石墨炉原子吸收法直接测定饮用水中的铍、镍、钡

采用石墨炉原子吸收法,使用热解涂层石墨管,加上硝酸镁作基体改进剂,直接测定水中的痕量铍、镍、钡。测定钡时采用原子化阶段不停气,通以10mL/min的流量;测定完成后,再使用“清除温度”空烧1～2次处理,可消除记忆效应的影响。     

受主杂质Mn对（Ba,Pb）TiO3系高温PTC热敏陶瓷的影响

本文研究了(Ba,Pb)TiO_3系高温PTC半导体陶瓷中半导化与其烧结工艺、铅空位、钡空位和施、受主杂质等相互之间的关系。着重分析讨论了引入受主杂质Mn对材料的半导化的影响,并采用复合缺陷模型自洽地解释了实验现象。     

(Ba,Pb)TiO_3系高温PTC半导体材料研究

本文研究了含铅高温PTC半导体陶瓷材料的性能和工艺特点。采用快速烧结法获得了性能优良的(Ba,Pb)TiO_3系半导体材料。     

Scaling Effect on the Dielectric Constant in Ba(Ti x Zr1−x )O3 Thin Films

Recent work on PZT and BST thin films reveal a thickness dependence of the dielectric constant for a film thickness below 100 nm. This effect is commonly attributed to an interfacial layer between the electrode and the dielectric film (dead layer). In this contribution we report on the influence of the film thickness on the dielectric constant of Ba(Ti_xZr_{1 – x})O₃ thin films with different Zr-contents (x = 0–30 at.%). The films were prepared by chemical solution deposition (CSD) with thickness between 30 and 350 nm.The electrical characterization was performed in a temperature range between 25 and 200C. Results were interpreted with respect to the formation of a serial dead layer capacitance.     

Ba_5(Nb_(1-x)Sb_x)_4O_(15)微波介电陶瓷的低温烧结

添加质量分数为1%的H3BO3为助烧剂。研究了Ba5(Nb1–xSbx)4O15(0≤x≤0.2)陶瓷的烧结特性、显微结构和微波介电性能。结果表明:当x≤0.15时,该类陶瓷可在900℃附近烧结,并伴有少量BaSb2O6和BaB2O4相;随着x从0增加到0.2,εr和τf均有较大幅度下降;Q.f先升后降。在900℃烧成温度下,x为0.15的陶瓷获得较好的微波介电性能:εr为29.21,Q.f为13 266 GHz,τf为11×10–6℃–1,并能与Ag电极很好相容,基本满足LTCC工艺的要求。     

巴蜀兵器虎图形性质新说

对虎图形的性质，学术界长期以来存在多种观点。这些观点有其出现时代的合理性，但随着虎图形兵器材料的增加和对巴蜀文化研究的不断深入，其缺陷逐渐暴露出来。通过对学术界图腾说、族徽说、文字说、虎神说4种主要观点的分析，倾向于认为兵器上的虎图形是春秋战国时期特有的，一种巫术色彩浓郁的虎神崇拜的体现，与当时的军事集团有很大关系；虎图形的主要性质一是虎神，二是在图形符号组合中表现出来的图语性质。     

LF/VD精炼炉中Ba合金对洁净度的影响

在LV／VD精炼炉中对Ba合金使中的相关问题进行了试验研究，对Si-Ba-Al和Si-Ca-Ba合金在脱氧、脱硫、去夹杂和对夹杂变性方面的效果进行比较，试验结果表明利用Ba合金冶炼洁净钢有着重要的价值。     

Characterization of creep-fatigue in ferritic 9Cr-1Mo-V-Nb steel using ultrasonic velocity

The microstructural evolution of ferritic 9Cr-1Mo-V-Nb steel, subjected to creep-fatigue at 550 °C, was evaluated nondestructively by measuring the ultrasonic velocity. The ultrasonic velocity was strongly depended on the microstructural changes during creep-fatigue. The variation in the ultrasonic velocity with the fatigue life fraction exhibited three regions. In the first region (within 0.2 N_f), a significant increase in the velocity was observed, followed by a slight increase between the fatigue life fractions of 0.2 N_f and 0.8 N_f and a decrease in the final region. The change of the ultrasonic velocity during creep-fatigue was interpreted in relation to the microstructural properties. This study proposes an ultrasonic nondestructive evaluation method of quantifying the level of damage and microstructural change during the creep-fatigue of ferritic 9Cr-1Mo-V-Nb steel.     

Structural and electrical properties of lead free ceramic: Ba(La1/2Nb1/2)O3

Abstract

Abstract

Lead free perovskite Ba(La_1/2Nb_1/2)O₃ was prepared by conventional ceramic fabrication technique at 1375°C for 7?h in air atmosphere. The crystal symmetry, space group and unit cell dimensions were estimated using Rietveld analysis. X-ray diffraction analysis indicated the formation of a single phase monoclinic structure with space group P2/m. Energy dispersive X-ray analysis and scanning electron microscopy studies were carried to study the quality and purity of the compound. Permittivity data showed low temperature coefficient of capacitance (T _CC = 11%) up to 100°C. The circuit model fittings were carried out using the impedance data to find the correlation between the response of real system and idealised model electrical circuit. Complex impedance analyses suggested the dielectric relaxation to be of non-Debye type. The correlated barrier hopping model was employed to successfully explain the mechanism of charge transport in Ba(La_1/2Nb_1/2)O₃. The AC conductivity data were used to evaluate the density of states at Fermi level, minimum hopping length and apparent activation energy.     

Isotopic separation of silicon atoms by atomic mirror

The isotopic separation of silicon by an atomic mirror has been demonstrated numerically, by which each silicon isotope encounters a different dipole force depending on the frequency detuning due to the different frequencies resonant to the silicon isotopes. It was found that the atomic mirror, which comprised a wave guide structure designed for the enhancement of evanescent waves at 252 nm, allows us to discriminate ²⁹Si from the other isotopes.