Mechanism of defect evolution in H+ and He+ implanted InP

The defect evolution in InP with the 75 keV H⁺ and 115 keV He⁺ implantation at room temperature after subsequent annealing has been investigated in detail. With the same ion implantation fluence, the He⁺ implantation caused much broader damage distribution accompanied by much higher out-of-plane strain with respect to the H⁺ implanted InP. After annealing, the H⁺ implanted InP did not show any blistering or exfoliation on the surface even at the high fluence and the H₂ molecules were stored in the heterogeneously oriented platelet defects. However, the He molecules were stored into the large bubbles which relaxed toward the free surface, creating blisters at the high fluence.     

调幅W(Mo)/Cu纳米多层膜He+离子辐照响应行为

用磁控溅射技术制备不同调幅波长 (L) 的W(Mo)/Cu纳米多层膜,所制膜系在60 keV氦离子 (He⁺) 辐照条件下注入不同剂量: 0, 1×10¹⁷ He⁺/cm², 5×10¹⁷ He⁺/cm². 用X射线衍射仪 (XRD) 和高分辨透射电子显微镜(TEM)表征W(Mo)/Cu纳米多层膜辐照前后微观结构. 研究结果表明: 1) He⁺离子轰击引起温升效应是导致沉积态亚稳相β-W 转变成稳态 α-W相的主因, 而与调幅波长无明确关联; 2) 纳米多层结构中W(Mo) 和Cu膜显现出的辐照耐受性与调幅波长相关, 调幅波长越小, 抗He⁺的辐照性能越强; 3) 在5×10¹⁷ He⁺/cm²注入条件下, 观察到He团簇/泡在纳米结构W(Mo) 和Cu膜中的积聚行为存在明显差异: 在W (Mo) 膜中He团簇/泡的分布与晶粒取向相关, He团簇/泡倾向于沿W (211) 晶面分布; 而Cu膜非晶化且He团簇/泡在其体内呈均匀分布. 关键词： W(Mo)/Cu纳米多层膜 +辐照')" href="#">He⁺辐照 He团簇/泡 相转变     

中能高浓度氦离子注入对钨微观结构的影响

采用15 keV, 剂量1×10¹⁷/cm², 温度为600 ℃氦离子注入钨, 分别以块体钨研究氦离子对钨的表面损伤; 以超薄的钨透射电镜样品直接注入氦离子, 研究该条件下钨的微观结构变化, 以了解氦离子与钨的相互作用过程; 采用扫描电子显微镜、聚焦离子束扫描显微镜、透射电子显微镜、高分辨透射电子显微镜等分析手段研究氦离子注入对钨表面显微结构的影响及氦泡在钨微观结构演化中的作用.     

Positron annihilation studies of defects in helium-irradiated silicon

Positron annihilation studies have been carried out on Si-n irradiated with He⁺ ions at the V.U.B. cyclotron, to a dose of 4×10¹⁷ He/cm². No temperature dependence on the S-parameter and lifetimes is seen below the irradiation temperature. The positron lifetime associated to the created defects is 290 ps. During the isochronal annealing, this lifetime stays constant up to 700 K. It is attributed to the annihilation of positrons from large vacancy-clusters filled with He atoms. From the isochronal annealing results, only one annealing stage is seen. This annealing stage which extends over a long range of temperature 700–1000 K, is ascribed to the degassing of helium atoms from defects and the growth of vacancy-clusters. The lifetime of positrons in those defects reaches a value of about 530±30 ps at 1000 K, indicating that the vacancy-clusters formed have a mean size of more than 8 vacancies.     

Evolution of helium bubbles in nickel-based alloy by post-implantation annealing

Nickel-based alloys have been considered as candidate structural materials used in generation IV nuclear reactors serving at high temperatures. In the present study, alloy 617 was irradiated with 180-keV helium ions to a fluence of 3.6×10¹⁷ ions/cm² at room temperature. Throughout the cross-section transmission electron microscopy (TEM) image, numerous over-pressurized helium bubbles in spherical shape are observed with the actual concentration profile a little deeper than the SRIM predicted result. Post-implantation annealing was conducted at 700 ℃ for 2 h to investigate the bubble evolution. The long-range migration of helium bubbles occurred during the annealing process, which makes the bubbles of the peak region transform into a faceted shape as well. Then the coarsening mechanism of helium bubbles at different depths is discussed and related to the migration and coalescence (MC) mechanism. With the diffusion of nickel atoms slowed down by the alloy elements, the migration and coalescence of bubbles are suppressed in alloy 617, leading to a better helium irradiation resistance.     

