退火诱导MgZnO薄膜(220)晶向晶化性质的研究

采用激光脉冲沉积法(PLD)在石英玻璃上成功制备了一系列MgZnO薄膜。并通过选用高Mg含量的靶材,成功将薄膜的吸收边调节至极紫外区域(200～280nm),经计算MgZnO薄膜的带隙高达5.46eV。进一步研究这种高Mg含量的MgZnO薄膜的结构特性,对薄膜进行了热退火处理,并首次观察到依赖于退火温度变化的(220)取向衍射峰的变化。     

Measurement of Molecular Orientation in Retrieved Ultra-high-molecular-weight Polyethylene (UHMWPE) Hip Sockets using Fourier-transform Infrared Spectroscopy

Abstract:  This paper describes the use of Fourier-transform infrared spectroscopy (FTIR) to measure the degree of orientation in retrieved ultra-high-molecular-weight polyethylene (UHMWPE) acetabular components of prosthetic hip joints quantitatively. Multidirectional shearing has been found to result in a wear rate that is several orders of magnitude higher than that for linear shear. This is because linear wear of UHMWPE is believed to induce orientation of the polymer lamellae. The FTIR technique described in this paper enables a direct comparison to be made between patient biomechanics and the molecular orientation of UHMWPE hip sockets. Patients were identified prior to revision surgery of the hip for loosening of components. Individual patient's hip-joint kinematics were quantified by the aspect ratio of movement loci developed from clinical gait analysis. It was found that patients with high aspect ratios and therefore more linear wear paths, exhibited measurable orientation of the UHMWPE polymer lamellae in their retrieved hip sockets. An aspect ratio of 5.36 resulted in 67% of the polymer lamellae being oriented in the a- axis direction. The technique was qualitatively validated by the use of transmission electron microscopy and it was found that an aspect ratio of 4.46 or greater resulted in the observed orientation of the polymer lamellae.     

石墨衬底上具有（220）/（400）择优取向多晶硅薄膜的制备及性质

在石墨衬底上分别制备了具有(220)和(400)择优取向的多晶硅薄膜.首先利用磁控溅射技术直接在石墨衬底上制备非晶硅薄膜层,以及先制备 ZnO 过渡层,再在 ZnO 过渡层上制备非晶硅薄膜层;然后采用快速退火法对非晶硅薄膜晶化,使其形成多晶硅薄膜籽晶层.XRD 测试表明,未引入 ZnO 过渡层的多晶硅薄膜籽晶层具有高度(220)择优取向,而引入 ZnO 过渡层的多晶硅薄膜籽晶层具有高度(400)择优取向;最后在多晶硅籽晶层上通过对流辅助化学气相沉积(CoCVD)制备多晶硅薄膜.根据 SEM、XRD、拉曼测试表明,多晶硅薄膜的性质延续了多晶硅籽晶层的性质,未引入 ZnO 过渡层的样品,具有高度(220)择优取向.引入 ZnO 过渡层后的样品,具有高度(400)择优取向,(400)择优取向的转变有利于后续多晶硅薄膜太阳电池的制作.同时对 Si(220)和 Si (400)择优取向的形成原因做了初步分析.     

Thermal, dielectric studies on pure and amino acid (l-glutamic acid, l-histidine, l-valine) doped KDP single crystals

Amino acids (l-glutamic acid, l-histidine, l-valine) doped potassium dihydrogen phospate crystals are grown by solution growth technique. Slow cooling as well as slow evaporation methods were employed to grow these crystals. The concentration of dopants in the mother solution was varied from 0.1 mol% to 10 mol%. The solubility data for all dopants concentration were determined. There is variation in pH value and hence, there is habit modification of the grown crystals were characterized with UV–VIS, FT-IR studies, SHG trace elements and dielectric studies reveal slight distortion of lattice parameter for the heavily doped KDP crystals. UV–Visible spectra confirm the improvement in the transparency of these crystals on doping metal ions. FT-IR spectra reveal strong absorption band between 1400 and 1600 cm⁻¹ for metal ion doped crystals. TGA–DTA studies reveal good thermal stability. The dopants increase the hardness value of the material and it also depends on the concentration of the dopants. Amino acids doping improved the NLO properties. The detailed results on the spectral parameters, habit modifications and constant values will be presented.     

