硼酸铝钕(NAB)晶体光学均匀性的测量

NAB晶体是一种综合性能较好的新型激光工作物质,有希望做成高效的小型固体激光器。本文介绍一种测量这种晶体光学均匀性的方法。 一般都采用在干涉仪上观测干涉图样来判定激光棒的光学均匀性。NAB晶体的吸收光谱曲线显示出其在可见光光谱区内有多个吸收峰。我们注意到:通常用做激光干涉仪光源的He-Ne激光器发射的632.8nm谱线正位于NAB晶体的一个吸收峰,并用输出约为45mW     

β—BBO晶体的电光性能

用干涉法测量了β－ＢＢＯ晶体的电光系数：γ２２＝２．６，γ３３＝０．２３，γ３１＝０．２５，γ５１＝－３．５×１０－１２ｍ／Ｖ。结果表明如果在Ｙ方向加电场，Ｚ方向通光，β—ＢＢＯ晶体可能制作成有应用价值的光开关。     

Sixty years of dislocations

It is well-known that with the appearance of three independent papers by Taylor, Polanyi and Orowan in the year 1934, the concept of crystal dislocations was born. Since then, dislocation theory has had many spectacular successes. It is quite appropriate therefore to be aware of the state of development of this exciting subject, sixty years after its discovery. A flavour for the vast subject of the applications of dislocation mechanisms to real materials is presented by choosing three examples, one each, drawn from metallurgy, physics and electronics. The topic of ‘Strength of metals and alloys’ is the first one, as this is also the author’s area of research. The phenomenon of solidification and crystal growth forms the next topic, especially in view of the seminal contributions made by A R Verma and his school from India. Dislocations play a useful role in the strengthening of solids, but how influential are they in affecting the performance of modern semiconductor devices? In the third example, the interesting and painstaking work done to settle this question is reviewed. Can we regard carbon fibre as thetransistor of dislocation theory? How shall we understand the long-established effects such as corrosion-fatigue, superplasticity and shape memory as well as the electrochemical and electro-mechanical properties of dislocations in semiconductor and non-metallic crystals? Answers to these questions belong to the realms of the future developments in dislocations. The talk is concluded with a discussion of these topics.     

Crystallization and Drying in Thin Sucrose Films During Panning

Sucrose crystallization in thin films (50–55 μm) was studied, using a videomicroscopy technique, at conditions encountered during hard panning processes. No nucleation occurred in unseeded films, while a linear increase in seeded crystals occurred during drying. Crystal growth rate increased with temperature (25–30°C) and with air velocity (2.4–12.5 m/sec), but did not change with varying sucrose concentrations (70–76% w/w) and relative humidities (0–66% at 30°C). FD & C Yellow No. 5 food coloring in the dye form (0.05–0.5 g/100 mL) showed no effects while similar concentrations in the lake form inhibited crystal growth rate.     

Growth and optical property of zinc oxide thornballs

A new microstructure, thornball, of zinc oxide (ZnO) was synthesized by a very simple solid vapor deposition process under lead oxide (PbO) atmosphere. The microthornballs consist of numerous needles, which extend outwards in all directions symmetrically. They have dimensions of 120 μm in diameter, while the average diameter of the needles is about 100-200 nm. The needles on the balls grow along the 〈0 0 0 1〉 orientation and have gradient compositions along radial. Control experiments proved that PbO played an important role in the growth. Additionally, photoluminescence property was observed and provided the evidence that PbO did not deteriorate the optical properties of ZnO thornballs. This kind of microstructures has potential applications in the field of photochemical catalysis.     

高频脉冲电铸Ni-Co纳米复合块体微观结构分析

采用高频脉冲电铸工艺制备出了镍钴纳米复合块体材料，利用场发射扫描电镜、能谱和X射线衍射的方法，重点研究了复合块体沉积层的表面形貌、相结构和结晶取向。结果表明．高频率和润湿剂的添加对沉积层的细化有重要影响，高频脉冲电铸能够获得微观组织致密、均匀的复合块体材料。     

刚性棒状全芳香液晶聚酯的合成及性质的研究

以溴和苯基取代的对苯二甲酰氯及2，2′-二甲基联苯-4，4′-二甲酰氯作为单体，分别与甲基、叔丁基、苯基取代的对苯二酚经熔融缩聚反应，合成一类具有刚性棒状结构的全芳香液晶聚酯。聚酯的热性质以TGA、DSC，热台偏光显微镜研究。所有的聚酯均为热致性液晶，它们具有相对较低的转变温度，在普通的有机溶剂中具有较好的溶解性质。     

Phase equilibria in the system Al-Rh

Methods of differential thermal analysis, x-ray diffraction, microstructural analysis and electron probe microanalysis are used to study alloys of the Al-Rh system over the whole concentration range. It is established that the phase of equiatomic composition AlRh melts congruently at 2060°C and it has an extended range of homogeneity (45.1–54.2 at.% Rh). The solubility of aluminum in rhodium reaches 9 at.%, decreasing to 6 at.% at 850°C. Coordinates are determined for the eutectic point l ⇆ AlRh + 〈Rh〉 as 70 at.% Rh and 1715°C. The existence of intermediate phases, their crystal structure, and also the method of forming phases in the field of composition rich in aluminum given in publications are confirmed. __________ Translated from Poroshkovaya Metallurgiya, Nos. 5–6(449), pp. 48–56, May–June, 2006.     

影响硼酸结晶形状的因素

从硼酸的结晶机理入手,探讨了影响硼酸结晶形状及大小的因素,在合理地控制操作条件的同时,加入合适的晶习改性剂,可以加大硼酸结晶体的粒状比例。     

钢带试样位向及拉伸性能的探讨

从碳素结构钢热轧钢带各向异性的事实出发 ,阐述不同试样位向导致同一钢带不同的拉伸性能 ,因而影响钢带合格与否的判定。在全面考虑钢带和焊管标准的基础上 ,提出解决钢带判定的两种方法。同时 ,还对标准中存在的缺点作了说明 ,提出改进意见 ,供标准修订时参考。