铝中气泡在电子束辐照下的异常放热现象

在室温下,利用离子加速器对纯铝透射样品分别注入He⁺,Ne⁺和Ar⁺三种惰性气体离子,通过透射电子显微镜原位观察分析了纯铝中三种气体气泡在电子束辐照下形貌及电子衍射花样的变化.实验表明,在200 keV电子束辐照下,三种惰性气体气泡均会合并长大,亮度逐渐增强,最终破裂,气泡内部产生许多约几个纳米的黑色斑点衬度像,选区电子衍射花样由单晶斑点衍射花样变为多晶衍射环.这一现象的原因可能是气泡在电子束辐照过程中发生了放热反应,使气泡附近铝熔化后再结晶产生多晶,从而在电子衍射花样中观察到了多晶衍射环.然而,氦气泡在80 keV电子束辐照下氦气泡形貌和选区电子衍射花样保持不变,辐照后衍射花样中无多晶衍射环产生;氦氩混合气体气泡在200 keV电子束辐照下气泡形貌和选区电子衍射花样同样保持不变;这可能与电子束能量和气泡内气体压力有关.     

氦、氘对纯铁辐照缺陷的影响

在核聚变堆的辐照环境中, 核嬗变产物氢、氦对结构材料的抗辐照性能将产生很大的影响. 本实验采用离子注入和电子辐照模拟研究了氦和氘对具有体心立方结构的纯铁的影响. 采用离子加速器在室温分别对纯铁注入氦离子和氘离子, 经500℃时效1 h后在高压电镜下进行电子辐照.结果表明: 室温注氦和室温注氘的纯铁在500℃时效后分别形成间隙型位错环和空位型位错环. 在电子辐照下, 间隙型位错环吸收间隙原子而不断长大, 而空位型位错环吸收间隙原子不断缩小. 通过计算位错环的变化速率发现, 空位型位错环比间隙型位错环吸收了更多的间隙原子, 即室温注氘纯铁的位错偏压比室温注氦纯铁的偏压参量大, 这意味着相同实验条件下空位型位错环对辐照肿胀的贡献大于间隙型位错环对辐照肿胀的贡献. 利用氦-空位复合体和氘-空位复合体的结构, 分析了注氦和注氘后在纯铁中形成不同类型位错环的原因. 关键词： 氦 氘 辐照损伤 位错环     

The BCC to FCC/HCP phase transformation of the Co70Fe30 alloy produced by ion irradiation of Co70Fe30/Cu discontinuous multilayers

We report on the BCC to FCC/HCP structural transformation of Co₇₀Fe₃₀ alloy produced by room temperature ion irradiation of Co₇₀Fe₃₀/Cu discontinuous multilayers. The structural changes were analyzed by X-ray diffraction and X-ray absorption spectroscopy. For this study, two different samples were examined, one irradiated with 50 keV He⁺ and another with 600 keV Kr⁺ with doses of 1×10¹⁷ and 3×10¹⁵ ions/cm², respectively. No substantial change is observed after He⁺ irradiation, while after Kr⁺ irradiation an unexpected structural transition from BCC to FCC/HCP closed packed of the Co₇₀Fe₃₀ alloy was found.     

He注入单晶Si表面形貌的变化研究

沿Si的（100）面注入He离子, 能量为30 keV、 剂量为5×1016 ions/cm2。 注入后样品切成几块, 在真空炉中分别做退火处理, 退火温度从600 ℃到1 000 ℃, 退火时间均为30 min。 利用原子力显微镜研究了各个样品表面形貌的演化。 发现样品表面形貌与退火温度相关联。 假设在气泡中He原子与空位的比值很高, 导致样品内部存在高压的He泡, 从而使样品表面形貌发生变化。 探讨了在Si中He泡随退火温度的演化和He原子在材料中的释放机制及其对表面的影响。     

Electron irradiation of polyesterurethane: study of chemical and structural modifications using FTIR, UV spectroscopy and GPC

To understand the electron irradiation effects on polymers, a polyesterurethane (ESPU) was irradiated by a 200 keV electron beam perpendicular to the surface under a vacuum of 0.04 Torr with electron fluxes of 0.25–1.25×10¹³ s⁻¹ on the irradiated zone. To perform a study of ESPU degradation versus the electron's penetration depth, a stratified structure was made with seventeen 30-μm-thick films. The irradiation was performed at both room temperature (293 K) and 77 K. The applied fluence was in the range of 10¹⁴–10¹⁷ cm⁻². Chemical transformations, such as degradation and oxidation, are studied by FTIR, by following NH and OH bond evolution, and by UV spectroscopy, by following the absorbance shift towards the visible region. These effects are analyzed versus depth, fluence and electron flux. Structural transformations are also characterized by GPC for soluble samples. An increase of crosslinking rate of the polymer is observed and analyzed.     

