Preparation of TiO2 thick film by laser chemical vapor deposition method

A TiO₂ film was prepared on Pt/Ti/SiO₂/Si substrate by a laser chemical vapor deposition method. The rutile TiO₂ film with pyramidal grains and columnar cross-section was obtained at a high deposition rate (R _dep = 11.4 μm h^?1). At 300 K and 1 MHz, the dielectric constant (ε _r) and loss (tanδ) of the TiO₂ film were about 73.0 and 0.0069, respectively. The electrical properties of TiO₂ film were investigated by ac impedance spectroscopy over ranges of temperature (300–873 K) and frequency (10²–10⁷ Hz). The Cole–Cole plots between real and imaginary parts of the impedance (Z′ and Z′′) in the above frequency and temperature range suggested the presence of two relaxation regimes that were attributed to grain and grain boundary responses. The ionic conduction in the rutile TiO₂ film was dominated by the oxygen vacancies.     

Atomistic simulation of chemical vapor deposition of (111)-oriented diamond film using a kinetic Monte Carlo method

Chemical vapor deposition (CVD) of (111)-oriented diamond film is modeled using a kinetic Monte Carlo atomic scale method. The method is parameterized by the rates of the accompanying surface chemical reactions and permits one of these reactions to take place at each simulation step. The effect of local surface structure and morphology on the rates of surface reaction is examined. Film growth at two different chemical compositions of the feed gas and two substrate temperatures is studied in order to determine the effect of these process parameters on (a) the quality of the deposed film and (b) the rate of deposition. The quality of the film is judged by concentration of the point defects (vacancies and H atoms embedded in the film) and by surface roughness. The results obtained show that the parameters that increase the deposition rate, primarily the substrate temperature and the concentration of CH4 in the feed gas, also increase the defect content and surface roughness.     

以Al2O3为过渡层脉冲激光法制备PZT铁电薄膜

为实现PZT铁电薄膜与半导体衬底的直接集成引入Al2O3为过渡层，首先用真空电子束蒸发法在Si(100)，多昌金刚石（111）衬底上生长约20nm厚的Al2O3过渡层，接着在上述衬底上采用脉冲激光淀积（PLD）法淀积PZT薄膜，衬底温度为350-550℃。X光电子能谱（XPS）测试表明，在高真空下，电子束蒸发Al2O3固态源能获得化学配比接近蒸发源的Al2O3薄膜。X射线衍射（XRD）测试说明，不论衬底是硅还是多晶金刚石，当衬底温度为550℃时，PZT在Al2O3过渡层上呈现（222）取向的焦绿石相结构，当衬底是金刚石时，通过如下工艺：（1）较低温度（350℃）淀积；（2）空气氛围650℃快速退火5min，可以在Al2O3过渡层上获得高度（101）取向的钙钛矿结构的铁电相PZT薄膜，最后AFM测试显示，在硅衬底上，PZT薄膜的表面均方根粗糙度为9.78nm；而在多晶金刚石衬底上，PZT薄膜的表面均方根粗糙度为17.2nm。     

Preparation and humidity-sensitive properties of nanocrystalline BaTiO3 thick film fabricated on Teflon substrate by using pressing method

Nanocrystalline BaTiO₃ precursor has been synthesized by using the stearic acid gel (SAG) method. After calcining the precursor at above 600 °C for 0.5 h, nanocrystalline BaTiO₃ powder with cubic perovskite structure is obtained. The powder is compacted further into solid material under a pressure of 0.1 to 2.0 GPa or fabricated into thick film by pressing on a Teflon substrate at room temperature and 200 °C. The powder and film samples are characterized by XRD, TEM and SEM. The results show that the average grain size of the powder is between 20 and 60 nm, and the thickness of the compacted film is about 56 μm. The investigation on the humidity-sensitive properties of nanocrystalline BaTiO₃ thick film shows that a compacted thick-film sample possesses higher humidity sensitivity, simpler preparation process, and enhanced adhesion strength on the Teflon substrate in comparison with a coated sensor, and the grain size and pressing pressure have obvious influence on its properties. In addition, the solid reaction mechanism and pressure effect on the material in the course of processing are also discussed.     

粉末溶胶法制备Pb0.90La0.10Ti0.975O30-3型厚膜的研究

使用溶胶-凝胶法制备了Pb0.90La0.10Ti0.975O3(简称为PLT-1O)粉体，使用XRD及日本SALD-2001型激光散射颗粒度分析仪对粉体进行了分析，结果表明PLT-1O粉体呈钙钛矿结构，一次颗粒细，颗粒尺寸随退火温度的升高而增大。将粉体分散在溶胶中，并采用粉末溶胶法制备了PLT-1O厚膜。利用XRD和SEM对厚膜进行了分析。实验结果表明，适当调控制备工艺技术，利用粉末溶胶法可望制备出符合要求的铁电“厚膜”。     

A new method for the exploration and measurement of crack growth using a thin conductor film

A method has been developed in which the length of a crack on any metallic or non-metallic surface can be measured in situ, simply and at low cost. This is done by applying a thin, conducting film to the surface and then measuring the increase in voltage that occurs as the crack lengthens.     

