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Nonlinear Electrical Properties of SnO_2-Li_2O-Nb_2O_5 Varistor System

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Journal of Materials Science & Technology 2002年第3期18卷 283-285页

作者： Changpeng LI, Jinfeng WANG, Wenbin SU, Hongcun CHEN and Wenxin WANGDepartment of Physics, Shandong University, Jinan 250100, China[ manuscript received September 11, 2001, in revised form October 20, 2001] Shandong Univ Dept Phys Jinan 250100 Peoples R China

The electrical properties of (Nb, Li)-doped SnO2 ceramics as a new varistor material were investigated. The sample 97.95%SnO2·0.50%Li2O·0.05%Nb2O5 (mol fraction) sintered at 1450= possess the highest density (ρ=6.77 g/cm3) and nonlinear electrical coefficient (α=11.6). The substitution of Sn4+ with Li+ increases the concentration of oxygen vacancies, together with the formation of solid solution, which will increase the sintering rate greatly and decrease the optimized sintering temperature. The substitution of Sn4+ with Li+ and the variation of temperature play very important effects on the densities, dielectric constant, nonlinear electrical properties and other characteristics of the samples. The properties of the grain boundary barrier and the microstructural characteristics were investigated to ensure the effect of the dopants and the temperature. A grain boundary defect barrier model was used to illustrate the grain boundary barriers formation in SnO2-Li2O-Nb2O5 varistors.

关键词： Varistors Tin oxide Lithium oxide Electrical properties

EPR and Magnetic Susceptibility Investigations of Fe Containing TeO_2-B_2O_3-SrF_2 Glasses

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Journal of Materials Science & Technology 2000年第6期16卷 596-600页

作者： I.Ardelean, M.Peteanut, V.Simon and F.Ciorcas (Faculty of Physics, Babes-Bolyai University, 3400 Cluj-Napoca, Romania) [manuscript received November 23, 1999, in revised form June 20, 2000] Faculty of Phys. Babes-Bolyai Univ. Cluj-Napoa Romania

Iron ions were used as probes to explore the structural and magnetic properties of 70TeO2'25B2O3' 5SrF2 vitreous matrix. The distribution of Fe3+ ions on different structural aggregates was revealed by means of EPR, as depending on Fe2O3 concentration. Strongly distorted octahedral sites were detected for the isolated paramagnetic ions, and also clusters of Fe ions especially at high Fe2O3 content of samples. Magnetic susceptibility measurements evidenced both dipoledipole and superexchange type interactions involving iron ions. Mixed valence states of iron ions were also detected

关键词： Te In Fe EPR and Magnetic Susceptibility Investigations of Fe Containing TeO2-B2O3-SrF2 Glasses line

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核破裂中的粒子发射和临界涨落

物理学报 1999年第10期48卷 1839-1844页

作者：马余刚中国科学院上海原子核研究所上海201800

用晶格气体模型系统地研究了１２９Ｘｅ热发射体的轻粒子、带电粒子和中间质量碎片的发射特性，发现了在温度５ —５５ＭｅＶ区间，以上物理量的平均多重性和发射源的最大碎片余核及源的热激发能随温度变化的斜率存在着各自的... 详细信息

用晶格气体模型系统地研究了１２９Ｘｅ热发射体的轻粒子、带电粒子和中间质量碎片的发射特性，发现了在温度５ —５５ＭｅＶ区间，以上物理量的平均多重性和发射源的最大碎片余核及源的热激发能随温度变化的斜率存在着各自的峰值，同时它们的分布宽度（即涨落）也存在着最大值．进一步研究发现在５ —５５ＭｅＶ区间，这些宽度随温度的变化的斜率显示了明显的不连续性．所有这些特征说明了在５ —５５ＭｅＶ的拐点温度处，最大的临界涨落是自发地伴随着相变和临界现象．

关键词：粒子发射临界涨落核核碰撞核破裂

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固体碳还原熔融氧化铁的速度研究