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1.
常温下利用TiO2陶瓷靶采用射频磁控溅射法在玻璃衬底上制备了N掺杂TiO2薄膜。利用光学轮廓仪、X射线衍射仪(XRD)、X射线光电子能谱仪分析(XPS)和分光光度计等对薄膜的沉积速率、化学组成、晶体结构和禁带宽度进行了系统研究。结果表明:磁控溅射N2流量和退火处理对薄膜的微观结构和性能有重要的影响。退火前,薄膜由非晶态TiO2构成;退火后,薄膜呈现锐钛矿相和金红石相的混合相。随着磁控溅射系统中N2流量的增加,退火前禁带宽度从3.19eV减少到2.15eV;退火后,薄膜由非晶相TiO2组织转化为锐钛矿TiO2和金红石TiO2构成的浑河相组织,禁带宽度相比退火前的非晶相TiO2薄膜略有增加。 相似文献
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以三聚氰胺为掺杂源,采用溶胶-凝胶法制得了平均粒径为20.1nm的锐钛矿型N、C共掺TiO2光催化剂.当n(N)∶n(C)∶n(Ti)为0.064∶0.055∶1时,TiO2对亚甲基蓝3h日光降解率可达68%.探讨了三聚氰胺的用量和煅烧温度对TiO2光催化性能的影响,确定了最佳制备工艺.XPS和FTIR分析表明,N主要以替代O的形式生成O-Ti-N,少量N以填隙式生成-Ti-N-O,而C主要以替位式生成O-Ti-C,以填隙式生成-Ti-C-O、-Ti- COOO.UV-Vis分析表明,N、C掺杂TiO2的吸收边从掺杂前的383nm红移到427nm,禁带宽度从掺杂前的3.2eV降到2.9eV,将TiO2的光响应波长拓展到了可见光区. 相似文献
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用电子束蒸发法制备TiO2薄膜,并对其进行300℃、400℃、850℃热处理和掺杂.详细研究了工艺参数、热处理和掺杂对TiO2薄膜折射率的影响.实验结果表明:镀制高折射率的氧化钛薄膜最佳工艺参数为基片温度200℃、真空度2×10-2 Pa、沉积速率0.2 nm/s;随着热处理温度的升高,薄膜折射率也逐渐增大;适量掺杂CeO2(CeO2:Ti0质量比1.7:12)会提高薄膜的折射率,过量掺杂CeO2反而会降低折射率. 相似文献
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热处理对溶胶-凝胶TiO2薄膜的晶相转变和性能影响 总被引:13,自引:1,他引:12
以钛酸丁酯(TPOT)为有机醇盐前驱体,采用溶胶-凝胶技术制备了TiO2溶胶。为测量方便起见,分别制备了凝胶粉体和薄膜,并对样品进行了不同温度的热处理。X射线衍射(XRD)、椭偏仪和紫外-可见光谱(UV-vis)的测量表明:随热处理温度的升高,TiO2的结构由非晶到锐钛矿再到金红石相转变,400℃为锐钛矿相,600℃开始出现金红石相,800℃完全转变为金红石相;晶粒尺寸随热处理温度的升高而逐渐增大,锐钛矿结构的晶粒尺寸范围是2.5-5.5nm,金红石结构的晶粒尺寸范围是5.9-6.8nm;TiO2薄膜的折射率随热处理温度的升高而增大,同时薄膜厚度降低;禁带宽度随热处理温度的升高而增大,同时薄膜厚度降低;禁带宽度随热处理温度升高而变窄,锐钛矿结构的禁带宽度为3.45eV,而金红石结构的禁带宽度为3.30eV。 相似文献
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采用陶瓷靶直流磁控溅射,以玻璃为基底制备2.5wt%Nb掺杂TiO2薄膜,控制薄膜厚度在300~350 nm,研究了不同基底温度下所制得薄膜的结构、形貌和光学特性.XRD分析表明,基底温度为150℃、250℃和350℃时,薄膜分别为非晶态、锐钛矿(101)和金红石相(110)结构.基底温度250℃时,锐钛矿相薄膜的晶粒尺寸最大,约为32 nm.薄膜表面形貌的SEM分析显示,薄膜粗糙度和致密度随基底温度升高得到改善.薄膜的平均可见光透过率在基底温度为250℃以内约为70%,随基底温度升高至350℃,平均透过率下降为59%,金红石相的存在不利于可见光透过.Nb掺杂TiO2薄膜的光学带宽在3.68~3.78 eV之间变化.基底温度为250℃时,锐钛矿相薄膜的禁带宽度最大,为3.78 eV. 相似文献
6.
