磁控溅射（TiO2-ZnO）/TiO2梯度复合薄膜的制备及光致亲水性研究

采用磁控溅射离子镀设备制备了(TiO2-ZnO)/TiO2梯度复合薄膜,通过TEM、AFM、Raman、XPS分析了复合薄膜的结构、形貌和表面羟基含量,以甲基橙作为有机降解物,研究了(TiO2-ZnO)/TiO2梯度复合薄膜与普通TiO2-ZnO复合薄膜和TiO2薄膜在光催化性能和光致亲水性能上的差异。结果表明:(TiO2-ZnO)/TiO2梯度复合薄膜具有以主体为TiO2-ZnO层、顶层为TiO2的梯度结构,且薄膜表面致密、粒径均匀(10～14 nm),光催化性和亲水性均优于普通TiO2-ZnO复合薄膜和TiO2薄膜,且其光波响应范围红移至450 nm、表面羟基含量高达12.53%,同时梯度复合薄膜的抗光腐蚀性能良好,4 h以后其润湿角仍保持不变。     

纳米CNTs/SiO2/TiO2复合颗粒的制备及表征

以碳纳米管为核心,采用溶胶-回流法制备了纳米CNTs/SiO2/TiO2复合颗粒.用透射电子显微镜(TEM)、X射线衍射(XRD)、傅里叶红外光谱(FT-IR)和BET法对其表面形貌、结构和比表面积进行表征.结果表明,所制纳米CNTs/SiO2/TiO2复合颗粒为双层包覆型结构,SiO2为中间层,最外层是锐钛矿型的TiO2;红外光谱分析显示SiO2和TiO2之间形成了Ti-O-Si键;复合颗粒的比表面积是纯碳纳米管的2倍多.     

CNTs/SBS/PANI复合电极材料的制备与电化学性能研究

本文以过硫酸铵为引发剂,植酸为掺杂酸,在溶液中原位聚合合成了碳纳米管(CNTs)/苯乙烯-丁二烯-苯乙烯(SBS)/聚苯胺(PANI)复合电极材料.通过红外光谱(IR)、扫描电镜(SEM)对电极材料的结构和微观形貌进行了表征.通过循环伏安法(CV)、交流阻抗谱(EIS)、恒电流充放电(GCD)等电化学手段对材料的电化学性能进行了表征.结果表明:与SBS/PANI复合材料相比,CNTs/SBS/PANI复合电极材料具有更高的比电容、循环稳定性和倍率性能.当CNTs的加入量占苯胺单体质量百分比为3;,在扫描速率为5 mV/s时,CNTs/SBS/PANI复合电极材料的比电容最大为356.7 F/g.     

不同结构TiO2-ZnO异质复合膜光催化活性的研究

采用多靶磁控溅射离子镀技术制备TiO2-ZnO和(TiO2-ZnO)/TiO2两种不同结构的复合薄膜.研究薄膜在pH值分别为5、7和9时对甲基橙的降解,并结合薄膜光催化实验后的透光率、表面形貌和电化学腐蚀性能,探讨TiO2顶层对TiO2-ZnO异质复合薄膜光催化活性的影响.结果表明:两种薄膜的光催化活性均在酸性中最好,依次为碱性和中性,但(TiO2-ZnO)/TiO2薄膜的降解率和降解速率始终高于TiO2-ZnO薄膜,且酸、碱性环境下更明显.光催化实验后,(TiO2-ZnO)/TiO2薄膜表面无变化,TiO2-ZnO薄膜出现明显的腐蚀、溶解形貌,且薄膜透光率在不同环境中的变化相差4～5倍.在不同pH值的3.5wt; NaCl溶液中,(TiO2-ZnO)/TiO2复合薄膜的腐蚀电位和腐蚀电流均优于TiO2-ZnO薄膜.由于TiO2顶层良好的耐酸碱腐蚀性能,(TiO2-ZnO)/TiO2薄膜在pH值较大范围的溶液中表现出更好的光催化活性.     

镍硫化物/碳纳米管复合材料的制备及电化学性能研究

采用溶剂热法以NiC12·6H2O为镍源,乙醇为溶剂制备Ni/CNTs前驱体,在水热反应条件下,用Na2S2O3·5H2O对Ni/CNTs前驱体进行硫化,得到NS/CNTs复合材料.对其电化学性能进行测试,NS/CNTs复合材料在1A·g-1电流密度下的比电容可达533.33 F·g-1,经1000次循环充放电后,比电容保持率为42.50;.相较于NS纳米片(146.67 F·g-1和27.27;),NS/CNTs复合材料的电化学性能得到了显著提升,表明CNTs的加入能明显改善镍硫化物的电化学性能.     

