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.     

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.     

高能Xe离子辐照引起的注碳a:SiO2中新结构的形成

先用120keV的碳离子注入非晶二氧化硅a:SiO2薄膜，再用能量为1754MeV的Xe离子辐照。注碳量为5．0×10^16—8．6×10^17ion／cm^2，Xe离子辐照剂量为1．0×10^11和5．0×10^11ion／cm^2。辐照后的样品中形成的新结构用显微傅立叶变换红外光谱仪进行测试分析。结果表明，Xe离子辐照引起了注碳a:SiO2中Si—C，C—C，Si—O—C键以及CO和CO2分子的形成与演化。在注碳量较高时，Xe离子辐照在样品中产生了大量的Si—C键。与注入未辐照和辐照的低注碳量样品比较，增强的Si—C键的形成，预示着辐照可引起注碳a:SiO2样品中的SiC结构相变。Amorphous silicon-dioxide （a:SiO2） films were firstly implanted at room temperature （RT） with 120 keV C-ions to doses ranging from 5.0 × 10^16 to 8.6 × 10^17 ion/cm^2, and then the C-doped a:SiO2 films were irradiated at RT with 1 754 MeV Xe ions to 1.0 × 10^11 and 5.0 × 10^11 ion/cm^2, respectively. The information of new tex- ture formation in the C-doped SiO2 films after high-energy Xe ion irradiation was investigated using micro-FTIR measurements. The obtained results showed that Si--C, C--C, Si--O--C bonds as well as CO and CO2 molecules were formed in the C-doped a-SiO2 films after Xe ion irradiation. Furthermore, Xe-ion irradiation induced a plenteous formation of Si--C bonds in the high dose C-ion implanted a:SiO2 films. Compared with the C-implanted sampies without Xe-ion irradiation and the low dose C-implanted samples with Xe-ion irraddiation, the enhanced and plenty of Si--C bond formation implied that the phase of SiC structures may be produced by Xe-ion irradiation in the high dose C-ion implanted a:SiO2 films.     

Krypton ion irradiation-induced amorphization and nano-crystal formation in pyrochlore Lu_2Ti_2O_7 at room temperature

Polycrystalline pyrochlore Lu2Ti2O7 pellets are irradiated with 600-ke V Kr3+ions up to a fluence of 1.45 ×1016Kr3+/cm2. Irradiation induced structural modifications are examined by using grazing incidence x-ray diffraction(GIXRD) and cross-sectional transmission electron microscopy(TEM). The GIXRD reveals that amorphous fraction increases with the increase of fluences up to 2 × 1015Kr3+/cm2, and the results are explained with a direct-impact model.However, when the irradiation fluence is higher than 2 × 1015Kr3+/cm2, the amorphous fraction reaches a saturation of~80%. Further TEM observations imply that nano-crystal is formed with a diameter of ~10 nm within the irradiation layer at a fluence of 4 × 1015Kr3+/cm2. No full amorphization is achieved even at the highest fluence of 1.45 × 1016Kr3+/cm2(~36 displacement per atom). The high irradiation resistance of pyrochlore Lu2Ti2O7 at higher fluence is explained on the basis of enhanced radiation tolerance of nano-crystal structure.     

Field-induced insulator-metal-insulator transitions in low-energy H_2~+ ion-irradiated epitaxial La_(2/3)Ca_(1/3)MnO_3 thin films

Epitaxial La 2/3 Ca 1/3 MnO 3 thin films grown on LaAlO 3 (001) substrates were irradiated with low-energy 120-keV H 2 + ions over doses ranging from 10 12 ions/cm 2 to 10 17 ions/cm 2 . The irradiation suppresses the intrinsic insulator-metal (I-M) transition temperature and increases the resistance by reducing the crystallographic symmetry of the films. No irradiation-induced columnar defects were observed in any of the samples. The specific film irradiated at a critical dose around 8 × 10 15 ions/cm 2 is in a threshold state of the electric insulator where the I-M transition is absent. In an external field of 4 T or higher, the I-M transition is restored and thus an enormous magnetoresistance is observed, while a negative temperature coefficient resumes as the temperature is reduced further. Magnetic relaxation behavior is confirmed in this and other heavily irradiated samples. The results are interpreted in terms of the displacement of oxygen atoms provoked by ion irradiation and the resulting magnetic glassy state, which can be driven into a phase coexistence of metallic ferromagnetic droplets and the insulating glass matrix in a magnetic field.     

