高能重离子辐照的ODS铁素体钢脆化效应研究

与传统的铁素体钢相比,氧化物弥散强化(ODS) 的铁素体钢具有更优的耐高温和抗辐照性能,近年来成为先进核能装置重要的候选结构材料。在HIRFL 的扇聚焦型回旋加速器(SFC) 材料辐照终端,对一种氧化物弥散强化(ODS) 铁素体钢MA956 进行了高能Ne 离子辐照实验,旨在研究级联碰撞损伤和惰性气体原子注入条件下该材料力学性能的变化。利用辐照终端的能量衰减装置将SFC出口123.4 MeV的离子能量分解为介于38.5~121.0 MeV之间的30 个入射能量值,并通过双面辐照在厚度60 μm的样品中均匀产生了损伤。辐照剂量为9x1016 ions/cm2,在样品中的平均位移损伤为0.7 dpa,注入的Ne原子浓度为350 appm。辐照期间样品温度保持在440 ℃附近。对辐照前后的样品分别在室温和500 ℃下进行了小冲杆试验(Small-punchTest),获得了辐照前后样品的加载位移曲线,由此得到该辐照条件下样品的延性损失为18%~26%。通过扫描电子显微镜观察了断口形貌和厚度变化,估算了样品的等效断裂应变和断裂韧性。结果表明,MA956 钢经过高能Ne离子辐照后等延伸率减小,断裂韧性降低,样品发生了一定的脆化。透射电镜结果说明氧化物弥散相界面处微空洞的形成可能是导致脆化的原因。Oxide dispersion strengthened (ODS) ferritic steels have better high-temperature creep rupture strength and higher irradiation resistance than conventional ferritic steels, and show high prominence of application in advance nuclear reactors. Their stability under high-dose radiation conditions needs to be clarified. In the present study, a commercial ODS ferritic steel MA956 were irradiated with high 20Ne ions at a terminal chamber of the Sector-focused Cyclotron (SFC) at HIRFL (Heavy-ion Research Facility in Lanzhou). With the energy gradient degrader of the irradiation chamber, the primary energy (123.4 MeV) of the Ne-ion was dispersed into 30 different energies between 38.5~ 121.0 MeV, which resulted in a plateau distribution of lattice damage in the specimens. The specimens were irradiated from both sides so that the whole 60 m thickness was nearly uniformly damaged. The specimen temperature was maintained around 440 ℃ during the irradiation. The irradiation dose is about 9x1016 ions/cm2, corresponding to a damage level of 0.7 dpa and a Ne concentration of 350 appm. The specimens before and after irradiation were tested with the Small-punch Test technique, at room temperature and 500 ℃, respectively. The fracture morphology was observed by scanning electron microscopy.The results show that MA956 underwent some loss of ductility and fracture toughness after the irradiation with high-energy 20Ne ions. It may be ascribed to the formation of nano-scale cavities at the oxides/matrix interfacesin the ODS steel specimens under irradiation .     

A self-driven photodetector based on a SnS2/WS2 van der Waals heterojunction with an Al2O3 capping layer

Photodetectors based on two-dimensional (2D) materials have attracted considerable attention because of their unique properties. To further improve the performance of self-driven photodetectors based on van der Waals heterojunctions, a conductive band minimum (CBM) matched self-driven SnS₂/WS₂ van der Waals heterojunction photodetector based on a SiO₂/Si substrate has been designed. The device exhibits a positive current at zero voltage under 365 nm laser illumination. This is attributed to the built-in electric field at the interface of the SnS₂ and WS₂ layer, which will separate and transport the photogenerated carriers, even at zero bias voltage. In addition, the Al₂O₃ layer is covered by the surface of the SnS₂/WS₂ photodetector to further improve the performance, because the Al₂O₃ layer will introduce tensile stress on the surface of the 2D materials leading to a higher electron concentration and smaller effective mass of electrons in the films. This work provides an idea for the research of self-driven photodetectors based on a van der Waals heterogeneous junction.     

Fe/Nb多层膜中离子辐照效应研究(英文)

〗采用磁控溅射技术在Si衬底上沉积Si/\[Fe(10 nm)/Nb(4 nm)/Fe(4 nm)/Nb(4 nm)\]2/ \[Fe(4 nm)/Nb(4 nm)\]4多层膜。 用2 MeV的 Xe离子在室温下辐照多层膜。采用俄歇深度剖析、X射线衍射和振动样品磁强计分析辐照引起的多层膜元素分布、 结构及磁性变化。AES深度剖析谱显示当辐照注量达到1.0×1014 ions/cm2时, 多层膜界面两侧元素开始混合; 当辐照注量达到2.0×1016ions/cm2时, 多层膜层状结构消失, Fe层与Nb层几乎完全混合。XRD谱显示, 当辐照注量达到1.0×1014ions/cm2时, Nb的衍射峰和Fe的各衍射峰的峰位相对于标准卡片向小角方向偏移, 这说明辐照引起Nb基和Fe基FeNb固溶体相的形成;当辐照注量大于1.0×1015 ions/cm2时, 辐照引起非晶相的出现。 VSM测试显示,多层膜的磁性随着结构的变化而变化。 在此实验基础上, 对离子辐照引起界面混合现象的机理进行了探讨。The behavior of the metallic multilayers of Si/\[Fe(10 nm)/Nb(4 nm)/Fe(4 nm)/ Nb(4 nm)\]2/\[Fe(4 nm)/Nb(4 nm)\]4 under 2 MeV Xe ion irradiation has been investigated by depth profile analysis of Auger electron spectroscopy,X ray diffraction and vibrating sample magnetometer. The obtained experimental results show that the inter mixing between Fe and Nb layers occurs in the 1.0×1014 ions/cm2 irradiated multilayer sample which results in the formation of Nb based and Fe based FeNb solid solution. For the samples irradiated to fluence larger than 1.0×1014 ions/cm2, amorphisation is observed, and moreover, the layered structure of the multilayer samples is broken up completely for the samples under 1.0×1016 or 2.0×1016 ions/cm2 irradiation. Vibrating sample magnetometer measurement also reveals that the magnetization of the samples changes with the evolution of the structure of multilayers. Possible mechanism of the modification in Fe/Nb multilayers induced by Xe ion irradiation is briefly discussed.     

