高温超导／铁磁多层膜样品制备与输运性质的初步研究

本介绍我们对高温超导／铁磁多层膜样品的初步研究结果。利用准分子脉冲激光淀积方法制备了由高温超导ＹＢａ２Ｃｕ３Ｏ７薄膜与铁磁巨磁电阻材料Ｐｒ．７Ｓｒ．３ＭｎＯ３薄膜组成的三夹层型和台阶边缘结型多层膜样品。对ＹＢａ２Ｃｕ３Ｏ７／Ｐｒ．７Ｓｒ．３ＭｎＯ３多层膜样品输运性质测量表明样品中存在超导转变及铁磁相变。对两种多层膜样品的电阻随温度变化测量曲线进行了讨论。     

YSZ／Si上溅射BSCCO超导膜的生长机理分析

本研究了利用ＹＳＺ（Ｙ稳定的ＺｒＯ２）缓冲层在Ｓｉ衬底上单靶偏轴溅射Ｂｉ－Ｓｒ－Ｃａ－Ｃｕ－Ｏ高温超导薄膜的工艺条件，给出了ＹＳＺ和ＢＳＣＣＯ薄膜的性能测试结果，并根据电镜分析结果，提出了ＢＳＣＣＯ薄膜的螺旋柱状生长机理。     

高能核－核作用中不同带电强子快度分布

在反应体质心系中，依据热化模型并考虑碰撞参量的涨落及核阻止性，对工作在ＢＮＬ／ＡＧＳ上Ｅ－８０２合作组给出的中心和周边Ｓｉ与Ａｕ、Ｃｕ和Ａｌ相互作用的强子快度分布进行了分析和讨论．     

Tc=95K的NdBa2Cu3Ox高温超导外延薄膜的研制

本采用倒筒式直流溅射法原位生长和Ｔｃ值为９５Ｋ的ＮｄＢａ２３Ｃｕ３Ｏｘ外延薄膜，样品的ＸＲＤ分析表明，样品为强烈ｃ轴织构，ｃ轴晶胞参数为１．１７４ｎｍ，样品衍射峰的ＦＷＨＭ＝０．２９°，ＲＢＳ分析表明：薄膜的化学计量为Ｎｄ１．０Ｂａ２．０Ｃｕ３．３Ｏｘ。对影响ＮｄＢａ２Ｃｕ３ＯＸ薄膜Ｔｃ值的因素进行了讨论。     

电场对Au—Ag薄膜结构影响的AFM和VAXPS研究

利用原子力显微镜（ＡＦＭ）和变角Ｘ射线光电子谱（ＶＡＸＰＳ）技术研究了Ａｕ－Ａｇ／ＳｉＯ２体系在直流电场作用下，Ａｕ，Ａｇ电迁移的特点及所引起的薄膜结构的变化，观察到较低温度下Ａｕ，Ａｇ聚集状态的显著变化，发现电迁移过程中Ａｕ－Ａｇ薄膜与ＳｉＯ２基底之间存在界面化学反应，膜层中Ａｕ，Ａｇ，Ｓｉ等元素的化学状态发生了相应的变化，这些结构表明ＳｉＯ２表面上Ａｕ－Ａｇ复合薄膜电迁移不只是一个水平方向的扩     

Nd薄膜靶表面氧化过程研究

用Ａｕｇｅｒ电子能谱（ＡＥＳ）对Ｘ光激光实验使用的Ｎｄ薄膜靶的表面氧化进行了分析，结合Ａｒ离子束刻蚀进行元素的深度分布剖析，得到了表面氧化层厚度，所得结果与Ｒｕｔｈｅｒ－ｆｏｒｄ背散射（ＲＢＳ）方法测量的结果相吻合。实验表明，样品暴露在空气中２０至３０ｍｉｎ，氧化即基本达到饱和，相应的氧化层厚度约为２０ｎｍ。     

ESR研究非晶Ag￣＋导体的晶化

用电子自旋共振（ＥＳＲ）方法对非晶Ａｇ￣＋离子导体０．８５ＡｇＩ～０．１５Ａｇ＿４Ｐ＿２Ｏ＿７的热处理晶化过程进行研究，在样品中掺入微量（约１×１０￣（－３）ｇ／ｇ）的Ｍｎ￣（２＋）或Ｖ￣（４＋）离子作为自旋探针离子，它们的ＥＳＲ谱强度随升温线性减弱，当样品完全晶化时ＥＳＲ谱消失。这样测定的样品完全晶化的温度分别为９８℃（掺Ｍｎ的）和１０８℃（掺Ｖ的）．本文还对Ｍｎ￣（２＋）和Ｖ￣（４＋）的ＥＳＲ谱进行了分析。     

