Barium ferrite (BaFe12O19) thin films prepared by pulsed laser deposition on MgO buffered Si substrates

Barium ferrite (BaFe₁₂O₁₉) thin films have been deposited by pulsed laser deposition (PLD) on Si substrates with MgO underlayers. The films were deposited in oxygen atmosphere by excimer laser (=248 nm, pulse duration=23 ns) in the temperature range 750–900 °C. The experiments showed that the substrate temperature has remarkable effect on the films magnetic and structural properties. The BaFe₁₂O₁₉ films deposited at 900 °C in 200 mTorr oxygen showed some perpendicular orientation, with a perpendicular squareness of 0.5 and an in-plane squareness of 0.3. Such thin BaFe₁₂O₁₉ films have platelet grains with a size of about 300 nm. The perpendicular saturation magnetization and coercivity are 185 emu/cm³ and 1.4 kOe, respectively. PACS 81.15.Fg.; 75.70.Ak; 75.50.Pp; 68.55.j     

大口径反射镜高反射膜研究进展

大口径反射镜是大型反射式光学系统中关键的光学元件,在工作波段的反射率直接决定了光学系统的性能。随着地基、天基观测设备的发展,对大口径反射镜高反射膜提出了更宽的工作波段、更高的反射率、更好的环境适应性等要求。针对这些挑战,各种新的膜系结构、新的镀制方法、新的膜层材料纷纷出现,满足了大口径反射镜高反射膜的各种需求。本文对近些年国内外的大口径反射镜高反射膜研究进展予以综述,并预测大口径反射镜高反膜制备的技术趋势将由铝反射膜向银反射膜、由热蒸发向磁控溅射发展。     

Bidirectional transfer of quantum information for unknown photons via cross-Kerr nonlinearity and photon-number-resolving measurement

We propose an arbitrary controlled-unitary(CU) gate and a bidirectional transfer scheme of quantum information(BTQI) for unknown photons.The proposed CU gate utilizes quantum non-demolition photon-number-resolving measurement based on the weak cross-Kerr nonlinearities(XKNLs) and two quantum bus beams;the proposed CU gate consists of consecutive operations of a controlled-path gate and a gathering-path gate.It is almost deterministic and is feasible with current technology when a strong amplitude of the coherent state and weak XKNLs are employed.Compared with the existing optical multi-qubit or controlled gates,which utilize XKNLs and homodyne detectors,the proposed CU gate can increase experimental realization feasibility and enhance robustness against decoherence.According to the CU gate,we present a BTQI scheme in which the two unknown states of photons between two parties(Alice and Bob) are mutually swapped by transferring only a single photon.Consequently,by using the proposed CU gate,it is possible to experimentally implement the BTQI scheme with a certain probability of success.     

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.     

火焰原子吸收和发射光谱法测定盐湖卤水中的钙

在波长422.7nm下,用火焰原子吸收和发射光谱法测定了盐湖卤水中钙的含量,考察了酸度及共存离子对测定结果的影响,并对两种方法的优缺点进行了比较.结果表明,原子吸收光谱法受酸度及共存离子的影响较小,火焰发射光谱法测定钙的灵敏度比原子吸收光谱法高,两种方法的RSD均小于2%,加标回收率介于103.7%-107.2%.     

NO分子在钙钛矿表面吸附的红外光谱分析

用柠檬酸络合法合成了LaMnO3、LaCoO3和LaFeO3.NO分子红外光谱表明在上述化合物中存在不同类型的不饱和配位阳离子.对于LaFeO3来说,不饱和配位Fe2 的出现与表面缺陷有关;对于LaCoO3和LaMnO3表面来说,主要是不饱和配位Me3 与氧的配位性更强.     

ZnO∶Eu3^＋纳米晶的制备及发光性质研究

为了探讨稀土Eu^3＋与纳米ZnO基质之间的能量传递,利用溶胶-凝胶法（Sol-Gel）制备了ZnO∶Eu^3＋纳米晶,测量了样品的X射线衍射谱（XRD）、光致发光谱（PL）和激发谱（PLE）。X射线衍射结果表明,ZnO∶Eu^3＋具有六角纤锌矿晶体结构。观察到稀土Eu^3＋强而窄的特征发射和ZnO基质弱而宽的可见发射。分析了稀土Eu^3＋激发态5^D0→7^F1,5^D0→7^F3和5^D0→7^F2特征发射机制。给出了Eu^3＋离子特征发射的峰值强度随掺Eu^3＋浓度增加而增强的变化关系,证实了纳米ZnO基质与稀土Eu^3＋离子之间存在能量传递。比较了Eu^3＋离子5^D0→7^F1磁偶极跃迁（MD）与5^D0→7^F2电偶极跃迁（ED）的相对强度,证实了在ZnO纳米晶基质中大多数Eu^3＋占据了对称性较低的格位。     

基于红外测温的试件内部缺陷的识别算法研究

内部缺陷形状位置的识别是传热逆问题的重要研究课题.本文对带有内部缺陷的试件建立了二维传热模型,通过有限元法求解了在一定加热条件下试件表面的温度分布;并通过共轭梯度法,提出了根据表面所测温度分布识别试件内部缺陷形状、位置的计算方法.数值实验证明了算法的有效性.     

处理污泥焦颗粒内部孔结构在燃烧过程中变化

在管式炉反应器中进行了1种污泥定温燃烧试验,进行了5个不同燃烬率样品的液氮静态容量法等温物理吸附试验.发现不同燃烬率的污泥样品孔分布特性相似,其孔系统可能主要是由一端封闭的不透气的孔构成;随着燃烬率的增加,比表面积、平均孔径和孔体积等参数变化不同;样品颗粒内孔表面分形维数随燃烬率的增长呈先降低再升高的趋势.     

半壳结构金纳米膜的局域表面等离子体共振效应

采用纳米模版印刷术和化学自组装技术制备了半壳结构的金粒子膜.利用场发射扫描电子显微镜和光谱仪等测试手段对样品的结构和光学性质进行了分析.研究发现，该结构的金膜所具有独特的局域表面等离子体共振效应取决于样品的粒子大小、间距等微观结构，且其峰值吸收波长对其周围环境介质的介电常数变化十分敏感.实验结果表明，粒子排列均匀的亚单层膜结构是控制光学性质稳定的关键. 关键词： 局域表面等离子体共振 半壳结构 纳米模版印刷术