ZrW2O8薄膜的制备及热膨胀性质

采用溶胶-凝胶技术结合退火工艺在Pt(111)/Ti/SiO2/Si(100)基片上制备ZrW2O8薄膜,并研究了退火温度、退火时间对薄膜的影响.利用X射线衍射(XRD)及扫描电镜(SEM)对薄膜的物相及表面形貌进行表征;利用变温XRD研究薄膜的热膨胀性能.薄膜的变温XRD结果表明,在室温～700℃温度范围内,随着温度的升高,(211)和(310)晶面间距变小,其热膨胀系数为负值,而(332)晶面间距随温度升高变大,显示出正膨胀性质.这表明ZrW2O8薄膜材料的热膨胀性能是各向异性的.     

退火温度对TiO2薄膜结构和光学性能的影响

为制备光学性能良好的TiO2薄膜.采用离子束溅射(IBS)的方法,改变退火温度,在Si基底上制备氧化钛(TiO2)薄膜.利用XRD、XPS、SEM测试薄膜的成分、结晶形式和表面形貌,椭圆偏振光谱仪分析薄膜折射率和消光系数.试验结果发现:随退火温度的增加,薄膜由锐钛矿相变为金红石相,400℃薄膜结晶为锐钛矿相TiO2,1 100℃退火后,薄膜结晶为金红石相TiO2;退火温度升高使薄膜折射率和消光系数随之升高.由此可得, 800℃退火时,TiO2薄膜具有最佳光学性能.     

Co-C纳米复合薄膜的微结构、磁性能和磁输运特性

采用磁控溅射法在硅基片上制备了Co原子分数为13.0%的Co-C纳米复合薄膜.在真空条件下,对薄膜进行退火处理,退火温度从473K逐步提高至773K,保温时间30min.形貌观察表明,未经退火处理的薄膜中,Co颗粒均匀分布在非晶C基体中,Co颗粒尺寸为1.5-3.0nm;673K退火后,Co颗粒尺寸增大.磁性能测试表明,未经退火处理的薄膜磁性较弱,随着退火温度升高,薄膜的磁化强度和矫顽力均明显增大;当退火温度增加至673—773K时,薄膜呈现出低温铁磁性、室温超顺磁性的典型颗粒体系磁性特征.磁输运特性研究表明,未经退火处理的薄膜在温度为4.2K,磁场为3980kA/m时表现出1.33%的负磁电阻,随着退火温度升高,样品磁电阻值下降;电阻与温度关系在4.2—60K范围内符合lnR-T~(-1/4)线性关系,磁输运遵循变程跳跃(variable range hopping)传导机制.     

退火温度和匀胶速率对SrBi_(3.88)Nd_(0.12)Ti_4O_(15)薄膜铁电性能的影响

用溶胶-凝胶法在Pt/Ti/ SiO_2/ Si基片上制备了SrBi_3.88 Nd_0.12 Ti_4O_(15)铁电薄膜材料,研究了退火温度和匀胶速率对铁电薄膜材料结构、铁电性能的影响.退火温度为750 ℃、匀胶速率为3000 r/min薄膜样品为纯的铋层状钙钛矿结构且没有其它杂相出现,a轴取向的晶粒较多,铁电性能较好,剩余极化强度和矫顽场分别为2P_r=26.7 μC/cm~2、2E_c=80 kV/cm.     

直流溅射沉积纳米晶氧化镍薄膜及电化学性能

采用直流溅射并结合热处理工艺制备氧化镍薄膜,利用X射线衍射仪(XRD)、扫描电镜(SEM)、能谱仪(EDX)考察退火温度对薄膜结构、形貌和组成的影响,并通过恒流充放电技术初步考察薄膜的电化学性能.结果表明,在400～500 ℃退火温度下制备了表面光滑、结构致密的NiO薄膜;随着退火温度的升高,薄膜的晶粒尺寸逐渐增大,晶形趋于完整;其中,500 ℃下退火2 h获得的NiO薄膜具有良好的电化学循环稳定性,有望成为高性能的全固态薄膜锂电池阳极材料.     