Ag／YBa_2Cu_3O（7－x）、Al／YB_2Cu_3O（7－x）界面特性

利用电学测量方法结合二次离子质谱（ＳＩＭＳ）技术对金属Ａｇ和Ａｌ与ＹＢａ２Ｃｕ３Ｏ（７－ｘ）（ＹＢＣＯ）超导薄膜接触界面电学性质和互扩散特征进行了测试分析．分析结果显示由于Ａｇ和Ａｌ具有不同的化学性质，二者与ＹＢＣＯ界面的互扩散特性有明显不同．这些不同影响到接触界面的电学性质和接触窗口下ＹＢＣＯ的超导性能．在Ａｇ／ＹＢＣＯ样品中，在高于３５０℃以上的温度下氧气氛中退火将引起Ａｇ和Ｏ的界面互扩散，但对ＹＢＣＯ体内Ｏ的分布及ＹＢＣＯ的超导性能影响不大，且有利于在界面形成好的电学接触；在Ａｌ／ＹＢＣＯ样品中，在高于３５０℃以上的温度下氧气氛中退火后，界面则主要发生Ｏ向Ａｌ膜体内的扩散，并在Ａｌ和ＹＢＣＯ界面生成一不导电的氧化层，这些将影响到ＹＢＣＯ体内Ｏ的分布和接触窗口下的ＹＢＣＯ的超导性能．在合适的退火条件（约５００℃氧气氛中）下退火，Ａｇ与ＹＢＣＯ将形成小的接触电阻，利用剥离工艺制备的样品，其界面接触电阻率ρ（ρｃ＝Ｒ×Ａ）高于是１０（－６）Ωｃｍ２．     

Bi—2212相欠掺杂区域的反常输运性质研究

测量了Ｂｉ２Ｓｒ２Ｃａ１－ｘＹｘＣｕ２Ｏ８单晶样品ａｂ平面内电阻率ρａｂ和多晶样品电阻率ρ．热电势Ｓ随温度Ｔ的变化关系（单晶：ｘ的范围从０到０．１５；多晶：ｘ的范围从０到０．４）．在单晶和多晶样品中，都系统地观察到类似于ＹＢａ２Ｃｕ４Ｏ８，ＹＢａ２Ｃｕ３Ｏ７－ｙ体系中由于自旋能隙出现而引起的输运性质反常现象．详细地讨论了上述实验结果，并与角分辨率光电子能谱实验（ＡＲＰＥＳ），电子拉曼实验结果进行比较，得出Ｂｉ２２１２相欠掺杂区域的电子相图．     

用卢瑟福背散射和弹性背散射分析高T＿c超导薄膜中的元素组份及氧含量

提出了用能量为１．５－２．５ＭｅＶ的质子弹性背散射分析（ｅｌａｓｔｉｃｂａｃｋｓｃａｔｔｅｒｉｎｇ，缩写为ＥＢＳ）来测定薄膜中的氧含量，这个方法对于厚度为几十纳米到几个微米的样品，测量精度约５％。采用ＲＢＳ分析并结合ＥＢＳ分析，可全面测得薄膜中各元素的含量。     

Energetic Ion Effects on the Ion Saturation Current

The ion saturation current is very important in probe theory, which can be used to measure the electron temperature and the floating potential. In this work, the effects of energetic ions on the ion saturation current are studied via particle-in-cell simulations. It is found that the energetic ions and background ions can be treated separately as different species, and they satisfy their individual Bohm criterion at the sheath edge. It is shown that the energetic ions can significantly affect the ion saturation current if their concentration is greater than T_e/(γi2 T_(i2))~(1/2), where Te is the electron temperature, and γ_(i2) and T_(i2) represent the polytropic coefficient and temperature of energetic ions, respectively. As a result, the floating potential and the I V characteristic profile are strongly influenced by the energetic ions. When the energetic ion current dominates the ion saturation current, an analysis of the ion saturation current will yield the energetic ion temperature rather than the electron temperature.     

