P2O5-SiO2-Na2O-B2O3玻璃陶瓷的制备及性能表征

采用溶胶-凝胶法制备CaO-P₂O₅-SiO₂-Na₂O-B₂O₃体系前驱体粉末,用CaF₂替代部分CaO再次制备前驱体粉末。 通过TG-DSC分析确定结晶温度为865 ℃,经过热处理获得主晶相为Na₆Ca₃Si₆O₁₈的玻璃陶瓷。 通过X射线衍射(XRD)、傅里叶红外光谱(FTIR)、扫描电子显微镜(SEM)等技术手段及体外生物活性实验分析玻璃陶瓷的显微结构及性能。 结果表明,CaF₂的加入能提高玻璃陶瓷的体积密度、抗折强度和弹性模量,并且不会破坏玻璃陶瓷的生物活性。     

Sm2O3Ga2O3 and Gd2O3Ga2O3 phase diagrams

Four definite compounds exist in the Sm₂O₃Ga₂O₃ binary phase diagram, namely: Sm₃GaO₆, Sm₄Ga₂O₉, SmGaO₃, and Sm₃Ga₅O₁₂. The $\text{3}\text{1}$ compound is orthorhombic (space group Pnna - Z.4) with the cell parameters: a = 11.40₀Å, b = 5.51₅Å, c = 9.07Å and belongs to the oxysel family. Sm₃GaO₆ and SmGaO₃ melt incongruently at 1715 and 1565°C; Sm₄Ga₂O₉ and Sm₃Ga₅O₁₂ have a congruent melting point at 1710 and 1655°C. With regard to the Gd₂O₃Ga₂O₃ system three definite compounds have been identified: Gd₃GaO₆, Gd₄Ga₂O₉, and Gd₃Ga₅O₁₂. Only the garnet melts congruently at 1740°C with the following composition: Gd_3.12Ga_4.88O₁₂. Gd₃GaO₆, and Gd₄Ga₂O₉ melt incongruently at 1760 and 1700°C. GdGaO₃ is only obtained by melt overheating which may yield an equilibrium or a metastable phase diagram.     

BaO-Al2O3-B2O3系密封玻璃的结构与性质

The BaO-Al₂O₃-B₂O₃ glasses manufactured for solid oxide fuel cell(SOFC) sealing were studied. The effect of different n_BaO/n_B2O3 on crystal, thermal properties, density and infrared spectra of this system has been discussed. The results show that the trends of crystallization, glass transformation temperature, dilatometric softening temperature and density increase with n_BaO/n_B2O3 values. But a typical property deviation occurs when n_BaO/n_B2O3 is 0.875, and its coefficient of thermal expansion has the maximum at this point. The changes of properties can attribute to the conversion of boron from tetrahedral coordination to trigonal, breakage of the local glass network and interaction between the network modifiers. These can be proved by infrared spectra of glasses. Thermal properties of some studied samples are suitable for the sealing of SOFC using Sm doped ceria electrolyte and operating at 400～600 ℃.     

Garnet-perovskite transformations in the Sm2O3Ga2O3 and Gd2O3Ga2O3 systems

The effect of heating garnet melts to various temperatures has been investigated. The previously reported decomposition of the garnet phase due to loss of Ga₂O₃ was corroborated. However, it was also observed that when gallium oxide loss is prevented and the maximum temperature of the melt exceeds a critical value, phase separation of garnet to perovskite and β-gallium oxide occurs:

$\text{RE}{}_3\text{Ga}{}_5\text{O}{}_{12}\text{?3RE}\text{GaO}{}_3\text{+}\text{Ga}{}_2\text{O}{}_3$

.The reverse reaction will occur by reheating the two-phase mixture to the garnet melting point.     

Sm3+掺杂CaO-SiO2-B2O3发光玻璃的制备、表征及性质

用高温固相法合制备了以CaO-SiO₂-B₂O₃为基质，Sm³⁺为激活离子的发光玻璃。对Sm³⁺的淬灭浓度、基质中的硼硅比例、其他稀土离子的敏化作用以及基质组成等因素对玻璃发光特性的影响进行了探讨，并用红外和X-衍射分析对样品的结构进行了表征。结果表明：当Sm^3＋掺杂的物质的量分数为1.2%,激发波长λ ＝ 404 nm时,玻璃体60CaO-20SiO₂-20B₂O₃∶1.2Sm^3＋的发光强度为4 838 A.U.( λ ＝ 606 nm );这种发光玻璃具有将紫外及近紫外光转换为橙红色光的特点。少量的Eu^3＋的掺入，对玻璃体的发光起敏化作用；玻璃体中的组分CaO可被ZnO替代。     