Determination of properties of wedged, nonuniformly thick, and absorbing thin films by using a new numerical method

Nonuniformity in the thickness of thin films can severely distort their transmission spectra as compared with those of flat, smooth films. Methods that extract properties such as refractive index, thickness, and extinction coefficient of such films can suffer inaccuracies when they are applied to wedged or nonuniformly thick films. To accurately extract optical properties of nonuniform films, we have developed a novel numerical method and efficient constitutive relations that can determine film properties from just the transmission spectrum for films that are locally smooth with negligible scattering loss. This optimum parameter extraction (OPE) method can accommodate films with two-dimensional thickness variation that would result in significant errors in the values of refractive index and film thickness if not considered. We show that for carefully chosen test cases and for actual pulsed-laser-deposition AlN thin films, properties such as refractive index, extinction coefficient, and film thickness were very accurately determined by using our OPE method. These results are compared with previous techniques to determine the properties of thin films, and the accuracy of and applicable conditions for all these methods are discussed.     

A cylindrical micro ultrasonic motor using PZT thin film deposited by single process hydrothermal method (phi2.4 mm, L=10 mm stator transducer)

A micro ultrasonic motor using PZT (lead zirconate titanate) thin film has been improved by a single process hydrothermal method. The hydrothermal method is a unique method for depositing PZT thin film in a solution. An earlier reported hydrothermal method consisted of two linked processes. Our new method, however, has only a single process. Hence, less distribution of chemical components of the PZT film contributes to a higher efficiency of the stator transducer. The piezoelectric factor d(31) was -30 pC/N for this new method, which is six times larger than that of the previous method. The output torque of the micro ultrasonic motor fabricated by the single process hydrothermal method was measured. The output torque was 7.0 muNm, and the maximum revolution speed was 880 rpm at 15 Vp-p driving voltage.     

A new approach towards the growth of cadmium sulphide thin film by CBD method and its characterization

Cadmium sulphide thin films were deposited by the chemical bath deposition method using tartaric acid as a complexing agent and annealed at different temperature in nitrogen atmosphere and characterized. The crystallographic structure and the crystallite size were studied by the X-ray diffraction (XRD) pattern. Transmittance of the deposited film is significantly higher in the visible region. The optical band-gap of deposited film is 2.4 eV and it decreases with increase in annealing temperature. Temperature dependence of resistivity confirmed the semiconducting behaviour of the film. Scanning electron micrographs (SEM) showed the presence of grain particles of size < 1 μm. X-ray photoelectron spectroscopy (XPS) studies supported the composition of cadmium sulphide thin film determined by EMPA and also indicated the presence of carbon and oxygen as impurity in the film.     

A possibility for new evaluating method of cytotoxicity by using heat shock protein assay

To determine whether heat shock proteins can be utilized as a biomarker for cytotoxicity of dental materials the induction of synthesis of heat shock proteins by mercuric chloride was examined. To analyse the synthesis of heat shock proteins, HeLa cells were labelled with [35S] methionine, and the labelled proteins were separated by SDS-PAGE and autoradiographed. Incubation of the cells in a medium containing 1.25 to 40 M mercuric chloride markedly increased the synthesis of HSP70. At 20 or 40 M mercuric chloride in medium, HeLa cells synthesized HSP70 at 2 h after exposure, maximally at 4–7 h, and gradually diminished thereafter. Examination of the cytotoxicity of mercuric chloride by the conventional neutral red uptake assay revealed a reduction of uptake of the dye in the presence of mercuric chloride at 40 M and above. These findings suggest that the induction of synthesis of HSP70 is one of the most sensitive cellular responses caused by mercury ion, and the heat shock protein assay can be utilized for evaluation of the cytotoxicity of dental materials.     

A new method to evaluate the consolidation behavior of pharmaceutical materials by using the Fraser-Suzuki function

A new method was developed to evaluate the consolidation behavior of different pharmaceutical materials. A method to evaluate the elastic deformation of the different parts of the tablet machine is described. The used model is based on the Fraser--Suzuki function, which was modified to fit the force-time course. This function has three parameters, which describe the consolidation behaviour of pharmaceutical materials. Parameter A (form of the increasing part of the force-time course) and tr parameter (time of force maximum) give qualitative evaluation of the irreversible deformation during the compression process. Parameter S (form of the decreasing part of the curve) describes the decompression phase and provides information about the elastic behaviour of the compressed material. In this article, the importance of the different parameters is presented. The applicability of this function to different kinds of ethylcellulose is also presented.