过渡族金属掺杂对TiO2薄膜光催化性能的影响

本文采用溶胶凝胶旋涂法在普通玻璃上制备了掺杂不同Fe3+浓度及不同Zn2+浓度的TiO2薄膜,并对薄膜进行了500℃退火处理。分析讨论不同Fe3+及Zn2+掺杂浓度下TiO2薄膜的光催化性能,得出了铁离子最佳掺杂浓度为0.5%,锌离子最佳掺杂浓度为5%。并利用XRD、SEM、UV-Vis对不同掺杂离子的薄膜进行了对比分析,结果表明:Fe2O3/TiO2和ZnO/TiO2薄膜在可见光范围内均具有很好的光透过性(>80%),ZnO/TiO2薄膜光催化性能略优于Fe2O3/TiO2薄膜,最佳状态下ZnO/TiO2薄膜的光降解率能达到Fe2O3/TiO2薄膜的两倍。     

Y2O3对火法合成HA影响的扩散偶研究

采用嵌套式扩散偶法对比研究了添加稀土氧化物(1.0%Y2O3)和未添加稀土氧化物时羟基磷灰石的火法合成过程.试验选用CaO和CaHPO4·2H2O作为合成HA的原材料,制备成扩散偶放入管式炉中进行烧结,随炉冷却后进行XRD、SEM分析.结果表明:Y2O3能够促进γ-Ca2P2O7向β-Ca3(PO4)2转变;Y2O3参加了化学反应,生成了Ca3Y(PO4)3;掺杂试样的HA的峰值强度变强,可见Y2O3对Ca10(PO4)6(OH)2的生成有一定的加速作用.Ca元素的扩散系数由4.59×10-11 cm2/s提高为1.145×10-10 cm2/s.     

低品质蓝宝石改善实验及热处理工艺研究

采用高温扩散方法对一种低品质蓝宝石进行改善实验,改善后的成品为黑色蓝宝石.从样品特性、改善目的及高温扩散原理出发,选用Fe2O3、TiO2、Co2O3作为着色剂,硼砂、Na2CO3为助熔剂,Mg(OH)2为催化剂进行改善实验,设计了系统的改善工艺流程并取得了预期的效果.运用紫外-可见光吸收光谱、X射线荧光光谱及能谱对改善后的样品进行了测试,并分析了改善后低品质蓝宝石呈黑色的原因.     

PNN／PZT系梯度功能压电陶瓷离子互扩散动力学

研究了ＰＮＮ／ＰＺＴ系梯度功能压电材料中各类离子互扩散反应及其随温度和时间的变化。用电子探针测量了互扩散偶的组分分布，利用“薄板叠加”扩散模型，对Ｎｉ＾２＋、Ｎｂ＾５＋，Ｔｉ＾４＋和Ｚｒ＾４＋的扩散浓度分布曲线进行数值逼近计算，确定了互扩散层的厚度，估算了各离子的扩散系数及其表现激活能。     

NiCrAlYSi涂层与镍基高温合金基体互扩散行为研究

采用电弧离子镀方法在镍基高温合金DZ125上沉积NiCrAlYSi涂层,通过对不同氧化时间后Al和Cr原子浓度分布曲线的分析,运用Boltzmann-matano方法,计算了Al和Cr元素在1373K分别加热0.5,2h和5h的互扩散系数,并拟合了这三个时间段的计算结果.结果表明:相同温度下,Al和Cr的互扩散系数分别随Al和Cr的原子浓度增加而增大.随氧化时间的延长,Al的互扩散系数随原子浓度的变化先增大然后基本不变,Cr的互扩散系数则逐渐减小;伴随着元素间互扩散行为的增强,涂层中的Al和Cr向基体扩散,基体合金元素Ni,Co,Mo,Ti和W则向涂层扩散,但涂层中Mo和Ti的含量相对较少.由于元素间互扩散行为,涂层中各元素的含量将趋向于更加均匀.     