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.      

Study on third-order nonlinear optical properties of a soluble poly(p-phenylene vinylene) derivative

A soluble poly(2-methoxyo5-decoxy)-p-phenylene vinylene (PMODOPV) was synthesized via dehydrochlorination reaction and characterized by UV-visible absorption spectrum. The results showed that PMODOPV had a broad optical absorption band in the range of 450-550 nm and the optical band gap was calculated to be around 2.12 eV. The third-order nonlinear optical susceptibilities (χ(3)) of PMODOPV films implanted by 30-kev N+ ions in the dose range of 3.8 × 1015-9.6 × 1016 ions/cm2 were measured by degenerate four-wave mixing (DFWM) technique. The results demonstrated that the resonant and offresonant χ(3) values were all enhanced significantly by means of ion implantation. The maximum resonant χ(3) value of 9.67 × 10-9 esu at 532 nm and off-resonant χ(3) value of 2.49 × 10-10 esu at 1.064μm were obtained when the ion dose was 3.8 × 1016 ions/cm2.     

Co+离子注入单晶TiO2铁磁性来源与微结构研究

在室温下,将能量为80 keV, 注量分别为1×1016和1×1017ions/cm2的Co+离子注入到10 mm×10 mm×0.5 mm的单晶TiO₂样品。在氮气保护下, Co+离子注量为1×1017 ions/cm2时样品在温度为900 ℃的条件下退火30 min。 利用超导量子干涉仪 （SQUID）测量样品磁性, 并应用X射线衍射（XRD）和扩展边X射线吸收精细结构谱（EXAFS）研究Co+离子注入后样品的微观结构。 样品磁性测量结果表明:Co+离子注入后的样品具有室温铁磁性, 并且其饱和磁化强度的大小与Co+离子注量及样品是否经退火处理有关。 EXAFS研究表明: Co元素在Co+离子注量为1×1017ions/cm2的样品中主要以团簇形式存在;样品经退火处理后, Co团簇消失, 并发现Co部分替代TiO₂单晶中的Ti。Co+离子注入后, 在样品中形成Co团簇与否受离子注量的影响。 阐述了样品微观结构与铁磁性来源之间的关系。 At room temperature, monocrystalline plates of rutile (TiO₂) were implanted with cobalt ions of an energy of 80 keV to fluences of 1×1016 and 1×1017 ions/cm2 respectively . The 1×1017 ions/cm2 Co implanted samples were annealed in nitrogen at 900 ℃ for 30 min. The magnetic properties of Co implanted samples were measured with a superconducting quantum interference device magnetometer (SQUID) at room temperature. Furthermore, the X ray diffraction (XRD) and Extended X ray Absorption Fine Structure (EXAFS) were applied to investigate the structural and compositional properties of Co implanted samples. The magnetic measurements of samples showed that the size of the saturation magnetization of the Co implanted samples were related to the fluence of ions, and the saturation magnetization of the sample after annealed decreased significantly. The EXAFS measurements showed the presence of cobalt metallic clusters in the sample implanted to ion fluence of 1×1017 ions/cm2. The Co metallic clusters disappeared in the sample after annealed, and resulted in the oxidized Co, which is presumed to substitute into the Ti site. The formation of Co clusters or not was determined by the ion fluence. The relation between ferromagnetic behavior and microscopic structure of the Co implanted samples is discussed.     

