退火真空度与氧化钒薄膜物相的相关性

以高纯五氧化二钒(V2O5)粉末(纯度≥99.99%,质量分数)为原料,用真空蒸发工艺制备出氧化钒薄膜,并测试其在真空退火前、后的X射线光电子能谱、X射线衍射谱及电阻-温度关系曲线.结果显示:低真空退火对氧化钒薄膜的还原性比高真空退火的强.但是,在高真空退火下得到的氧化钒薄膜的晶粒尺寸要比在低真空下退火的大.随退火温度升高,高真空下退火制备的薄膜经历了从VO2(B)到V02(B)与V6O13混合,再到V6O13的转变过程,B表示薄膜无热致相变特性.低真空下退火制备的薄膜经历了从VO2(B)到VO2(A)的转变,A表示薄膜有热致相变特性.这些薄膜的电学性质也有很大不同.     

退火温度对铁电薄膜钛酸锶钡的影响

用醋酸盐和钛酸酯为原料,采用Sol-Gel工艺在Pt/TiO2/SiO2/Si基片上制备出Ba0.5Sr0.5TiO(3BST)铁电薄膜,然后在650-800℃下对BST薄膜进行退火,研究退火温度对钛酸锶钡铁电薄膜的影响。X射线衍射分析表明:退火温度在750℃以上时,BST薄膜转变成较为完整的ABO3型钙钛矿结构;SEM分析表明:750℃热处理的薄膜颗粒较大,且颗粒生长较好;阻抗分析仪测试表明:750℃退火处理的薄膜介电性能最佳;TEM分析表明:750℃晶粒发育完善、清晰,晶粒与晶粒之间比较紧密,且存在微畴区域。     

聚乙烯薄膜拉伸过程中结构变化的原位研究

使用差示扫描量热分析(DSC)研究了其拉伸前后结晶动力学与热力学行为的区别,使用同步加速器小角X射线散射(SAXS)和广角X射线衍射(WAXD)研究了薄膜拉伸过程中晶体结构、尺寸和长周期的变化.结果表明,拉伸使薄膜结晶度提高;拉伸过程中,二维散射图案发生明显变化,片晶结构被破坏后高应力诱导下重新结晶,拉伸使薄膜晶体取向...     

化学溶液沉积法制备掺镧Bi2Ti2O7薄膜及其特性的研究

采用化学溶液沉积法,在Si(100)衬底上制备了(Bi0.925La0．075)2Ti2O7薄膜。通过对其X射线衍射图谱分析表明：用一定量的La^3 来代替部分Bi^3 ,提高了Bi2Ti2O7相薄膜的稳定性。研究发现：经过高温(850℃)退火处理后,该薄膜的结晶性和取向性都很好,[111]方向取向率为90X。根据XRD谱图中的(444)衍射峰,计算出晶格常数a≈20．66A。薄膜的电流-电压和电容-电压特性的测量结果表明,该薄膜具有良好的绝缘性和较高的介电常数。     

氧化铋薄膜的制备及其性能表征

利用化学水浴沉积法在室温下制备了多晶氧化铋薄膜,并在350℃的空气气氛条件下进行退火处理,得到纯的α-Bi2O3,薄膜.对它们的晶相结构、光电性能进行测试.从X衍射分析结果来看,在退火过程中,薄膜结构由四方相和非化学计量相向单斜相转变.光学性质显示退火处理的薄膜吸收边缘明显的向长波的方向移动,发生红移现象,而且禁带宽度减少了0.4eV.退火后的薄膜在室温下暗电导率下降2个数量级.电导率的变化显示具有半导体行为的性质.     

TbFeCo缓冲层对钴铁氧体薄膜的微观结构和磁性能影响

采用射频磁控溅射技术在非晶TbFeCo缓冲层上制备了钴铁氧体(CoFe2O4)薄膜,并在空气中于300～1 000℃退火.采用X射线衍射仪、振动样品磁强计对薄膜的微观结构和磁性能进行表征.研究表明:样品均以单相尖晶石结构存在.在300℃退火时具有(111)择优取向;而高于300℃退火时薄膜的(111)择优取向逐渐消失;在800℃以上退火时出现(400)择优取向.所有薄膜均具有高矫顽力和高垂直各向异性,800℃退火样品垂直于膜面方向具有最大矫顽力832×103A/m,矩形度为0.73,900℃退火时矩形度达0.9.     

