K.El-Menshawy
材料科学技术（英文）
The electrical conductivity of sintered Cr2O3 mixed with 2% and 5% (in molar fraction) TiO2 or CuO was investigated in the temperature range 500~900℃ in air and in Ar/4 vol. pct H2 atmospheres. The effect of different Mn-oxides on the electrical conductivity of Cr2O3 was also studied under the same conditions. From the conductivity measurements it is established that additions of TiO2 change the defect structure of Cr2O3 and the effect of TiO2 on the electrical conductivity is controlled by TiO2 concentration as well as temperature and O2 partial pressure of the surrounding atmosphere. The conductivity of Cr2O3 increased in air and decreased in the Ar/H2 atmosphere by CuO additions. The effect of CuO was discussed with possible changes in the defect concentration in Cr2O3. Mixing of Cr2O3 with different Mn-oxides at the same Mn to metal atom fraction decreased the conductivity in air and in Ar/H2 atmospheres. No clear correlation between the spinel fraction and the changes in conductivity could be found.
关键词:
Electrical conductivity
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null
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null
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null
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null
Ahmed A.Hassan
,
Omar Abdelal A.
材料科学技术（英文）
Yttria stabilized tetragonal zirconia polycrystals (3Y-TZP) doped with CuO was prepared, to get two compositions, 0.3 and 1 mole fraction CuO, respectively. The dilatometric study of the samples showed sintering to be improved for the samples doped with 0.3 mole fraction CuO, and to be deteriorated for the samples doped with 1 mole fraction CuO. The 1 mole fraction CuO doped 3Y-TZP showed higher tetragonal/monoclinic phase transformation which was accompanied by grain growth. The electrical conductivity decreased with the addition of CuO.
关键词:
Y2O3
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D.
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Sintering
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aids
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C.electrical
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co
H.T.Shaban
,
M.M.Nassary
,
M.S.El-Sadek
材料科学技术（英文）
Bi2S3 single crystals were grown by using a modification of Bridgman method. Measurements of the electrical conductivity, Hall effect and thermoelectric power (TEP) were preformed in two crystallographic directions (parallel and perpendicular to the c-axis). The measurements showed that the electrical conductivity, Hall mobility, and Seebeck coefficient have anisotropic nature. From these measurements some physical parameters were estimated and the crystals showed n-type of conduction mechanism. Also, values of the energy gap were found to be different in the two directions.
关键词:
Bi2S3
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null
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null
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null
Hui Lu
材料科学技术（英文）
The perovskite Cr-doped La0.6Sr0.4CrxFe1-xO3-δ (x=0.10, 0.20) oxides were synthesized via the citrate gel method. The perovskite forming of the La0.6Sr0.4CrxFe1-xO3-δ (x=0.10, 0.20) oxides were studied by thermogravimetric analysis (TG), differential scanning calorimetry (DSC), and X-ray diffraction (XRD). Structural and chemical stability under H2-containing helium atmospheres of La0.6Sr0.4CrxFe1-xO3-δ (x=0.10, 0.20) were investigated by TG and XRD. The sintering microstructures of the perovskite La0.6Sr0.4CrxFe1-xO3-δ (x=0.10, 0.20) ceramics were investigated by scanning electron microscopy (SEM), and the electrical conductivities of both oxide ceramics were also measured up to 900 ±C. The results demonstrated that the chemical stability of the Co-free La0.6Sr0.4CrxFe1-xO3-δ (x=0.10, 0.20) oxides was significantly improved compared to the Co-containing La0.6Sr0.4CrxFe1-xO3-δ and Ba0.5Sr0.5Co0.8Fe0.2O3-δ oxides. The incorporation of Cr cations in the B-site of the pervoskite oxides resulted in the improved structural and chemical stability of the as-synthesized La0.6Sr0.4CrxFe1-xO3-δ(x=0.10, 0.20) oxides.
关键词:
Perovskite
Qing GONG
,
Xiaoming CAO
,
Jinsong ZHANG
,
Zheng FANG
材料科学技术（英文）
3D reticulated ceramics (3DRCs) with the composition containing SrFe12O19-SiC-TiO2 were prepared by a replication process with polyurethane sponges as the template in ceramic slurry. The electrical conductivity, dielectric and magnetic parameters of 3D reticulated ceramics (3DRCs) were measured with changes in cell size of the sponges, contents in the slurry and sintering temperature in this paper. Discussions about the influential factors of those parameters were focused on their electrical conductivity. The experimental results indicated that the electrical conductivity of 3DRCs raised with the increase of cell size, SiC/SrO·6Fe2O3 with weight ratio and sintering temperature. X-ray diffractions and SEM were used to investigate the relationship between electrical conductivity and sintering temperature. Deoxidizing reactions of SrO·6Fe2O3 caused the increasing electrical conductivity. The real part of permittivity (ε') and imaginary part of permeability (μ'') raised with the increase of electrical conductivity (σ). The imaginary part of permittivity (ε'') has a maximum at 100S/cm with the increase of sigma, and the real part of permeability (μ') changes slightly with the increase ofσ. When sigma is at the range of 10-4 S/cm to 100 S/cm (a semi conductive state), both the imagine part of permittivity and permeability raises with increasing sigma, therefore, the 3DRCs present their high electromagnetic loss properties.
关键词:
3D reticulated ceramics
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null
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null
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null
宁远涛
,
张晓辉
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秦国义
,
张婕
贵金属
doi:10.3969/j.issn.1004-0676.2005.03.009
以冷却速率101～103K/s的不同凝固条件制备了Cu-10Ag合金及其原位纤维复合材料.研究了铸态和形变态合金的结构与性能.铸态合金的结构由Cu相、Ag沉淀相和(Cu+Ag)共晶组成.通过大变形发展为Cu-Ag合金原位纳米纤维复合材料,其中由Ag沉淀相所形成的Ag纤维尺寸(d)与真实应变(η)呈指数函数关系:d=C·exp(-0.228η),(Cu+Ag)共晶中Ag层转变为更细的纳米Ag纤维.Cu-Ag合金原位纳米纤维复合材料显示了两阶段应变强化效应:在低真实应变阶段主要表现为加工硬化或位错强化,在高真实应变阶段主要表现为超细Ag纤维强化或界面强化.快速凝固的Cu-Ag合金原位纳米纤维复合材料比慢速凝固材料具有更高的包括极限拉伸强度和电导率在内的综合性能.在形变过程中复合材料的强度与电导率的演变出于相同的结构原因.
关键词:
金属材料
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复合材料
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Cu-Ag合金
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凝固
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力学性能
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电导率
胡学飞
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郑红梅
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崔接武
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王岩
,
周士昂
,
吴玉程
功能材料与器件学报
铜包铝镁合金导线因其大大节约铜资源,有很高的经济效益,同时又能保持同种使用条件下电学性能而广泛的应用在高频信号线缆中.本文在Al-1.2Mg的铝镁合金中添加微量的Sc元素,通过研究组织结构、力学性能、耐热性和电导率等性能指标来分析Al-Mg-Sc合金材料做为导线材料的可行性.结果表明:微量的Sc元素后,Al-Mg合金的晶粒得到显著的细化,电导率会有所下降,但其力学性能得到很大的提升和优化,且耐热性良好.这为五系铝合金导线作为中高强度电力电缆的应用提供参考.
关键词:
铜包铝
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Al-Mg-Sc合金
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退火处理
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电导率
