Micro-patterning of PZT thick film by lift-off using ZnO as a sacrificial layer

Micro-pattern of 8.2-μm-thick PZT films was prepared on Pt/Ti/SiO₂/Si (1 0 0) substrate wafer by combining composite sol–gel and a novel lift-off using ZnO as a sacrificial layer. The processes include ZnO sacrificial layer deposition and patterning, PZT film preparation, and final lift-off. The results reveal the micro-pattern was better than that formed by wet etching, the PZT thick films patterned by lift-off possessed similar dielectric characters, better ferroelectric properties, and higher breakdown voltage than those of films patterned by wet etching. The lift-off is suitable for micro-patterning of PZT thick films.     

溶胶-凝胶法制备掺铝氧化锌薄膜及其近红外反射性能研究

采用溶胶-凝胶法制备了掺铝氧化锌(ZAO)薄膜,用X射线衍射(XRD)、紫外-可见光-近红外分光光度计等分析测试手段对薄膜进行了表征;通过正交试验探讨了镀膜层数、溶胶浓度、铝离子的摩尔分数以及退火温度等因素时掺铝氧化锌(ZAO)薄膜近红外反射率的影响,优选了制备具有高近红外反射率的薄膜的工艺参数.研究结果表明,当溶胶浓...     

Effect of metal oxide as antibacterial agent on thermoplastic starch/metal oxide biocomposites properties

ABSTRACT

This research was purposed at studying the effect of the addition of metal oxide (MO) as antibacterial agent on thermoplastic starch (TPS) properties. TPS/MO biocomposites with 0.1 until 2.0 phr of metal oxide were prepared. Antibacterial activity of TPS and TPS/MO biocomposites against bacteria was investigated. The inhibition zone of biocomposite films was dramatically increased along with the increasing of metal oxides contents. The addition of ZnO content resulted in an increase in inhibition zone for E. coli and S. aureus. The incorporation of MO into TPS/MO biocomposites tends to reduce mechanical properties, the mass loss and T50% of TPS/MO biocomposites.     

Improving purity and size of single-crystal diamond plates produced by high-rate CVD growth and lift-off process using ion implantation

The lift-off process using ion implantation has recently been applied to produce large and thick single-crystal diamond plates by chemical vapor deposition (CVD). CVD growth conditions for undoped, as opposed to nitrogen-doped, diamond were investigated to improve the purity of plates produced by this technique. This utilized apparatus identical to that for high-rate growth with nitrogen addition under high-density plasma. By lowering the growth temperature to 900 °C, an undoped single-crystal CVD diamond plate with a maximum length of 9 mm and thickness of 0.47 mm was successfully produced without formation of non-epitaxial crystallites. The UV–Vis–NIR transmission spectrum of this plate was identical to high-pressure high-temperature (HPHT) synthetic IIa diamond, suggesting high purity of the plate. To increase the size of single-crystal CVD diamond plates, a process to enlarge the seed crystal by combining the lift-off process and a side-surface growth technique is proposed. By this process, a half-inch single-crystal CVD diamond seed crystal was successfully synthesized and half-inch freestanding single-crystal CVD diamond plates were produced from the seed.     

Measurement of the adhesion strength of metal oxide and metal nitride thin films sputtered onto glass by the direct pull-off method

We have measured the adhesion strengths of metal oxide and metal nitride thin films reactively sputtered onto glass substrates using a specially devised direct pull-off test. For double-layer coatings such as metal nitride (CrN_x, TiN_x)/metal oxide (Al₂O₃, SnO₂, Ta₂O₅, TiO₂, ZnO, ZrO₂)/glass, separation usually took place at the nitride/oxide interface. The adhesion strength at the interface was found to depend on the strength of chemical bonding in the films concerned: for the same nitride top layer, the adhesion strength increased as the strength of the metal-oxygen (M-O) bond in the oxide underlayer decreased. X-ray photoelectron spectroscopy (XPS) measurements showed that a mixed layer was created at the nitride/oxide interface and that the adhesion strength at the interface increased with increasing thickness of the mixed layer. For single-layer coatings such as metal nitride (CrN_x, TaN_x, TiN_x, ZrN_x)/glass, the adhesion strength of the film to the glass substrate was found to increase with increasing strength of the M-O bond between the metal atom (M) in the nitride film and an oxygen atom (O). These adhesion behaviors could be explained by adhesion models based on chemical bonds at the interfaces.     

