Structures and magnetic behaviours of TiO2—Mn—TiO2 multilayers

The TiO₂--Mn--TiO₂ multilayers are successfully grown on glass and silicon substrates by alternately using radio frequency reactive magnetron sputtering and direct current magnetron sputtering. The structures and the magnetic behaviours of these films are characterised with x-ray diffraction, transmission electron microscope (TEM), vibrating sample magnetometer, and superconducting quantum interference device (SQUID). It is shown that the multi-film consists of a mixture of anatase and rutile TiO₂ with an embedded Mn nano-film. It is found that there are two turning points from ferromagnetic phase to antiferromagnetic phase. One is at 42 K attributed to interface coupling between ferromagnetic Mn₃O₄ and antiferromagnetic Mn₂O₃, and the other is at 97 K owing to the interface coupling between ferromagnetic Mn and antiferromagnetic MnO. The samples are shown to have ferromagnetic behaviours at room temperature from hysteresis in the M--H loops, and their ferromagnetism is found to vary with the thickness of Mn nano-film. Moreover, the Mn nano-film has a critical thickness of about 18.5 nm, which makes the coercivity of the multi-film reach a maximum of about 3.965times 10 ^{- 2} T.     

Amorphous Er2O3 films for antireflection coatings

This paper reports that stoichiometric, amorphous, and uniform Er₂O₃ films are deposited on Si(001) substrates by a radio frequency magnetron sputtering technique. Ellipsometry measurements show that the refractive index of the Er₂O₃ films is very close to that of a single layer antireflection coating for a solar cell with an air surrounding medium during its working wavelength. For the 90-nm-thick film, the reflectance has a minimum lower than 3% at the wavelength of 600 nm and the weighted average reflectances (400--1000 nm) is 11.6%. The obtained characteristics indicate that Er₂O₃ films could be a promising candidate for antireflection coatings in solar cells.     

铁磁薄膜中圆偏振光感应的瞬态磁光Kerr峰的物理起源

使用飞秒时间分辨抽运-探测磁光Kerr光谱技术,实验研究了圆偏振光抽运面内磁化FePt和垂直磁化GdFeCo薄膜的磁化演化动力学,发现在时间延迟零点处均出现瞬态Kerr峰.分析了此Kerr峰的起源,指出此瞬态Kerr峰与铁磁性无关,可能起源于自由电子的顺磁磁化,而顺磁磁化的外磁场来自圆偏振抽运光的逆Faraday效应.基于顺磁磁化模型的计算结果支持此观点.基于此观点,逆Faraday效应感应的磁场脉冲宽度应该与激光脉冲宽度一致.     

两种植物类囊体膜在纳米ZnO 上的组装和光电性质

用水热合成法在掺氟氧化锡(SnO₂: F, FTO)导电玻璃上合成了ZnO 纳米线并用原子力显微镜(AFM)和扫描电镜(SEM)对其进行了表征。利用LB 膜技术将高等植物菠菜(Spinacia oleracea)和海洋绿藻石莼(Ulva lactuca)的类囊体膜分别固定在纳米ZnO 上组装成光电池, 用太阳能测试系统检测比较了其光电性质。研究表明, 由两种植物的类囊体膜LB 膜组成的光电池都能产生光生电流; 蛋白LB 膜的层数显著影响了光电池的光电转化效率, 随着层数的增加, 光电转化效率大大增加。此外, 石莼类囊体膜组装的光电池光电转化效率明显高于菠菜类囊体膜。     

相变存储材料Ge1Sb2Te4和Ge2Sb2Te5薄膜的结构和电学特性研究

采用射频磁控溅射方法制备了两种用于相变存储器的Ge₁Sb₂Te₄和Ge₂Sb₂Te₅相变薄膜材料,对其结构、电学输运性质和恒温下电阻随时间的变化关系进行了比较和分析.X射线衍射(XRD)和原子力显微镜(AFM)的结果表明:随着退火温度的升高,Ge₁Sb₂Te₄薄膜逐步晶化,由非晶态转变为多晶态,表面出现均匀的、     