PAN/TiO2复合微粒的制备与表征

采用沉淀法合成聚丙烯腈(PAN),并通过化学吸附法制备得到PAN/TiO2纳米复合微粒.采用透射电镜(TEM)、X射线衍射(XRD)、红外光谱(IR)、X射线光电子能谱(XPS)、紫外可见漫反射吸收光谱(DRS)等方法对复合微粒的结构和性能进行了分析表征.结果表明,复合微粒的形貌、晶型和粒径和纯二氧化钛比较基本没有发生改变;PAN/TiO2纳米复合微粒在可见光区的光吸收能力增强.对甲基橙降解实验研究结果表明,所制备的PAN/TiO2纳米复合微粒具有良好的光催化降解性能,其14 h对甲基橙的降解去除率可以达到86.5;.     

Cu∶CdS/TiO2的制备及其光电化学性能研究

采用水热法制备(001)晶面裸露的TiO2纳米片阵列薄膜,并采用水热法进行CdS纳米颗粒复合,探讨不同水热反应时长对复合薄膜结构及性能的影响.为了提高复合薄膜的光电化学性能,在水热反应过程中引入Cu前驱体,并探讨不同掺杂浓度对复合薄膜性能的影响.研究结果表明Cu元素掺杂有效拓宽了CdS复合TiO2纳米片阵列薄膜(CdS/TiO2)的光吸收范围,并且提高了CdS/TiO2的光电化学性能.当水热反应3h,Cu掺杂浓度为1∶1 000时,CdS/TiO2的光电性能达到最佳.     

CsPbI3复合TiO2纳米管阵列的制备及表征

为提高二氧化钛纳米管阵列(TiO2 NTAs)的光电化学性能,对其进行半导体复合改性处理.采用阳极氧化法制备得到TiO2 NTAs,热注入法制备得到全无机钙钛矿CsPbI3,浸渍法实现CsPbI3与TiO2 NTAs的复合,制备得到不同浸渍次数的CsPbI3/TiO2 NTAs.通过一系列光电性能测试表明,经CsPbI3复合改性处理后,TiO2 NTAs的光电化学性能有明显的提高,且经4次浸渍得到的CsPbI3/TiO2 NTAs光电性能最佳,其饱和光电流密度为0.92 mA/cm2,约为TiO2 NTAs的2.97倍,且对应的光转换率最高约为0.55;.除此之外,其瞬态光电流密度最大,约为0.69 mA/cm2,并表现出最佳的光响应特性.     

三维有序大孔TiO2/CeO2光催化剂的制备及性能研究

以自组装SiO2纳米球为模板,通过煅烧和模板刻蚀制备具有三维有序大孔结构的TiO2/CeO2复合光催化剂(3DOM TiO2/CeO2).用XRD、SEM、FT-IR、DRS、PC等手段对所制备的光催化剂进行表征,在模拟太阳光下,以罗丹明B为模型降解物,对样品的光催化活性进行测试.结果表明,3DOM TiO2/CeO2的光催化降解活性与TiO2/CeO2相比得到进一步提高,其原因可能是由于3DOM结构可以产生慢光子效应,提高了TiO2/CeO2复合光催化剂的光吸收能力,进而提高了TiO2/CeO2的光催化性能.     

不同浓度碳纳米管/聚乙烯醇薄膜的机械性能的研究

基于化学气相沉积法制备碳纳米管(CNTs),利用浸入滚动法制备CNTs/聚乙烯醇(PVA)复合薄膜.研究不同浓度的PVA对CNTs/PVA复合薄膜机械性能的影响.实验表明,CNTs/PVA复合薄膜的应力随着PVA的浓度的增加呈现先增加后减小的趋势,PVA的浓度为2wt;的时候CNTs/PVA复合薄膜的抗拉强度最大,其值为561 MPa.并且实验研究发现CNTs/PVA复合薄膜的应变随着PVA的溶度的增加而增加,不同浓度的复合薄膜具有良好的均匀性.     

Calculation of phase diagrams in AlxIn1−xAs/InP,AsxSb1−xAl/InP and AlxIn1−xSb/InSb nano-film systems

The models for calculation of phase diagrams of semiconductor thin films with different substrates were proposed by considering the contributions of strain energy, the self-energy of misfit dislocations and surface energy to Gibbs free energy. The phase diagrams of the Al_xIn_1−xAs and As_xSb_1−xAl thin films grown on the InP (1 0 0) substrate, and the Al_xIn_1−xSb thin films grown on the InSb (1 0 0) substrate at various thicknesses were calculated. The calculated results indicate that when the thickness of film is less than 1 μm, the strain-induced zinc-blende phase appears, the region of this phase extends with decreasing of the layer thickness, and there is small effect of surface energies of liquid and solid phases on the phase diagrams.     