The preparation of a high surface area metal oxide prepared by a matrix-assisted method for hot gas desulphurization

Metal oxide sorbents with high surface area for ultra hot gas cleanup were prepared by a matrix-assisted method. A granular type of activated carbon was used as a matrix in order to increase the surface area of the metal oxide. Zinc was loaded on the surface of activated carbon by an impregnation method. Metal oxide maintained in the form of a matrix structure was observed by scanning electron microscope (SEM). A Wurtzite structure of ZnO was also confirmed by XRD measurement of the prepared granular particles. Particle sizes of metal oxide were distributed in the range of 5-50 nm in transmission electron microscope (TEM) images. The surface area of the zinc oxide calcined at 500 °C was around 56 m²/g. The values of the particle size and the surface area were directly related to the temperatures of calcination. The curves of sulphidation rates for the zinc oxides with high surface areas were measured by a Cahn balance at several different calcination temperatures. It was found that a catalyst with a large surface area showed a high activity in the desulphurization. Not only sulphur content in a simulated coal gas was completely removed by the ZnO with high surface area but also COS formed by a secondary reaction was not detected in the sulphidation tests performed in a fixed-bed reactor system. It was believed that the high surface area ZnO prepared in this study is a suitable sorbent for the ultra hot gas cleaning from the experimental results.     

制备工艺对溶胶-凝胶法制备BeFeO3薄膜的影响

利用溶胶-凝胶法在Pt/Ti/SiO2/Si基体上制备了BiFeO3薄膜,构架了Pt/BiFeO3/Pt电容器。对不同退火温度和保温时间制备薄膜的微观形貌和铁电性能做了研究。X射线衍射仪（XRD）结果显示,不同的退火温度和保温时间并没有改变BiFeO3（BFO）的钙钛矿结构,但温度的改变会产生不同的晶相。通过扫描电子显微镜（FE-SEM）可以观察到,随着烧结保温时间的延长,薄膜晶粒有减小的趋势。P-E曲线结果表明,BFO薄膜在外加电场较高时易击穿,难以得到清晰饱和的电滞回线。     

Electrodeposition of titanium(IV) oxide film from sacrificial titanium anode in I2-added acetone bath

A TiO₂ film was fabricated by a simple electrochemical method using a sacrificial titanium anode as a cationic source in an I₂-dissolved acetone bath, where the solvent contains iodide ions as a supporting electrolyte but no Ti salt as an electrolyte. At the initial stage of electrolysis, anodic oxidation of Ti anode occurred under the presence of water as an impurity to acetone. Subsequently, TiO²⁺ was produced as a result of the dissolution of oxide films under the influence of iodide ions, and was then electrodeposited on the cathode surface. The morphologies of as-deposited films were found to be dependent on the film thickness, which in turn is determined by the voltage applied during the electrolysis. Moreover, the obtained films show photocatalytic activity for decomposition of gaseous acetaldehyde without annealing. In this paper, the electrodeposition mechanism is discussed in detail.     

金属卟啉仿生催化制备环氧丙烷

制备了四苯基卟啉、四-4-甲氧基苯基卟啉、四-4-氟苯基卟啉及3种卟啉相对应的钴、锰、铁金属卟啉,并利用Cary紫外可见分光光度计(UV-vis)和傅里叶变换红外光谱仪(FTIR)对金属卟啉进行了表征;以制备的不同金属卟啉为催化剂,丙烯为原料,氧气为氧化剂,仿生催化丙烯氧化合成环氧丙烷。考察了金属卟啉催化剂类型、金属卟啉催化剂浓度、反应压力、反应温度、反应时间对反应的影响,结果发现上述因素对反应收率、转化率、选择性均有显著影响,且都有一个最佳值,获得的最优化反应条件为:选取四-4-氟苯基铁卟啉为催化剂,催化剂浓度为1.35×10^-5mol/L,反应压力1.75MPa,反应温度100℃,反应时间为2h。在最优化的反应条件下,环氧丙烷的收率达到了40.38%,丙烯转化率达到了47.09%,环氧丙烷选择性达到了85.75%。     

