Crystallization and Microstructure of (Sm, Pb)TiO3 Thin Films Prepared from Sol-Gel Synthesized Solutions

A sol-gel route is developed for the synthesis of samarium modified lead titanate precursor solutions. The solutions are used for the deposition of thin films. After thermal treatment of the films, two crystalline phases are observed by X-ray diffraction analysis: an undesirable pyrochlore phase and a ferroelectric perovskite. These two phases are clearly distinguished in the film microstructure, showing a fined grained fraction of pyrochlore anda-axis oriented rosette grains of perovskite. The development of these phases as well as the evolution of the perovskite/pyrochlore ratio in the films is related to the chemistry of the synthesized solutions and the thermal treatment used for crystallization.     

Chemical Solution Deposition of ZnO Thin Films by an Aqueous Solution Gel Precursor Route

An aqueous chemical solution deposition method was used to prepare thin films of ZnO on SiO₂/Si (1 1 1) substrates. Starting from an aqueous solution of Zn acetate, citric acid and ammonia, very thin films could be deposited by spin coating. Heating parameters, necessary for thin film annealing, were determined using FTIR experiments on dried gel precursors, heated up to different temperatures. The morphology and the thickness of the films were investigated by SEM. It is found that homogeneous thin films with grain sizes of about 20 nm are formed. XRD experiments show that there is an indication that the films, crystallized at 500°C, exhibit preferential grain growth along the c-axis.     

Multielement XRF Semimicroanalysis of Pb(Zr,Ti)O3 Type Ferroelectric Ceramic Materials Doped with Pb(Nb,Mn)O3 and Bi2O3 by the Thin Layer Method

A method of wavelength-dispersive XRF analysis of Pb(Zr,Ti)O₃ type ferroelectric ceramics doped with Pb(Nb,Mn)O₃ and Bi₂O₃ is presented. The major elements Pb, Zr, Ti and minor elements Nb, Mn, Bi were determined. Matrix effects were minimized by using the thin layer method. Standards of the same chemical composition but varied masses were prepared to simplify calibration. To minimize errors resulting from inhomogeneity of a mass per unit area, the internal standard was used. Preparation of the sample consisted in digesting 25mg of the materials (with nickel as the internal standard) in sulfuric acid, evaporating to dryness and digesting in nitric acid and hydrogen peroxide, filling up to 25mL, and dropping 0.5mL of the solution onto a substrate. Standard samples were prepared by dropping different amounts of the multielement solution onto the substrate. The residual standard deviation for the reference sample of mass from 0.25mg to 0.7mg was within the range of 0.001–0.009mg (correlation coefficient 0.998–0.999) for major elements and within the range of 0.00003–0.0009mg (correlation coefficient 0.989–0.993) for minor elements. The detection limits for 0.5mg samples were within the range of 0.015%–0.35% for manganese and zirconium, respectively.     

化学浴沉积cawo4薄膜的动力学

对化学浴沉积法制备的CaWO4薄膜进行了动力学研究。采用Avrami-Erofeev方程进行计算,得到反应温度40~80℃和反应溶液pH值为8~12条件下,CaWO4薄膜的动力学方程。结合实验分析各动力学参数的变化,发现反应温度越高,反应速率常数k越大,薄膜趋向于自发形核生长;反应溶液pH值越高,反应速率常数k显著减小,Avrami指数n则几乎不变。结果可见,pH值对反应速率的影响大,而对成核和生长方式影响小。pH值对反应速率的影响主要在于改变了Ca-EDTA螯合体的络合稳定性,进而影响整个反应的进行速度。通过动力学研究可以明确反映反应参数对薄膜生长的影响,体现了薄膜生长过程的本质,有助于达到有效控制反应过程的目的。     

化学溶液沉积法制备单分散氧化锌纳米棒阵列

在由溶胶凝胶法制备的纳米ZnO薄膜基底上, 采用化学溶液沉积法制备了单分散、高度取向的ZnO纳米棒阵列膜. 通过控制纳米ZnO薄膜的制备工艺, 可以调节氧化锌纳米棒的直径. 利用FESEM, TEM, HRTEM, SAED和XRD表征了氧化锌纳米棒阵列的形貌和晶体结构. ZnO纳米棒的室温PL谱具有很高的紫外带边发射峰, 在可见光波段无发射峰, 表明该方法制备的ZnO纳米棒晶体结构完整, 晶体中O空位的浓度很低.     

