Crystallographic evaluation of ZnSe crystals by x-ray diffraction

Crystallographic quality and the lattice constant of ZnSe crystals grown from Te/ Se solutions by the temperature gradient solution growth method were evaluated by using a high resolution x-ray diffractometer. The full width at half maximum of the x-ray rocking curve was 5.7 sec, a value almost equivalent to that of GaAs. The distribution of crystallographic properties along the growth direction was nearly the same excepting just on the heat-sink. The accurate lattice constant of the ZnSe crystal measured by this system was 5.6700 ± 0.000025 A.     

超薄膜磁性材料上XY模型的临界现象

采用经典XY模型，阐明了三角格子上层状超薄膜磁性材料的相变和临界现象.并用Monte-Carlo方法对该模型的内部能量、比热、chirality等热力学量进行了计算.使用finite-size scaling 分析法对临界现象的性质进行了论述.通过上述分析和计算，发现该模型在反强磁性层与强磁性层内的chirality在一定范围内随温度的变化急剧增加，这是一种新的chirality相变；而在另一范围内存在Kosterliz-Thouless相变和通常的chirality相变.这种新的chirality相变的 关键词： 层状XY模型 临界现象 Monte-Carlo模拟 磁性薄膜     

Electron beam-induced decomposition of graphite fluoride

Irradiation of graphite fluoride with electron beams has been carried out on a electron probe microanalyzer. Radiation-induced decomposition took place predominantly instead of thermal decomposition. The decomposition tended to occur in the following order: powdery (CF)_n, white flaky (CF)_n, and (CF₂F)_n. The kinetics of the decomposition reaction induced by electron beams was evaluated by the ZAF correction of the measured intensities of F K- and C K-emission bands. It was found that the kinetic of the decomposition of graphite fluoride was of Avrami-Erofejev type; the rate equations were $\text{-}\text{ln}\text{(1?α)=kt}{}^{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ for (CF)_n and -ln(1?α)=kt² for (C₂F)_n. An application to the electron microbeam processing of graphite fluoride was suggested in relation to its unique physicochemical properties.     

XPS for in situ observation of an Ag electrode on a solid electrolyte used as oxygen sensor

The Ag electrode surface of a solid electrolyte in its working state has been studied by X-ray photoelectron spectroscopy. The nature of the AgO system on the electrode is dependent on the temperature. There are three types of AgO systems at 400°C. Type 1 with an O is binding energy of 532.6 eV only appeared at 325°C. However, when the temperature was raised to 400°C, types II and III (with BEs 531.1 and 529.2 eV) appeared. These O is signals are discussed in detail.     

Stereoselective synthesis of (±)-phomenone,a phytotoxic metabolite of phoma exigua, and (±)-3-epiphomenone

Stereoselective synthesis of (±)-phomenone, a phytotoxic metabolite from the fungus Phoma exigua, and (±)-3-epiphomenone is described.     

Invar effects on some iron-base amorphous alloys

The thermal expansion and magnetic properties of Fe-B and Fe-P amorphous alloys prepared from melts have been investigated. These amorphous alloys show distinct Invar characteristics. heir magnetic properties are also very similar to those of Fe-Ni crystalline Invar alloys; that is, the high-field susceptability and forced-volume magnetostriction are remarkably large, the magnetic moment per Fe atom does not increase linearly, the Curie temperature decreases with a decrease in concentration of B or P, and their reduced their magnetization curves are much flatter than those of crystalline pure Fe.     

Three unusual 22-beta-O-23-hydroxy-(5 alpha)-spirostanol glycosides from the fruits of Solanum torvum

Three novel 22-beta-O-spirostanol oligoglycosides, torvosides J (1), K (2) and L (3) have been isolated from the fruits of Solanum torvum SWARTZ and their chemical structures have been characterized based on the spectroscopic means. They are worth of note as rare 22-beta-O-spirostanol glycosides.     

A new tomato pregnane glycoside from the overripe fruits

A new pregnane glycoside has been isolated from the overripe fruits of Cherry tomato (Mini tomato), Lycopersicon esculentum var. cerasiforme (DUNAL) ALEF. The structure was determined to be 3-O-beta-lycotetraosyl 3beta-hydroxy-5alpha-pregn-16-en-20-one on the basis of spectroscopic analysis. The seasonal variation of the tomato saponin is discussed.