Synthesis and Electrical Characterization of BaTiO3 Thin Films on Si(100)

BaTiO3 thin film has been deposited on Si(100) substrate using sol-gel process and deposited by using spin – coating technique. The BaTiO3/Si(100) structures were studied by structural and electrical characteristics. The X-ray diffrac-tion of BaTiO3/Si(100) shows that the diffraction peaks become increasing sharp with increasing calcination tempera-tures indicating the enhance crystallinity of the films. Scanning electron microscopy of BaTiO3 thin films shows the crack free and uniform nature. The capacitance-voltage measurement of BaTiO3 thin film deposited on Si(100) an-nealed at 600℃ shows large frequency dispersion in the accumulation region. The current-voltage measurement of BaTiO3/Si shows the ideality factor was approaches to unity at 600℃.

自支撑BaTiO_(3)薄膜的制备与铁电性研究

BaTiO_(3)(BTO)铁电氧化物薄膜因其在非易失信息存储、智能传感、生物医疗、纳米发电机等领域潜在的应用而受到了人们的广泛关注。目前,为了保证BTO薄膜能高质量外延生长,通常选择晶格匹配的氧化物做衬底,所生长的薄膜与衬底之间存在较强的化学键,很难将其从衬底上大面积地剥离下来,所以也无法实现下一步转移到可用于高密度器件集成的的Si基衬底上。文章使用水溶Sr_(3)Al_(2)O_(6)(SAO)为牺牲层的方法,将生长在Nb-SrTiO_(3)(Nb-STO)衬底上的BTO外延薄膜可以大面积、无褶皱地转移到Si基衬底上。并且,转移后的自支撑薄膜仍然保持了完美的结晶度和室温铁电性。此结论对自支撑氧化物薄膜在高密度铁电器件的集成方面奠定了一定的基础。

P(VDF-CTFE)/DA@BTO层叠式结构复合薄膜的介电与储能特性研究

聚偏氟乙烯(PVDF)基聚合物在高储能密度、高脉冲储能领域具有广泛的应用前景。本文采用钛酸钡(BTO)纳米颗粒掺杂聚偏氟乙烯-三氟氯乙烯(P(VDF-CTFE))溶液,采用流延法制备P(VDF-CTFE)/BTO复合薄膜,探讨了不同BTO掺杂含量对复合薄膜微观结构、介电性能、储能特性的影响;采用多巴胺(DA)改性BTO以提升BTO与聚合物基体的相容性,改善复合薄膜的介电常数和电气强度;同时利用薄膜层间“击穿阻碍效应”制备层叠式结构复合薄膜以提升薄膜的储能特性。结果表明:使用DA改性BTO质量分数为10%的P(VDF-CTFE)/DA@BTO复合薄膜作为中间层、P(VDF-CTFE)作为外层制备的PV-BT-PV层叠式三明治结构复合薄膜,介电常数达到10.44,最大电气强度为362.25kV/mm,在500kV/cm电场强度下的充放电效率达到86.63%。

Co/BaTiO3纳米复合薄膜的PLD法制备及其Raman光谱

采用脉冲激光气相沉积(PLD)技术在MgO(100)衬底上生长了Co/BaTiO3纳米复合薄膜,利用原子力显微镜、透射电镜、X射线衍射(XRD)及Raman光谱等测试分析手段对Co/BaTiO3纳米复合薄膜进行测试分析。结果表明:薄膜表面均匀、致密,具有原子尺度的光滑性;Co纳米晶粒呈单分散、均匀分散在沿C轴呈单取向生长的BaTiO3单晶基体中;随着掺杂Co含量的增高,BaTiO3的Raman峰的峰强随之增大。

Effect of Er substituting sites on upconversion luminescence of Er^(3+)-doped BaTiO_3 films

Erbium-doped BaTiO3 films on LaNiO3/Si substrates were fabricated by sol-gel method. The crystalline structure, morphologies and upconversion （UC） luminescence properties of films were respectively investigated by X-ray diffraction （XRD）, atomic force microcopy （AFM） and photoluminescence （PL）. The results indicate that both of the microstructure and luminescence are found to be dependent on Er^3＋ substituting sites. The samples with A-site substitution have smaller lattice constants, larger grains and smoother surface than those with B-site substitution. The photoluminescence spectra show that both of the samples have two stronger green emission bands centered at 528 and 548 nm and a weak red emission band centered at 673 nm, which correspond to the relaxation of Er^3＋ from ^2H11/2, ^4S3/2, and ^4F9/2 levels to the ground level ^4I15/2, respectively. Compared with B-site doped films, A-site doped films have a stronger integrated intensity of green emissions and a weaker relative intensity of red emissions. The differences could be explained by the crystalline quality and cross relaxation （CR） process.