液相沉积法制备光催化活性TiO2薄膜和纳米粉体

采用液相沉积法 ,在 3 5℃通过向六氟钛酸铵水溶液中添加硼酸和结晶诱导剂锐钛矿型TiO2 纳米晶 ,沉积出具有光催化活性的TiO2 薄膜和纳米粉体 .用XRD ,AFM ,阶梯仪 ,UV vis ,BET法对TiO2 薄膜和粉体的沉积条件、结构、厚度和性能进行了测定和表征 ,并用亚甲兰的降解 ,评价了TiO2 薄膜和纳米粉体的光催化活性 .结果表明 ,当反应物六氟钛酸铵与硼酸的摩尔比为 1∶2～ 1∶4时 ,沉积的粉体和薄膜含有锐钛矿相TiO2 ;经 3 0 0℃热处理的TiO2 薄膜和纳米粉体具有最高的光催化活性 ,它的光催化活性是未经热处理前的 5倍 .本文还解释了经 3 0 0℃热处理的薄膜和纳米粉体具有最高光催化活性的原因     

Synthesis,Ferroelectric and Optical Properties of (Pb,Ca)TiO3 Thin Films by Soft Solution Processing

Calcium modified lead titanate sol was synthesized using a soft solution processing, the so-called polymeric precursor method. In soft chemistry method, soluble precursors such as lead acetate trihydrate, calcium carbonate and titanium isopropoxide, as starting materials, were mixed in aqueous solution. Pb_0.7Ca_0.3TiO₃ thin films were deposited on platinum-coated silicon and quartz substrates by means of the spinning technique. The surface morphology and crystal structure, dielectric and optical properties of the thin films were investigated. The electrical measurements were conducted on metal-ferroelectric-metal (MFM) capacitors. The typical measured small signal dielectric constant and dissipation factor at a frequency of 100 kHz were 299 and 0.065, respectively, for a thin film with 230 nm thickness annealed at 600°C for 2 h. The remanent polarization (2P_r) and coercive field (E _c) were 32 C/cm² and 100 kV/cm, respectively. Transmission spectra were recorded and from them, refractive index, extinction coefficient, and band gap energy were calculated. Thin films exhibited good optical transmissivity, and had optical direct transitions. The present study confirms the validity of the DiDomenico model for the interband transition, with a single electronic oscillator at 6.858 eV. The optical dispersion behavior of PCT thin film was found to fit well the Sellmeir dispersion equation. The band gap energy of the thin film, annealed at 600°C, was 3.56 eV. The results confirmed that soft solution processing provides an inexpensive and environmentally friendly route for the preparation of PCT thin films.     

Chemical Solution Deposition of Epitaxial Metal‐Oxide Nanocomposite Thin Films

Epitaixial metal‐oxide nanocomposite films, which possess interesting multifunctionality, have found applications in a wide range of devices. However, such films are typically produced by using high‐vacuum equipment, like pulse‐laser deposition, molecular‐beam epitaxy, and chemical vapor deposition. As an alternative approach, chemical solution methods are not only cost‐effective but also offer several advantages, including large surface coating, good control over stoichiometry, and the possible use of dopants. Therefore, in this Personal Account, we review the chemistry behind several of the main solution‐based approaches, that is, sol‐gel techniques, metal‐organic decomposition, chelation, polymer‐assisted deposition, and hydrothermal methods, including the seminal works that have been reported so far, to demonstrate the advantages and disadvantages of these different routes.     

化学溶液沉积法制备自取向BiFeO3多铁薄膜

通过化学溶液沉积法在氧化铟锡(ITO)/导电玻璃上生长了BiFeO₃多晶薄膜.利用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、X射线光电子能谱分析仪(XPS)、磁性测量系统(MPMS)和铁电测试仪对样品的结构、形貌、元素价态、铁磁性和铁电性进行研究.结果表明, 薄膜为自取向生长, 具有良好的[101] 生长取向和平整的表面.室温下, 样品呈铁磁性, 沿样品取向方向为易磁化轴方向.铁电测试结果表明, 其饱和电极化强度达到51.3 μC/cm².     