He离子辐照6H-SiC引入缺陷的光谱研究

实验采用300 keV的He²⁺辐照6H-SiC,辐照温度分别为室温,450,600和750 ℃,辐照剂量范围为1×10¹⁵–1×10¹⁷ cm^-2,辐照完成后对样品进行拉曼散射和紫外可见透射光谱测试与研究. 这两种分析方法的实验结果表明,He离子辐照产生的缺陷以及缺陷的恢复与辐照剂量和辐照温度有着直接关系. 室温下辐照会使晶体出现非晶化,体现在拉曼特征峰消失,相对拉曼强度达到饱和(同时出现了较强的Si-Si峰);高温下辐照伴随着晶体缺陷的恢复过程,当氦泡未存在时,高温辐照很容易导致Frenkel对、缺陷团簇等缺陷恢复,当氦泡存在时,氦泡会抑制缺陷恢复,体现在相对拉曼强度和相对吸收系数曲线斜率的变化趋势上. 本文重点讨论了高温辐照情况下氦泡对缺陷聚集与恢复的影响,并与高温下硅离子辐照碳化硅结果进行了对比. 关键词： 6H-SiC 氦泡 拉曼散射光谱 紫外可见透射光谱     

Ne离子束辐照引起Gd2Ti2O7烧绿石体积肿胀效应研究

在液氮低温下用400 keV的Ne2+离子束对Gd₂Ti₂O₇多晶烧绿石进行了辐照实验研究, 离子束辐照量范围为5×1014—1×1016ions/cm2。利用掠X射线衍射技术对样品辐照层的结构变化进行了分析表征, X射线的掠射角分别为γ=0.25°, 0.5°, 1°和3°。结果表明: 在该实验条件的离子束辐照下, Gd₂Ti₂O₇辐照层会发生明显的体积肿胀效应, 体积肿胀程度随入射离子束辐照量的增大而增大; 在同一辐照量下, 辐照层的体积肿胀程度也随X射线入射角的增大而增大。当辐照量达到1×1016ions/cm2时, 辐照层发生非晶化相变。Polycrystalline pyrochlore Gd₂Ti₂O₇ compounds were irradiated with 400 keV Ne2+ ions at cryogenic temperature (~77 K). The irradiation fluences was ranging from 5×1014 to 1×1016 ions/cm2, corresponding to a peak ballistic damage dose of ~0.16 to 3.3 displacements per atom . Irradiation\|induced structural evolution was examined using grazing incidence X\|ray diffraction (GIXRD) at angles from 0.25° to 3° degrees. It was found that the lattice parameter increases as a function of (1) X\|ray incident angle and (2) ion irradiation fluence, suggesting that the irradiated layer is volumetrically swelled compared with the underlying un\|irradiated substrate. At ion fluence of 1×1016 ions/cm2, the irradiation layer was found to be amorphous.     

(e,2e)反应三重微分截面的计算

给出了利用BBK模型计算电子碰撞电离H,He⁺,He和Li⁺三重微分截面的通用方法,适用于中、高入射能量下的各种几何条件。计算结果与其它理论结果和实验数据进行了比较,符合得很好。     

Helium bubble formation and evolution in NiMo-Y2O3 alloy under He ion irradiation

We report helium ion irradiation experiments for a new type of dispersion-strengthened NiMo-Y₂O₃ alloy with three different irradiation doses and varying irradiation dose rates at 750 ℃ to evaluate its helium-induced damage behavior. Transmission electron microscopy was used to reveal the evolution of helium bubbles after irradiation. The experimental results show that with increasing ion dose, the number density of helium bubbles increases continuously. However, the mean size of helium bubbles first increases and then decreases, mainly due to the varied ion dose rates. The volume fractions of helium bubbles in the three investigated samples after irradiation are 0.15%, 0.32%, and 0.27%, which are lower than that of the Hastelloy N alloy (0.58%) after similar irradiation conditions. This indicates that the NiMo-Y₂O₃ alloy exhibits better helium-induced-swelling resistance than the Hastelloy N alloy, highlighting its potential applicability to MSRs, from the perspective of irradiation performance.     

退火对Pb辐照Al2O3单晶发光特性的影响

研究了230MeV的²⁰⁸Pb²⁷⁺辐照Al₂O₃样品及随后在600,900,1100K高温条件下退火后的光致发光特性。从辐照样品的测试结果可以清楚地看到在波长为390,450nm处出现了强的发光峰。辐照量为1×10¹³ions/cm²时,样品的发光峰最强。经过600K退火2h后测试结果显示,380nm发光峰剧烈增强,而其他发光峰显示不明显。在900K退火条件下,380nm的发光峰开始减弱,而在360,510nm出现了明显的发光峰,至到1100K退火完毕后380nm的发光峰完全消失,而360,510nm的发光峰相对增强。从被辐照样品的FTIR谱中看到,波数在460~510cm^-1间的吸收是振动模式,经过离子辐照后,吸收带展宽,随着辐照量的增大,Al₂O₃振动吸收峰消失,说明Al₂O₃振动模式被完全破坏。1000~1300cm^-1之间为Al—O—Al桥氧的伸缩振动模式,辐照后吸收带向高波数方向移动,说明其振动模式受到影响。辐照剂量较小的样品,损伤程度相对较低,经退火晶化后,振动模式基本恢复到单晶状态;辐照剂量较高的样品,损伤程度大,退火处理后表面变得较粗糙,振动模式并未出现,说明结构破坏严重。     