TiO2/Fe2O3复合光催化超亲水性薄膜的研究

采用溶胶-凝胶法及浸渍提拉法在普通的载玻片上制得了TiO2/Fe2O3复合薄膜,通过对薄膜及相应干凝胶和粉体的DSC、XRD、UV透射光谱等的测量,分析了Fe2O3的含量对TiO2/Fe2O3复合薄膜的光催化及超亲水性能的影响.结果表明:复合薄膜均优于纯TiO2薄膜的光催化活性,Fe2O3的摩尔含量为0.5%时光催化活性最好;复合薄膜的亲水性能也随Fe2O3含量的不同而不同,Fe2O3的摩尔含量为0.05%～0.1%时得到了接触角为0°的超亲水性复合薄膜.     

Au-Ag系统的扩散系数及其扩散激活能的研究

在银基底上蒸镀80nm的金薄膜,然后用不同温度和时间间隔对这些样品进行热处理。再用PHI 550型俄歇电子能谱仪测出上述样品金膜中银的浓度剖面分布。根据银的浓度剖面分布及Hall公式算出Au-Ag系统的互扩散系数。由Leclaire公式计算出该系统的晶界扩散系数。从Arrhenius方程得出互扩散及晶界扩散激活能。并对实验和计算结果进行了讨论。     

稳恒强磁场对Al-Cu扩散偶界面中间相形成和生长的影响

研究了稳恒强磁场作用下Al-Cu扩散偶界面中间相组成和扩散行为.结果表明:强磁场作用下扩散偶中间相厚度显著增加,并且随磁场强度增大,界面中间相组成发生变化.按照抛物线规律计算了强磁场作用下扩散偶中间相的扩散系数,发现在平行和垂直于磁场的两个方向上扩散系数有显著差异,垂直于磁场方向的扩散系数比平行于磁场方向更大.强磁场促进了Al-Cu扩散偶中Al和Cu原子的扩散,加速了界面中间相的形成和生长过程.磁场作用差异导致了扩散的各向异性.利用原子扩散理论初步分析了产生上述现象的原因.     

Ni2O3/TiO2-xNx可见光催化剂的制备及表征

用溶胶-凝胶法制备了一种新型可见光催化剂Ni2O3/TiO2-xNx,用热分析、X射线光电子能谱及X射线衍射等进行了分析表征,并以偶氮染料阳离子红为目标污染物,分析了催化剂可见光下的催化活性.结果表明,Ni2O3/TiO2-xNx催化剂样品450℃处理后呈锐钛矿型.N元素进入TiO2晶格,Ni元素以Ni2O3的形式游离于TiO2晶格之外.相对于无掺杂TiO2,Ni2O3/TiO2-xNx催化体系由于N元素的掺杂使其在可见光区域的吸收大大增强, Ni2O3掺入加快了光生电子-空穴的分离和转移,因此可见光下的催化活性和光电化学活性大大提高.     

Fe_3O_4/Ce~(3+)-TiO_2复合光催化材料的制备及其光催化性能研究

采用溶胶-凝胶法,以钛酸四丁酯、硝酸铈为主要原料,无水乙醇为溶剂,冰醋酸为抑制剂,浓硝酸为催化剂制得稳定的Ce3+掺杂TiO2溶胶,其凝胶经不同温度煅烧3 h后制得Ce3+掺杂量不同的TiO2粉体。用XRD对TiO2进行了测试对比分析,以紫外光为光源,亚甲基蓝溶液为模拟有机染料废水,研究了TiO2的光催化性能。用化学共沉淀法制备了具有强磁性的纳米Fe3O4水基磁流体,再与Ce3+掺杂TiO2进行复合,制备了Fe3O4负载量不同的磁性Ce3+掺杂TiO2,研究了其对亚甲基蓝的光催化降解效果、磁分离回收率的影响。结果表明,TiO2凝胶热处理温度、Ce3+掺量、TiO2晶型及Fe3O4负载量对亚甲基蓝的光催化活性均有影响。掺Ce3+量为1%,热处理温度650℃的Ce3+掺杂TiO2粉体光催化活性最高。Fe3O4负载量为10%的Fe3O4/Ce3+-TiO2对亚甲基蓝的降解率8 h时达到90.3%,磁分离回收率达96.8%。     

VLE data for CO2-CF2Cl2, N2-CO2, N2-CF2Cl2 and N2-CO2-CF2Cl

Knowledge about vapour-liquid (VLE) is required as a basis of reliable calculations for separation processes. Correlations available for the prediction of T, p, x, y data are less accurate for mixtures at high pressures and mixtures containing supercritical components. The results of VLE experiments are reported and compared with data calculated with equations of state.     