电泳沉积法制备V2O5薄膜的结构和性能

V2O5 thin films were successfully prepared on ITO substrate with electrophoresis deposition (EDP) through V2O5 sol. X-ray diffraction and scanning electron microscopy were used for studying the structure of the films. The optical and electrochemical properties were measured by the transmittance spectra and cyclic voltammetry measurements, respectively. It is found that V2O5 thin films deposited by EDP are a compact microstructure with finer adhesive force with ITO substrate and the thickness is uniform. During the cycle experiment, the films exhibited reversible two-color (yellow at oxidation and green at reduction) with a maximum transmittance change of around 30%. Moreover, the films had an excellent cycle for lithium intercalation/deintercalation and good cycle stability, the cycle efficiency for the 50th cycle was 88.02% and the films still had fine adhesive force with ITO substrate with no dissolving over more than 50 cycles. The Li+ diffusion coefficient in V2O5 thin film was 5.10×10-12 cm2/s by the electrochemical impedance spectra method. All results indicate that V2O5 thin films by the electrophoresis deposition may be suitable for the use in the electrochromic devices.     

液相沉积法制备光催化活性TiO2膜

锐钛矿型TiO2薄膜;液相沉积法制备光催化活性TiO2膜     

Low-Pressure Chemical Vapor Deposition of Silicon Carbide Thin Films from Organopolysilanes

(Me₃Si)₂SiMe₂, (Me₃Si)₃SiMe and (Me₃Si)₄Si were used as precursors for the deposition of polycrystalline β-SiC thin films on silicon substrates at 1000–1200°C in a low-pressure hot-wall chemical vapor deposition reactor. The thin films were analyzed by X-ray diffraction, scanning electron microscopy and X-ray photoelectron spectroscopy.     

Metal-Organic Chemical Vapor Deposition (MOCVD) Synthesis of Heteroepitaxial Pr0.7Ca0.3MnO3 Films: Effects of Processing Conditions on Structural/Morphological and Functional Properties

Calcium-doped praseodymium manganite films (Pr_0.7Ca_0.3MnO₃, PCMO) were prepared by metal-organic chemical vapor deposition (MOCVD) on SrTiO₃ (001) and SrTiO₃ (110) single-crystal substrates. Structural characterization through X-ray diffraction (XRD) measurements and transmission electron microscopy (TEM) analyses confirmed the formation of epitaxial PCMO phase films. Energy dispersive X-ray (EDX) and X-ray photoelectron spectroscopy (XPS) characterization was used to confirm lateral and vertical composition and the purity of the deposited films. Magnetic measurements, obtained in zero-field-cooling (ZFC) and field-cooling (FC) modes, provided evidence of the presence of a ferromagnetic (FM) transition temperature, which was correlated to the transport properties of the film. The functional properties of the deposited films, combined with the structural and chemical characterization collected data, indicate that the MOCVD approach represents a suitable route for the growth of pure, good quality PCMO for the fabrication of novel spintronic devices.     

Chemical Solution Deposition of Barium Titanate Thin Films with Ethylene Glycol as Solvent for Barium Acetate

Chemical solution deposition (CSD) of BaTiO₃ (BT) or BT-based thin films relies on using a carboxylic acid and alcohol as the solvents for alkaline-earth carboxylate and transition-metal alkoxide, respectively; however, the esterification reaction of the solvents may lead to in-situ water formation and precipitation. To avoid such an uncontrolled reaction, we developed a route in which ethylene glycol (EG) is used as the solvent for Ba-acetate. The EG-based BT coating solutions are stable for at least a few months. The thermal decomposition of the BT xerogel obtained by drying the EG-based solutions depends on the choice of the solvent for the Ti-alkoxide as well: in the case of EG and 2-methoxyethanol solvents carbon residues are removed at only about 1100 °C, while in the case of ethanol it is concluded at about 700 °C. About 100 nm thick BT films derived from the EG-ethanol solution deposited on platinized silicon reveal dense, crack-free columnar microstructure. They exhibit local ferro- and piezoelectric properties. The macroscopic polarization-electric field loops were obtained up to a quite high electric field of about 2.4 MV/cm. The EG-ethanol based CSD route is a viable alternative to the established acetic acid–alcohol route for BT and BT-based films.     

Absorption-Reflection Infrared Spectroscopy Studies of Sol-Gel Prepared Ferroelectric Pb(Zr,Ti)O3 Thin Films on Pt Electrodes

Although the sol-gel method is ideally suited for the preparation of ferroelectric PZT thin films, poor reproducibility and the need to lower crystallization temperatures remain an issue. To address these problems, we have studied the mechanism of thin film formation using absorption-reflection infrared spectroscopy for a novel and less harmful precursor solution system based on butoxyethanol. By recording in situ infrared spectra we were able to monitor hydrolysis, condensation, decomposition and crystallization phenomena versus temperature. We speculate that the lower reactivity of butoxyethanol is responsible for the higher quality of Ti rich PZT based ferroelectric capacitors prepared by a butoxyethanol precursor solution compared with the more widely used methoxyethanol one. Finally, we observed that film's decomposition kinetics is faster as compared to bulk samples and depends on film thickness and electrode layer.     

