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采用复阻抗技术对三元系ZrO2-Y2O3-Yb2O3材料在573-873K内的离子电导率随组成的变化关系进行了研究,发现该材料的低温电导率随Yb2O2含量的增加而降低。用Arrhenius公式对实验数据进行的分析表明,电导率降低的原因在于Yb^2+与结构中氧空位之间的缔合比Y^3+与氧空位之间的缔合更甚,阻碍了氧空位在低温下的定向迁移。 相似文献
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纳米(ZnO,Al2O3)复合掺杂对3Y2O3-ZrO2材料电性能的影响 总被引:1,自引:0,他引:1
以3Y2O3—ZrO2纳米粉和ZnO,A12O3纳米粉为原料,采用交流阻抗谱技术对掺少量ZnO和A12O3的3Y2O3—ZrO2烧结陶瓷进行电性能研究。研究表明:少量纳米ZnO掺杂降低了3Y2O3—ZrO2的电导率,但随着掺人量的增加,电导率开始回升。在ZnO掺杂样品中加入少量纳米A12O3进行复合第二相掺杂,结果提高了3Y2O3—ZrO2材料的电导率。同时少量A12O3的掺人降低了晶粒电导活化能,使得晶粒电导率增加。 相似文献
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ZnO掺杂的ZrO2(3Y)纳米复合相材料的中低温电导研究 总被引:3,自引:1,他引:2
采用交流阻抗技术对掺纳米ZnO的纳米ZrO2(3Y)复合掺杂材料在473—973K温度范围电导率随ZnO第二相质量分数(0.0%-5.0%(质量分数))的变化关系进行了研究。研究发现掺很少量的纳米ZnO(0.5%-1.0%(质量分数)),纳米ZrO2(3Y)材料晶粒和晶界电阻显著增加,电导率降低,原因在于缺陷缔合效应和晶界偏聚效应的加剧,阻碍了氟空位的迁移。随着ZnO掺入量的增加(>1.0%(质量分数)),晶界电阻显著减小,晶粒电阻变化不大,总电导率回升,在中低温范围,总电导活化能与晶界电导活化能具有相同的变化趋势。 相似文献
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利用X射线衍(XRD)、扫描电子显微镜(SEM)和器件测试等方法对TiO2:Nb2O5混合晶体结构、表面形貌及敏感机理进行分析与讨论.结果认为:Nb2O5为10%的富钛敏感材料含有大量氧空位,晶粒之间的空隙增大,显著提高了电导率和气敏特性;使器件阻值Ra降低和灵敏度K提高得到统一优化效果;为动物食品测鲜传感器研究开辟了一条新途径. 相似文献
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为了制备ZrO2掺杂的BaCo0.7Fe0.2Nb0.1O3-δ(BCFN)样品并研究其高温化学稳定性和电学性能,分别通过XRD研究了材料相成分的变化;通过收缩率和密度的测量并结合SEM研究了材料的微观结构;通过TG实验研究了材料在一定气氛下随温度的失重变化;通过直流四电极法测量了材料总电导的变化规律.研究结果表明,BCFN掺杂ZrO2之后材料为双相复合结构.随着ZrO2掺杂量的增加,材料在惰性气氛和氢气气氛下表现出更好的结构稳定性.ZrO2掺杂与未掺杂的BCFN体系其电学性能随温度的变化规律相同,在570℃之前的低温范围以P型半导体电子空穴导电机制为主,在高温则是同时存在电子空穴导电与氧离子导电,随着ZrO2掺杂量的增加,材料在空气气氛下的总电导率依次下降. 相似文献
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以含In的TiO2为基质,与重量比为10%的Nb2O5混合,TiO2-In-Nb2O5混合敏感材料有效解决了三甲胺(TMA)动物食品测鲜气敏器件中提高电导率和保持高灵敏度之间的矛盾.并利用XRD、SEM对该混晶体的结构、形貌及其机理进行分析,发现:该富钛混晶体中颗粒间的空隙增大、颗粒颈部变细,有效提高了响应TMA敏感特性;混合过程中所形成含铌的氧化态混晶体是缺氧态的,氧空位的增多有助于敏感材料电导率的增加. 相似文献
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A microstructural study has been carried out of plasma-sprayed Al2O3 and mixed and sintered Al2O3Y2O3. In order to ascertain the degree of metastability achieved by plasma spraying, these results are compared with a similar experiment utilizing a CO2 laser for melting and the hammer-and-anvil technique for quenching of the same materials. X-ray diffraction methods were used to determine the obtained phases and crystal structures. In addition, transmission electron microscopy was used to confirm the phases present and to study their morpology. The porosity was studied with both mercury intrusion porosimetry and small angle neutron scattering. The addition of Y2O3 is shown to decrease the porosity from 15% to 7.5%. Adhesion is likewise related to the addition of Y2O3 and it is seen that adhesion of the mixture is measurably improved over that of pure Al2O3. The implication of these results is discussed. 相似文献
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The surface tensions of xPbO-(100?x) B2O3 (x = 30–80 mol%) and xBi2O3-(100?x) B2O3 (x = 0–100 mol%) melts were measured using the ring method over the temperature range 973 to 1373 K. The compositional and temperature dependences of surface tension were investigated. Addition of PbO and Bi2O3 to B2O3 increased the surface tensions of their respective PbO-B2O3 and Bi2O3-B2O3 melts. The surface tension showed a maximum at 60 mol% PbO in the PbO-B2O3 melts and at 70–80 mol% Bi2O3 in the Bi2O3-B2O3 melts. The temperature coefficient of surface tension was examined on the basis of its relationship to the structure, and it was suggested that the temperature coefficient of surface tension decreases with an increasing content of four-coordinated boron. 相似文献
