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.     

聚合物材料的快重离子辐照效应

简要介绍了快重离子辐照损伤的特点,通过与低电离辐射粒子辐照在聚合物材料中产生的效应的类比论述了快重离子辐照在聚合物材料中产生的效应及其研究现状 ,并结合快重离子辐照效应的应用展望了该领域未来的发展.The irradiation effects in polymers induced by swift heavy ions were reviewed in comparison with that induced by low ionization particles based on the characteristics of swift heavy ion irradiations. It is shown that bond breaking and cross linking, gas releasing, amorphization and carbonization of polymers depend strongly on the electronic energy loss. Besides special effects such as alkynes production, can be induced under swift heavy ion irradiation. The perspectives...     

快重离子辐照引起Ni/SiO2界面原子混合及相变研究

在室温下用308 MeV的Xe离子和853 MeV的Pb离子辐照Ni/SiO2样品, 用卢瑟福背散射和X射线衍射技术对样品进行了分析。 通过分析Ni/SiO2样品中元素成分分布和结构随离子辐照剂量和电子能损的变化, 探索了离子辐照在Ni/SiO2样品中引起的界面原子混合与结构相变现象。 实验结果显示, Xe和Pb离子辐照均能引起明显的Ni原子向SiO2基体的扩散并导致界面附近Ni, Si和O原子的混合。 实验观测到低剂量Xe离子辐照可产生NiSi2相, 而高剂量Xe离子辐照则导致了Ni3Si和NiO相的形成。 根据热峰模型, Ni原子的扩散和新相的形成可能由沿离子入射路径强电子激发引起的瞬间热峰过程驱动。Ni/SiO2 interface were irradiated at room temperature with 308 MeV Xe ions to 1×1012, 5×1012 Xe/cm2 and 853 MeV Pb ions to 5×1011 Pb/cm2, respectively. These samples were analyzed using Rutherford Backscattering Spectrometry (RBS) and X ray diffraction spectroscopy (XRD), from which the intermixing and phase change were investigated. The obtained results show that both Xe and Pb ions could induce diffusion of Ni atoms to SiO2 substrates and result in intermixing of Ni with SiO2. Furthermore, 1.0×1012 Xe/cm2 irradiation induced the formation of NiSi2 and 5.0×1012 Xe/cm2 irradiation created Ni3Si and NiO phases. The diffusion of Ni atoms and the formation of new phase may be driven by a transient thermal spike process induced by the intense electronic energy loss along the incident ion path.     

金属材料中高能重离子辐照效应的理论描述

简要介绍了高能重离子在金属材料中引起辐照效应的主要理论 ,特别是与电子能损引起的缺陷产生与演化、离子潜径迹形成、辐照相变以及各向异性塑性形变等效应相应的理论描述.Experimental results showed that, for high energy heavy ion irradiations, electronic energy loss could play a dominant role in damage process in solid materials. In order to explain the experimental phenomena and results, a series of theoretical models based on Coulomb explosion or thermal spike mechanisms have been proposed. In the present paper, more attention was paid to theoretical expressions of high energy heavy ion irradiation induced effects in metallic materials ...     

离子辐照单晶Si损伤效应的研究

回顾了低能离子注入单晶Si经由核弹性碰撞引起的损伤特征及其常规的研究方法,介绍了快重离子辐照单晶Si经由电子能损引起的损伤特点及研究现状,并对该领域的研究作了展望. The radiation damage in silicon induced by low energy ion implantation was briefly reviewed together with a short introduction to the common techniques in the area. The damage characteristics of swift heavy ion irradiation in silicon and its investigations were introduced with emphasis on the effects induced by processes of electronic energy losses. It is shown that swift heavy ion can induce defects far beyond the projected range and up to 28 MeV/μm the electronic energy ...     

Modification of Fe/Cu multilayers under 400 keV Xe20+ irradiation

Two kinds of Fe/Cu multilayers with different modulation wavelength were deposited on cleaved Si(100) substrates and then irradiated at room temperature using 400 keV Xe²⁰⁺ in a wide range of irradiation fluences. As a comparison, thermal annealing at 300—900℃ was also carried out in vacuum. Then the samples were analyzed by XRD and the evolution of crystallite structures induced by irradiation was investigated. The obtained XRD patterns showed that, with increase of the irradiation fluence, the peaks of Fe became weaker, the peaks related to Cu-based fcc solid solution and Fe-based bcc solid solution phase became visible and the former became strong gradually. This implied that the intermixing at the Fe/Cu interface induced by ion irradiation resulted in the formation of the new phases which could not be achieved by thermal annealing. The possible intermixing mechanism of Fe/Cu multilayers induced by energetic ion irradiation was briefly discussed.     

