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991.
Al/Ti multilayers with columnar grains were deposited by electron-beam evaporation on piezoelectric LiNbO3 substrates. After annealing in air and under vacuum conditions dissolution of the Ti interlayer was observed for all samples. The original Ti interlayer dissolved completely and globular Al3Ti grains were formed within an Al matrix. All samples had an oxidized adhesive Ti bottom layer and a 10 nm thin Al layer below this adhesive Ti bottom layer, which remains intact after the applied heat treatment. This resistance against dissolution by interdiffusion could be caused by the oxidation. These changes in the microstructure and in the chemical composition were investigated by conventional and analytical TEM. 相似文献
992.
Chiara Ferrara Antonio Gentile Stefano Marchionna Riccardo Ruffo 《Current Opinion in Electrochemistry》2021
Since their discovery in 2011, MXene compounds, and in particular the Ti3C2-based phases, have gained increasing interest from researchers leading to over 2000 scientific works in 2020. The peculiar morphological, charge transport, and surface properties make the MXenes ideal materials for energy storage applications such as active material in alkaline ion batteries and supercapacitors, as conductive or buffer agent in composite electrodes for high energy applications, and as electrocatalytic materials for oxygen evolution or redox flow batteries. Among this almost endless literature, this work focuses on 5 recent articles (2019/2020) that summarize the potential of MXenes in different energy storage applications, also resuming the most promising preparatory routes regarding industrial scalability. 相似文献
993.
Poly(vinyl chloride) (PVC) was prepared using a titanium complex with an anionic oxygen tripod ligand [CpCo{P(O)(OEt)2}3]− () as catalyst and methyl aluminoxane (MAO) as cocatalyst. The polymerization behavior was compared with that of pentamethyl cyclopentadienyl titanium trichloride (Me5CpTiCl3). It is observed that LOEtTiCl3 can polymerize vinyl chloride with activity comparable to that of Me5CpTiCl3. The PVC samples prepared with LOEtTiCl3/MAO exhibit bimodal molecular weight distribution and the fraction of high molecular weight peak decreases with polymerization temperature. The microstructure and thermal decomposition of the PVC obtained were studied. Five types of structural defect were detected by 1H-NMR. Only saturated structural defects are found at low polymerization temperature, but at high polymerization temperature unsaturated structural defects, possibly resulting from dehydrochlorination of the saturated structural defects, appear as well. No head-to-head structural defect is observed. 13C-NMR shows that the PVC prepared by LOEtTiCl3 has an atactic stereostructure. Compared with the PVC from radical polymerization and anionic polymerization, the PVC samples prepared with LOEtTiCl3 show improved thermal stability. 相似文献
994.
Martin J. Fay Andrew Proctor Douglas P. Hoffmann Marwan Houalla David M. Hercules 《Mikrochimica acta》1996,122(3-4):311-321
The structure of Ti/Al2O3 supports (0–14 wt% Ti) and Co/Ti/Al2O3 catalysts (3 wt% Co) was examined by EXAFS. The results indicated that the Ti was present primarily as a highly dispersed surface phase. The Ti EXAFS results indicated that the Ti species were octahedrally coordinated. Evidence of Ti—Ti interactions was found for all loadings (2–14 wt% Ti) suggesting that the Ti surface species are present as small clusters of TiO2.The Co EXAFS results showed evidence for several structurally different Co surface phases as a function of Ti loading. Evidence of a Co species interacting with the Ti surface phase was observed for the 3% Co/2% Ti-3%Co/6%Ti catalysts. At the highest loadings studied, 3%Co/8%Ti and 3%Co/14%Ti, evidence was found for a CoTiO3-like phase. 相似文献
995.
996.
997.
近年来,化学发光在分析上的应用越来越广泛,但用于测定Ti(Ⅳ)体系尚不多见[1],我们发现,在碱性条件下,用ClO--H2O2可氧化曙红而发光,同时发现CTMAB阳离子表面活性物质对该化学发光体系有强烈的敏化作用,Ti(Ⅳ)对该发光体系有催化作用,且可增强发光强度,被增强的发光强度与Ti(Ⅳ)浓度有良好的线性关系.据此可进行痕量Ti(Ⅳ)的测定,并拟定了新的流动注射化学发光测定钛的方法.该法用于合成水样、铝合金试样分析获得满意的效果,检测限达2.1×10-9g/mL,线性范围为4×10-9~8×10-7g/mLTi(Ⅳ),测试的精密度良好,回收率为92.2%~107%,对含10×10-9g/mLTi(Ⅳ)连续测11次,其RSD为1.5%,分析结果与标样推荐值颇为一致. 相似文献
998.
999.
非铁电巨介电压敏材料CCTO 总被引:1,自引:0,他引:1
本文主要介绍了近年来一种新型类钙钛矿型非铁电巨介电非线性压敏陶瓷材料——CaCu3Ti4O12,概述了其在晶体结构、相结构、微观形貌、多条件下介电特性和I-V特性等方面的研究进展。比较了CaCu3Ti4O12陶瓷的各种巨介电性理论和模型,阐述了压敏特性的起源。在讨论CaCu3Ti4O12陶瓷巨介电性和压敏特性机理的同时,指出了CaCu3Ti4O12作为介电材料和压敏材料的研究方向及应用的可能性。掺杂、复合及热处理工艺等对CaCu3Ti4O12电性能影响的系统性研究工作还需要进一步深入;纳米化可能会导致其某项特性的进一步提升,而薄膜化尽早与微电子领域的需要相结合会产生更广阔的应用空间。 相似文献
1000.
采用基于密度泛函理论的第一性原理,针对PbZr0.5Ti0.5O3无氧和含氢的顺电相和铁电相的二层超晶胞,分别计算了 Ti 沿 c 轴位移时体系总能量的变化、电子云密度分布和Ti-O、Zr-O和H-O的重叠布居数.结果表明,含氢铁电相的Ti-O键和Zr-O 键相埘无氢铁电相明显减弱,氢氧之间较强的轨道杂化使它们趋于形成共价键;晶格中氧氧键的钉扎效应使含氢情况下的顺电相能昔始终低于铁电相能量,说明氢的引入阻碍了PbZr0.5Ti0.5O3从立方顺电相到四方铁电相的相变,并推断其为含氧气氛退火过程中PbZr0.5Ti0.5O3铁电性能下降的主要原因之一.所得结果对于深入理解铁电材料在氮氢混合气氛退火后铁电件能下降的微观机制具有参考价值. 相似文献