N719染料敏化BaTiO3@TiO2纳米复合电极的制备及性能研究

BaTiO3是非常常见的铁电材料,经常用于制备铁电光伏器件或与半导体器件相结合来优化光伏器件的光电性能。采用水热法合成了BaTiO3纳米颗粒,并在FTO玻璃上制备了BaTiO3纳米晶薄膜,通过TiCl4水溶液后处理的方法在BaTiO3纳米薄膜上形成不同厚度的TiO2层,利用XRD、SEM和TEM分别对BaTiO3@TiO2纳米复合薄膜的物相和形貌进行了表征。将此电极经N719染料敏化后作为染料敏化太阳能电池的光阳极,并进行了光电性能测试。研究结果表明,水热法制备的BaTiO3薄膜晶型为四方相,呈球形多孔,平均粒径约50 nm;经过TiCl4后处理,在BaTiO3薄膜表面形成了锐钛矿相的TiO2颗粒。180℃下水热合成的BaTiO3纳米颗粒经过4次TiCl4后处理制备成的染料敏化太阳能电池取得了最优性能,其光电流密度9.78 mA cm-2,开路电压765 mV,填充因子76.1%和光电转换效率5.69%。

Structural characteristics of BaTiO_3 films prepared by microarc oxidation

BaTiO3 ferroelectric films were prepared on titanium substrate by microarc oxidation(MAO) technology. The effects of current density and electrolytic concentration on chemical composition, crystal phase, and surface morphologies of the films were characterized by XRD, SEM and EDS. The results show that the films made by MAO technology have a two layer structure with a good combinability between them and with the substrate. The inner layer is composed of Ti oxide without Ba, and the outer layer is mainly composed of BaTiO3 and Ti oxide. The compactability of the films decreases and the surface roughness of the films increases with the increase of current density and electrolytic concentration. Films with a high content of primitive tetragonal and end-centered orthorhombic BaTiO3 are obtained in 0.2 mol/LBa(OH)2 solution with current density of 5A/cm2 after 18 min.

微通道连续沉淀法制备球形BaTiO3颗粒及其在医学检测干片上的应用

以BaCl2、TiCl4、NaOH为原料,采用微通道连续沉淀法制备纳米级球形形貌的BaTiO3颗粒。考察了钡浓度、体积流量、反应温度及两分支物料流量比等因素对产物形貌及粒径大小的影响,并将其与间歇沉淀法得到的产物进行了比较。实验结果表明:钡浓度0.15 mol/L,碱浓度3 mol/L,两分支物料体积流量均为2 ml/min,反应温度90℃条件下可制备得到具有规整球形形貌、粒径分布均匀的纳米级BaTiO3颗粒,其粒径为80~150 nm。最后,将所得BaTiO3扩散层应用到肌酸激酶干片中,重复性较好,且浓度梯度明显,光反射率值与浓度的关系与之对应。结果具有较高的可信度,说明微通道连续沉淀法得到的BaTiO3颗粒在医用干片上应用是可行的。

Synthesis and Electrochemical Properties of Transparent Nanostructured BaTiO₃Film Electrodes

Transparent nanostructured BaTiO3 film electrodes were synthesized on conductive substrates from BaTiO3 nanocrystals forming at low temperature. Electrochemical and spectroelectrochemical methods were employed to investigate its properties of band energetics and the trap state at different pH values. The flat band edges greatly depended on the pH value of electrolyte, and the flat band edges were -0.70, -0.92 and -1.20 V vs saturated Ag/AgCl at the pH value of 3.0, 6.8 and 13.0, respectively. The results showed that trap state densities also highly depended on pH. The total trap state densities were 3.73 × 1015, 4.02 × 1015 and 6.48 × 1016 cm-2 at pH value of 3.0, 6.8 and 13.0 respectively with maximum located at -0.36 V, -0.50 V and -0.80 V. The results obtained from CVs were in good agreement with that obtained from the measurements of time resolved currents. The size of the peak potentials in the cyclic voltammograms experiments was increased dramatically with the pH value increasing, indicating that traps were surface-related.