Polymerization of propylene oxide by using double metal cyanide catalysts and the application to polyurethane elastomer

Polymerizations of propylene oxide have been carried out by using double metal cyanide (DMC) catalysts based on Zn₃[Co(CN)₆]₂. By controlling the type and the amount of complexing agent during preparation of catalyst the catalytic activity, initiation time, and the unsaturation level in polyether polyols could be tuned. Various catalysts prepared by changing the complexing and co-complexing agents were characterized by x-ray photoelectron spectroscopy, infrared spectroscopy, and X-ray powder diffraction. Highly active catalyst prepared by choosing a polytetramethylene ether glycol as a co-complexing agent resulted in polyoxypropylenes (POP) with low very low unsaturation level (0.003-0.006 meq/g) and with narrow molecular weight distribution (MWD=1.02-1.04). The active sites of DMC-catalyzed polymerization of propylene oxide have both cationic and coordinative characters. ¹³C NMR analysis showed that the polyols have a random distribution of the configurational sequences and head-to-tail regiosequence, even if the amount of [rr] triad of polyol produced by DMC catalyst was larger than that of polyol by conventional KOH catalyst. The distortionless enhancement by polarization transfer analysis showed that there exist regioirregular sequences as well. The stress-strain curves of methylene diisocyanate/1,4-butanediol cured POP-based polyurethane elastomers showed that the unsaturation content contained in POP showed a dramatic effect on the mechanical properties.     

Electrical and chemical stability engineering of solution-processed indium zinc oxide thin film transistors via a synergistic approach of annealing duration and self-combustion process

The electrical and chemical stability of solution-processed indium zinc oxide (IZO) channel thin-film transistors (TFTs) were engineered via a synergistic approach of annealing duration and self-combustion process. In particular, the amorphous IZO TFTs that were thermally treated at 400 °C for 3 h using the specific precursor combination to generate internal self-combustion energy showed the best electrical performance [high saturation mobility (μ_SAT)=2.7 cm²/V s] and stability [low threshold voltage shift (ΔV_TH) under positive bias stress of 10.5 V] owing to the formation of oxide films with excellent metal–oxide–metal (M–O–M) bonds, fewer impurities, and an amorphous phase compared to IZO TFTs using other precursor formulas and annealing times. Longer annealing times led to a saturated M–O bond ratio and crystallization via extreme thermal annealing, which induced electrical degradation (low μ_SAT and high ΔV_TH) of IZO TFTs. In the wet chemical patterning of electrodes, conventional acidic and basic wet etchants cause severe damage to the surfaces of the IZO channels; thus, insufficiently annealed IZO TFTs exhibited considerable degradation in terms of their on-current level and mobility. Alternatively, the TFTs subjected to an excessively long-term thermal annealing showed only a moderate decrease in mobility with the formation of small nanocrystals.     

镍镁铝复合金属氧化物催化剂制备生物柴油

采用共沉淀法先制备镍镁铝类水滑石化合物,以其为前驱体经400℃煅烧后制得镍镁铝复合金属氧化物催化剂。研究了过渡金属含量、n(甲醇)∶n(大豆油)和反应温度对生物柴油转化率的影响。当n(Ni 2+)∶n(Mg2+)∶n(Al 3+)=0.64∶2.36∶1时,转化率最高,可达到92.8%。而n(甲醇)∶n(大豆油)=10∶1,w(催化剂)=4%,反应温度为65℃,反应时间4h是所得的最佳操作条件。研究出的镍镁铝复合金属氧化物可作为多相催化剂,具有生产生物柴油的潜力。     

Phosphorus diffusion gettering process of multicrystalline silicon using a sacrificial porous silicon layer