纯金属中电子能损效应的实验研究

简要评述了快重离子辐照在纯金属中引起的电子能损效应的实验研究结果 ,特别是强电子能损在金属中引起的辐照缺陷的部分退火、新缺陷的产生 .离子潜径迹的形成和辐照相变等. As swift heavy ions are available for irradiation damage study, it has been tried to evidence whether electronic energy loss might play a role in the damage processes of metallic targets. Experimental investigations showed that, as increase of electronic energy loss, large amount of electronic energy loss can result in radiation annealing of part of defects produced by elastic collisions, defect creation, latent track formation, as well as phase transition, and so on. Pure metals...     

钨辐射损伤随辐照剂量变化的重离子辐照模拟研究

采用重离子辐照模拟方法和正电子湮没寿命测量技术研究了钨辐射损伤随辐照剂量的变化。20,60和90dpa（每个原子的位移次数）辐照损伤水平的实验结果表明,辐照在钨中产生单空位、双空位、位错和空位团等缺陷;随辐照剂量的增大,单空位、双空位和位错浓度增加,空位团的尺度和浓度都随之增大。Radiation damage in W has been studied as a function of irradiation dose by heavy ion simulation and positron annihilation lifetime measurement. The experimental results of 20, 60 and 90 dpa irradiations illustrate that the mono-and di-vacancies, dislocations and vacancy clusters are produced by the irradiation. The concentrations of the mono-and di-vacancies and dislocations and both the concentration and size of the vacancy clusters or voids all increase with the increasing of the irradiation dose.     

快重离子辐照金红石型TiO2的肿胀效应及化学蚀刻行为研究

二氧化钛（Titatium Dioxide,简称TiO₂）晶体在中能重离子辐照时表面会出现肿胀效应, 肿胀高度与入射离子的电子能损和辐照注量有关。 辐照后的TiO₂在一定条件下能够被氢氟酸溶液化学蚀刻,化学蚀刻的电子能损阈值为8.2keV/nm,未辐照TiO₂呈现几乎零蚀刻率。要达到饱和蚀刻深度,辐照离子的注量必须大于或等于1×1013ions/cm2。采用离子辐照的潜径迹理论分析研究了辐照损伤及对化学蚀刻的影响, 快重离子辐照结合化学蚀刻是制备TiO₂微结构的有效方法。 There appears volume swelling on the surface of the irradiated rutile TiO₂ crystal and the volume swelling is affected by the ion fluence and the electronic stopping power. To induce adequate irradiation damage for the chemical etching, the irradiation parameters must fulfill some requirement. There is minimum electronic stopping power for the chemical etching of the irradiated region in TiO₂ crystal, which is about 8. 2 keV/nm. If the ion fluence is below 1×1013ions/cm2, the saturated etching depth of the irradiated region in TiO₂crystal cannot be reached. The irradiation damage based on latent track formation frame and the theoretical linkage to the etching technique is investigated. It is hopeful to fabricate micro and nano scale structurce in rutile TiO₂ crystal by using the ion irradiation and chemical etching technique.      

利用高能离子模拟研究反应堆结构材料中的辐照效应

简要介绍了载能粒子辐射损伤对反应堆结构材料性能的影响,阐述了载能粒子束特别是高能离子束开展模拟研究的优势,并举例说明了国内利用高能重离子模拟研究反应堆结构材料辐射效应取得的进展。实验结果和理论分析表明,载能离子特别是高能离子辐照非常适合用于模拟研究反应堆结构材料中由粒子辐射引起的材料微观结构和宏观性能变化,是模拟研究反应堆结构材料辐射效应的非常有效的手段。 Radiation damage in structural materials of fission/fusion reactors is mainly attributed to the evolution of intensive atom displacement damage induced by energetic particles （ n, α and/or fission fragments） and highrate helium doping by direct α particle bombardments and/or （n, α） reactions. It can cause severe degradation of reactor structural materials such as surface blistering, bulk void swelling, deformation, fatigue, embrittlement, stress erosion corrosion and so on that will significantly affect the operation safety of reactors. However, up to now, behavior of structural materials at the end of their service can hardly be fully tested in a real reactor. In the present paper, damage process in reactor structural materials is briefly introduced, then the advantages of energetic ion implantation/irradiation especially high-energy heavy ion irradiation are discussed, and several typical examples on simulation of radiation effects in reactor candidate structural materials using high-energy heavy ion irradiations are introduced. Experimental results and theoretical analysis suggested that irradiation with energetic particles especially high-energy heavy ions is a very useful technique for simulating the evolution of microstructures and macro-properties of reactor structural materials.     