Li2TiO3/BaTiO3纳米复合薄膜的制备

目的分析钛酸钡(BaTiO3,BT)作为压电薄膜材料的优缺点及其改进方法,研究Li2TiO3/BaTiO3纳米复合薄膜的制备工艺,并为后期探索其介电、铁电性能做好基础性工作。方法以层状钛酸H1.07Ti1.73O4晶体和Ba(OH)2为原料,采用溶剂热法制备BT粉体。再分别以钛酸锂(Li2TiO3,LT)晶体和BT晶体作为基料和反应模板,采用水系流延法制备Li2TiO3/BaTiO3纳米复合薄膜(LT/BT)。探索混合时间和添加剂比例对制备薄膜的影响。结果当固相粉体的质量含量为55%,分散剂(PVP)、粘结剂(苯丙乳胶)以及增塑剂(丙三醇)的含量分别占添加剂总质量的5.5%,11%和5.5%,并将球磨时间控制在24 h时,可制备得到较稳定的基体浆料。所得基体浆料经流延成型后可得到LT/BT纳米复合薄膜。结论调控基体浆料的制备方法和添加剂组分,可制备得到表面平整光滑、质地均匀、塑性和延展性良好且不易开裂的LT/BT纳米复合薄膜。

Kinetic Monte Carlo simulation of growth of BaTiO_3 thin film via pulsed laser deposition

Considering the characteristics of perovskite structure, a kinetic Monte Carlo(KMC) model, in which Born-Mayer- Huggins(BMH) potential was introduced to calculate the interatomic interactions and the bonding ratio was defined to reflect the crystallinity, was developed to simulate the growth of BaTiO3 thin film via pulsed laser deposition(PLD). Not only the atoms deposition and adatoms diffusion, but also the bonding of adatoms were considered distinguishing with the traditional algorithm. The effects of substrate temperature, laser pulse repetition rate and incident kinetic energy on BaTiO3 thin film growth were investigated at submonolayer regime. The results show that the island density decreases and the bonding ratio increases with the increase of substrate temperature from 700 to 850 K. With the laser pulse repetition rate increasing, the island density decreases while the bonding ratio increases. With the incident kinetic energy increasing, the island density decreases except 6.2 eV<Ek<9.6 eV, and the bonding ratio increases at Ek<9.6 eV. The simulation results were discussed compared with the previous experimental results.

Strongly enhanced flux pinning in the YBa_2Cu_3O_(7-X) films with the co-doping of Ba TiO_3 nanorod and Y_2O_3 nanoparticles at 65 K

YBa2Cu3O7-x（YBCO） films with co-doping BaTiO3（BTO） and Y2O3 nanostructures were prepared by metal organic deposition using trifluoroacetates（TFA-MOD）. The properties of the BTO/Y2O3co-doped YBCO films with different excess yttrium have been systematically studied by x-ray diffraction（XRD）, Raman spectra, and scanning electron microscope（SEM）. The optimized content of yttrium excess in the BTO/Y2O3co-doped YBCO films is 10 mol.%, and the critical current density is as high as - 17 mA/cm^2（self-field, 65 K） by the magnetic signal. In addition, the Y2Cu2O5 was formed when the content of yttrium excess increases to 24 mol.%, which may result in the deterioration of the superconducting properties and the microstructure. The unique combination of the different types of nanostructures of BTO and Y2O3 in the doped YBCO films, compared with the pure YBCO films and BTO doped YBCO films, enhances the critical current density（JC） not only at the self-magnetic field, but also in the applied magnetic field.

Fabrication and optical properties of InGaN/GaN multiple quantum well light emitting diodes with amorphous BaTiO_3 ferroelectric film

BaTiO3 （BTO） ferroelectric thin films are prepared by the sol,el method. The fabrication and the optical properties of an InGaN/GaN multiple quantum well light emitting diode （LED） with amorphous BTO ferroelectric thin film are studied. The photolumineseence （PL） of the BTO ferroelectric film is attributed to the structure. The ferroeleetric film which annealed at 673 K for 8 h has the better PL property. The peak width is about 30 nm from 580 nm to 610 nm, towards the yellow region. The mixed electroluminescence （EL） spectrum of InGaN/GaN multiple quantum well LED with 150-nm thick amorphous BTO ferroelectric thin film displays the blue-white light. The Commission Internationale De L＇Eclairage （CIE） coordinate of EL is （0.2139, 0.1627）. EL wavelength and intensity depends on the composition, microstructure and thickness of the ferroelectric thin film. The transmittance of amorphous BTO thin film is about 93% at a wavelength of 450 nm-470 nm. This means the amorphous ferroelectrie thin films can output more blue-ray and emission lights. In addition, the amorphous ferroelectric thin films can be directly fabricated without a binder and used at higher temperatures （200 ℃-400 ℃）. It is very favourable to simplify the preparation process and reduce the heat dissipation requirements of an LED. This provides a new way to study LEDs.

