Electrolytic Formation of Crystalline Silicon/Germanium Alloy Nanotubes and Hollow Particles with Enhanced Lithium‐Storage Properties

Crystalline silicon(Si)/germanium(Ge) alloy nanotubes and hollow particles are synthesized for the first time through a one‐pot electrolytic process. The morphology of these alloy structures can be easily tailored from nanotubes to hollow particles by varying the overpotential during the electro‐reduction reaction. The continuous solid diffusion governed by the nanoscale Kirkendall effect results in the formation of inner void in the alloy particles. Benefitting from the compositional and structural advantages, these SiGe alloy nanotubes exhibit much enhanced lithium‐storage performance compared with the individual solid Si and Ge nanowires as the anode material for lithium‐ion batteries.     

高纯锗探测器的广泛应用和自主研制进展

以目前国际上极为活跃开展的暗物质探测、无中微子双 衰变研究为例,评述了高纯锗探测器的重要性及其广泛的应用前景。介绍了己开展的高纯锗单晶、探测器制备的关键技术研究进展:合作单位已研制出了用于高纯锗单晶材料制备的区熔炉、单晶炉;并制备出直径为20  50 cm、纯度为12N(< 41011  atoms/cm3)、位错< 5000 atoms/cm2 的锗单晶;掌握了高纯锗探测器(平面型、同轴型)制备的关键技术,用进口高纯锗单晶材料制备出的同轴型高纯锗探测器对射线的能量分辨率及探测效率均达到进口产品指标,使用自制的12N 高纯锗单晶材料己制备出平面型高纯锗探测器。呼吁加速高纯锗研制的自主创新步伐,尽早实现其国产化目标。The article reviews importance and wide applications of HPGe detector, especially the application on the dark matter search experiment and double beta decay experiment. The research progress on the Highpurity germanium single crystal and HPGe detector in China has been introduced. The cooperation partner developed new type zone-refining furnace and single crystal furnace. The ultra-purity germanium single crystal with 20~50 cm, purity up to 12N(net impurity concentration is less than 41011 atoms/cm3), and dislocation less than 5 000 /cm3 was prepared. The key technologies for preparing planar and coaxial HPGe detector were mastered. The coaxial detector, which has been made of imported ultra-purity germanium single crystal has excellent energy resolution and efficiency as the imported commercial detector. The planar detector using selfmade germanium single crystal was also successfully manufactured. The research group appeals for speeding up the pace of independent innovation on the high-purity germanium, and achieving the high-purity germanium localization as soon as possible.     

离子色谱法快速连续测定锗和锡的研究

介绍了一种快速测定锗和锡的新方法──离子色谱法。锗和锡在双功能的分离柱上被分离后进行柱后显色反应,然后经可见检测器于５２０ｎｍ处检测。此法具有较高的灵敏度和选择性,整个分析过程仅需５ｍｉｎ,样品分析结果令人满意。     

Axial macrosegregation in Ga‐doped germanium grown by the vertical gradient freeze technique with a rotating magnetic field

The impact of a rotating magnetic field (RMF) on the axial segregation in Vertical Gradient Freeze (VGF) grown, Ga doped germanium is investigated. Growth experiments were performed using the VGF‐RMF as well as the conventional VGF technique. Carrier concentration profiles characterising the Ga segregation were measured by the Spreading Resistance method and calibrated using Hall values of carrier concentration and mobility. The Ga concentration rises more gradually under RMF action, i.e., the dopant segregation is significantly reduced by the rotating field. This effect is attributed to a better mixing of the melt. Numerical results on the flow velocity confirm this explanation. The RMF induced flow is much more intense than the natural buoyant convection due to the radial temperature gradient and leads to a pronounced decrease of the effective partition coefficient k_eff. In the early stages of growth a k_eff value close to k₀ was obtained, i.e., the gallium was almost homogeneously distributed within the melt. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Local Vibrations of Oxygen-Containing Thermal Donors in Germanium

The vibrational absorption bands associated with some types of double thermal donors (TD) in Ge enriched with the oxygen isotopes ¹⁶O and ¹⁸O have been identified. The thermal donors were formed during heat treatment of Ge:O crystals at 300 and 350°C. Absorption spectra were measured at room temperature and at 10 K. The formation of the thermal donors was accompanied by the appearance of three absorption bands, which in the Ge:¹⁶O spectra at room temperature are located at 600, 740, and 780 cm^–1. In low-temperature measurements, the bands at 600 and 780 cm^–1 exhibited splitting into series of narrow lines (up to 9) associated with some types of thermal donors (TD1–TD9). The absorption spectra measured at 10 K after different cooling conditions display bistability of the first four types of thermal donors (TD1–TD4). In the samples cooled by illumination with light in the region of frequencies of the fundamental absorption of Ge, pairs of lines are observed that belong to the bistable thermal donors in the helium-like configuration of double donors (DD). After cooling the samples in the dark, these pairs of lines are replaced by three new bands, which belong to local vibrational modes of bistable thermal donors in the low-energy neutral configuration. Based on the isotopic shift of the local vibrational modes of the thermal donors in Ge:¹⁶O and Ge:¹⁸O, a rigorous proof of the oxygen atoms entering into the composition of thermal donors is obtained.     

碰撞池-电感耦合等离子体质谱法测定芝麻中痕量的锗

建立了碰撞池-电感耦合等离子体质谱法测定芝麻中痕量的锗元素(germanium , Ge)。采用微波消解,碰撞池(KED模式)-电感耦合等离子体质谱检测,在线引入内标元素铑(Rh),同时消解液中加入3%正戊醇增敏。结果 3 % 正戊醇可使_⁷⁴Ge的上机检测信号强度提高2.85倍,_⁷⁴Ge校正曲线线性相关系数为1.00000,检出限为0.0555 μg/kg,加标回收率为92.0%~106%,相对标准偏差(relative standard deviation, RSD%)为2.6%~4.3%。采用建立的方法测定7种国家标准物质,检测结果均在认定值范围内,RSD%为2.5%~8.8%。结论 该方法灵敏度高、准确,可实现批量检测,适用于芝麻中痕量锗的检测。