keV质子辐照Kapton/Al的能量传输过程

采用TRIM和SRIM2003软件模拟计算了10—300keV能量区间质子辐照Kapton/Al的能量传输过程. 依据模拟结果选取了辐照能量参数, 在室温真空条件下, 采用空间综合辐照设备对Kapton/Al进行了质子辐照. 借助于表面红外光谱技术, 对Kapton的重要官能团特征峰做了定量分析, 通过特征峰处吸光度的变化得到了典型分子键的损伤截面. 平均损伤截面和电子能损的强烈依赖关系及TRIM计算结果一致说明keV质子辐照Kapton/Al的辐照损伤主要来自电子能损效应. 太阳吸收比的变化趋势和模拟结果都表明在入射能量80keV附近, 质子辐照Kapton/Al的辐照效应最大.     

Defects mediated diffusion in Pt/Co/Pt multilayers induced by dense electronic excitations

Present study compares the effects of 200 MeV Ag¹⁵⁺ and 100 MeV O⁷⁺ ion irradiations on the structural, interfacial mixing and magnetic properties of annealed Pt/Co/Pt layers fabricated by DC magnetron sputtering. X-ray diffraction analysis shows that ion irradiations coupled with post annealing results in the formation of the face centred tetragonal L1₀ CoPt phase. Irradiation using 200 MeV Ag¹⁵⁺ ions having higher ionizing energy transfer to the film was found to be more efficient in causing structural phase transition as compared with that using 100 MeV energy O⁷⁺ ions having lower ionizing energy transfer at similar fluence. Rutherford back scattering analysis reveals the role of defect mediated inter-atomic diffusion in tailoring the alloy composition of the film irradiated by different energetic ions. A broad magnetic switching field distribution for O⁷⁺ ion irradiated films compared to Ag¹⁵⁺ ion irradiation was evident from the magnetic measurements. The contribution of alloy composition to switching field distribution has been discussed in details. Above results showed that the electronic energy loss and fluence dependent defects, generated by irradiation, played an important role in tuning the structural, atomic diffusion and magnetic reversal properties of Pt/Co/Pt.     

Alloy formation at the Ni–Al interface for nickel films deposited on Al(110) surfaces

Alloy formation at the Ni–Al interface for thin nickel films deposited on Al(110) surfaces has been studied using high-energy ion scattering/channeling (HEIS) and X-ray photoelectron spectroscopy (XPS). For nickel atoms deposited at room temperature on Al(110), a large amount of nickel–aluminum intermixing occurs at the interface. For the first two monolayers (ML) of deposited nickel, an NiAl-like compound is formed. The intermixing continues with a different rate, forming an Ni₃Al-like compound for nickel coverages from 2 to 8 ML, at which point a nickel metal film begins to grow on the surface. Nickel atoms deposited at 250°C on the Al(110) surface exhibit no surface compound formation, but diffuse up to 400 Å into the aluminum substrate. Interatomic potentials based on the embedded-atom method (EAM) are used in a Monte Carlo approach to simulate the evolution of the Ni–Al(110) interface as a function of the nickel coverage. The calculated ion-scattering yields and X-ray photoelectron intensities from nickel and aluminum atoms in these simulated interfaces are in good quantitative agreement with the experimental results. The simulations show a high-density Ni–Al alloy forming at the Al(110) surface which apparently inhibits outward diffusion of aluminum, leading to the more nickel-rich alloy and finally nickel film growth. The ion-scattering simulations show an unusually large amount of backscattering occurring below the Ni–Al(110) interface, apparently associated with defocusing of the incident ion beam.     