四方相BaTiO_3薄膜的自组装制备与表征

以(NH4)2TiF6、Ba(NO3)2和H3BO3为主要原料,采用自组装单层膜(SAMs)技术,以三氯十八烷基硅烷(octadecyl-trichloro-silane,OTS)为模版,在玻璃基片上制备了四方相钛酸钡晶态薄膜.改性基板的亲水性测定与原子力显微镜(AFM)测试表明,紫外光照射使基板由疏水转变为亲水,能够对OTS-SAM起到修饰作用.金相显微镜观察结果显示,OTS单分子膜指导沉积的薄膜样品表面均匀,表明OTS-SAM对钛酸钡薄膜的沉积具有诱导作用;X射线衍射(XRD)与扫描电镜(SEM)表征显示,空气中600℃下保温2h实现了薄膜由非晶态向四方相BaTiO3晶态薄膜的转化过程,制备的钛酸钡薄膜在基板表面呈纳米线状生长,线长约在500～1000nm之间,相互连接的晶粒大小约为100nm.文章同时对自组装单层膜和钛酸钡薄膜的形成机理进行了探讨.

锶掺杂对BaTiO_3薄膜粒径与结晶温度的影响

采用溶胶-凝胶法制备了钛酸钡和掺锶钛酸钡薄膜,结合DTA-TGA,XRD和SPM等分析手段,重点考察了锶掺杂对薄膜的结晶温度、粒径和晶胞参数的影响,发现随着锶含量的增加,Ba1-xSrxTiO3薄膜中晶体的晶胞参数逐渐减小,且锶的掺入可降低薄膜的结晶温度、减小粒径和粗糙度.

梯度应变对钛酸钡薄膜介电行为的影响

考虑膜中应变随位置的变化,应用Pertsev热力学理论,研究了BaTiO3薄膜介电常数随温度的变化。发现衬底与膜间热膨胀系数差和膜的沉积温度显著影响介电常数的值及其峰值温度,介电常数随沉积温度的降低而增大,计算结果与实验数据较好地吻合。

BaTiO_3超薄膜的制备和性能研究

用LB(Langmuir Blodgett)膜技术制备的BaTiO3超微粒-硬脂酸复合LB膜,热处理后形成BaTiO3超薄膜.用紫外-可见光吸收光谱、电子自旋共振、红外光谱和X射线衍射对BaTiO3超薄膜进行研究.BaTiO3超薄膜在190～287nm范围内具有明显的吸收,而在299 nm附近有强烈的吸收;超薄膜中的BaTiO3微粒存在氧空位,分子内部结构和晶体结构都发生了明显的变化.

利用微弧氧化法制备四方相BaTiO_3薄膜的结构特征及铁电性能

利用微弧氧化技术在钛衬底上直接制备了四方相钛酸钡铁电薄膜。利用X射线（XRD）、HP4192A阻抗分析仪和铁电测试系统（FTS）等手段对薄膜样品的相结构、介电和铁电性能进行了研究。结果表明,工艺参数为Ba（OH）2浓度为0.5mol/L,电流密度为150mA/cm^2,温度为57℃,反应时间5-20min的薄膜主要要由四方相BaTiO3构成。在微弧氧化过程中,弧点的连续移动是形成四方相BaTiO3的主要原因。此工艺参数下薄膜的剩余极化值为0.271和-4.62μC/cm^2（Pr）,与其对应的矫顽场强度分别为20和-2.8kV/cm（Ec）。该薄膜具有良好的铁电性能。

BaTiO_3铁电薄膜的光致发光研究

以分析纯的乙酸钡和钛酸正四丁酯为前躯体溶液,冰乙酸为溶剂,乙酰丙酮为稳定剂,采用溶胶-凝胶法在硅基上制备了钛酸钡(BaTiO3)铁电薄膜。研究了BaTiO3铁电薄膜的光致发光性能。结果表明,室温下非晶态的BaTiO3铁电薄膜在蓝光激发下具有很强的光致发光现象。其中,经8h 673K退火处理的非晶BaTiO3铁电薄膜的光致发光性能最佳,当455nm光激发时,非晶薄膜在540～660nm内发出强烈的黄光,峰值波长为580～610nm,峰宽约30nm,发光强度随薄膜的厚度增加而增强。晶态BaTiO3铁电薄膜无任何发光现象。

纳米钛酸钡掺杂聚酰亚胺基高介电复合薄膜的制备及性能

采用原位聚合法和高速砂磨法制备了纳米钛酸钡/聚酰亚胺高介电常数复合薄膜,分析了不同制备方法及钛酸钡粉体用量对复合薄膜结构和性能的影响。实验结果表明,高速砂磨法对于纳米钛酸钡粉体的分散效果优于原位分散法;钛酸钡粉体的引入,有效提高了复合薄膜的热稳定性和介电性能。当粉体的体积分数达到50%时,复合薄膜介电常数相较于纯膜提高了10倍,而介电损耗只有少量增加。