Characterization and physical properties of Li2O-CaF2-P2O5 glass ceramics with Cr2O3 as a nucleating agent—Physical properties

In this paper, studies on various physical properties, viz., dielectric properties (dielectric constant, loss tan δ, a.c. conductivity σ) over a wide range of frequency and temperature, optical absorption, ESR at liquid nitrogen temperature and magnetic susceptibility at room temperature of Li₂O-CaF₂-P₂O₅: Cr₂O₃ glass ceramics, have been reported. The optical absorption, ESR and magnetic susceptibility studies indicate that the chromium ions exist in Cr⁵⁺, Cr⁴⁺ and Cr⁶⁺ states in addition to Cr³⁺ state in these samples. The dielectric constant and loss variation with the concentration of Cr₂O₃ have been explained on the basis of space charge polarization mechanism. The dielectric relaxation effects exhibited by these samples have been analysed by a graphical method and the spreading of dielectric relaxation has been established. The a.c. conductivity in the high-temperature region seems to be connected both with electronic and ionic movements.     

氧化镓纳米带的合成和发光性质研究

采用化学气相沉积法，以碳纳米管作还原剂还原Ga₂O₃粉末，生成的气态Ga₂O和载气Ar中的微量O₂反应，在多孔氧化铝模板上沉积得到了Ga₂O₃纳米带。用扫描电子显微镜，透射电子显微镜和选区电子衍射对产物的结构和形态进行表征，发现产物为β-Ga₂O₃纳米带，宽度在20～500 nm之间，厚度为5～100 nm，长度可达几十微米。产物中还有几微米宽的Ga₂O₃纳米片。光致发光谱结果表明β-Ga₂O₃纳米带能发射蓝光和紫外光。文中还简单推测了β-Ga₂O₃纳米带的形成机理。     

CaF2对CaO-CaF2-B2O3-SiO2：Sm2O3玻璃的光致发光增强效应

用高温熔融法制备了掺杂Sm₂O₃的CaO-CaF₂-B₂O₃-SiO₂(CFBS:Sm)发光玻璃材料, 并借助X射线衍射(XRD)谱、傅里叶变换红外(FTIR)光谱以及光致发光(PL)光谱等分析手段研究了玻璃基体中CaF₂的摩尔分数及其结构、红外透过性能以及荧光性能的关系. XRD和FTIR测试表明, 玻璃基体中引入CaF₂并未引起非晶结构的变化但其红外透过峰发生移动. 光谱学测试表明, CFBS:Sm发光玻璃在404 nm波长激发下出现对应于Sm³⁺离子位于566、603和650 nm的特征荧光峰, 其发光颜色为橙红色(x=0.531, y=0.371). 此外, 随着玻璃基体中CaF₂摩尔分数的增加, CFBS:Sm发光玻璃的荧光发射强度、荧光寿命(Sm³⁺的⁴G_5/2能级)和荧光量子效率也表现出增大的趋势. 这种CFBS:Sm发光玻璃中荧光发射强度和荧光寿命的提高主要是由于玻璃基体中的CaF₂替代CaO引起基体相互作用和声子能量降低、无辐射跃迁减弱造成的.     

Ce0.67Zr0.33O2对CH4燃烧催化剂Fe2O3/Al2O3的改性作用

固定n(Ce)/n(Zr)比为0.67/0.33, 用共沉淀法制得一系列CeO2-ZrO2-Al2O3固溶体. 采用这些固溶体作载体, 以Fe2O3为活性组分, 用浸渍法制备了一系列催化剂. BET结果显示, 将适量Ce0.67Zr0.33O2引入到Al2O3载体中有助于催化剂保持较高的比表面积. TPR结果显示, 载体中引入适量的Ce0.67Zr0.33O2可以改善催化剂的氧化还原性能. XRD结果表明, Fe2O3在CeO2-ZrO2-Al2O3载体上呈现出良好的分散状况, 老化前后催化剂的晶相结构基本无明显变化. 特别是当载体中m(Ce0.67Zr0.33O2)∶m(Al2O3)的值为1∶2时, Fe2O3/CeO2-ZrO2-Al2O3催化剂在甲烷催化燃烧中显示出最佳的催化性能和抗高温老化性能.     