Bubble-loop complexes induced by helium irradiation and effect of pre-irradiation and post-irradiation of hydrogen in reduced-activation ferritic/martensitic steel

In the present work, the synergistic effect of high concentration hydrogen and helium on the dislocation loops and bubbles as well as their correlations in reduced-activation ferritic/martensitic (RAFM) steels is investigated. Such an effect was transmuted from 14?MeV neutron irradiation and has been one of the most challenging issues for RAFM steels for future fusion reactors. After low dose (0.18?dpa) high concentration (5000 appm) single-ion helium irradiation at 723?K, very large dislocation loops were observed, and the majority of bubbles were inside dislocation loops, forming bubble-loop complexes. These bubble-loop complexes defects were also present in hydrogen/helium and helium/hydrogen sequential-ion irradiated steels. Pre-irradiated hydrogen ion effectively inhibited the later growth of loops induced by helium post-irradiation, and the higher the ratio of hydrogen to helium fluence, the greater the effect of inhibition. At high fluence of hydrogen pre-irradiation, the structure of bubble-loop complexes disappeared. On the other hand, hydrogen post-irradiation promoted the growth of loops induced by helium pre-irradiation, and the higher the ratio of hydrogen to helium fluence, the greater the effect of promotion. The mechanisms for hydrogen/helium synergistic effects are discussed.     

Optical properties of He+-implanted and diamond blade-diced terbium gallium garnet crystal planar and ridge waveguides

Terbium gallium garnet (Tb₃Ga₅O₁₂, TGG) crystal can be used to fabricate various magneto-optical devices due to its optimal Faraday effect. In this work, 400-keV He⁺ ions with a fluence of 6.0×10¹⁶ ions/cm² are irradiated into the TGG crystal for the planar waveguide formation. The precise diamond blade dicing with a rotation speed of 2×10⁴ rpm and a cutting velocity of 0.1 mm/s is performed on the He⁺-implanted TGG planar waveguide for the ridge structure. The dark-mode spectrum of the He⁺-implanted TGG planar waveguide is measured by the prism-coupling method, thereby obtaining the relationship between the reflected light intensity and the effective refractive index. The refractive index profile of the planar waveguide is reconstructed by the reflectivity calculation method. The near-field light intensity distribution of the planar waveguide and the ridge waveguide are recorded by the end-face coupling method. The He⁺-implanted and diamond blade-diced TGG crystal planar and ridge waveguides are promising candidates for integrated magneto-optical devices.     

氦氢离子协同注入对锆膜形貌及物相结构的影响

 采用磁控溅射法制备了Zr-Mo膜，随后在低能静电加速器上分别采用剂量为2.80×10¹⁷~1.12 ×10¹⁸ions·cm^-2的He⁺、H⁺离子辐照Zr-Mo膜，利用光学透镜、扫描电镜、原子力显微镜和X射线衍射研究He⁺、H⁺离子协同注入效应对Zr-Mo膜微观结构的影响。实验结果表明：原始Zr-Mo膜表层晶粒清晰可见，尺寸约为200nm；辐照效应可导致Zr-Mo膜表层产生微观损伤区域，在注He⁺基础上注H⁺导致Zr-Mo膜出现更为严重的损伤现象；离子注入的表面溅射效应可使膜面晶粒边界逐渐刻蚀退让，导致膜面更加光滑、细致；He⁺、H⁺ 离子协同注入可使Zr-Mo膜晶格发生畸变，注入期间未使Zr-Mo膜发生吸H相变生成氢化物。     

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.     

SURFACE PHASE DECOMPOSITION IN Bi2Sr2CaCu2O7-y SINGLE CRYSTALS UNDER NITROGEN IONS IRRADIATION

The influence of irradiation by 30 keV nitrogen ions with a fluence 1×10¹⁸N⁺·cm^-2 on the crystal structure of single crystal Bi₂Sr₂CaCu₂O_7-y was investigated by means of X-ray photoelectron spectroscopy and X-ray diffraction. The irradiation caused a transformation from Bi₂Sr₂CaCu₂O_7-y (2212 phase) to Bi₂Sr₂CuO_5-x (2201 phase). It was observed that. a small amount of metallic bismuth with an average thickness of about 6.3nm appeared after the irradiation. The possible reaction mechanism under nitrogen-ion irradiation was discussed.