激发频率对高氢稀释下纳米晶硅薄膜生长特性的影响

利用等离子体增强化学气相沉积技术,在高氢稀释条件下,研究不同激发频率对纳米晶硅薄膜生长特性的影响.剖面透射电子显微镜(TEM)分析结果显示,不同激发频率下制备的纳米晶硅薄膜晶化区均呈锥状结构生长,但13.56 MHz激发频率下制备的纳米晶硅薄膜最初生长阶段存在非晶态孵化层,即纳米晶硅薄膜的形成经历了由非晶态孵化层到晶态结构层的转变.而高激发频率(40.68 MHz)下硅纳米晶则能直接在非晶态衬底上生长形成.Raman谱和红外吸收谱测量结果表明高激发频率(40.68 MHz)下制备的纳米晶硅薄膜不但具有较高     

掺铝氧化锌厚膜制备及其对三甲胺和海产品鲜度的敏感性

用烧结法制备掺铝氧化锌厚膜，把氧化锌粉末分别同０％，１％，３％，５％的Ａｌ２Ｏ３粉末机械研磨混合均匀，在１１００℃下烧３ｈ，再同粘合剂，有机溶剂混合制成浆料，用刮刀法在氧化铝基片上浆料制成膜，在１００℃下烘干后再经１１００℃烧结２ｈ。膜的灵敏度的测量方法是将膜放在玻璃管内加热到测量温度，测量膜暴露在一定浓度ＴＭＡ气体或由牡蛎放出的气体时电阻值的变化。测量温度为２００，２５０，３００℃和４００℃，Ｔ     

High frequency behaviours and Mõssbauer study of field annealed FeCuNbSiB alloy ribbons

This paper investigates the high frequency behaviours and magnetic anisotropy of rapidly solidified FINEMET (Fe_73.5Si_13.5B₉Nb₃Cu₁) alloy ribbons annealed in an applied magnetic field. It finds that the ribbons annealed with the applied magnetic field show much higher resonance frequencies and have even higher permeability at higher frequencies than the samples annealed without the magnetic field and the non-annealed ribbons. M?ssbauer spectroscopy had been employed to study the spatial distribution of the magnetic moments of five selected FINEMET alloy ribbons in different heat-treated conditions. The results show that an easy plane has been established after annealling in the magnetic field, while for the other ribbons this effect is not significant. Hence, the relationship between magnetic field annealing and high frequency property has been bridged by the bianisotropic theory.     

Pb(Zr0.3Ti0.7)O3铁电薄膜激光感生电压效应

采用脉冲激光沉积(PLD)技术在LaSrAlTaO₃(LSATO),LaAlO₃(LAO)和SrTiO₃(STO)的单晶倾斜衬底上成功制备了Pb(Zr_0.3Ti_0.7)O₃(PZT)薄膜,在三种倾斜衬底上生长的PZT薄膜中都首次发现了LIV效应.对PZT/LSATO薄膜在a,c轴两种不同取向择优生长下的LIV效应做了研究,发现在薄膜c轴取向择优生长     

First-principle study on phase Al0.8Ni3Sn0.2 in Sn-Ni-Al alloy as anode for lithium ion battery

The mechanism of lithium intercalation/deintercalation for phase Al_0.8Ni₃Sn_0.2 as anode material used in lithium ion battery was studied carefully based on the first-principle plane wave pseudo-potential method. The calculated results indicated that Sn--Ni--Al alloy had high theoretical capacity when used as anode material, however, there was high initial irreversible capacity loss because of the large volume expansion. Therefore the technological parameters during preparing the Sn-Ni-Al anode should be controlled strictly to make the content of Al_0.8Ni₃Sn_0.2 phase as low as possible and to make the anode consist of promising Sn--Ni and Al--Ni phases. For comparison, an experiment based on magnetron sputtering was done. The result showed that the calculation is in good agreement with the experiment. We found that the first-principle investigation method is of far-reaching significance in synthesising new commercial anode materials with high capacity and good cycle performance.     