TiO2/Gd2O3纳米粉体的制备、表征及光催化活性

利用酸催化的溶胶-凝胶法制备了纯TiO₂和Gd³⁺(0.5wt%)掺杂的TiO₂纳米粉体，采用XRD、BET、XPS、紫外-可见漫反射谱(DRS)和表面光电压谱(SPS)等技术进行了表征；以亚甲基蓝(MB)的光催化降解为探针反应，评价了其光催化活性；探讨了Gd³⁺掺杂对TiO₂纳米粉体的光催化活性的影响机制。结果表明，TiO₂/Gd₂O₃纳米粒子对MB溶液的光催化活性提高到纯TiO₂的1.5倍。掺杂Gd³⁺可以强烈抑制TiO₂由锐钛矿相向金红石相的转变；阻碍TiO₂晶粒的生长；提高高温组织稳定性，改善粉体的表面织构特性；形成光生电子的浅势捕获陷阱，抑制e^-/h⁺复合，这些因素共同作用最终导致TiO₂/Gd₂O₃纳米粉体的光催化活性明显提高。XPS分析结果证实，掺杂Gd³⁺导致粉体的表面羟基含量降低。由于产生了量子尺寸效应，复合粉体的紫外吸收带边蓝移，光的吸收能力略有降低。     

Structural changes resulting from doping Ti2O3 with Sc2O3 or Al2O3

The crystal structures of (Ti_1?xSc_x)₂O₃, x = 0.0038, 0.0109, and 0.0413, and of (Ti_0.99Al_0.01)₂O₃, have been determined from X-ray diffraction data collected from single crystals using an automated diffractometer, and have been refined to weighted residuals of 25–34. Cell constants have also been determined for x = 0.0005, 0.0019, and 0.0232. The compounds are rhombohedral, space group $\text{R}\text{3}\text{c}$, and are isomorphous with α-Al₂O₃. The hexagonal cell dimensions range from a = 5.1573(2)Å, c = 13.613(1)Å for (Ti_0.9995Sc_0.0005)₂O₃ to a = 5.1659(4)Å, c = 13.644(1)Å for (Ti_0.9587Sc_0.0413)₂O₃, and a = 5.1526(2)Å, c = 13.609(1)Å for (Ti_0.99Al_0.01)₂O₃. Sc and Al substitution cause similar increases in the short near-neighbor metal-metal distance across the shared octahedral face; for Sc doping the increase is from 2.578(1) Å in pure Ti₂O₃ to 2.597(1) Å in (Ti_0.9587Sc_0.0413)₂O₃. By contrast, changes in the metal-metal distance across the shared octahedral edge appear to be governed by ionic size effects. The distance increases from 2.994(1) Å in Ti₂O₃ to 3.000(1) Å in (Ti_0.9587Sc_0.0413)₂O₃ and decreases to 2.991(1) Å in (Ti_0.99Al_0.01)₂O₃.     

Preparation and Characterization of Fe/Al2O3 Nanocomposites

IntroductionAl2O3ceramic objects have a wide scope of appli-cations because of their high hardness, high intensity,low density, and superior chemical stability, whereasmetals are widely used for their excellent propertiessuch as good ductibility, electric…     

Characterization of paramagnetic hole-centers in Al2O3 and Al2O3:Fe by optical and EPR absorption

The electron paramagnetic resonance (EPR) and optical absorption spectra of nominally pure and Fe-doped single crystals of Al₂O₃ have been examined before and after gamma-ray irradiation at 77°K. The EPR spectra for doped and irradiated crystals were found to be a function of the iron concentration. Analysis of the optical and EPR spectra observed on the same Fe-doped crystals which had been subjected to gamma-ray irradiations suggests that the center which accounts most satisfactorily for the details of these spectra is: a single trapped-hole localized on an anion which is adjacent to a substitutional divalent iron impurity atom. The optical absorption band ascribed to this center occurs at 3.08 eV.     