Nanostructuring by Energetic Ion Beams

Development of nanostructured materials has become of wide interest due to their exotic properties and interesting physics aspects. Energetic ions play a crucial role in the development of nano materials. Ions of different energy regimes have different roles in growth of nano particles. Low energy ions (typically up to a (kiloelectronvolt) keV) in plasma, have been in use for growth of nano particle thin films. Low energy ions (typically a few hundred (kiloelectronvolt) keV) from ion implanters are used for growth of nano particles in a matrix. High energy heavy ions (swift heavy ions) have been in use in recent years for growth of nanostructures and also for modifying nanostructures. Highly charged slow moving ions and focused ion beams too, have potential for creating nanostructures. Out of these several possible roles of energetic ions, there have been developments at NSC Delhi in growth of nanostructures by RF plasma, low energy ions and swift heavy.     

离子辐照引起的金属／绝缘体界面混合与相变研究

载能离子穿过固体界面引起界面原子迁移使界面原子混合和物质成分变化，从而导致界面发生材料相变。简要介绍了载能离子辐照引起金属／绝缘体界面混合效应及相变现象的主要实验研究进展、低能离子和高能离子辐照引起金属／绝缘体界面现象差异，并对离子辐照引起界面混合及相变的机制进行了初步探讨。When penetrating an interface between two kind of solids, energetic ions can induce atomic diffusion at both sides of the interface and then result in intermixing, atom re-distribution or composition change, as well as phase transformation. Main progress on the study of intermixing and phase change at metal/insulator interface induced by energetic ion irradiations, the difference of phenomena occurred at metal/insulator interfaces induced by high-and low-energy ions were briefly reviewed. Furthermore, the possible mechanisms related to intermixing and phase change at metal/insulator interface produced by energetic ion irradiations were also discussed in short words.     

荷能重离子径迹刻蚀纳米通道技术及其应用

纳米通道; 离子径迹刻蚀; 核酸测序; 生物传感器     

载能团簇离子诱发的非线性二次离子发射

载能团簇离子进入固体时, 由于集体相互作用,在入射路径上产生非常高的能量沉积密度。 实验发现, 载能团簇离子的作用结果并不等于团簇中各原子独立作用的总和, 而是具有非线性效应。 就二次离子发射而言, 这种非线性通常与团簇的能量、 团簇的大小、 离子的电荷态以及靶物质的结构有关。 通过研究二次离子发射有助于理解载能团簇离子与物质相互作用过程中的能量沉积与释放机制。 Using energetic cluster as projectile is a unique way to produce simultaneous impacts of several atoms and deposit extremely high energy density in a very small area. The cluster impingement on solids has exhibited some non linear effects not presented in collisions of individual atoms with those solids. The study of the secondary ion emissions can give insight into the energy deposition and relaxation steps of the cluster solid interaction. The dependence of the yields of secondary ion emission induced by clusters on the energy of clusters,cluster sizes,charge states and material structures of the targets was reviewed in this paper.     

用离子辐照模拟研究反应堆结构材料中金属/金属界面原子扩散行为

介绍了利用载能离子辐照模拟研究反应堆结构材料中金属／金属界面原子扩散行为的实验进展,特别是辐照参数（如辐照剂量、辐照温度、核能损、电子能损以及膜结构等）对界面原子扩散行为的影响,并对可能的机理进行了简要的评述。 Atom diffusion at metal/metal interfaces is very important for property of reactor structural materials, which can be simulated by using energetic ion irradiations. The present situation of experimental studies on atom diffusion at metal/metal interfaces induced by energetic ion irradiations is reviewed. The influence of experimental parameters such as the irradiation dose, irradiation temperature, electronic energy loss, nuclear energy loss and the interface structure on the intermixing is emphatically introduced. In addition, the possible mechanisms of metal/ metal intermixing are also briefly described.     