Preparation of ZrO2-CeO2 and HfO2-CeO2 nanopowders

We prepared weakly agglomerated powders of ZrO₂-CeO₂ and HfO₂-CeO₂ solid solutions 5–8 nm in particle size, consisting of monoclinic and tetragonal phases. After heat treatment at 1200°C, the crystallite size was 30 and 14 nm, respectively. We also examined the effect of precipitate freeze drying on the crystallization of hafnia-based solid solutions containing up to 20 mol % CeO₂.     

Thermal diffusion in binary mixtures H2-CCl2F2 and H2-CHClF2

Thermal diffusion coefficients were measured in two gaseous mixtures, in which one component was close to the critical temperature, in the pressure range (19.6–127.4)·10⁴ N/m² and at a freon concentration of 0.25–0.8.     

Radial GRIN glasses in Li2O-Na2O-Al2O3-TiO2-SiO2 systems

A series of GRIN glass rods have been developed in Li2O-Na2O-Al2O3-TiO2-SiO2 systems. Negative radial refractive index profiles were generated by exchanging Na+ for Li+ ions in these glass rods. It has been observed that TiO2 plays a vital role in increase in the profile depth and maximum change in the refractive index because of its ambivalent nature. Change in the refractive index can be further increased by increasing the concentration of exchanging cation in the base glass.     

Comparison of the Electronic Structures of La2CuO4, Sr2CuO2Cl2, and Sr2CuO2F2

First-principles cluster calculations are reported of the local electronic structure of the three compounds: La₂CuO₄, Sr₂CuO₂Cl₂, and Sr₂CuO₂F₂. The copper ${\text{3d}}_{x^2 - y^2 } $ and the planar oxygen 2p _σ atomic orbitals exhibit a similar degree of covalency. The out-of-plane orbitals, however, are quite different with the ${\text{3}}d_{3z^2 - r^2 } $ atomic orbital lowered significantly in energy for chlorine and fluorine apical positions.     

Elastic and Electronic Properties of Superconducting CaPd 2 As 2 and SrPd 2 As 2 vs. Non-superconducting BaPd 2 As 2

The first-principles calculations were performed to predict the elastic and electronic properties of the superconducting ThCr₂Si₂-type phases CaPd₂As₂ and SrPd₂As₂ in comparison with the non-superconducting CeMg₂Si₂-type phase BaPd₂As₂. Besides, the same properties were compared for CeMg₂Si₂- and ThCr₂Si₂-type polymorphs of BaPd₂As₂. We found that all these phases are mechanically stable and belong to soft materials with low hardness. The near-Fermi region is formed by the valence states of the blocks [Pd₂As₂] with decisive contributions of Pd 4d states. The values of N(E _F) increase in the sequence: CaPd₂As₂ < SrPd₂As₂ < BaPd₂As₂, i.e. in the reverse sequence relative to the transition temperatures T _C. Thus, the change in T _C cannot be explained by the electronic factor, i.e. by the simple correlation T _C～N(E _F). Most likely the decrease in T _C in the sequence CaPd₂As₂ → SrPd₂As₂ and the absence of a superconducting transition in BaPd₂As₂ are related to the structural factors and the peculiarities of the electron–phonon coupling mechanism.     

Thermoelectric power of single-phase samples of Tl2CaBa2Cu2O y and Ba2CaSr2Cu2O y

Single-phase 2122 samples of thallium and bismuth superconductors were made by the precursor matrix method. The thermopower of these samples was measured in the temperature range 250 K-T _c . The thermopower was positive and decreased linearly with increasing temperature aboveT _c (onset). The exponential enhancement of thermopower seen in the undoped and doped YBCO was not observed in these samples. The linear variation of thermopower can be explained on the basis of either a two-band model or a narrow band model.