Structures and properties of [CoPt/Ag]<Subscript><Emphasis Type="Italic">n</Emphasis></Subscript> multilayer fims

The magnetic properties and structures of [CoPt/Ag] _n , multilayer films deposited by DC magnetron sputtering have been studied. During the deposited process, two kinds of deposited sequences, that is Ag layer (FDAG) first deposited or CoPt layer (FDCP) first deposited, have been chosen. The results show that the microstructures and coercivities were strongly influenced by the deposited sequence and the thickness of films. The coercivities of [Ag/CoPt] _n with FDAG are obviously higher than those of [CoPt/Ag] _n with FDCP. Especially, when the thickness of films is 8 nm, the difference of coercivities between the FDAG film and the FDCP film is the largest. It is possibly because Ag plays a role of underlayer in FDAG multilayers, which can induce both the transformation from fcc to fct and the oriented growth along c-axis. In addition, δM curves reveal that the [CoPt/Ag]₈ multilayer, film has a lower intergrain interaction than the CoPt/Ag bilayer film.     

The inorganic-organic hybrid junction with n-ZnO nanorods/p-polyfluorene structure grown with low-temperature aqueous chemical growth method

The inorganic-organic hybrid junction was synthesized on ITO glass substrate,which was consisted of an n-type ZnO nanorods(NRs)grown by low-temperature aqueous chemical growth method and a p-type polyfluorene(PF)organic film fabricated by spin-coating.The experimental results indicate that densely and uniformly distributed ZnO nanorods are successfully grown on the PF layer.The thickness of the PF layer plays a dominant role for the current-voltage(I-V)characteristic of the ZnO NRs/PF inorganic-organic hybrid junction device,and a p-n junction with obviously rectifying behavior is achieved with optimal PF layer thickness.The photoluminescence(PL)spectrum covering the broad visible range was obtained from the n-ZnO nanorods/p-polyfluorene(PF)structure,which was originated from the combination of the PF-related blue emission and the ZnO-related deep level emission.     

A commutativity condition for s -unital rings

LetR be ans-unital ring, and we prove a commutativity theorem ofR satisfying the following conditions: (1) For eachx, y εR, there exist bounded positive integersk=k(x,y), s=s(x,y), t=t(x,y) (where, at least one ofk, s, t is not equal to 1) such that (xy)k=x ^sy^t, (xy)k+1=x ^s+1 y ^t+1; (2)N, the set of all nilpotent elements ofR, isp-torsion free, wherep is the L. C. M. (least common multiple) of allk, s, t. Project supported by The Science Foundation of NECC for Returns Synopsis of the first author Yin Zhiyun, professor, born in May, 1960, study fields are commutative algebras and economical mathematics.     

Interface structure of Ag (111)/SnO<Subscript>2</Subscript> (200) composite material studied by density functional theory

Electric contact material of Ag/SnO₂ was successfully synthesized by in situ process method. The interface structure was characterized by high-resolution transmission electron microscopy (HTEM) and simulated at atomic scale on computer. The mean-square displacements of atoms near the interface were calculated, and the results showed that near the interface both Ag side and SnO₂ were mismatched and this effect decays rapidly far from the interface. By inspecting the calculated density of states (DOS), we found that the electric-conductivity of this composite material was decreased because of the localized 4d and 2p electrons of Ag and O near the Fermi surface, respectively. Electron density changed acutely across the interface, so that there was no extra compound precipitated. A micro-electric field also formed in the whole material due to the interface structure, and this may affect the electron conduction and the related electric-conductivity of the composite. It is found that the interface cohesive energy of Ag (111)/SnO₂ (200) was −3.50 J/m², which is higher than the experimental results. Supported by the National Natural Science Foundation of China (Grant No. 2008CB617609), the Natural Science Foundation of Yunnan Province (Grant No. 2006E003Z) and Science Innovation Foundation of Kunming University of Science and Technology     

Studying the operation characteristics and structure of vertical channel copper-phthalocyanine organic semiconductor transistor

The creation of Au/CuPe/Al/CuPc/strueture is a perpendicular type electricity found in the channel of organic static induction transistor. In the following we analyze transistor operation characteristics and machine structural relation. The results express that the transistor drives the voltage low and has no-saturation currentvoltage characteristics. Its operation characteristics are dependant on gate bias voltage and the construction of the aluminum eleetrode. The vertical ehannel of organic static induction transistor （OSIT） , with structure of Au/CuPc/Al/CuPc/ Cu, has been determined. According to the test results, the relation of its operation characteristics aud device structure was analyzed. The results show that this transistor has a low driving voltage and unsaturation Ⅰ-Ⅴ characteristies. Its operation characteristics are dependant on gate bias voltage and the structure of the aluminum electrode.     

