Effect of bismuth replacement at barium site in Y-Ba-Cu-O system

X-ray diffraction, electron paramagnetic resonance, microwave absorption and resistivity measurements were carried out on YBa_2−x Bi _x Cu₃O₇ (0≤x≤0·5) superconductors in order to study the effect of bismuth on the structural and superconducting properties. A decrease in sintering temperature increased the amount of impurity phase. Transition from an orthorhombic (superconducting) phase to tetragonal structure produced no significant change in EPR zero-field signal at liquid nitrogen temperature (LNT). The non-resonance signal height decreased on higher concentration of bismuth. Sintered YBa_2−x Bi _x Cu₃O₇ superconductor had a strong EPR zero-field signal at LNT. We have evaluated particle size from XRD and EPR studies. The average particle size was about 0·4μm.     

电炉钢外来夹杂控制的研究

介绍了夹杂物的来源,包括内生夹杂和外来夹杂,着重于二次氧化产物、卷渣、内衬侵蚀.同时介绍了鄂钢电炉厂在冶炼和连铸过程中控制夹杂物的操作实践.     

Effect of Hydrogen Heat Treatment on the Chemical Composition of Aluminum Nitride Powder

The effect of hydrogen heat treatment on impurity contents in aluminum nitride powder of different fineness is studied. Thermodynamic calculations are provided pointing to the possibility of forming gaseous hydrogen compounds with impurity elements. It is established that as a result of treatment the contents of impurity elements, i.e. oxygen, carbon, sulfur, are reduced by a factor of 3-13. The optimum hydrogen heat treatment regime is determined: a temperature of 1323 K and an exposure time of 30 min.     

Magnetic properties of high-temperature superconductors: Analysis within the framework of the impurity mechanism

The impurity mechanism proposed earlier is used to interpret the magnetic properties of hightemperature superconductors. The appearance of superconductive granules and the existence of weak bonds in grains of ceramics and in single crystals is explained. The irreversibility line is obtained and its new interpretation as the line of thresholds of appearance of infinite nonsuperconductive cluster is given. The relaxation time of the magnetic susceptibility in alternating magnetic fields is calculated. The decrease of the Meissner fraction with increase in magnetic field and decrease in doping, and other magnetic properties are explained.     

GaAsP混晶中Fe杂质能级的无序分裂

GaAsP混晶中Fe杂质基态与激发态的光离化截面的幅度比S(x)随组分x有规律地变化,本文提出一种理论估算,认为它是Fe能级无序分裂的结果.     

扫描电镜在质量事故分析中的应用

应用扫描电镜断口分析、能谱定性分析、光学显微形貌测试等方法 ,针对公司重要产品因细小裂纹而连续四炉产品全部报废的重大质量事故 ,分析了引起报废裂纹缺陷的性质及产生原因。结果表明 :缺陷主要是大量集聚分布的脆性Al2 O3 夹杂及其裂纹 ,属原材料缺陷 ,是冶炼时氧化还原工艺控制不当 ,或加Al量不均匀所致。据此立即采用了相应调整和改进冶炼工艺措施 ,有效消除了原始缺陷 ,迅速提高了产品质量和效益。     

结晶法提纯在高纯镓生产中的应用

目前镓提纯方法多采用电解法。单一电解法提纯镓．由于一些主要杂质析出严重，常常形成个别杂质元素超标，造成产品品级降低。本项目通过对电解尾料结晶法镓提纯新方法的研究，进一步补充完善提纯工艺路线，提高产品质量的稳定性。将该方法与湿法提纯技术相联合．可以提高产品产出率，降低生产成本。     

金属锑中微量杂质的光谱测定

利用直接光谱法测定锑中Ａｓ、Ｃｏ、Ｂｉ、Ｐｂ、Ｃｒ、Ｓｎ、Ｍｇ、Ｆｅ、Ａｌ、Ｎｉ、Ｃｄ、Ｃｕ、Ｚｎ、Ａｇ等微量杂质，选择石墨粉作为缓冲剂，改善了谱线的重复性，对样品处理进行了详细的分析研究，以最佳的光谱测定条件，使元素测定下限达到３×１０－４％─３×１０－３％，相对误差在２２％以内，为金属锑纯度的全面分析建立了可靠的分析方法。     

成色剂COY—5中主要杂质的分析研究

应用高效液相色谱、薄层色谱、质谱及核磁共振谱等仪器分析手段，提出了成色剂ＣＯＹ—５中主要杂质的分子结构，指出了该杂质的产生原因和机理，以及降低该杂质含量的最佳途径     

原料中杂质对丙烯与苯烷基化催化剂性能的影响

分析了原料中杂质对催化剂活性和稳定性的影响及脱除杂质的方法。不同来源的丙烯所含杂质不同 ,炼厂丙烯杂质主要是氮化物和双烯 ,而裂解丙烯杂质主要是双烯 ;苯的主要杂质是饱和烷烃和微量水 ,这些杂质对催化剂活性和稳定性都有影响。实验结果表明 ,杂质含量越高 ,催化剂的活性和稳定性越低 ,而采用强酸性阳离子交换树脂可以脱除丙烯中的杂质。