Microtube-Czochralski (μT-CZ) growth of bulk benzophenone single crystal for nonlinear optical applications

Microtube-Czochralski technique was employed to grow large size benzophenone single crystal for the first time. In conventional Czochralski pulling technique, the growth of bulk single crystal will be initiated by a pre-grown seed, whereas in microtube-Czochralski technique a microtube that is made out of a metal such as stainless steel (8 μm ID) can be used to grow bulk single crystal. A specially designed furnace having inert gas atmosphere, condensation free enclosure and in situ annealing facility was employed. Benzophenone crystal having cubic facet (15 mm) with high optical quality was grown when the following vital growth parameters are set to the corresponding optimized values such as pulling rate: 1–2 mm/h, seed rotation rate: 5–10 rpm and the axial thermal gradient: 8 °C/cm. The grown crystals were cut and polished. Thin plate like polished samples were used to justify the optical quality of the grown samples by UV–VIS–NIR spectroscopy. Powder SHG measurement shows that the grown samples exhibit three times higher second harmonic generation than potassium dihydrogen phosphate (KDP).     

Solution of stationary heat-conduction problems for curvilinear regions using eigenfunction expansions (fundamental solutions)

Formulas for solution of stationary problems of heat conduction in bodies of a curvilinear shape have been obtained in explicit form using eigenfunction expansions; an analogous solution has been constructed for temperature fluctuations. An algorithm of computation of the boundary functions for classical regions has been proposed; these functions make it possible to reduce the boundary conditions of the problem to a homogeneous form. The exact fundamental solutions in the region of a rectangle with arbitrary smooth boundary conditions of the 1st kind have been constructed using them. These solutions are fundamental, since they can be used when boundary-value problems and inverse problems with unknown boundary conditions are considered for a wide range of curvilinear regions. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 82, No. 1, pp. 163–169, January–February, 2009.     

Nanoparticle size control of theophylline using rapid expansion of supercritical solutions (RESS) technique

This paper presents the strategy for nanoparticle design of theophylline using rapid expansion of supercritical solutions (RESS) technique. In this study, the production of nanoparticles of theophylline via the RESS technique using supercritical CO₂ has been presented. The effects of five different operating parameters including equilibrium temperatures (313.2, 323.2, and 338.2 K), equilibrium pressures (14.0–22.0 MPa), pre-expansion temperatures (333.2–373.2 K), nozzle temperatures (323.2–383.2 K), and collection temperatures (265–303 K) on the size and morphology of the nanoparticles were investigated. The mean size of the produced particle was in the range of 200–300 nm, which was about 1/300 of the size of the unprocessed particle. Furthermore, the results of summarizing the dependence of the five operating parameters on particle size showed that nanoparticle size was strongly influenced by supersaturation between the pre-expansion and post-expansion sections. The supersaturation-based design will enable the control of nanoparticle size produced using the RESS technique.     

Competitive adsorption of Cu (II), Co (II) and Ni (II) from their binary and tertiary aqueous solutions using chitosan-coated perlite beads as biosorbent

A new composite chitosan-coated biosorbent was prepared and was used for the removal and recovery of heavy metals from aqueous solution. In the present investigation, equilibrium adsorption characteristics of Cu (II), Ni (II), and Co (II) from their binary and tertiary solution on newly developed biosorbent chitosan-coated perlite beads were evaluated through batch and column studies. These beads were characterized by using FTIR, EDXRF and surface area analysis techniques. The effect of various biosorption parameters like effect of pH, agitation time, concentration of adsorbate and amount of adsorbent on extent of adsorption was investigated. The adsorption follows Lagergren first order kinetic model. The equilibrium adsorption data were fitted to Freundlich and Langmuir adsorption isotherm models and the model parameters were evaluated. Both the models represent the experimental data satisfactorily. The sorbent loaded with metal was regenerated with 0.1N NaOH solution. Furthermore the column dynamic studies indicate the re-usage of the biosorbent.     