Copper Ion Beam Irradiation-Induced Effects on Structural,Morphological and Optical Properties of Tin Dioxide Nanowires

The 0.8 MeV copper(Cu) ion beam irradiation-induced effects on structural,morphological and optical properties of tin dioxide nanowires(SnO_2 NWs) are investigated.The samples are irradiated at three different doses5 × 10~(12) ions/cm~2,1 × 10~(13) ions/cm~2 and 5 × 10~(13) ions/cm~2 at room temperature.The XRD analysis shows that the tetragonal phase of SnO_2 NWs remains stable after Cu ion irradiation,but with increasing irradiation dose level the crystal size increases due to ion beam induced coalescence of NWs.The FTIR spectra of pristine SnO_2NWs exhibit the chemical composition of SnO_2 while the Cu-O bond is also observed in the FTIR spectra after Cu ion beam irradiation.The presence of Cu impurity in SnO_2 is further confirmed by calculating the stopping range of Cu ions by using TRM/SRIM code.Optical properties of SnO_2 NWs are studied before and after Cu ion irradiation.Band gap analysis reveals that the band gap of irradiated samples is found to decrease compared with the pristine sample.Therefore,ion beam irradiation is a promising technology for nanoengineering and band gap tailoring.     

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.     

94MeV Xe离子辐照引起的薄膜硅光学带隙变化研究

室温下,用94MeV的Xe离子辐照纳米晶和非晶硅薄膜以及单晶硅样品,辐照量分别为1.0×1011,1.0×1012和1.0×1013ions/cm2。所有样品均在室温下用UV/VIS/NIR光谱仪进行检测分析。通过对比研究了纳米晶、非晶、单晶硅样品的光学带隙随Xe离子辐照量的变化。结果表明,不同结构的硅材料中Xe离子辐照引起的光学带隙变化规律差异显著:随着Xe离子辐照量的增加,单晶硅的光学带隙基本不变,非晶硅薄膜的光学带隙由初始的约1.78eV逐渐减小到约1.54eV,而纳米晶硅薄膜的光学带隙则由初始的约1.50eV快速增大至约1.81eV,然后再减小至约1.67eV。对硅材料结构影响辐照效应的机理进行了初步探讨。     

Structural and magnetic study of swift heavy ion irradiated W/Fe multilayer structure

The present study reports the effect of swift heavy ion irradiation on structural and magnetic properties of sputtered W/Fe multilayer structure (MLS) having bilayer compositions of [W(10 Å)/Fe(20 Å)]_10BL. The MLS is irradiated by 120 MeV Au⁹⁺ ions of fluences 1×10¹³ and 4×10¹³ ions/cm². Techniques like X-ray reflectivity (XRR), cross-sectional transmission electron microscopy (X-TEM) and DC magnetization with a vibrating sample magnetometer (VSM) are used for structural and magnetic characterization of pristine and irradiated MLS. Analysis of XRR data using Parratt’s formalism shows a significant increase in W/Fe layer roughness. X-TEM studies reveal that intra-layer microstructure of Fe layers in MLS becomes nano-crystalline on irradiation. DC magnetization study shows that with spacer layer thickness interlayer coupling changes between ferromagnetic to antiferromagnetic.     

80keV N离子注入对ZnO薄膜结构的影响

室温下用80keVN离子注入ZnO薄膜样品,注量分别为5.01014,5.01015和5.01016ions/cm2,然后用X射线衍射和透射电镜技术对样品的结构特性进行了表征。实验结果表明,由高度(002)择优取向的致密柱状晶构成的薄膜中,注入5.0×1015ions/cm2时,观测到缺陷生成和局域无序化现象,但薄膜总体结构仍保持柱状晶和(002)择优取向;随着注量的增大,晶格常数c和压应力呈增大趋势。对注入N离子对ZnO薄膜结构特性的影响机理进行了简单的讨论。     

