共查询到20条相似文献,搜索用时 640 毫秒
1.
水热合成镧掺杂钛酸铋粉体的初步研究 总被引:1,自引:0,他引:1
初步研究了镧掺杂钛酸铋粉体的水热合成工艺,借助XRD及TEM对粉体的组成、结构、晶粒度及粉体形貌进行了研究。结果表明:合成该粉体的最佳工艺条件为240℃保温6h;粉体的微观形貌呈片状;镧的掺杂抑制了钛酸铋晶体的生长。 相似文献
2.
在该项研究中,通过化学溶胶凝胶法,将纯铁酸铋薄膜与钬掺杂铁酸铋薄膜镀在Pt(100)/Ti/SiO_2/Si衬底上面,然后进行材料的性能研究。通过对铁酸铋薄膜进行电性能的测试,发现在掺杂稀土元素钬之后,铁酸铋薄膜的铁电性能显著增强,漏电流明显减少。铁酸铋电性能的增强归因于钬元素掺杂后该物质一种从六方相到四方相的结构转变。与此同时,通过对铁酸铋薄膜进行疲劳测试,发现在掺杂钬元素后,该物质的疲劳行为也得到了显著的增强,这也归因于掺钬后铁酸铋结构的转变与氧空位的减少。目前的工作为铁酸铋薄膜铁电和疲劳特性的增强提供了一种可用的方法,使其的实际应用成为可能。 相似文献
3.
水热合成掺镧钛酸铋粉体及其光催化性能探讨 总被引:1,自引:0,他引:1
以硝酸铋、四氯化钛和硝酸镧为原料,以氢氧化钾为矿化剂,采用水热法合成了不同镧掺杂量的钛酸铋粉体.用X射线衍射(XRD)和透射电镜(TEM)对所得粉体进行了表征,借助紫外-可见分光光度计考察了样品降解甲基橙的光催化性能.实验结果显示:在水热合成温度为220~280 ℃、保温时间为6 h的条件下,可得到各向异性、短轴为30 nm、长轴大于100 nm的掺镧钛酸铋粉体,且该方法所制备的掺镧钛酸铋(Bi 4-xLaxTi3O12)粉体具有一定的光催化效果. 相似文献
4.
5.
6.
采用溶胶-凝胶法制备了纯的TiO2和铋镧共掺杂的TiO2光催化剂,以活性黑KN-B为模型降解物,考察了铋单掺杂和铋镧共掺杂对TiO2光催化剂的活性影响,研究了催化剂投加量、染料初始质量浓度、溶液pH对活性黑KN-B降解率的影响.结果表明,铋掺杂的TiO2光催化活性高于TiO2,而适量铋镧共掺杂TiO2光催化活性进一步提高,最佳掺杂比是0.5%的Bi和0.2%的La.当铋镧共掺杂TiO2催化剂投加量为2.0 g·L-1,初始质量浓度为40 mg·L-1,pH为2.2时,活性黑KN-B在125W高压汞灯光照下20min后的降解率可达100%. 相似文献
7.
用固相法研究了钨离子(W6 )掺杂对铋层状钛酸铋钙镧[Ca0.7La0.3Bi4(Ti1-xWx)4O15,CLBTWx]陶瓷的铁电性能、介电性能和压电性能的影响,得到了W6 掺量与铋层状CLBTWx陶瓷性能的关系.用X射线衍射和扫描电镜研究了W6 掺量对铋层状CLBTWx陶瓷微观结构和物相的影响,探讨了W6 掺杂改性的机理.结果表明:随着W6 掺量的增加,CLBTWx陶瓷的介电常数(ε)先增大后减小;介质损耗(tanδ)先减小后增大;压电应变常数(d33)先增大后减小;剩余极化强度(Pr)先增大后减小然后再增大再减小;矫顽场(Ec)变化规律与Pr的相同.当W6 掺量为0.025mol时,可得到综合性能好的无铅铋层状CLBTWx陶瓷,其烧结温度为1 120~1 140℃时,CLBTWx陶瓷的ε=183.15;tanδ=0.00446;d33=14×10-12C/N;2Pr=26.7μC/cm2;2Ec=220kV/cm.该类材料适合于制备铁电随机存取存储器和高温高频压电器件.W6 掺杂从生成钙空位或铋空位、形成焦绿石相、促进陶瓷致密化、偏析晶界影响陶瓷晶粒的均匀生长等方面来影响铋层状CLBTWx陶瓷性能和结构. 相似文献
8.