Component analysis of volatile oil from Illicium Verum Hook. f.

Volatile oil was extracted from Illicium Verum Hook. f. by using steam distillation. 41 kinds of compounds were separated and identified by GC/MS, and their relative contents were determined by normalization method. Among 41 identified compounds, there are 14 hydrocarbon components and 22 oxygenated hydrocarbon derivatives, and a small amount of nitrogenous compounds. The main component is anethole, accounting for 76.23%, and the other components such as anisyl acetone, anisaldehyde, p-allylanisole, p-cumic aldehyde and p-allylpen take up more than 10%. Foundation item: Science Foundation of Education for Hunan Province (No. 00C324) Biography of the first author: YAN Jian-hui, associate professor, doctorate candidate, born in 1958, majoring in applied chemistry.     

Al/CuPc/Cu肖特基气敏二极管制备与特性

实验采用溅射和蒸发镀膜工艺,制备了一种新型的Al/CuPc/Cu三明治结构NO2气敏传感器.这种器件对NO2气体具有较高的敏感性,制备工艺简单,成本较低.通过研究其在NO2气体中电学特性的变化,来表征其敏感特性.研究结果表明,在10 ppm的NO2气体环境中,器件的正向电流明显增大.通过比较器件在空气和NO2气体中器件的肖特基势垒高度的变化,发现通入NO2气体50分钟后,CuPc/Al势垒高度降低了60 meV,正向整流电流增加77倍.     

Structural and optical characteristics of Al x Ga1- x N/AlN superlattice

AlN/Al_0.3Ga_0.7N superlattices were grown on (0001) sapphire substrate by metal-organic chemical vapor deposition (MOCVD). The superlattice period varies from 6 to 30. The layer thickness of different period stack was designed. GaN or AlGaN template was employed for growing AlN/AlGaN superlattices. Reflectivity, SEM, AFM and XRD data of the Al _x Ga_1-x N/AlN superlattices are presented. It is found that the templates used have an intensive impact on surface roughness and interfacial properties of following AlN/AlGaN superlattices. The result of atomic force microscopy indicates that AlN/AlGaN superlattices grown on GaN template exhibit quasi-two-dimensional growth mode. The resulting superlattice has a smooth surface morphology and distinct interface. No crack is observed in the area of a 2-inch wafer. Supported by the Special Funds for Major State Basic Research Project (973 Project) (Grant No. 2006CB6049), the Hi-tech Research Project (Grant Nos. 2006AA03A103, 2006AA03A118, and 2006AA03A142), the National Natural Science Foundation of China (Grant No. 60676057), and the Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20050284004)     

Growth kinetics of Thiobacillus ferrooxidans in bioelectrochemical cell

Thiobacillus ferrooxidans might be the most important bacteria used in biometallurgy. The foundation way of its growth process is oxidizing ferrous in order to obtain energy needed for metabolism, but the variation of ferrous concentration and mixed potential of the culture media would have crucial effect on the bacteria growth. Based on the characteristics of Thiobacillus ferroxidans growth and redox potential of ferric and ferrous, an electrochemical cell was designed conventionally to study growth rule and the relationship between redox potential and bacteria growth was built up, and some growth kinetics of Thiobacillus ferrooxidans were elucidated. It demonstrates that the variation of open potential of electrochemical cell ΔE shows the growth tendency of Thiobacillus ferrooxidans, at the initial growth stage, the value of δE increases slowly, when at logistic growth stage, it increases drastically, and the growth rate of bacteria is linear with the oxidation rate of ferrous. The bacteria growth kinetics model is proposed using Monod and Michealis-Menten equation, and the kinetics parameters are got. The consistence of the measured and the calculated results proves that it is proper to use the proposed kinetics model and the electrochemical cell method to describe the growth rule of Thiobacillus ferrooxidans. Foundation item: Project (50204001) supported by the National Science Foundation of China     

Preparation of p-menthane hydroperoxide from p-menthane in presence of metalloporphyrins

The aerobic oxidation of p-menthane to p-menthane hydroperoxide (PMHP) in the presence of metalloporphyrins was investigated in an intermittent mode under an atmospheric pressure of air. Several important reaction parameters, such as the structure of metalloporphyrin, the air flow rate, and the temperature, were studied. The preliminary mechanism of the aerobic oxidation of p-menthane catalyzed by metalloporphyrins was also discussed. The results show that the reaction is greatly accelerated by the addition of metalloporphyrins at very low concentration, in terms of both the yield and formation rate of PMHP, and the high selectivity of PMHP is maintained during the reaction. Temperature of 120 ℃ and reaction time of around 5 h are the optimal conditions for the best result in the presence of 0.06 mmol/L monomanganeseporphyrins ((p-Cl)TPPMnCl). Furthermore, the yield of PMHP is increased remarkably when the reaction is carried out under programmed temperature compared with the constant temperature. When the reaction is catalyzed by 0.06 mmol/L((p-Cl)TPPMnCl) at the air flow rate of 600 mL/min and 120 ℃ for 4 h, and then the temperature is reduced to 110 ℃, for another 4 h, the yield of PMHP reaches 24.3%, which is higher than that of the reaction at a constant temperature of 120 ℃ or 110 ℃ for 8 h.     