液相沉积法制备光催化活性掺铁TiO2薄膜

 通过在氟钛酸铵－氟铁酸混合溶液中加入硼酸溶液，应用液相沉积法制备了具有高光催化活性的掺铁TiO2薄膜．用ICP－AES测定了掺铁TiO2薄膜中Fe3＋的浓度，用XRD，AFM，UV－Vis和阶梯仪等对TiO2薄膜的沉积条件、结构、膜厚和性能进行了表征，并以亚甲蓝降解反应评价了掺铁TiO2薄膜的光催化活性．结果表明，在硼酸／六氟钛酸铵摩尔比为2～4时，掺铁TiO2薄膜中含有锐钛矿相TiO2．当掺Fe3＋浓度为0．05％，热处理温度为300℃时，掺铁TiO2薄膜具有最高的光催化活性，其光催化活性是未经热处理时的3．9倍，是经300℃热处理但未掺铁TiO2薄膜的1．4倍．     

Chemical Processing of Potassium Substituted (Pb0.6Ba0.4)Nb2O6 Powders and Thin Films Through Metallo-Organics

Highly oriented tungsten bronze K_0.4(Pb_0.6Ba_0.4)_0.8Nb₂O₆ ferroelectric thin films have been prepared from metal alkoxides and metal acetate by chemical process. The formation of solid solution with potassium was found to be very effective to form the tungsten bronze phase at lower temperatures compared with (Pb_0.6Ba_0.4)Nb₂O₆. The amount of potassium in the composition of K_x(Pb_0.6Ba_0.4)_{1 – x/2}Nb₂O₆ [0 x 0.4] is also important to crystallize in the tungsten bronze phase. K_0.4(Pb_0.6Ba_0.4)_0.8Nb₂O₆ films with c-axis preferred orientation were successfully synthesized on MgO(1 0 0) and Pt(1 0 0)/MgO(1 0 0) substrates above 700°C. KPBN60 thin film on Pt(1 0 0)/MgO(1 0 0) showed a remnant polarization of 20 C/cm² and a coercive field of 140 kV/cm at –150°C.     

Luminescent Thin Films Enabled by CsPbX3 (X=Cl,Br, I) Precursor Solution

Inorganic cesium lead halide perovskite nanocrystals are candidates for lighting and display materials due to their outstanding optoelectronic properties. However, the dissolution issue of perovskite nanocrystals in polar solvents remains a challenge for practical applications. Herein, we present a newly designed one-step spin-coating strategy to prepare a novel multicolor-tunable CsPbX₃ (X=Cl, Br, I) nanocrystal film, where the CsPbX₃ precursor solution was formed by dissolving PbO, Cs₂CO₃, and CH₃NH₃X into the ionic liquid n-butylammonium butyrate. The as-designed CsPbX₃ nanocrystal films show high color purity with a narrow emission width. Also, the blue CsPb(Cl/Br)₃ film demonstrates an absolute photoluminescence quantum yields (PLQY) of 15.6 %, which is higher than 11.7 % of green CsPbBr₃ and 8.3 % of red CsPb(Br/I)₃ film. This study develops an effective approach to preparing CsPbX₃ nanocrystal thin films, opening a new avenue to design perovskite nanocrystals-based devices for lighting and display applications.     

用脉冲激光溅射法制备的Yb~(3 )和Er~(3 )共掺杂氟化物薄膜的上转换发光

脉冲激光溅射法 (PLD) ,作为一种制备高质量薄膜的方法 ,被广泛地用于制备超导、铁电等薄膜。用PLD法制备的Yb3 和Er3 共掺杂氟化物薄膜的上转换发光性质。在 978nmLD激发下 ,薄膜发出强烈的橙色光 ,用日立 -F45 0 0光谱仪测量了其上转换发光光谱 ,观测到了Er3 很强的2 H9/2 →4 I1 5/2 (4 0 8nm) ,2 H1 1 /2 →4 I1 5/2 (5 2 0nm) ,4 S3/2 →4 I1 5/2 (5 5 0nm)和4 F9/2 →4 I1 5/2 (65 0nm)跃迁发射峰。给出了上转换发光强度随激发强度的关系 ,分析了其上转换发光机制及紫色上转换发光增强的原因。