9.
含铋光催化材料的研究进展 总被引:1,自引:0,他引:1
含铋光催化材料因其能吸收可见光、催化活性高而具有广阔的应用前景。本文主要回顾了含铋光催化材料近年来的研究概况,详细介绍了铋氧化物、卤氧化铋及钛酸铋、钨酸铋、钒酸铋、钼酸铋、铁酸铋等光催化剂的结构、制备和光催化性能,重点对光催化性能的改进方法进行了综述,包括制备方法的改良、催化剂的掺杂改性及复合催化剂的制备等;最后针对进一步提高光催化剂整体性能、实现工业化应用两点,提出了未来可以利用多元元素掺杂、多元半导体复合进行改性和负载于某些载体制备整体催化剂进行改良的观点。 相似文献
10.
稀土掺杂钛酸铅系陶瓷是一类重要的电子陶瓷材料,其表面形貌及粒径对材料性能有显著影响。采用水热法,以三水合乙酸铅和钛酸四丁酯为主要原料合成了一系列镧掺杂量不同的钛酸铅粉体,利用XRD、SEM、EDS、LPA等手段对粉体的物相、表面形貌及粒径进行了表征。结果表明:水热条件下制得的粉体中只有极少的镧(Ⅲ)取代铅(Ⅱ)进入晶格,大部分则以氢氧化镧的形式存在于晶粒间界处或被吸附在颗粒表面。未进入晶格的镧使晶粒产生择优取向,生长成棒状。粉体的粒径也因镧的引入而发生规律性变化。随着镧掺杂量的增加,粒径先减小后增大,当掺杂量x=0.05时出现临界点。 相似文献
11.
J. F. Scott F. D. Morrison M. Miyake P. Zubko Xiaojie Lou V. M. Kugler S. Rios Ming Zhang T. Tatsuta O. Tsuji T. J. Leedham 《Journal of the American Ceramic Society》2005,88(7):1691-1701
A review is given of ceramic and single-crystal thin film ferroelectric oxides, emphasizing perovskite phases, together with some new developments on hafnia films. It is shown that single-crystal barium titanate films behave as bulk down to at least 77 nm, with no finite size effects, no phase transition temperature shifts, and no dielectric peak broadening or change from first- to second-order transitions, suggesting that the gradient defect model of Bratkovsky and Levanyuk correctly describes such effects as extrinsic in experimental studies of equally thin ceramic thin films. In ceramic barium–strontium titanate (BST) thin films, it is shown that there is also no intrinsic broadening or shifts in phase transitions, with sharp, unshifted, bulk-like transitions observed only as re-entrant upon warming from cryogenic temperatures; this shows that phase transitions in ceramic thin films are dominated by kinetics and not thermodynamics and are definitely not equilibrium measurements. At high fields (>1 GV/m), the films exhibit space charge-limited conduction; no variable-range hopping is observed, contrary to recent studies on SrTiO3 . Some novel, unconventional switching processes are discussed, comparing the "perimeter effect" (non-equilibrium, ballistic) with Molotskii's equilibrium model. Theory and experiment are described for [3D] nanotubes, nanorods, and nano-ribbons (or micro-ribbons). The layered-structure-perovskite–pyrochlore conversion in bismuth titanate is described together with the PbO+TiO2 phase separation in lead zirconate titanate during electrical breakdown, as are novel HfO2 precursors that demonstrate enhanced temperature crystallization from the amorphous state and hence commercial advantages for front-end processing. 相似文献
12.
Peter Jörg Schorn Theodor Schneller Ulrich Böttger Rainer Waser 《Journal of the American Ceramic Society》2005,88(5):1312-1314
In this paper, lead hafnate titanate (PHT) was derived by chemical solution deposition (CSD) and characterized as a thin film material. The thin films were tested for the usage as a ferroelectric thin film in view of Ferroelectric Random Access Memory (FRAM) devices and compared with an equivalent lead zirconate titanate (PZT) thin film, which was prepared under the same conditions. After determining the thickness and the morphology of the PHT films, electronic measurements were performed to investigate this material as a promising candidate in view of FRAM applications due to failure mechanisms like fatigue and imprint. 相似文献
13.