Coating of Fe, Ni on α-alumina microspheres by heterogeneous precipitation

1INTRODUCTION Themagneticmetal coatedceramicoxides,core shellstructuralcompositematerials,inwhichthinmetallicfilmsarecoatedonaceramicoxide matrixwithmicrometerparticlesizes,areattrac tiveduetothecombinationofthefunctionalchar acteristicsofmetalsandmechanicalpropertiesoftheceramicmatrix.Theceramic basedtransition metal coated,core shellcompositessuchasNi coatedAl2O3[1],Fe coatedAl2O3[2],FeNi coated Al2O3[3]orCoFe coatedSiO2[4],havebeenfoundtoexhibitinterestingfunctionalperformancesdue…     

Organic light emitting diodes with p-Si anodes and semitransparent Ce/Au cathodes

The Ce (x nm)/Au (15 nm) stacked layers were used as semitransparent cathodes in the top-emission organic light emitting devices (TOLEDs) fabricated on a p-type silicon anodes and substrate, where x varies from 4 to 16. The consequence of the Ce layer thickness on transmittance and the device performance were studied when the organic layers NPB (60 nm)/ALQ (60 nm) were kept unchanged, where NPB was N, N′-bis-(1-naphthl)-diphenyl-1, 1′-biphenyl-4, 4′-diamine, and AlQ is tris-(8-hydroxyquinoline) aluminum. The cathode of Ce (11 nm)/Au (15 nm) has a transparency of 46%, and the TOLED with it achieves the highest luminescence efficiencies: a current efficiency of 0.91 cd/A at 13.7 V and a peak power efficiency of 0.28 lm/W at 9 V. The turn-on voltage is 3.0 V. The Ce/Au cathode is both chemically and electrically stable.     

酞菁铜薄膜光电晶体管的制备与特性

无机光敏器件难于做成大面积光电传感器,且其生产成本高、工艺复杂,而有机光敏器件多采用二极管或平面场效应三极管结构,导致光电流增益小或驱动电压较大.针对这些问题,提出一种新的器件结构.采用真空蒸镀和溅射的方法,制备了结构为氧化铟锡(ITO)/酞菁铜(Cu Pc)/铝(Al)/酞菁铜(Cu Pc)/铜(Cu)的有机光电晶体管.对器件的光电特性进行了测试分析,结果显示晶体管的I-V特性表现出显著的不饱和特性和光敏特性.当发射极集电极偏压为3 V时,器件无光照时电流放大系数为16.5,当625 nm光照射时的电流放大系数为266.2.     

Dielectric Properties of Ag（Nb1-xTax）O3 and Bi2O3 Doped Ag（Nb1-xTax）O3 Ceramics

Dielectric properties of Ag（Nb1-xTa）O3 and Bi2O3 doped Ag（Nb1-xTax）O3 solid solutions were investigated. The results show that with the increase of Ta content （x）, the sintering temperature increased, and the dielectric loss （tanδ） and the temperature coefficient （αc） decreased. Ag（Nb1-xa）O3 （x=0.4） ceramics sintered at 1 100℃ had the highest permittivity （516.8） and a lower tanδ （0.0021） at 1 MHz, and its temperature coefficient was about 191 ppm/℃. The sintering temperature of Ag（Nb1-xTa）O3 （x=0.4） was lowered by the addition of Bi2O3, and its dielectric properties were improved. Ag（Nb0.6Ta0.4）O3 ceramics with 2.5 wt% Bi203 addition presented the optimum dielectric properties （ε=566, tanδ= 0.0007 and αc≈0ppm/℃） （1 MHz）,     

单极型有机半导体酞菁铜晶体管的工作特性

根据试制的Au／CuPc／Al／CuPc／Au结构的垂直导电沟道有机薄膜晶体管的测试结果,分析了该晶体管的工作机理．由实验结果可知,驱动电压低,呈不饱和电流-电压特性．晶体管的工作特性依赖于栅极电压和铝电极的结构,垂直导电沟道有利于改善有机晶体管的工作特性．     

Structural stability and magnetism of metastable Ni-Pt intermetallic compounds studied by ab initio calculation