退火对氧化钒薄膜成分及热敏性能的影响

在衬底上溅射沉积一层金属钒膜,然后对其退火制备氧化钒薄膜.研究了原位退火热处理和后续退火热处理对氧化钒薄膜成分及其热敏性能的影响.XPS分析表明,原位380 ℃退火处理得到的氧化钒薄膜中4价态和5价态钒的比例为1.097:1,经后续退火处理后,该比例变为0.53:1;同时,原位退火处理得到的氧化钒薄膜的V/O比为1:2.24,经后续退火处理变为1:2.33.AFM分析后显示,经后续退火处理的薄膜晶粒尺寸有所增大.测试了薄膜方阻随温度的变化,结果显示,生成的薄膜具有明显的金属-半导体相变;原位退火热处理后的薄膜方阻(R)为5.46 kΩ/□(25 ℃),方阻温度系数(TRC)为-1.5%/℃(25 ℃);后续退火热处理后,薄膜方阻增大到231 kΩ/□(25 ℃),方阻温度系数升高为-2.74%/℃(25 ℃).此外,就氧化钒薄膜的成分、热敏性能与退火处理之间的关系进行了讨论.     

钛酸铋薄膜的磁控溅射及其退火处理

采用射频磁控溅射技术,在Pt/Ti/SiO2/Si衬底上制备了钛酸铋(Bi4Ti3O12,简称BIT)薄膜。研究了衬底温度及后续退火处理对薄膜结构和表面形貌的影响。结果表明:适宜的衬底温度为200℃。随着退火温度(650~800℃)的升高,BIT薄膜的结晶性变好,晶粒尺寸增大,c轴取向增强。当退火温度达到850℃时,开始出现焦绿石相;700~800℃为适宜的退火温度,在此条件下得到的BIT薄膜结晶良好,尺寸均匀,表面平整致密。     

氧化铱薄膜的制备及其导电机理研究

采用脉冲激光沉积技术在Si(100)衬底上制备了高导电的IrO2薄膜,重点研究了退火前后其电学性能和微观结构的变化规律。采用X射线衍射(XRD)、原子力显微镜(AFM)、光电子能谱(XPS)和四探针法对退火前后IrO2薄膜的结构和电性能进行了表征,并利用霍尔效应研究了IrO2薄膜的导电机理。结果表明:IrO2薄膜在空气中退火后,导电性能得到提高,其中在750℃退火的电阻率达到最小值37μΩ.cm。在25～500℃范围内,IrO2薄膜的高温电阻率随着温度的升高呈线性关系逐渐增大,呈现出类似金属的导电特征。在250～400℃沉积的IrO2薄膜载流子的类型为p型;沉积温度较高(500℃)或在更高温度退火处理后,IrO2薄膜载流子的类型为n型,其导电机理以电子导电为主。     

退火处理对室温制备Bi0.5Sb1.5Te3薄膜热电性质的影响

利用射频磁控溅镀法在SiO2/Si基板上制备了Bi0.5Sb1.5Te3薄膜样品,并且测量了薄膜样品在不同退火时间与退火温度下的热电性质。结果表明,薄膜样品经30 h退火后的热电性质与1 h退火后的热电性质相差不大,这说明长时间退火并不是Bi0.5Sb1.5Te3薄膜的最佳退火时间。而在不同退火温度下,样品的塞贝克系数在275～300℃退火下降比较快,当退火温度为300℃时降至最小,约为181μV/K;而其电阻率则随退火温度的升高呈现出先减小后增大的趋势,退火温度为225℃时具有最小的电阻率,约为6.1 mΩ.cm。最后本文得出经225℃退火10 min后可得到最佳的热电性质,即薄膜样品的塞贝克系数为208μV/K,电阻率为6.1mΩ.cm,功率因子则为6.9×10-4W/(m.K2)。     

TiO2薄膜在玻璃材料上的亲水性研究

用真空蒸镀法在玻璃基片上制备TiO2薄膜,分别在300、400、500、600℃下退火.用紫外-可见吸收光谱、X射线衍射(XRD)、扫描电镜(SEM)、接触角测定等分析方法研究蒸镀时间、退火温度和退火时间对薄膜亲水性的影响,找出真空蒸镀法制备亲水性TiO2薄膜的最佳工艺条件.结果表明:经紫外光照射1h后,所有TiO2薄膜都能被水润湿,在蒸镀时间为45s,退火温度为500℃,退火时间为2h条件下制得的薄膜样品亲水性能最佳.     