ABSTRACT: The aim of this work is to getter undesirable impurities from low cost multicrystalline silicon (mc-Si) wafers and then enhance their electronic properties. We used an efficient process which consists in applying phosphorus diffusion into a sacrificial porous silicon (PS) layer in which the gettered impurities have been trapped after the heat treatment. As we have expected, after removing the phosphorus-rich porous silicon (PS) layer, the electrical properties of the mc-Si wafers were significantly improved. The PS layers, realized on both sides of the mc-Si substrates, were formed by the stain-etching technique. The phosphorus treatment was achieved using a liquid POCl3-based source on both sides of the mc-Si wafers. The realized phosphorus/PS/Si/PS/phosphorus structures were annealed at a temperature ranging between 700 degreesC and 950 degreesC under an O2 controlled atmosphere, which allows phosphorus to diffuse throughout the PS layers and to getter eventual metal impurities towards the phosphorus doped PS layer. The effect of this gettering procedure was investigated by means of the internal quantum efficiency (IQE) and the dark current-voltage (I-V) characteristics. The minority carrier lifetime measurements were made using a WTC-120 photoconductance lifetime tester. The serial resistance and the shunt resistance carried out from the dark (I-V) curves confirm this gettering-related solar cell improvement. It has been shown that the photovoltaic parameters of the gettered silicon solar cells were improved as regard to the ungettered one, what proves the beneficial effect of this gettering process on the conversion efficiency of the multicrystalline silicon solar cells.     

Low temperature incineration of mixed wastes using bulk metal oxide catalysts

Volume reduction of low-level mixed wastes from former nuclear weapons facilities is a significant environmental problem. Processing of these materials presents unique scientific and engineering problems due to the presence of minute quantities of radionuclides which must be contained and concentrated for later safe disposal. Low-temperature catalytic incineration is one option that has been utilized at the Rocky Flats facility for this purpose.

This paper presents results of research regarding evaluation of bulk metal oxides as catalysts for low-temperature incineration of carbonaceous residues which are typical by-products of fluidized bed combustion of mixed wastes under oxygen-lean conditions. A series of 14 metal oxides were screened in a thermogravimetric analyzer, using on-line mass spectrometry for speciation of reaction product gases. Catalyst evaluation criteria focused on the thermal—redox activity of the metals using both carbon black and PVC char as surrogate waste materials. Results indicated that metal oxides which were P-type semiconductor materials were suitable as catalysts for this application. Oxides of cobalt, molybdenum, vanadium, and manganese were found to be particularly stable and active catalysts under conditions specific to this process (T < 650°C, low oxygen partial pressures).

Bench-scale evaluation of these metal oxides with respect to stability to chlorine (HCl) attack was carried out at 550°C using a TG/MS system. Cobalt oxide was found to be resistant to metal loss in a HCl/He gaseous environment while metal loss from Mo, Mn, and V-based catalysts was moderate to severe. XRD and SEM/EDX analysis of spent Co catalysts indicated the formation of non-stoichiometric cobalt chlorides. Regeneration of chlorinated cobalt was found to successfully restore the low-temperature combustion activity to that of the fresh metal oxide.     

金属氧化物吸附剂脱硫过程中羰基硫的生成

金属氧化物脱硫剂脱硫过程中产生羰基硫的现象缩小了脱硫剂的使用范围。本文从气体中存在一氧化碳、二氧化碳、单质硫和硫化氢出发给出了均相、非均相生成羰基硫的途径,特别综述了生成羰基硫的催化作用。在总结氧化铁基、氧化锌基、氧化锰基及氧化铜基主流金属氧化物脱硫剂脱硫过程中产生羰基硫研究结果的基础上,发现吸附在金属硫化物表面上的一氧化碳与活性硫化物的相互作用是生成羰基硫的主要反应步骤,活性硫化物可能是硫化氢热解成蒸气硫或硫氢根离子及硫化氢与金属氧化物反应生成的金属硫化物。     

Application of porous oxide layer in plastic/metal direct adhesion by injection molding