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Weiwei Zhu Jichun Chen Chuanyong Hao Jinsong Zhang 《材料科学技术学报》2014,30(9):944-948
ZnO-Al2O3-B2O3-SiO2 (ZABS) glass powder was used as interlayer to join alumina ceramics. The effect of joining temperature on the microstructure and strength of joints was investigated. The results showed that the ZABS glass can react with alumina substrate to form a layer of ZnAl2O4 at Al2O3/glass interface. Bending test exhibited that low joining temperature (1150℃) led to low joint strength due to the formation of pores in the interlayer, originated by high viscosity of the glass. High joining temperature (1250 ℃) also resulted in low joint strength, because of large CTE (coefficient of thermal expansion) mismatch between amorphous interlayer and alumina substrate. Therefore, only when the joining temperature was appropriate (1200℃), defect-free interface and high joint strength can be obtained. The optimum joint strength reached 285 MPa, which was the same as the base material strength. 相似文献
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E. Burzo L. Stănescu V. Teodorescu I. Ardelean M. Coldea 《Journal of Materials Science》1978,13(9):1855-1867
Various methods have been used to study the physical properties of the V2O5-Fe2O3 and V2O5-Fe2O3-Li2O systems, including X-ray, electron microscope, Mössbauer effect, NMR and thermogravimetric measurements. The iron ions are approximately equally distributed in substitutional and interstitial sites in the V2O5 lattice. The maximum number of iron ions dissolved in the V2O5 matrix corresponds to 4 mol % Fe2O3. In all the samples a quantity of Fe2O3 which has not been included in lattice is observed. The V2O5-Fe2O3 and V2O5-Fe2O3-Li2O systems are formed from solid solutions mixed with very small Fe2O3 particles. The analysis of the charge compensation of iron ions suggests that V2O5 is a quasi-amorphous semiconductor. Irradiation of V2O5-based samples with an electron beam induces the V2O5 platelets to convert to the VO
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phase. 相似文献
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Yang LI Jianhu YANG Shiqing XU Guonian WANG Lili HU Laserglass Laboratory Shanghai Institute of Optics & Fine Mechanics Chinese Academy of Sciences Shanghai China Graduate School of the Chinese Academy of Sciences Beijing China 《材料科学技术学报》2005,21(3):391-394
The physical and thermal properties of P2O5-Al2O3-BaO-La2O3 glasses were investigated. The effects of glass compositions on the transition temperature, thermal expansion coefficient, density, hardness and refractive index of glasses were studied. The highest hardness of the glasses is 4143.891 MPa and the lowest thermal expansion coefficient of the glasses is 71.770×10-7/℃. A phosphate glass with high mechanical strength and good thermal characteristic is obtained. 相似文献