Magnetic study of serpentinized harzburgites from the Islas Orcadas Fracture Zone

Magnetic properties and bulk densities of 27 serpentinized harzburgite samples from the Islas Orcadas Fracture Zone, located in the vicinity of the Bouvet Triple Junction, have been measured and analyzed. Polished sections were examined using reflected light and scanning electron microscopy to characterize the size and geometric arrangement of opaque minerals. The relationship between the saturation magnetization (I_S) and remanent coercive force (H_R) is considered in terms of the amount of ferrimagnetic material and maghemitization. A suite of continental serpentinites from Canada is offered as contrast, to consider the role of weathering and maghemitization. Magnetite in the Islas Orcadas serpentinites is variably maghemitized, whereas continental serpentinites do not appear to contain maghemitized oxides. We verify this with optical microscopy, thermomagnetic analyses and cryogenic temperature cycling of saturation remanence. Maghemitization serves to reduce initial magnetic susceptibility, and introduce error in the use of I_S to evaluate the magnetic mode of magnetite. The presence of maghemite and the existence of a three dimensional vein network for magnetite geometry would suggest that magnetic hysteresis parameters can not reliably indicate grain size. Magnetic hysteresis ratios fall in a restricted range regardless of coercivity. The apparent grain size configured in a three dimensional vein network plus maghemitization might be responsible for this observation. Maghemitization does not affect thermal magnetic stability and enhances the geophysical importance of remanence in serpentinites. Paleomagnetic data suggest that important information about the geologic circumstances for oceanic rock serpentinization is embodied in the paleomagnetic records. This observation may be very important for generation of long wavelength aeromagnetic and possibly even satellite magnetic anomalies.     

掺Ga对ZnO电子态密度和光学性质的影响

采用密度泛函理论下的第一性原理平面波赝势方法,研究了掺Ga对纤锌矿ZnO电子态密度和光学性质的影响.从晶体配位场理论分析了掺Ga前后ZnO的成键情况及态密度的变化.计算得到掺Ga后电子浓度为2.42×10²¹ cm^-3,ZnO的载流子浓度提高了10⁴倍.比较分析掺Ga前后ZnO的介电函数、复折射率、吸收光谱和反射光谱可得,ZnO光吸收边向高能端移动,光学带隙增大.在可见光区,ZnO光吸收系数与反射率减小,光透过率显著提高,使ZnO:Ga成为     

Li,N双受主共掺杂实现p型ZnO的第一性原理研究

基于密度泛函理论,采用第一性原理平面波超软赝势法,首先对六方纤锌矿结构的ZnO晶体和N,Li分别掺杂ZnO以及Li-N共掺杂ZnO晶体的几何结构分别进行了优化计算,在此基础上计算得到了未掺杂ZnO晶体和不同掺杂情况下ZnO晶体的能带结构、总体态密度、分波态密度和电荷布居数.利用计算的结果,从理论上分析了Li-N共掺杂ZnO更容易得到稳定的p型ZnO.     

Spectroscopic ellipsometric study of the optical properties of Ag2O film prepared by direct-current magnetron reactive sputtering

The Ag₂O film, as-deposited by direct-current magnetron reactive sputtering at a substrate temperature of 150 °C, clearly shows a preferential orientation (111), and is capable of lowering the threshold value of the thermal decomposition temperature to about 200 °C, which is helpful to its application in optical and magneto-optical storage. This paper fits its optical constants in terms of a general oscillator model by using measured ellipsometric parameters. The fitted oscillator energy 2.487 eV is close to the optical direct interband transition energy value of the Ag₂O film determined by Tauc equation; whereas, the fitted oscillator energy 4.249 eV is far from the fitted plasma oscillator energy 4.756 eV by single-oscillator energy. The photoluminescence spectrum centred at about 2.31 eV indicates a direct-energy gap photoluminescence mechanism of the Ag₂O film.     