In this study, porous oxide layers were coated on aluminum sheets by plasma electrolytic oxidation (PEO) treatment. The PEO-treated aluminum sheets were then inserted and direct heated in the injection mold. The melting plastic penetrated and solidified in the micropores during the injection molding process, consequently achieving plastic/metal direct adhesion through micro-mechanical interlocking. The effects of the different surface morphologies of PEO coatings on plastic/metal adhesion were studied by shear test and microscopic characterizations. The microstructures were varied by changing PEO process parameters. The bonding strength was affected by the surface morphology changes, and the experimental results show that the surface porosity is a major factor in the direct adhesion. Reliable joints can be achieved on the porous coating, and the strength was proportional to the surface porosity. The shear strength in this study was in a range of approximately 3–8 MPa with 7–20% surface porosity.     

CuNiAl复合金属氧化物催化ClO2氧化处理苯酚废水

采用共沉淀法合成CuNiAl类水滑石(CuNiAl-LDHs),将水滑石在600℃下焙烧制备出高分散CuNiAl复合金属氧化物催化剂,用XRD、FTIR和SEM对产品进行表征,并用CuNiAl复合金属氧化物催化ClO2氧化处理苯酚。研究结果表明,类水滑石中Cu、Ni、Al的摩尔比影响类水滑石的晶形结构,当n(Cu)∶n(Ni)∶n(Al)=1∶1∶1,可以得到结晶度高、晶体单一的CuNiAl类水滑石,该水滑石焙烧得到的复合金属氧化物催化ClO2氧化处理苯酚废水,可促进废水中苯酚的深度降解,使COD去除率大大提高。适宜的反应条件是:催化剂投加量为3 g/L,废水pH=7.0,反应时间60 min,反应温度室温,废水COD去除率达到65%左右。     

溶胶-凝胶法制备TiO_2-GO光催化剂的研究

采用改进Hummer法制备氧化石墨烯(GO),以钛酸丁酯为前驱物,采用溶胶-凝胶法制备Ti O2-GO光催化剂,利用光催化降解偏二甲肼(UDMH)来检验其光催化活性,探讨GO的添加对Ti O2晶型、粒径以及光催化活性的影响。结果表明,GO的添加不会改变Ti O2的晶型,但会提高锐钛矿向金红石的相变温度,相变速度减缓,随着GO添加量增多,颗粒粒径减小,吸附性增强;Ti O2-GO的光催化活性高于相同条件下制备的纯Ti O2。     

溶胶-凝胶法制备TiO_2-GO光催化剂的研究

采用改进Hummer法制备氧化石墨烯(GO),以钛酸丁酯为前驱物,采用溶胶-凝胶法制备Ti O2-GO光催化剂,利用光催化降解偏二甲肼(UDMH)来检验其光催化活性,探讨GO的添加对Ti O2晶型、粒径以及光催化活性的影响。结果表明,GO的添加不会改变Ti O2的晶型,但会提高锐钛矿向金红石的相变温度,相变速度减缓,随着GO添加量增多,颗粒粒径减小,吸附性增强;Ti O2-GO的光催化活性高于相同条件下制备的纯Ti O2。     

Photochemical diodes of a TiO2 film prepared by a sol-gel method

Photochemical diodes were prepared using a thin film of TiO₂ made from titanium isopropoxide by a sol-gel method. A half part of a conductive SnO₂ film plated on a quartz plate was coated with the TiO₂ film, and the other parts of the SnO₂ substrate were coated with a thin Pt film. The photochemical diode thus prepared shows photocatalytic activity for hydrogen evolution from aqueous ethanol solutions containing NaOH or HClO₄. No other products are detected in the gas phase. Hydrogen evolution from the Pt part is definitely observed, indicating electron transfer from the TiO₂ film to the Pt film through the SnO₂ film. Another type of photochemical diode, the TiO₂ film coated on a Pt plate, is found to show higher activity than the TiO₂/SnO₂/Pt device for the hydrogen photo-evolution without any support electrolyte. Hydrogen evolution on this device, however, occurs on the TiO₂ side but not on the Pt side. These results are discussed in terms of a photo-electrochemical mechanism at semiconductor surfaces.