Lauren M. Garten Matthew Burch Arnab Sen Gupta Ryan Haislmaier Venkataraman Gopalan Elizabeth C. Dickey Susan Trolier‐McKinstry 《Journal of the American Ceramic Society》2016,99(5):1645-1650
The development of barium strontium titanate‐based tunable dielectrics is currently hindered by high losses in the paraelectric phase. Barium strontium titanate (BST) thin films and ceramics show a range of ferroelectric transition behavior, from normal, diffuse, and relaxor‐like ferroelectric responses, depending on the sample preparation route. Rayleigh analysis, the temperature‐dependent dielectric response, and the optical second harmonic generation were used to characterize the ferroelectric response of bulk and thin film BST. Ferroelectricity is observed to persist in BST for 30°C above the global phase transition temperature in ceramics and over 50°C in thin films. Piezoresponse force microscopy on BST ceramics with extensive residual ferroelectricity reveals the coexistence of nanoscale polar regions, typical of relaxor ferroelectrics, as well as micrometer scale domain structures. The nature of the phase transition was probed using electron energy loss spectroscopy and found to correlated with the nanoscale A‐site chemical inhomogeneity in the samples. 相似文献
14.
S. Sriram M. Bhaskaran A. Mitchell D. R. G. Mitchell G. Kostovski 《Nanoscale research letters》2009,4(1):29-33
We report the first instance of deposition of preferentially oriented, nanocrystalline, and nanocolumnar strontium-doped lead
zirconate titanate (PSZT) ferroelectric thin films directly on thermal silicon dioxide. No intermediate seed or activation
layers were used between PSZT and silicon dioxide. The deposited thin films have been characterised using a combination of
diffraction and microscopy techniques. 相似文献
15.
A technique has been developed for the TEM examination of ferroelectric thin films in transverse section. Some preliminary results are reported for three different thin-film/substrate systems. The microstructures of thin films of lead scandium tantalate deposited onto sapphire and MgO, and lead titanate deposited onto AIN, have been examined, with particular attention being paid to the quality of the thin-film/substrate interfaces and to the changes in the nature of the microstructures of the thin films as a function of distance from their substrates. It is demonstrated that the technique successfully produces adequate electron transparent regions for the characterization of the thin-film/substrate interface of all the samples examined and that it is possible to prepare transverse sections of ferroelectric thin films routinely. 相似文献
16.
17.
18.
In this work, we apply nano-embossing technique to form a stagger structure in ferroelectric lead zirconate titanate [Pb(Zr0.3, Ti0.7)O3 (PZT)] films and investigate the ferroelectric and electrical characterizations of the embossed and un-embossed regions, respectively, of the same films by using piezoresponse force microscopy (PFM) and Radiant Technologies Precision Material Analyzer. Attributed to the different layer thickness of the patterned ferroelectric thin film, two distinctive coercive voltages have been obtained, thereby, allowing for a single ferroelectric memory cell to contain more than one bit of data. 相似文献
19.
D. Remiens J. F. Tirlet B. Jaber H. Joire B. Thierry C. Moriamez 《Journal of the European Ceramic Society》1994,13(6):493-500
The growth of ferroelectric lead titanate (PT) thin films by RF magnetron sputtering using a single mixed-oxide target is described. This study has been focused on producing perovskite thin (2000 Å) films with the desired composition on different substrates. Depositions were performed at room temperature and the process gas is pure argon. The effects of deposition and post-annealing conditions on film composition and microstructure were evaluated. Optimization of process conditions is discussed in terms of stoichiometry, structure and reproducibility. The optical properties of the films have also been characterized. 相似文献
20.
Zebin Lin Wei Cai Weihai Jiang Chunlin Fu Chun Li Yunxia Song 《Ceramics International》2013,39(8):8729-8736
Bismuth ferrite thin films were prepared via sol–gel spin-coating method and the effects of annealing temperature on microstructure, optical, ferroelectric and photovoltaic properties have been investigated. The results show that the bismuth ferrite thin films annealed at 550 °C is single phase and the grain size increases with the rise of annealing temperature. The band gap of bismuth ferrite thin films annealed at 550–650 °C is between 2.306 eV and 2.453 eV. With the rise of the annealing temperature, the remnant polarization gradually decreases and the coercive electric field increases. The short circuit photocurrent density decreases with the rise of annealing temperature, and the open circuit photovoltage and the power conversion efficiency of bismuth ferrite thin films annealed at 550 °C are higher than the thin films annealed at higher temperature. 相似文献