Synthesis of molybdenum (IV) disulfide using a single-source method

Molybdenum(IV) disulfide was prepared by the thermalysis of the single molecule precursor [Mo₂O₄(S₂CNEt₂)₂] (Et: ethyl group). The thermalysis was monitored by thermogravimetric analysis and FT-infrared spectroscopy. The MoS₂ materials obtained during the thermalysis experiments were characterized in terms of their morphological and optical characteristics.     

Atomic layer deposition of MnO using Bis(ethylcyclopentadienyl)manganese and H2O

Manganese oxide (MnO) atomic layer deposition (ALD) was accomplished using sequential exposures of bis(ethylcyclopentadienyl)manganese (Mn(CpEt)₂) and H₂O. Rutherford backscattering analysis revealed a nearly 1:1 atomic ratio for Mn:O in the MnO ALD films. X-ray diffraction determined that the films were crystalline and consistent with the cubic phase of MnO. Quartz crystal microbalance (QCM) measurements monitored the mass deposition rate during MnO ALD and verified self-limiting reactions for each reactant. Extremely efficient reactions were observed that required reactant exposures of only 3 × 10⁴ L (1 L = 1.33 × 10^− 4 Pa s). X-ray reflectivity (XRR) studies were used to confirm the QCM measurements and determine the film density and film thicknesses. The MnO ALD film density was 5.23 g/cm³. The growth per cycle was investigated from 100-300 °C. The largest MnO ALD growth per cycle was 1.2 Å/cycle at 100 °C and the growth per cycle decreased at higher temperatures. Transmission electron microscopy images observed the conformality of MnO films on ZrO₂ nanoparticles and confirmed the growth per cycle observed by the XRR studies. Fourier transform infrared spectroscopy was used to study the -CpEt? and -OH? surface species during MnO ALD and also monitored the bulk vibrational modes of the growing MnO films. The results allowed a growth mechanism to be established for MnO ALD using Mn(CpEt)₂ and H₂O. Only 54% of the Mn sites are observed to retain the -CpEt? surface species after the Mn(CpEt)₂ exposure. Efficient MnO ALD using Mn(CpEt)₂ and H₂O should be useful for a variety of applications where metal oxides are required that can easily change their oxidation states.     

The method of approximate fundamental solutions (MAFS) for elliptic equations of general type with variable coefficients

The paper presents a meshless method for solving elliptic equations of general type with variable coefficients. It is based on the use of the delta-shaped functions and the method of approximate fundamental solutions first suggested for solving equations with constant coefficients. The method assumes that the solution domain is embedded in a square and the initial equation is extended onto the square with the help of the CICE −(Chebyshev interpolation + C-expansion) approximation scheme. As a result the coefficients of the equation are approximated by the truncated Fourier series over some orthogonal system in the square. The approximate fundamental solutions (AFSs) satisfy L[u]=I(x), where I(x) is the delta shaped function in the form of the truncated Fourier series. Thus, the AFSs due to the special form of the operator can be obtained in the similar form of truncated series. The next part of the MAFS follows the general scheme of the MFS. The numerical examples are presented and the results are compared with the analytical solutions. The comparison shows that the method presented provides a very high precision in solution of two-dimensional elliptic equations of general type with different boundary conditions (Dirichlet, Neumann, mixed) in arbitrary domains.     