磁控溅射法制备Fe-Si化合物薄膜的研究

笔者采用磁控溅射的方法,在高真空不同的溅射气压条件下,沉积金属Fe到Si(100)衬底上,然后通过真空退火炉在2h和12h条件下对两组样品进行热处理,直接形成了Fe-Si化合物薄膜。采用X射线衍射仪对样品进行了晶体结构分析,利用卢瑟福背散射对Fe-Si化合物的形成过程中的Fe原子和Si原子的互扩散机理进行了研究,结果表明,在溅射气压为1.0~1.5Pa,退火温度为800℃退火12h能够得到质量很好的Fe-Si薄膜,超过1.5Pa时就会朝其他的Fe-Si化合物转变,还可能有Fe和Si的氧化物生成。     

掺钕钛酸铋薄膜的金属有机溶液分解法制备和性能研究

以无机盐为原料 ,采用金属有机溶液分解法在石英衬底上制备了不同钕含量的掺钕钛酸铋 (Bi4 -xNdxTiO1 2 ,BNT)薄膜。用X射线衍射和Raman光谱研究了薄膜的相组成和结构特征 ,用原子力显微镜对薄膜表面形貌和结晶颗粒度大小进行了分析。经过光学透射谱研究得到了薄膜的光学常数。结果表明 :不同钕含量的薄膜经 70 0℃退火处理后 ,都结晶为铋系层状钙钛矿结构 ,薄膜表面平整、无裂纹和空洞 ,颗粒大小为 80～ 10 0nm。Raman光谱分析发现 :当薄膜中钕含量 (x值 )小于 1时 ,钕离子只取代钙钛矿层中A位铋离子 ;而当钕含量超过 1以后 ,Bi2O2 层中的铋离子也被部分取代。透射谱分析得到了Bi3.2 5Nd0 .75Ti3O1 2 薄膜的线性折射率、线性吸收系数和光学带隙分别为 1.92 ,1.98× 10 2cm- 1 和 3 .5 6eV。     

基于表面化学吸附的ABS塑料化学镀铜新工艺的研究

采用生物高聚物(壳聚糖薄膜)通过化学吸附将催化剂金属(Pd)固定在丙烯腈-丁二烯-苯乙烯(ABS)塑料基体上,实现了一种低成本、环保的ABS塑料表面活化新工艺。对预处理后的ABS薄膜进行X射线光电子能谱(XPS)分析,了解其反应机理。结果表明:化学吸附法相比传统的物理吸附法,提高了镀层与基体的结合强度,获得了致密且连续的Cu-P铜层结构。     

热处理温度对溶胶凝胶法制备ZnO∶Sn薄膜性能的影响

采用溶胶-凝胶法在石英玻璃上制备掺锡氧化锌(ZnO∶Sn)透明导电薄膜,研究了干燥温度和退火温度对薄膜结晶度、微观结构、光电特性的影响.采用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、紫外-可见光光度计(UV-VIS)和四探针法等分析方法对ZnO∶Sn薄膜进行分析表征,结果表明:在300℃温度下干燥10min后,在700℃空气中退火1h制备出的ZnO∶Sn薄膜表面平整,具有c轴择优取向,平均透过率达到92％以上,电阻率仅为13.6Ω· cm.     

Al3+/Bi4Ti3O12薄膜的制备及其光催化性能表征

采用溶胶一凝胶法制备了掺 Al3+ 的Bi4 Ti3 O12 薄膜(Bl-xAlxTi3O12).采用分光光度法研究了薄膜对甲基橙溶液的降解,以及Al3+对薄膜的光催化效果影响.光催化结果表明,Al3+的掺杂量为 2atm% 时,薄膜的光催化效果最好,比未掺杂前提高 57.9%,且吸收边红移量为 36nm.     