采用EPR谱和TEM对YSZ单晶辐照损伤的研究

 利用电子顺磁共振(EPR)谱和透射电子显微镜(TEM)研究了YSZ单晶的辐照效应。200 keV的Xe和400 keV的Cs离子注入［111］取向的YSZ单晶中，注量均为5×10¹⁶ cm^-2。EPR结果表明辐照产生了共振吸收位置g‖=1.989 和 g⊥=1.869、对称轴为［111］的六配位Zr³⁺顺磁缺陷。Cs辐照产生了比Xe 离子辐照多约150倍的六配位Zr³⁺顺磁缺陷。两种样品的剖面电子显微分析表明没有发现非晶化转变，但是Cs离子辐照的样品在损伤集中区域产生了密度较高的缺陷。因此，EPR谱和电子显微观察均说明在相同离位损伤(约160 dpa)的情况下，Cs离子辐照比Xe 离子辐照产生了更多的缺陷。造成这一现象的原因是Cs离子是化学活性的而Xe 离子却是惰性的。     

掺铥钨酸钡单晶生长和光谱研究

采用Czochralski 法生长出光学质量的BaWO₄:Tm³⁺单晶,利用X粉末衍射实验确定了不同掺杂浓度晶体的晶胞参数.测定了晶体的室温吸收光谱,应用Juud-Ofelt理论,拟合了光谱的3个强度参数,其值分别为Ω₂=404×10^-20cm²,Ω₄=0509×10^-20cm²,Ω关键词： 4：Tm³⁺单晶')" href="#">BaWO₄：Tm³⁺单晶 吸收谱 光谱参数 上转换发光     

八元瓜环诱导菲、芴的室温磷光研究

以八元瓜环为诱导剂、碘化钾作重原子微扰剂,在亚硫酸钠除氧下,实现了菲、芴的室温磷光发射。在该体系中菲、芴的最大激发和发射波长分别为282和509 nm,276和518 nm,磷光寿命分别为1.82和3.68 ms。在最佳实验条件下,菲在1.0×10-7～1.5×10-6mol·L-1,1.5×10-6～1.0×10-5 mol·L-1和芴在8.0×10-7～8.0×10-6mol·L-1的浓度范围内分别与其磷光强度呈良好的线性关系,检出限分别为4.8×10-9和8.0×10-9 mol·L-1。     

低能离子在C60薄膜中引起的辐照效应

用Raman(拉曼)散射技术分析了120keV的H,Ar和Fe离子在C₆₀薄膜中引起的辐照效应,主要指由晶态向非晶态的转变.分析结果表明,在Fe和Ar离子辐照的C₆₀薄膜中,核碰撞主导了由晶态向非晶态的转变过程.而在H离子辐照的情况下,电子能损起主导作用,并发现在H离子辐照过程中,电子能损有明显的退火效应,致使由晶态向非晶态转变的过程中,经历了一个石墨化的中间过程.     

高位K2(1Λg) 与基态原子的碰撞转移

在K原子密度约为0.5～5×1016cm-3的样品池中,脉冲激光710 nm线双光子激发K2基态到高位1Λg态,研究了K2(1Λg)+ K(4S)碰撞转移过程.K原子密度由测量KD2线蓝翼对白光的吸收得到.测量不同K密度下1Λg态发射的时间分辨荧光强度,它是一条指数衰减曲线,由此得到1Λg态的有效寿命,从描绘出的有效寿命倒数与K原子密度关系直线的斜率得到1Λg态总的碰撞猝灭截面为(2.1±0.2)×10-14cm2,从截距得到的辐射寿命为(22±2)ns.测量了K的6S →4P3/2和4D→4P3/2在不同K密度下的时间积分荧光强度,得到了K2(1Λg)+K→K2(11∑ +g)+K(6S,4D)碰撞转移截面为(1.5±0.3)×10-15cm2(对转移到6S)和(8.5±3.0)×10-15cm2(对转移到4D).