The self-consistent electronic structure calculations were carried out with the accurate frozen-core full-potential projector augmented-wave method on 13 Ni-Pt intermetallic compounds of simple crystalline structures, i.e. A15, D0₁₉, D0₃ and L1₂ Ni₃Pt and NiPt₃, and α-NiAs, B1, B2, L2 _a , and L1₀ NiPt. The calculations reveal that the L1₂ Ni₃Pt, L1₀ NiPt and L1₂ NiPt₃ are energetically more stable than their respective competitive structures, indicating that the three structures may be formed in some appropriate conditions. The obtained results match well with the experimental observation or other theory predictions. It is found that there is hybridization between Ni 3d and Pt 5d states, which may significantly affect the structural stability and magnetism of metastable Ni-Pt intermetallic compounds. Supported by the National Natural Science Foundation of China (Grant Nos. 50531040, 50871058), the Ministry of Science and Technology of China (Grant No. 2006CB605201), and the Administration of Tsinghua University     

Fabrication and properties of Ag/Mg<Subscript>0.2</Subscript>Zn<Subscript>0.80</Subscript>/La<Subscript>0.67</Subscript>Ca<Subscript>0.33</Subscript>MnO/p<Superscript>+</Superscript>-Si resistive switching heterostructure devices

Mg_0.2Zn_0.8O (MZO)/La_0.67Ca_0.33MnO (LCMO) heterostructure was deposited on p⁺-Si substrates by sol-gel spin coating technique. The Ag/MZO/LCMO/p⁺-Si devices exhibit a bipolar, reversible, and remarkable current-voltage characteristic at room temperature. An obvious multilevel resistive switching effect is observed in the devices. The dominant conduction mechanism of the devices is trap-controlled space charge limited current. The resistance ratio of high resistance state and low resistance state of the devices is about six orders of magnitude, and the degradation is invisible in the devices after 250 successive switching cycles. The present results suggest that the Ag/MZO/LCMO/p⁺-Si devices may be a potential and multilevel candidate for nonvolatile memory application.     

Ways of constructing optimal magic cube of order n when ( n , 2·3·5·7)=1

An optimal magic cube of order n is a magic cube whose row sums, column sums and oblique sums of 9n layers are n(n ³ + 1)/2. The author proved that optimal magic cubes of order n may be constructed as long as n and 2, 3, 5, 7 are relatively prime, and a formula for making optimal magic cubes by using optimal Latin squares and optimal magic squares was given. Foundation item: Supported by the Arts and Science Foundation of Central South University (No.2000007) Biography of author: CHEN Xiao-song, associate professor, born in 1956, majoring in algebra and number theory.     

Characterization of tricalcium phosphate solubilization by Stenotrophomonas maltophilia YC isolated from phosphate mines

The phosphate solubilizing characteristics of a strain YC, which was isolated from phosphate mines (Hubei, China), were studied in National Botanical Research Institute’s phosphate (NBRIP) growth medium containing tricalcium phosphate (TCP) as sole phosphorus (P) source. The strain YC is identified as Stenotrophomonas maltophilia (S. maltophilia) based upon the results of morphologic, physiological and biochemical characteristics and 16S rRNA sequences analysis. The results show that the strain S. maltophilia YC can solubilize TCP and release soluble P in NBRIP growth medium. A positive correlation between concentration of soluble P and population of the isolate and a negative correlation between concentration of soluble P and pH in the culture medium are observed from statistical analysis results. Moreover, gluconic acid is detected in the culture medium by HPLC analysis. It indicates that the isolate can release gluconic acid during the solubilizing experiment, which causes acidification of the culture medium and then TCP solubilization. S. maltophilia YC has a maximal TCP solubilizing capability when using maltose as carbon source and ammonium nitrate as nitrogen source, respectively, in NBRIP growth medium. Foundation item: Project(2004CB619201) supported by the Major State Basic Research and Development Program of China; Project(Z200515002) supported by the Key Project Foundation of the Education Department of Hubei Province, China; Project(GCP200801) supported by the Open Research Fund of Key Laboratory for Green Chemical Process of Ministry of Education, China; Project(Q200811) supported by the Youths Science Foundation of Wuhan Institute of Technology, China     

Effect of silver growth temperature on the contacts between Ag and ZnO thin films

Highly c-axis oriented ZnO thin films were deposited on Si substrates by the pulsed laser deposition (PLD) method. At different growth temperatures, 200 nm silver films as the contact metal were deposited on the ZnO thin films. The growth temperatures have great influence on the crystal quality of Ag films. Current-voltage characteristics were measured at room temperature. The Schottky contacts between Ag and ZnO thin films were successfully obtained when silver electrodes were deposited at 150°C and 200°C. Ohmic contacts were formed while the growth temperatures were lower than 150°C or higher than 200°C. After analysis, the forming of Ag/ZnO Schottky contacts was shown to be dependent on the appearance of the p-type inversion layer at the interface between Ag and ZnO layers.