Formation and stability of pyrochlore in sputtered SBT thin films

Abstract

In magnetron sputtering of SrBi₂Ta₂O₉ (SBT) thin films, bismuth deficiency tends to result in formation of an unwanted pyrochlore phase. In this paper, the dependence of deposition parameters on phase evolution in Sr deficient SBT thin films is studied. Only when bismuth is over stoichiometric (Sr_0.74Bi_2.2Ta₂O_9+x) can one obtain pure SBT structure. Decreasing the Bi content encourages formation of the Bi deficient pyrochlore phase. At 1.04 of Bi, only the pyrochlore phase forms. The pyrochlore phase is very stable even at 900°C.     

Enhanced visible-light catalytic activity of Au nanoparticles loaded c-axis oriented Bi2VO5.5 porous thin films

Au nanoparticles loaded c-axis oriented Bi₂VO_5.5 (BVO) porous thin films were prepared by using a simple spin-coating technique. The porous structures were formed through the hydrolysis of bismuth nitrate, Bi(NO₃)₃, one of the raw materials for synthesizing the BVO precursor solutions. The optimal photocatalytic rate of the porous thin film is three times more than that of pure BVO thin film. The enhancement of photocatalytic activity can be attributed to the Schottky barrier in the intimate interface between Au nanoparticles and BVO grains and the increase of absorption of light caused by surface plasmon resonance effect of gold nanoparticles. The possible degradation mechanism of Au–BVO-Methylene Blue system has been discussed based on the energy band structure and further trapping experiments. This study provides a simple method to prepare bismuth-containing oxide porous thin films without any pore-forming reagents, and the results suggest that the Au nanoparticles loaded BVO thin film is a promising candidate material for water or air treatment.     

Effect of excess Bi2O3 on structures and dielectric properties of Bi1.5Zn1.0Nb1.5O7 thin films deposited at room temperature by RF magnetron sputtering

To compensate for bismuth loss that occurred during the film deposition process, Bi_1.5Zn_1.0Nb_1.5O₇ (BZN) thin films were deposited at room temperature from the ceramic targets containing various excess amounts of bismuth (0–20 mol%) on Pt/TiO₂/SiO₂/Si substrates by using RF magnetron sputtering technique. The effect of bismuth excess content on the microstructure and electrical properties of BZN thin films was studied. The microstructure and chemical states of the thin films were studied by SEM and XPS. EPMA was employed to assess the film stoichiometry. The X-ray diffraction analysis reveals that the BZN thin films exhibit the amorphous structure in nature. An appropriate amount of excess bismuth improves the dielectric and electrical properties of BZN thin films, while too much excess bismuth leads to deterioration of the properties. BZN thin film with 5 mol% excess bismuth exhibits a dielectric constant of 61 with a loss of 0.4% at 10 kHz and leakage current of 7.26×10^?7 A/cm² at an electric field of 200 kV/cm.     

Effect of the excess of bismuth on the morphology and properties of the BaBi2Nb2O9 thin films

In this study, the effect of bismuth content on the crystal structure, morphology and electric properties of barium bismuth niobate (BaBi₂Nb₂O₉) thin films was explored with the aid of X-ray diffraction (XRD), scanning electron microcopy (SEM), atomic force microscopy (AFM) and dielectric properties. BaBi₂Nb₂O₉ (BBN) thin films have been successfully prepared by the polymeric precursor methods and deposited by spin coating on Pt/Ti/SiO₂/Si (1 0 0) substrates. The phase formation, the grain size and morphology of the thin films were influenced by the addition of bismuth in excess. It was observed that the formation of single phase BBN for films was prepared with excess of bismuth up to 2 wt%. The films prepared with excess of the bismuth showed higher grain size and better dielectric properties. The 2 wt% bismuth excess BBN thin film exhibited dielectric constant of about 335 with a loss of 0.049 at a frequency of 100 kHz at room temperature.     