干／湿相转化法制备偏氟乙烯—六氟丙烯共聚物对称微孔膜

用干／湿相转化成膜法制备了偏氟乙烯－六氟丙烯共聚物（PVDF－HFP）为基材的对称微孔膜,该膜可用于塑料锂离子电池的聚合物电解质,通过扫描电镜,孔隙率和湿膜电子导率,主要考察了成膜工艺中干态处理的环境因素,温度和温度对所制微孔膜的形态和性能的影响,研究结果表明,在较低的温度湿度下干态处理铸膜液,易形成小颗粒为主的对称性微孔膜;而在较高的温湿度下随处理时间的延长,形成的微孔膜从有致密皮层的不对称结构转变为对称有缺陷海绵体结构,采用FT－IR研究了成膜机理,证明铸膜液压低温处理后形成了γ晶型的结晶结构。     

Adsorption of Pb(II) and Cd(II) from aqueous solutions using titanate nanotubes prepared via hydrothermal method

Titanate nanotubes (TNs) with specific surface areas of 272.31 m(2)g(-1) and pore volumes of 1.264 cm(3)g(-1) were synthesized by alkaline hydrothermal method. The TNs were investigated as adsorbents for the removal of Pb(II) and Cd(II) from aqueous solutions. The FT-IR analysis indicated that Pb(II) and Cd(II) adsorption were mainly ascribed to the hydroxyl groups in the TNs. Batch experiments were conducted by varying contact time, pH and adsorbent dosage. It was shown that the initial uptake of each metal ion was very fast in the first 5 min, and adsorption equilibrium was reached after 180 min. The adsorption of Pb(II) and Cd(II) were found to be maximum at pH in the range of 5.0-6.0. The adsorption kinetics of both metal ions followed the pseudo-second-order model. Equilibrium data were best fitted with the Langmuir isotherm model, and the maximum adsorption capacities of Pb(II) and Cd(II) were determined to be 520.83 and 238.61 mg g(-1), respectively. Moreover, more than 80% of Pb(II) and 85% of Cd(II) adsorbed onto TNs can be desorbed with 0.1M HCl after 3h. Thus, TNs were considered to be effective and promising materials for the removal of both Pb(II) and Cd(II) from wastewater.     

Simulation of dynamic crack growth using the generalized interpolation material point (GIMP) method

Dynamic crack growth is simulated by implementing a cohesive zone model in the generalized interpolation material point (GIMP) method. Multiple velocity fields are used in GIMP to enable handling of discrete discontinuity on either side of the interface. Multilevel refinement is adopted in the region around the crack-tip to resolve higher strain gradients. Numerical simulations of crack growth in a homogeneous elastic solid under mode-II plane strain conditions are conducted with the crack propagating along a weak interface. A parametric study is conducted with respect to varying impact speeds ranging from 5 m/s to 60 m/s and cohesive strengths from 4 to 35 MPa. Numerical results are compared qualitatively with the dynamic fracture experiments of Rosakis et al. [(1999) Science 284:1337–1340]. The simulations are capable of handling crack growth with crack-tip velocities in both sub-Rayleigh and intersonic regimes. Crack initiation and propagation are the natural outcome of the simulations incorporating the cohesive zone model. For various impact speeds, the sustained crack-tip velocity falls either in the sub-Rayleigh regime or in the region between (c _S is the shear wave speed) and c _D (c _D is the dilatational wave speed) of the bulk material. The Burridge–Andrews mechanism for transition of the crack-tip velocity from sub-Rayleigh to intersonic speed of the bulk material is observed for impact speeds ranging from 9.5 to 60 m/s (for normal and shear cohesive strengths of 24 MPa). Within the intersonic regime, sustained crack-tip velocities between 1.66 c _S (or 0.82 c _D ) and 1.94 c _S (or 0.95 c _D ) were obtained. For the cases simulated in this work, within the stable intersonic regime, the lowest intersonic crack-tip velocity obtained was 1.66 c _S (or 0.82 c _D ).     