Ag/TiO2薄膜结构和光催化性能研究 总被引:18,自引:0,他引:18
采用溶胶-凝胶技术制备了Ag掺杂的TiO2薄膜.用XRD、氮吸附法、UV-VIS-NIR分光光度计以及XPS对Ag掺杂后TiO2薄膜结构的变化进行了分析;用分光光学法通过在紫外光照下分解亚甲基蓝的实验比较了TiO2薄膜与Ag/TiO2薄膜的光催化性能.结果发现,掺杂适量的Ag有助于TiO2薄膜光催化氧化性能的提高,原因在于:(1)Ag通过引入耗尽层提高了TiO2的电荷分离能力,并吸引空穴向薄膜表面移动,结果使薄膜表面空穴的浓度提高,薄膜光催化效率提高;(2)Ag减小了TiO2粒子的粒径,使TiO2禁带宽度增大,薄膜光催化氧化的能力提高;(3)Ag掺杂后,TiO2薄膜表面对-OH基和水的吸附增加,使光照后TiO2薄膜表面活性自由基·OH的浓度增加,空穴向薄膜所吸附物质的转移能力提高. 相似文献
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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. 相似文献
12.
C. Bersier E. P. Stoll P. F. Meier T. A. Claxton 《Journal of Superconductivity and Novel Magnetism》2002,15(5):399-402
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. 相似文献
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V Vijayashree C K Subramaniam R Srinivasan I K Gopalakrishnan PVPSS Sastry J V Yakhmi R M Iyer 《Bulletin of Materials Science》1991,14(3):827-830
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. 相似文献
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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. 相似文献
16.
X-ray radial distribution analysis and Raman spectroscopic measurement were carried out on Na2O-2TiO2 glass prepared by twin-roller quenching method. It is found that four-coordinated Ti4+ ions may be predominant over six-coordinated ones in the present glass. It is also found that the fraction of six-coordinated Ti4+ ions is larger in the present glass than in K2O·2TiO2 and Cs2O·2TiO2 glasses. Poorer glass-forming ability of the Na2O-TiO2 system compared with the K2O-TiO2 and Cs2O-TiO2 systems is ascribed to a larger fraction of TiO6 octahedron for the former system. 相似文献
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SiO2—TiO2—ZrO2系涂层的制备及其特性 总被引:11,自引:3,他引:8
用溶胶-凝胶法(sol-gel method)在不锈钢表面制备了SiO2-TiO2-ZrO2系无机氧化膜(STZ)。用DTA/TG、IR、XRD和SEM等手段研究了涂层制备时由凝胶向玻璃态的转变以及涂层薄膜的显微结构特点,考察了涂层对基体的保护效果。试验结果表明,在溶胶至凝胶最终转变为无机氧化物的过程中形成了无机网络,Si^4 和Zr^4 充当了网络骨架的形成离子。涂层为无定型玻璃态,其间混有石英、锐钛矿或金红石等微晶。 相似文献
18.
I. R. Shein S. L. Skornyakov V. I. Anisimov A. L. Ivanovskii 《Journal of Superconductivity and Novel Magnetism》2014,27(1):155-161
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. 相似文献
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Bi2Sr2CaCu2Ox superconductor was studied by differential scanning calorimetry (DSC) and thermogravimetry (TG) in different atmospheres. It is discovered that there is a thermal anomaly in the DSC curve, associated with a weight loss in the TG curve before the melting of the sample. Careful thermal analysis and high temperature X-ray diffraction reveal that the thermal anomaly and the weight loss show an instability of the crystalline Iattice. By annealing the sample in oxygen and argon, respectively and then by TC measurement and thermal analysis, the coincidence of transition temperature with the instability is found. The coincidence is further confirmed by Y-doped 2212 phase. 相似文献
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F. N. Dresvyannikov 《Journal of Engineering Physics and Thermophysics》1968,14(6):563-565
Experimental data on the thermal conductivity of dissociating nitrogen tetroxide have been obtained by the hot-wire method in the temperature range from 290 to 870° K at pressures up to 105 N/m2. 相似文献