Composition control of lead-free piezoelectric BNT thin ceramic films deposited by ex situ sputtering

(Bi_0.5Na_0.5)TiO₃ thin film growth by ex situ sputtering has been investigated and reported in this paper. An original approach, based on the growth process, was used in order to precisely control the film composition, which has never been reported in BNT growth. The bismuth content in the films and so the composition of amorphous sputtered films was controlled by a slight heating of the substrate during the growth (150–240°C). Then, films were crystallized, obviously without any change in composition, by a post-annealing treatment. More precisely, without substrate heating and using a stoichiometric target, the film presents an excess of Bi but when it is deposited at 200°C the film becomes stoichiometric. It was shown that the sticking coefficient of Bi is particularly sensitive even at low substrate temperatures, whereas Na and Ti sticking coefficients are not impacted. Followed by a post-annealing in air at 650°C, the composition of the amorphous BNT films deposited at 200°C remains stoichiometric and the film exhibits a high (100) preferred orientation in a pure perovskite phase and a dense microstructure. The evaluation of the electrical properties as a function of the Bi content in the film, adjusted by the deposition temperature, shows a strong impact on the ferroelectric properties where the best performances were obtained with the stoichiometric BNT film deposited at 200°C.     

Heat treatment of amorphous electrochromic WO3 thin films deposited onto indium-tin oxide substrates

Electrochromic tungsten oxide thin films, obtained by vacuum evaporation, were studied before and after heat treatment between 25 and 250°C for 2 h in air. Electrochromic properties were investigated in acid electrolyte by simultaneous measurements of the electrical and optical parameters. A.c. complex impedance techniques and voltammetry were used to characterize the films from an electrical point of view. We observed an enhancement of the electrochromic response times during both coloration and bleaching after heat treatment carried out between 150 and 220°C. This phenomenon was associated with a decrease of the ohmic drop in the electrode and a continuous variation of the impedance diagrams of these electrochromic electrodes. Moreover, we observed that the diffusion coefficient of H⁺ ions into WO₃, obtained on colored thin films, increased as the electrochromic kinetics increased.     

共沉淀法制备Bi3.25La0.75Ti3O12纳米粉体

用硝酸铋、硝酸镧和钛酸四丁酯为原料，硝酸、无水乙醇和去离子水为溶剂，氨水为沉淀剂，采用共沉淀法合成了单相铋层状钙钛矿结构Bi3.25La0．75Ti3O12(BLT)纳米粉体。用DTA／TG和XRD研究了BLT前驱体的热行为和晶相转化过程，用场致发射扫描电子显微镜观察了BLT粉体的颗粒形貌和大小的变化。结果表明：共沉淀前驱体溶液的配制过程中，硝酸铋水解生成的硝酸氧铋不利于层状钙钛矿结构BLT相的合成。利用浓度较高的硝酸作溶剂，可以防止硝酸铋的水解，采用氨基共沉淀法直接合成出了单一相的BLT纳米粉体，在煅烧过程中，未出现Bi2Ti2O3焦绿石相。700℃煅烧2h合成的BLT粉体颗粒不大于100nm，颗粒间结合疏松，具有良好的分散性。     

多铁性铁酸铋陶瓷研究进展

自上个世纪六十年代发现铁酸铋(BiFeO3)钙钛矿具有铁电性以来,近些年借助于第一性原理计算,对其铁电性及磁性结构又有了新的认知,对多铁性的理解也进一步深化。不同于大多数BiFeO3研究所关注的薄膜和异质结构,本文从陶瓷的角度简要回顾了BiFeO3铁电性的发现历史,并从BiFeO3的晶体结构,Bi2O3-Fe2O3二元相图与BiFeO3陶瓷粉体、陶瓷的合成,BiFeO3陶瓷的磁电耦合及应用等多个面较为详细地阐述了BiFeO3陶瓷的最新研究进展;总结归纳了BiFeO3陶瓷研究中急需解决的科学问题和未来的一些发展趋势。     

Interaction Kinetics of Bismuth Borate Glasses and Orthophosphoric Acid

Glass and Ceramics - The interaction of orthophosphoric acid with the bismuth borate glasses having the compositions (weight content, %) 70Bi2O3 - 30B2O3, 70Bi2O3 - 27B2O3 - 3MoO3, 70Bi2O3 -...