纳米氧化锌和菲对长江口附近海域沉积物反硝化作用及功能菌群落结构的影响

本研究在长江口附近海域采集表层沉积物,采用实验室模拟培养与分子生物学手段相结合的方法,通过测定纳米氧化锌(ZnO NPs)和菲(Phe)胁迫下沉积物中NO^-₃-N和NO^-₂-N浓度和反硝化还原酶活性及反硝化细菌基因丰度和群落多样性变化,目的是比较研究ZnO NPs和Phe对河口区沉积物反硝化作用及功能菌群落结构的影响,并探讨其作用过程和可能的作用机制。结果表明:ZnO NPs和Phe对沉积物硝酸盐还原能力和亚硝酸还原能力均产生抑制作用,浓度越高,抑制作用越强,其中亚硝酸盐还原过程受到2种污染物抑制更强烈,加重了沉积物亚硝酸盐的累积。ZnO NPs对沉积物硝酸盐还原能力、硝酸还原酶活性、narG基因丰度的抑制程度大于Phe,Phe对沉积物亚硝酸盐还原能力、亚硝酸还原酶和nirS基因丰度的抑制程度大于ZnO NPs,表明对反硝化还原酶和反硝化功能基因的抑制是外源污染物胁迫影响反硝化过程的主要机制。ZnO NPs和Phe降低了沉积物反硝化菌群落多样性水平,增加沉积物中Halomonas的优势度,降低了Bacillus的优势度,但Phe对沉积物群落多样性和组成的影响更加明显,说明Phe对长江口海区的生态影响大于ZnO-NPs。     

Comparison between the magnetic and petrological characteristics of the peridotites from the gorringe ridge and the peridotites from the mid-ocean ridges

The purpose of our work was to obtain the most possible detailed information about the composition, concentration, and structural features of the magnetic minerals contained in the rock to reveal the differences in the magnetic properties of the peridotites under various circumstances of the mantle magmatism and different conditions of metamorphism. To do this, we examined and analyzed the magnetic and petrographic characteristics of four collections of oceanic and alpinotype spinel peridotites. The main object for comparing the magnetic characteristics was the Gorringe ridge, which lies in the eastern part of the Atlantic Ocean. The peridotite samples from the Gorringe ridge differ from the other collections in many magnetic parameters: I _n , χ, Q, I _rs /I _s , H _c , H _cr , and H _m . The principal question of our work was to clarify the nature of the Earth’s crust where the Gorringe ridge formed. This subject was studied many times in the literature, but the researchers did not reach a common opinion. In accordance with our data, the spinel peridotites from the Gorringe ridge represent a subcontinental lithosphere mantle of the Iberian continental margin. During the metamorphism, the formation of magnetite occurred in the peridotites of the Gorringe ridge in several stages and had a regressive character. Our investigations explain the results of the analysis of the anomalous magnetic field over the Gorringe ridge, which is characterized by sharp roughness and high intensity of the local signchanging anomalies.     

Comparison between petroleum hydrocarbon concentrations and magnetic properties in Chennai coastal sediments,Bay of Bengal,INDIA

Petroleum hydrocarbon concentrations (PHC) of surface sediments along the Chennai coast, India, were measured by UV-Fluorescence (UVF) Spectroscopy and the results are expressed in terms of Chrysene equivalents. The concentration of PHC in sediment varies widely (from 1.88 ppm to 39.76 ppm) as compared to the baseline (1.88 ppm) with higher values obtained in the northern part of the study area. The highest magnetic susceptibility (96.8 × 10⁻⁸ m³kg⁻¹) value was determined from the Chennai harbour area. The magnetic parameters show that the Chennai coastal sediments are dominated by ferrimagnetic minerals. The positive correlation (r² = 0.86; p < 0.05) between petroleum hydrocarbon concentrations and magnetic susceptibility suggests that the magnetic minerals and petroleum hydrocarbons along the Chennai coast are derived from the same sources. Factor analysis shows that the magnetic concentration dependent parameters (χ, χ_ARM and SIRM) covary with the petroleum hydrocarbon concentration, suggesting that large amounts of magnetic minerals originate from anthropogenic activities. It is evident that using magnetic measurements may be considered a simple, rapid, cheap and non-destructive method to determine petroleum hydrocarbon concentrations in coastal sediments. Furthermore, this technique may be applied to petroleum exploration studies. Magnetic susceptibility measurements in sediments have been proposed as complementary or alternative means of exploration and assessment of hydrocarbon reservoirs.     