Fe_2O_3/TiO_2纳米管阵列的制备及其光催化性能

在钛基体上采用阳极氧化法制备了TiO2纳米管阵列,采用化学浴方法在TiO2纳米管阵列上修饰了Fe2O3纳米颗粒。利用扫描电镜、X射线衍射和紫外可见漫反射光谱等手段对材料进行了表征,同时测试了材料的光电化学性能及其光催化降解亚甲基蓝染料废水的性能。结果表明,Fe2O3纳米颗粒的修饰将TiO2纳米管阵列的光响应拓宽至可见光区域,提高了光电流,Fe2O3/TiO2纳米管阵列的光电流是未修饰的TiO2纳米管阵列的9倍。而在光催化反应中,亚甲基蓝最高降解率可达80%,比未修饰的TiO2纳米管阵列高出30%。     

一维Ga2O3/SnO2纳米纤维的制备及其气敏性能

通过静电纺丝法制备了一维Ga2O3/SnO2纳米纤维,采用X射线衍射(XRD)、扫描电镜(SEM)、紫外可见漫反射光谱(UV-Vis DRS)等方法对材料进行了表征,测试了不同Ga2O3质量分数(0、40%、50%、60%、70%、100%)的Ga2O3/SnO2纳米纤维(650℃,5 h)对应元件对三甲胺、丙酮、乙醛、乙酸、氨气、乙醇、甲醛7种气体的气敏性能。结果表明:在室温(25℃)时,60%(w/w)Ga2O3-40%(w/w)SnO2纳米纤维对三甲胺气体具有较高的灵敏度和较短的响应/恢复时间。对1000μL·L^-1三甲胺的灵敏度达到51;检出限达到0.8μL·L^-1,其灵敏度为1.3。     

Al2O3-ZrO2复合膜的制备与表征

以异丙醇铝和氧氯化锆为原料,用溶胶-凝胶法在Al₂O₃中空纤维上制备了Al₂O₃-ZrO₂复合膜。应用TG、DTA、XRD、SEM等测试手段对复合膜的热稳定性、结构、形貌进行了表征。结果表明复合膜的热稳定性比单一由氧化铝或氧化锆制成的膜有显著的提高,在1100℃之前,复合膜以t-ZrO₂存在,1200℃时,出现了m-ZrO₂和α-Al₂O₃相。扫描电镜分析表明,膜表面完整、无缺陷。气体渗透实验进一步表明所得膜具有一定的气体选择性,0.3MPa和0.5MPa下对氮气和氩气的分离因子α分别为1.191和1.185,和氮气与氩气的理论分离因子(α=1.194)相当,说明气体通过膜的扩散以Knudsen扩散传质为主。用等温氮气吸附实验测定了非担载膜的孔径大小和分布,最可几孔径约为4.3nm。     

Fe2O3/TiO2纳米管阵列的制备及其光催化性能

在钛基体上采用阳极氧化法制备了TiO₂纳米管阵列,采用化学浴方法在TiO₂纳米管阵列上修饰了Fe₂O₃纳米颗粒.利用扫描电镜、X射线衍射和紫外可见漫反射光谱等手段对材料进行了表征,同时测试了材料的光电化学性能及其光催化降解亚甲基蓝染料废水的性能.结果表明,Fe₂O₃纳米颗粒的修饰将TiO₂纳米管阵列的光响应拓宽至可见光区域,提高了光电流,Fe₂O₃/TiO₂纳米管阵列的光电流是未修饰的TiO₂纳米管阵列的9倍.而在光催化反应中,亚甲基蓝最高降解率可达80%,比未修饰的TiO₂纳米管阵列高出30%.     

Gd2O3:Eu@mSiO2核壳双功能纳米棒的制备及性质

通过水热法和正硅酸乙酯水解法制备了一种新颖的Gd2O3:Eu@mSiO2核壳双功能(荧光和介孔)纳米棒。用扫描电镜(SEM)、透射电镜(TEM)、X射线粉末衍射(XRD)、红外光谱(FTIR)等多种测试手段对样品的形貌、物相结构进行分析表征。结果表明,该核壳结构纳米材料以Gd2O3:Eu纳米棒(长~400 nm,直径~100 nm)为核,介孔SiO2为壳,尺寸均匀,分散性良好。荧光光谱表明,在紫外光激发下,核壳纳米棒发射强烈的橙红色荧光。同时该核壳纳米棒能成功标记NCI-H460肺癌细胞。以布洛芬(IBU)为药物模型研究核壳纳米棒的药物负载和释放行为,结果表明,Gd2O3:Eu@mSiO2核壳纳米棒对IBU的负载量可达10.25%,而且其具有明显的缓释效果。IBU负载的样品(IBU-Gd2O3:Eu3+@mSiO2)在紫外光照射下仍呈现Eu3+的橙红色发光,且Eu3+在载药系统中的发光强度随IBU释放量的变化而变化,因此通过发光强度的变化可以跟踪和监测药物及其释放情况。