基于HIRFL 的高温应力材料载能离子辐照实验装置

针对未来先进核能装置候选结构材料在高温和应力等条件下抗辐照性能的评价与快速筛选的需求,基于兰州重离子研究装置( HIRFL ) 可提供的离子束流条件,设计制作了国内第一套高温应力材料载能离子辐照装置。该装置由束流扫描及探测系统、高温系统、应力系统、真空冷却系统和远程控制系统等5 部分组成,可以同时提供高温和拉/ 压应力下材料的离子束均匀辐照件,温区覆盖了室温至1 200 °C范围,拉/ 压应力范围为0 ~1176 N,x-y 方向均匀扫描面积可大于40 mmx40 mm。利用该装置,已经成功进行了多次高温和应力条件下载能离子辐照先进核能装置候选材料的实验研究,并取得了初步成果。In order to expedite the evaluation of properties of irradiated materials and the selection of candidate materials for future nuclear energy systems, we developed a specific ion irradiation equipment installed on the Heavy Ion Research Facility of Lanzhou ( HIRFL ) for materials under high temperature and stress. This equipment consists of ion beam scanning and detector system, high temperature load system, stress load system, water cooling system as well as telecommunication and control system. It can supply a wide range of temperature (from room temperature to 1 200 °C ) and stress ( pull / push from 0 to 1 176 N) simultaneously for materials under ion irradiation. The x-y scanning area with high uniformity is larger than 40 mm40 mm. This is the first suit of ion irradiation equipment made in China that can be used to study co-operating effects of high temperature and stress in an irradiated material. It has been successfully used several times for materials irradiations under high temperatures and stress, which proved that the new equipment has very good performances in experiments.     

Effects of Energetic Electrons on Collector and Source Potentials in a Finite Ion Temperature Plasma

Formation of the potential in a two-electron-temperature plasma region facing a floating collector was studied theoretically with a kinetic plasma-sheath model and by electrostatic particle simulation. The electrons were described by truncated full Maxwellian velocity distribution functions and the ions by an accelerated half-Maxwellian velocity distribution function. The collector potential and the plasma source sheath or presheath potential drop were evaluated as functions of the hot to cool electron temperature ratio and the hot electron density ratio using Vlasov and Poison equations. The results showed that the presheath potential drop varied continuously with electron composition ratio for lower values of the electron temperature ratio, while for higher values in a narrow composition ratio range, triple values of the potential were found. Of the two physically acceptable values, the lower was characterized by the cool electrons and the higher by the hot electrons. It is anticipated that a current-free double layer structure is formed in the plasma system between these two potential regions. The collector floating potential, as a function of electron composition ratio, is mainly dominated by the hot electrons, since already a small value of hot electron current is sufficient to compensate the ion saturation current. In order to complete the theoretical investigation we also study the hydrogen plasma system with the XPDP1 particule-in-cell simulation code composed at Berkeley. At certain plasma parameter values formation of a double layer structure was observed. The potential Values on the upper and lower side of the double layer, as well as that of the collector floating potential, corresponded very well to the calculated values. On the upper side the plasma was composed of ions, accelerated through the source sheath potential drop, and electrons consisting of cool full Maxwellian and hot truncated full Maxwellian populations. On the lower side only hot electrons and ions additionally accelerated through the double layer were found.     

中高能重离子碰撞的高能光子测量及相关物理

高能光子探测为研究中高能重离子碰撞的许多重要问题如核物质性质、韧致辐射、阈下和阈上中性介子产生等提供了机遇.简要回顾了近几年国外开展的中能与相对论重离子碰撞高能光子实验概况,并简要介绍了欧洲合作研制的高能光子探测器TAPS的基本构造.另外,用GEANT程序模拟计算了50—1000MeV光子在TAPS标准8×8阵列中的能量响应. The Measurement of energetic photon produced in intermediate energy and relativistic energy heavy ion collisions provides opportunities for investigating many interesting and sophisticated problems such as properties of nuclear matter under extreme condition, bremsstrahlung, neutral meson production both below and above the production threshold in free nucleon nucleon collision. The related experiments performed at GANIL and GSI as well as the structure of the popular used detector ...     

Energetic Characteristics of Oxygen Plasma

A low-temperature oxygen plasma is studied using the thermocouple, probe and spectral method in the range of 2–8 Torr pressure, 30–100 mA discharge currents, 0, 5, 10 m/s pumping velocity. The gas temperature, concentrations of electrons and oxygen atoms in the 3 p⁵P state, and the longitudinal electric field are measured. Radial distributions of gas temperature and electron concentration are obtained. Ranges of pressures and currents are found in which considerable increases in electric field, discharge voltage, temperatures of gas and electrons are observed at pumping switched on. An estimate of the rate constant of the steplike ionization through the O₂(a¹Δg) state is given. The concentration of atomic oxygen in the ground state and excitation constant of the triplet O(3p⁵P) by electron impact are obtained from the solution of the balance equations and our experimental data.