Teleportation and thermal entanglement in two-qubit Heisenberg XYZ spin chain with the Dzyaloshinski—Moriya interaction and the inhomogeneous magnetic field

This paper studies the average fidelity of teleportation and thermal entanglement for a two-qubit Heisenberg XYZ chain in the presence of both an inhomogeneous magnetic field and a Dzyaloshinski--Moriya interaction. It shows that for a fixed D_z, the increase of b_z will broaden the critical temperature at the cost of decreasing the thermal entanglement. And it can modulate the inhomogeneous magnetic field and the Dzyaloshinski--Moriya interaction for the average fidelity of teleportation to be optimal.     

Super-speed centrifugation at sea using a gimballed platform

The use of a super-speed centrifuge at sea for the recovery of suspended solids or interstitial pore fluids requires a stabilizing platform. In this report, we describe a simple platform gimball and magnetic rotor stabilizer that have been fitted to a Sorvall model SS_?3 super-speed centrifuge. In principle, any centrifuge of comparable weight (86 kg) could be easily adapted for use at sea with gimbals of similar design.The magnetic rotor coupler is designed to eliminate rotor precession when the centrifuge is operated at sea. This attachment is particularly useful when the Sorvall SS_?3 (equipped with a conventional rotor) is used to recover interstitial pore fluids.     

缢蛏(Sinonovacula constricta)重组Fe-铁蛋白和Mn-铁蛋白的性质解析

利用缢蛏(Sinonovacula constricta)重组铁蛋白富集Fe~(3+)和Mn~(2+)制备重组Fe-铁蛋白和Mn-铁蛋白,通过扫描电镜、X射线能量色散能谱仪(EDS)和MALDI TOF/TOF质谱系统测定蛋白的表面形貌变化、金属元素的能量变化和肽段分子量。利用综合物性测量系统(PPMS)测定蛋白纳米颗粒在室温300K,外加磁场3T下的磁学性质变化。结果显示,重组Fe-铁蛋白和Mn-铁蛋白与空白相比,表面形貌发生明显变化,Fe-铁蛋白仍为小球状,Mn-铁蛋白聚集体呈片层花球状,Cd-铁蛋白聚集体呈小圆球状,Mn-铁蛋白富集Cd~(2+)后呈片层花瓣散落状。Fe-铁蛋白和Mn-铁蛋白分别检测出相应金属元素且都有其特征能量态。两种重组蛋白的肽谱图与空白组相比,除铁蛋白保守肽段外还出现各自的特征肽段,推测与铁蛋白对Fe~(3+)和Mn~(2+)的富集功能密切相关。Fe-铁蛋白和Mn-铁蛋白纳米颗粒磁滞回线形状与铁蛋白空白组基本相同,呈顺磁性特征,磁性强度随Fe~(3+)和Mn~(2+)富集量的增加而增大。通过比较Fe-铁蛋白和Mn-铁蛋白与空白组在富集Hg~(2+)、As O43–和Cd~(2+)三种重金属离子方面能力的差异,发现Fe-铁蛋白对Hg~(2+)、AsO_4~(3–)和Cd~(2+)三种重金属的富集能力是空白组的2.4倍、1.7倍和3.7倍。Mn-铁蛋白对Hg~(2+)、AsO_4~(3–)和Cd~(2+)三种重金属离子在相同条件下的富集能力也有明显提高,分别为铁蛋白空白组的1.8倍、3.0倍和4.6倍。本研究结果为Fe-铁蛋白和Mn-铁蛋白在重金属污染治理方面的应用提供了数据参考。