Effect of annealing on the structural properties of AlN thin films containing Co particles

This paper describes a new approach for preparing AlN thin films containing various Co contents by using a two-facing targets type sputtering system. The as-deposited films exhibited a variable nature expected from the AlN-rich phase, as well as an amorphous-like phase, depending on the Co content in the films. The films were annealed isothermally at different temperatures and their microstructure, magnetic properties and resistivity were examined. The saturation magnetization of the as-deposited films was quite small and almost constant, irrespective of the Co content in the films, because Co was not in the crystalline state. At elevated annealing temperatures, the as-deposited AlN-Co amorphous films crystallized into two phases of AlN and Co. The saturation magnetization and resistivity of the films increased with increasing annealing time and temperature. The coercivity of the films was independent of the annealing time, but it increased with increasing annealing temperature due to the increase in grain size. A saturation magnetization, coercivity and resistivity of 360 emu/cm³, ～25 Oe and 2200 μΩ-cm, respectively, were obtained. Further improvement in the soft magnetic properties might lead to this material being applied as a high density magnetic recording head material.     

Study of microstructure and magnetic properties of electrodeposited nanocrystalline CoFeNiCu thin films

In this study the nanocrystalline CoFeNiCu thin films were electrodeposited from baths containing sodium citrate as a complexing agent and pH of around 5. Electrodeposition conditions were changed in order to achieve optimum soft magnetic properties which are required for new generation magnetic head core. SEM, EDS, XRD and VSM were used for characterization of the deposited films. The SEM micrographs of the deposited films exhibited no micro-voids and more uniform surface morphology compared with films electroplated from conventional baths (with low pH and no additives). According to X-ray diffraction patterns, the films electroplated at current densities lower than 4 mA/cm² showed FCC (Cu) phase structure, and other films exhibited BCC (Fe) and/or FCC (Co) phases. Calculating grain size of the films by using Scherrer equation showed that all the coatings were nanocrystalline and double phase films had lower average grain size in comparison with single phase films. The VSM results demonstrated that the coercivity of the nanocrystalline films dramatically reduced with decreasing grain size and followed D⁶ law. However, grain size had no effect on the saturation magnetization, whereas the chemical composition significantly affected saturation magnetization of the films. The results also indicated that in order to obtain films with low coercivity and high saturation magnetization, the nickel and copper contents of the deposits must not exceed 12 and 5 at.%, respectively.     

纳米晶(FeCo)78Nb6B15Cu1合金晶化过程及其磁特性研究

采用熔体快淬法制备(FeCo)78Nb6B15Cu1非晶薄带,通过DSC测试薄带的晶化特性,并据此在400,500,700和750℃进行1h退火处理。用XRD和SEM分析薄带在不同退火温度下的晶化行为,并用VSM测试薄带与粉体的静态磁参数。结果表明:对于固定成分的Hitperm合金,选择合适的退火温度,可控制晶粒大小和晶相比例。由于晶粒表面无序磁矩含量的变化,导致材料比饱和磁化强度发生变化,同时更小的纳米晶粒对降低矫顽力有利。由于淬态引入的微量结晶,薄带存在表面晶化现象,这在一定程度上会恶化材料的静态磁特性。     

Nd56Fe30Al10Dy4大块非晶合金晶化过程中磁性及微观结构的研究

采用铜模吸铸法制备Nd56Fe30Al10Dy4大块非晶合金,利用差示扫描量热仪(DSC)、振动样品磁强计(VSM)、X射线衍射仪(XRD)和扫描电镜(SEM)研究了该合金晶化过程中磁性及微观结构的变化。结果表明,铸态下合金表现为明显的硬磁性,在765 K退火后,合金中有少量晶态相产生,内禀矫顽力和饱和磁化强度略有下降。随着退火温度升高,合金中晶态相的相对含量逐渐增加,非晶相的相对含量逐渐减少,饱和磁化强度逐渐降低,但其内禀矫顽力变化不大。810 K退火后,合金完全晶化,铁磁性消失。结合合金的磁性能、微观结构、铁磁交换耦合作用的结果分析,Nd基大块非晶合金的矫顽力来源于合金中非晶相,但非晶相的相对含量却对矫顽力影响不大,这可以用强钉扎机制进行解释。     

退火温度对非晶合金Fe69Al5Ga2P9.65B4.6Si3C6.75磁性能的影响

通过7种不同的温度对非晶合金Fe69 Al5 Ga2 P9.6s B4.6Si3 C6.75进行了退火处理,以研究退火温度对合金磁性能的影响.试验磁性能数据表明,合金的饱和磁化强度随退火温度的升高先增加后急剧减小,在450℃时的值最大,M.为628.76emu/g;而矫顽力曲线和剩磁比曲线的走势相近,且在490℃附近的值较小,其软磁性能较好.试验证明,合金的最大饱和磁化强度的退火温度与软磁性能最佳的退火温度不是同一温度值,其综合磁性能的退火温度应选择450～490℃之间的值.     