Elastic properties of GexAsySe100−x−y glasses

The elastic properties of Ge_xAs_ySe_100−x−y (0x30; 10y40) glasses have been studied. The results were analyzed in terms of the dependence on the theoretical mean coordination number (mean number of covalent bonds per atom) m (m=2+(2x+y)×0.01). Three ranges of m (2.1m2.51, 2.51<m2.78, 2.78<m3) were revealed, where different dependencies of elastic moduli (Young’s modulus, shear modulus) and Poisson’s ratio of glasses on m were observed.     

Crystal growth of NdAl3(BO3)4 from K2O/MoO3/Nd2O3/B2O3/KF flux

NdAl₃(BO₃)₄ single crystals were grown by the flux method and the TSSG technique using a K₂O/3MoO₃/B₂O₃/0.5Nd₂O₃/KF flux system. Light-violet clear crystals could be obtained. The effects of fluoride on the growth of NAB crystals were investigated. As the content of KF was gradually increased, the growth form of NAB was changed from the equant to the columnar and the primary crystalline region of NAB was shrinked. At the ratio of KF/K₂O = 0.75, NAB crystals could not be grown.     

Synthesis and structure of new phases of the Am?1Bi2BmO3m+3 (m = 2) type

Three polycrystalline bismuth-containing layered perovskite-like oxides are synthesized by high-temperature solid-state reactions. One of these compounds was described previously, namely, Bi₃Ti_1.5W_0.5O₉, for which the unit cell parameters a = 5.372(5) Å, b = 5.404(4) Å, and c = 24.95(2) Å are determined in this study. The other two compounds, namely, Na_0.75Bi_2.25Nb_1.5W_0.5O₉ with the unit cell parameters a = 5.463(1) Å, b = 5.490(7) Å, and c = 24.78(0) Å and Ca_0.5Bi_2.5Ti_0.5Nb_1.5O₉ with the unit cell parameters a = b = 3.843(2) Å and c = 24.97(6) Å, are synthesized for the first time. The compositions of these compounds are based on the composition of the well-known compound Bi₃TiNbO₉ with a high Curie temperature (T _C = 1223 K), in which bismuth, niobium, and titanium atoms are partially or completely replaced by other atoms. The experimental and calculated interplanar distances determined from the X-ray diffraction patterns of the studied compounds are presented. __________ Translated from Kristallografiya, Vol. 50, No. 1, 2005, pp. 59–64. Original Russian Text Copyright ? 2005 by Geguzina, Shuvaev, Shuvaeva, Shilkina, Vlasenko.     

Vapour epitaxial growth and characterization of InAs1-xPx

The vapour growth of InAs_1-xP_x layers has been carried out by the hydride process. The phosphorus rich part of the system (0.7 ? x ? 1) was especially investigated. Heteroepitaxial deposits of InAs_1-xP_x and InP have been performed on substrates such as InAs, GaAs and GaP. A systematic study of the influence of the substrate orientation on the quality of the layer has been carried out by growth on hemispherical substrates. Preferential planes have been pointed out: (100) and (111) A for InAs, (111) for GaAs and GaP. The band gap variation as a function of the composition has been determined by photoluminescence at 4.2 °K and X-ray diffraction measurements. It fits the equation: E_G(x) eV = 0.425 + 0.722 x + 0.273 x² at 4.2 °K.     

Digitally alloyed modulated precursor flow epitaxial growth of AlxGa1−xN layers with AlN and AlyGa1−yN monolayers

We propose a new growth scheme of digitally alloyed modulated precursor flow epitaxial growth (DA-MPEG) using metalorganic and hydride precursors for the growth of Al_xGa_1−xN layers with high-Al content at relatively low temperatures. The growth of high-quality, high-Al content Al_xGa_1−xN layers (x_Al>50%) that are composed of AlN and Al_yGa_1−yN monolayers on AlN/sapphire template/substrates by DA-MPEG was demonstrated. The overall composition of the ternary Al_xGa_1−xN material by DA-MPEG can be controlled continuously by adjusting the Column III mole fraction of the atomic Al_yGa_1−yN sub-layer. X-ray diffraction and optical transmittance results show that the AlGaN materials have good crystalline quality. The surface morphology of DA-MPEG AlGaN samples measured by atomic force microscopy are comparable to high-temperature-grown AlGaN and are free from surface features such as nano-pits.     

Crystallization behaviours ofCo100−1(x+y)NbxBy amorphous alloys

The crystallization behaviours of Co_100?1(x+y)Nb_xB_y amorphous alloys were investigated by means of differential thermal analysis and a conventional X-ray diffractometer. The crystallization sequences are discussed in terms of the equilibrium phase diagram of the ternary alloy system.Assuming crystallization occurs as a result of nucleation and growth, the stabilizing effect of eutectic phase separation on the crystallization is shown by introducing the effective free energy of the critical nucleus.