分光光度法测定银杏叶中的总黄酮

分别以甲醇、乙醇、四氢呋喃为溶剂,采用水浴回流的方法提取银杏叶中总黄酮,并通过正交试验对提取温度、溶剂用量、提取时间进行探讨.结果表明:以甲醇为溶剂,当温度为50℃,溶剂用量为13.33mL · g-1,提取时间为2h时,黄酮提取率可达14.8％.     

用SCLC法研究低k多孔SiO2:F薄膜的隙态密度

用溶胶-凝胶法制备了低k多孔SiO₂:F薄膜，用空间电荷限制电流法(SCLC)研究了多孔SiO₂:F薄膜中的隙态密度以及掺F量对隙态密度的影响，得到了平衡费米能级附近的隙态密度约为7×10¹⁵cm^-3·eV^-1，以及带隙中隙态随能量的分布. 并对造成隙态的主要原因也进行了讨论.     

Pressure-Induced Topological and Structural Phase Transitions in an Antiferromagnetic Topological Insulator

Recently,natural van der Waals heterostructures of(MnBi₂ Te₄)_m(Bi₂ Te₃)_n have been theoretically predicted and experimentally shown to host tunable magnetic properties and topologically nontrivial surface states.We systematically investigate both the structural and electronic responses of MnBi₂ Te₄ and MnBi₄ Te₇ to external pressure.In addition to the suppression of antiferromagnetic ord...     

电子束辐照剂量对PAN/PEO交联度的影响

对PAN/PEO凝胶(5%PAN,5%PEO)在1.0 MeV电子束下进行了不同剂量的辐照。红外光谱测量表明,PAN/PEO凝胶辐照后发生了化学交联。分析结果指出,PAN/PEO的凝胶分数随着辐照剂量的增加而不断增加;其凝胶分数增长率的变化可以分为3个阶段,即快速增加阶段(0~39kGy)、下降阶段(39~130 kGy)和稳定阶段(130 kGy)。拟合发现,引入材料刚性参数β的半经验修正方程与未考虑材料刚性的Char1esby-Pinner方程相比,更符合实际测量值(对于该配比PAN/PEO,β为0.166)。交联度-辐照剂量曲线显示,交联度随辐照剂量的增加而增加,为设计新型能功能材料中所需的固定交联度的PAN/PEO凝胶提供了辐照剂量参考值。     

联苯胺分子印迹聚合物零流电位法传感器的制备及其应用

考察了在石墨烯修饰的铅笔芯电极( G-PEC)表面制备联苯胺分子印迹聚合物( BZ-MIP)的电聚合参数以及模板分子从印迹聚合物中去除的洗脱时间对BZ-MIP与BZ结合前后零流电位响应差值的影响,优化了最佳制备条件;计算出联苯胺及与其结构相近的4-氨基偶氮苯、4-氯苯胺、4-氨基联苯和单偶氮染料胭脂红在BZ-MIP上的印迹容量分别为0.632,0.1123,0.1123,0.0847和0.0725。实验结果表明,本方法制备的BZ-MIP对联苯胺特异识别性和选择性良好,其它物质不干扰模板分子与印迹聚合物印迹位点的结合。在联苯胺4伊10-8~1伊10-5 mol/L浓度范围内,BZ-MIP与BZ结合前后的零流电位差与其浓度对数呈正比,检出限为1.89伊10-8 mol/L,基于此制备出检测联苯胺的BZ-MIP-G-PEC零流电位传感器。应用此传感器检测实际样品,回收率为95.7%~104.2%。     

基于对偶自信双层语言偏好关系的多属性群决策方法

针对自信双层语言中“自信度”主观性较强、缺乏对应调节机制等问题,提出了一种新型决策语言术语和基于对偶自信双层语言偏好关系的多属性群决策方法.首先,引入社会网络法获取专家间“信任关系”矩阵,考虑信任传递的全面性和信息失真情况,采用OWA算子和最短链路原则补全“信任关系”.其次,耦合“信任关系”和自信双层语言创建对偶自信双层语言,拓展对偶自信双层语言偏好关系,研究其一致性及共识性指标,并构建对偶自信双层语言的反馈调节机制.进而,利用反馈调节机制中调节后“自信度”和“他信度”指标构建新的专家赋权模型.最后,结合反馈调节机制和专家赋权模型,提出对偶自信双层语言偏好关系的多属性群决策方法.通过湖南省新能源投资项目分析,验证了方法的适用性和有效性.     

物理光学中多光束叠加强度求解方法的探讨

大学物理光学中多光束相遇叠加强度的求解问题占据了课程内容的很大比重,涵盖了叠加原理、干涉、衍射、互补屏原理、复振幅、共轭波和偏振等理论和概念。为了使非光学特色工科大专院校的学生在有限的课程学习期间内快速方便地解决多光束叠加强度求解问题,有效地对实际的干涉测量设备原理进行分析,总结了一套“叠加强度求解六步法”的程序化解题流程,通过杨氏实验、单矩形孔夫琅禾费衍射、巴比涅互补屏系统和一个复杂习题解答为例对该方法的使用进行了充分举例说明,有效地论证了该方法的有效性和通用性。