Radiation enhanced diffusion in face centered cubic cu-zn alloys

The enhancement of diffusion by neutron irradiation has been investigated on a Cu-36 percent Zn alloy for various neutron fluxes and irradiation temperatures by means of in-pile measurements of electrical resistivity. For fresh samples the diffusion rate depends on temperature with an activation energy of 0.35 eV. During repeated irradiations the diffusion rate decreases and becomes nearly temperature independent. The variation of the concentration of interstitials and vacancies with irradiation time has been numerically calculated for various neutron fluxes, irradiation temperatures and sink concentrations. A comparison of the experimental and theoretical results shows that the point defects annihilate in fresh samples mainly by pair recombination and in samples which had been repeatedly cycled by pair recombination and at fixed sinks. Point defect clusters acting as sinks are created during the course of the irradiation as shown by electron microscope investigations. The radiation enhanced diffusion rate was found to depend on interstitials only, the activation energy of which was determined to 0.70 eV.     

Conductivity of irradiated Kapton in relation to energy loss of ions and electrons

Abstract

We have studied the effects of 2.5 MeV electron irradiation and ion (C, N, F, Si and Kr) bombardment on the electrical conductivity of a polyimide (Kapton-H) with ion energies ranging between 320 keV (N) and 1.25 GeV (Kr). In this wide range of situations we have tried to sort out the respective effects of nuclear and electronic excitation energy losses.

For all ion irradiation the conductivity is found to scale with the electronic excitation absorbed dose: i.e. a power law of conductivity versus absorbed dose with an exponent around 9 is observed. At a given absorbed dose (in Gray units) the efficiency of each ion to enhance conductivity is found to be proportional to the electronic energy loss; electrons are much less efficient than ions and thus collective excitations are required to achieve this process.

The nuclear energy loss can perhaps play some role at conductivities higher than 100 Ω^?1 m^?1, but its effects are negligible in the range explored here.     

Wetting, Bonding and Interfacial Energy of Nanocrystalline Metal Particles on Crystalline DCH Polymer and Amorphous Carbon Substrates

Experimental results concerning the interaction between a variety of nanocrystalline metals (gold, silver, nickel and chromium) and both crystalline polymer [poly-DCH (1,6-di (N-carbazolyl)-2,4-hexadiene)] and amorphous carbon substrates, are presented and analyzed. Attention is focused on aspects of the interaction that concern interfacial bonding, its correlation with the cohesive energies of the various metals and the energy of the interfaces. Experimental contributions include qualitative estimates of the magnitude of interfacial energies for the crystalline polymer/metal and amorphous carbon/metal interfaces and a direct measurement of the interfacial energies for gold and silver nanocrystals deposited on the amorphous carbon substrate. The sequence of interfacial energy values for the polymer/metal and amorphous carbon/metal systems is also determined. The interfacial energies for both the poly-DCH and amorphous carbon substrates decreases in the order silver, gold, nickel, and chromium, as expected from cohesive energy, melting point and surface energy data for these elements. The crystalline polymer/metal interfaces were examined for the presence of orientation relationships using selected area diffraction and optical diffractometry of high-resolution TEM images. No orientation relationships were found for any of the polymer/metal combinations spanning a large range of metal reactivities. Lack of atomic matching or some as yet unknown surface condition on the polymer may be responsible for this effect.     

快重离子辐照对非晶态SiO2薄膜光致发光谱的影响

用湿氧化法在单晶硅表面生长了非晶态SiO2薄膜,再用高能Pb和Xe离子对薄膜进行辐照,最后用荧光光谱分析了辐照参数(剂量、电子能损值)与发光特性改变的相关性.研究发现,快重离子辐照能显著影响薄膜的发光特性,进一步分析显示,辐照导致了SiO2薄膜内O-Si-O缺陷、缺氧缺陷和非桥式氧空位缺陷的产生,且缺氧缺陷和非桥式氧空...     

He,Au离子辐照AuCu_3致元素表面偏析

采用磁控溅射方法在单晶硅(111)衬底上制备了AuCu_3薄膜,用2 MeV He离子和1 MeV Au离子对薄膜进行辐照,用卢瑟福背散射对He,Au离子辐照前后AuCu_3薄膜近表面的成分变化进行了分析,对不同离子辐照导致的表面元素偏析行为进行了研究.结果表明:当2 MeV He离子辐照时,随着辐照剂量增大,观察到样品近表面Au元素偏析的趋势;当1 MeV Au离子辐照时,随着辐照剂量增大,观察到样品近表面Cu元素偏析的趋势,与He离子辐照相反.通过对He,Au离子在样品中产生的靶原子空位及其分布分析,发现靶原子空位浓度分布的梯度是导致两种不同表面元素偏析趋势的原因,空位扩散是其中的主要机理.