Effect of annealing temperature on structure and electrochemical properties of LiCoO2 cathode thin films

LiCoO2 thin films, which can be used as a cathode material in microbatteries, were deposited using radio frequency (r.f.) magnetron sputtering system from a LiCoO2 target and in an O2+Ar atmosphere.The films were characterized by various methods such as XRD, SEM and AFM.The LiCoO2 films were annealed in air at 300, 500, 700 and 800 ℃ respectively.The effect of the annealing temperature on the structure, the surface morphology and the electrochemical properties of the films were investigated.The LiCoO2 thin film deposited at room temperature is amorphous and has smaller grain size.With increasing of annealing temperature, the crystallinity of the films is promoted.When the annealing temperature increases to 700 ℃, the films have a perfect crystalline LiCoO2 phase.The LiCoO2 thin film without annealing has no discharge plateau and small discharge capacity (about 27 μAh·cm-2μm).The discharge capacity increases with the increasing of annealing temperature and reaches 47 μAh·cm-2μm for the film annealed with 700 ℃, which also shows the typical discharge plateau of 3.9 V.The cycle performance of LiCoO2 thin films of as grown and annealed at different temperatures were studied.In the case of the film without thermal treatment, the capacity fading is much faster than that of the film annealed at different temperature, showing about 40% capacity loss only after 25 cycles.However, in the case of the film annealed at 700 ℃, the capacity reaches to steady state gradually and maintained constantly with cycling.After 25 times cycling, the discharge capacity of the film annealed at 700 ℃ decreases to about 36.9 μAh·cm-2·μm, only 0.8% capacity loss per cycle.     

PREPARATION OF Fe/Ni MULTILAYER FILMS AND THEIR MAGNETIC PROPERTIES

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Effect of magnetic fields on pulse plating of cobalt films

Magnetic fields parallel to the electrodes were introduced during a pulse plating process to obtain cobalt thin films from alkaline baths. Ef-fects of different magnetic intensities on the composition, microstructure, and magnetic properties of cobalt thin films were investigated. It was found that the deposition speed increased gradually with the increase of magnetic intensity. Almost all of the deposited films were crys-talline and showed Co(002), Co(100) peaks. With the rise on the magnetic intensity, the intensity of Co (002) peak raised gradually. Mag-netic fields would induce cobalt growing along (002) orientation. The films were densely covered with typical nodular structure. Films of smaller grain size and smooth surface could be formed under high magnetic intensity (1 T) as a result of magnetic force and MHD effects. Moreover, higher magnetic intensity induced larger saturation magnetization and lower coercivity. With the rise on magnetic intensity, cobalt contents in the films increased gradually, which led to the rise of saturation magnetization.     

Magnetic properties of cobalt ferrite/SiO2 nanocomposite

Nanocrystalline cobalt ferrite dispersed in silica was prepared by mechanical alloying and subsequent heat-treatment. For Co-ferrite with 15 wt% silica, a high coercivity of up to 3.3 kOe and a magnetization of 68 emu/g were obtained after an optimized heat treatment (in air at 900°C). Experiments were conducted to study the optimum amount of silica required to obtain optimum magnetic properties. It was found that a small amount of 4.5 wt% silica (SiO₂) allows the composite to possess good magnetic properties (coercivity of 3 kOe and saturation magnetization of 72 emu/g).     

热处理对FeCuNbSiB单层膜磁性能的影响

本文研究了热处理对FeCuNbSiB薄膜结构及磁性能的影响。XRD分析表明制备态的FeCuNbSiB为非晶态,并且在300℃热处理仍然保持非晶态。300℃热处理后,薄膜释放应力,软磁性能有所提高。热处理温度进一步升高,薄膜由非晶态转化为纳米晶,矫顽力及饱和磁化场明显增加,磁矩向垂直膜面方向转动,软磁性能下降。