Supramolecular Coordination Polymers by Self-assembling of Bis-monodentate Ligands with HgI2

Two supramolecular coordination polymers, [HgI₂(L¹)·0.5H₂O]_∞ (1) and [HgI₂(L²)·0.4CH₃OH]_∞ (2), have been prepared by ligands L¹ (L¹ = bis[4-(4- pyridylmethyleneamino)phenyl] ether) and L² (L² = N,N′-bis(3-pyridylmethyl)-diphthalic diimide) with HgI₂, respectively. 1 formed an interestingly infinite cross-linked double helical structure, whereas 2 formed the one-dimensional zigzag chains, which are parallel with each other.     

Nd2O3掺杂BaTiO3陶瓷的结构和电性能研究

研究了组份为Ｂａ１－ｘＮｄｘＴｉＯ３（ｘ＝０．００２－０．０４）陶瓷的结构和电性能，实验结果表明：当０．００２≤ｘ≤０．００４时，轻度Ｎｄ２Ｏ３掺杂的ＢａＴｉＯ３陶瓷呈半导体；而当０．０１２≤ｘ≤０．０４时呈绝缘性。ＢａＴｉＯ３陶瓷的室温电阻率ρｖ随Ｎｄ＾３＋含量的变化呈Ｕ型特曲线。组份为Ｂａ０．９９７０Ｎｄ０．００３０ＴｉＯ３的材料具有最低的ρｖ和最佳的ＰＴＣＲ效应，相应于最大的平均晶粒尺寸和最     

氧化铝生产中“硅渣”的组成和结构研究

综合运用Ｘ射线衍射,红外光谱,差热分析等方法,研究氧化铝生产脱Ｓｉ反应生成物－－水合铝硅酸钠渣的组成和结构,证明其为有硅原子缺位的羟基方钠石,ＳｉＯ２与Ａｌ２Ｏ３摩尔比小于２．０主要系方钠石晶格骨架上硅原子缺位所致。     

应用氢化物原子荧光法同时测定蔬菜中的砷和汞

采用氢化物发生-原子荧光法同时测定蔬菜中的砷和汞，具有操作简便，灵敏度高、准确度高、基体干扰少、节省试剂等特点。方法的回收率为：砷87．25％-113．15％，汞89．0％-106．5％；检出限为：砷0．13μg／L，汞0．009μg／L；线性范围为：砷0．5-150μg／L，汞0．2-50μg／L；相关系数达0．9995以上。     

Impact of a system of material points against an absolutely rigid obstacle: A model for its impulsive action

The impact of a system of elastically linked material points against an absolutely rigid obstacle is analytically described and limit to an elastic homogeneous rod is studied.     

不同掺杂对Yb半导的（Ba,Sr）TiO3系PTCR材料性能的影响

研究了不同掺杂方式对ＰＴＣＲ材料电学性能的影响,结果表明,Ｙｂ一次掺杂ＢａＴｉＯ３电阻变化“Ｕ”型曲线,低阻区为０．１ｍｏｌ％～０．３ｍｏｌ％,其移峰效率为３～５℃／ｍｏｌ。二次单一掺杂Ｙｂ提高电阻率,降低对升阻比,二次单一掺杂Ｍｎ提高电阻率与升阻经,二次Ｙｂ,Ｍｎ共掺杂可降低电阻率,提高升阻比,并探讨了二者配合作用的机理,Ｙｂ：Ｍｎ＝１：１效果最佳。     

A Mathematical-Physical Model for the Charge Transport in p-Type SrTiO3 Ceramics Under dc Load: Maxwell-Wagner Relaxation

A mathematical-physical model to describe the current response of p-type SrTiO₃ ceramics in the low-temperature regime upon dc voltage step was developed, utilizing the numerical class library DIFFPACK (Numerical Objects, Norway). The current response in the time domain shows the experimentally observed Maxwell-Wagner relaxation (space charge polarization), followed by leakage current, and, eventually, resistance degradation. The relaxation behavior is analyzed by means of the simulation results for the spatial profiles of the electrical potential and the respective point defects. The impact of bias voltage and grain boundaries on the relaxation time is investigated. The simulation results are compared with experimental data.     

Ab initio insights into the visible luminescent properties of ZnO

The luminescence spectrum of ZnO exhibits, besides a UV band-edge recombination line, a broad visible band around 2.2-2.4 eV whose origin has not been satisfactorily established. Recently, analysis of the luminescence of nanostructured materials with high surface-to-volume ratios has led some authors to suggest that the band could be related to surface states. This work presents a novel ab initio study of the most relevant ZnO surfaces and their intrinsic point defects. It reveals the existence of intragap surface states 0.5 eV above the valence band maximum. If additional bulk defect levels are considered, several bulk-to-surface transitions are compatible with the observed visible luminescence.     

Lanthanum Distribution and Oxygen Vacancy Concentration in SrBi4-x Lax Ti4O15

The Raman and X-ray photoemission spectroscopy of lanthanum-doped SrBi4Ti4O15 (SBLT -x, x =0.00, 0. 05, 0. 10, 0. 25, 0.50, 0. 75 and 1.00) ferroelectric ceramics were investigated to explore the La substitution site and the influence of La-doping on the oxygen vacancy concentration. The results suggest that La3 ions behave pronounced site selectivity for the A site in the case of x ≤ 0.10, and they are incorporated into Bi2O2 layers at higher content. The oxygen vacancy concentration declines with La-doping, and the decrease seems saturated as La content is higher than 0.10.     

Effect of thermo-mechanical processing on microstructure and creep properties of the foils of alloy 617

The effect of rolling and annealing on the microstructure and high temperature creep properties of alloy 617 were investigated. Two types of foil specimens with different thickness reductions were prepared by thermo-mechanical processing. Recrystallization and grain growth were readily observed at specimens annealed at 950 and 1100 °C. The uniform coarse grains increase resistance against creep deformation. The grain size effect in creep deformation was dominant up to 900 °C, while dynamic recrystallization effect became dominant at 1000 °C. Dynamic recrystallization was observed in all the creep deformed foils, even though some specimens had already been (statically) recrystallized during annealing. Steady state creep rates decreased with increasing annealing temperature in the less rolled foils. The apparent activation energy Q_app for the creep deformation increased from 271 to 361 kJ/mol as the annealing temperature increased from 950 to 1100 °C.