溶胶-凝胶法制备PZT(95/5)反铁电纳米粉

采用溶胶-凝胶法制备Pb(Zr0.95Ti0.05)O3(简称PZT(95/5))反铁电纳米粉,差热分析确定干燥后粉体的煅烧温度范围为550~750℃。将干燥后粉体分别在550,600,650,750℃下煅烧,保温2 h,经XRD分析发现,随着煅烧温度的升高,主晶相的强度逐渐升高,杂质相的峰高逐渐减弱。当煅烧温度为750℃时,形成了完全的钙钛矿相。所制PZT95/5粉体的平均粒径约100 nm。     

Prediction of interfacial fracture between concrete and fiber reinforced polymer (FRP) by using cohesive zone modeling

Interfacial debonding between concrete and fiber reinforced polymer (FRP) is investigated through integrating experiments and computations. An experimental program is designed to evaluate interfacial fracture parameters of mode-I through cutting and bonding specimens with an FRP sheet. The evaluated fracture parameters, i.e. the fracture energy and the bonding strength, are confirmed by predicting FRP debonding failure with the cohesive zone modeling approach. In the cohesive zone model, a traction-separation relation for FRP debonding is proposed with a shape index while providing various initial descending slopes. Computational results of the cohesive zone model agree well with three-point bending test results for both FRP debonding and plain concrete fracture. Furthermore, both experimental and computational results demonstrate that the fracture energy and the cohesive strength are essential fracture parameters for the prediction of FRP debonding behavior.     

Electrical characterization of wafer-bonded Ge(111)-on-insulator substrates using four-point-probe pseudo-metal-oxide-semiconductor field-effect transistor method

The electrical properties of wafer-bonded n-type Ge(111)-on-insulator (Ge(111)-OI) substrates were characterized using a four-point-probe pseudo-metal-oxide-semiconductor field-effect transistor (pseudo-MOSFET) method. Average electron and hole mobilities in the Ge(111)-OI channel were measured to be ~ 1000 cm²/V s in accumulation mode and ~ 310 cm²/V s in inversion mode, respectively. The measured mobility strongly depended on the sample position, due to the spatially inhomogeneous distribution of the interface states. Despite the existence of interface states, the carrier mobility exhibited a high value demonstrating the prospect of wafer-bonded Ge(111)-OI as a channel material in MOSFETs.     

J-Resistance curve testing of HY80 steel using SE(B) specimens and normalization method

The normalization method is adopted for standard and nonstandard specimens in this paper to develop J-R curves for HY80 steel directly from load versus load-line displacement records without use of automatic crack length measurement. The standard specimens usually contain high crack-tip constraints, while the nonstandard specimens involve low crack-tip constraints. To obtain J-R curves with different constraints, a series of single edge notched bend (SE(B)) specimens with different crack lengths for an HY80 steel are tested in accordance with ASTM standard E1820. The normalization method is then used for determining crack extension and J-R curves for these SE(B) specimens.To validate the normalization method, the J-R curves determined using the normalization method are compared with those obtained by the elastic unloading compliance method for the SE(B) specimens. The comparison shows that good agreements exist between the two methods, and the normalization method is a viable tool to be used to determine J-R curves of the HY80 steel for the standard as well as nonstandard SE(B) specimens. In the J-integral calculations, the resistance curve test method, the basic test method and the modified basic test method specified in ASTM E1820 are evaluated. The results indicate that the modified basic method can be equivalent to the resistance curve method.     

Selective absorption of water from different oil-water emulsions with Psy-cl-poly(AAm) synthesized using irradiation copolymerization method

The present paper deals with the functionalization of psyllium with acrylamide under the influence of gamma radiation using hexamethylene tetramine as a crosslinker. The polymer synthesized was characterized using FTIR spectroscopy, scanning electron microscopy and thermogravimetric analysis. The superabsorbent was then used further for the selective absorption of water from different oil-water emulsions.