共查询到17条相似文献,搜索用时 125 毫秒
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测量了Bi1.8Pb0.4Sr2Ca2Cu3Oy银夹板厚膜的应力与应变、应变和临界电流密度关系,及其在不同应变下的Jc(H)特性.结果表明,在应力-应变曲线上存在两个应变转变,分别对应于Bi1.8Pb0.4Sr2Ca2Cu3Oy关键词: 相似文献
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用固相反应法合成了名义组分为Bi1.92Pb0.32Sr2Ca1.7Mg0.3Cu3.07Ox的块状样品。X射线衍射谱(XRD)、扫描电子显微镜(SEM)和电子探计X射线分析(EDAX)结果以及块状和粉状试样的交流磁化率测量表明,样品中存在110和85K两个超导相;2223相(110K)首先在2212相(85K)晶体的晶界和外部区域生成。本文认为,最初存
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采用固相反应法合成了名义组份为Bi2-xPbxSr2Ca2Cu3Oy (x=0.30;0.35;0.40;0.45)的样品。对样品进行了物相和结构分析,同时测量了电阻-温度关系和直流磁化率。结果表明:x=0.35的样品为单相材料,X射线相分析和电子衍射表明其相结构类似2223相,为四方结构,其晶格常数为a=b=5.414?,c=37.106?,且沿a,b两个方向都观察到调制结构。电阻和直流磁化率测量结果显示:在温度高于50K以上,仅存在一个107K超导相。此外,单相材料的制备条件(组分、烧结温度、室温下淬火及淬火速率)非常苛刻。如同1-2-3相材料一样,氧含量不仅影响样品的成相规律、零电阻温度,而且还严重影响其正常态的输运性质。
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M. B. Solunke P. U. Sharma M . P. Pandya V. K. Lakhani K. B. Modi P. Venugopal Reddy S. S. Shah 《Pramana》2005,65(3):481-490
The compositional dependence of elastic properties of Al3+-substituted Bi(Pb)-2223 superconducting system with the general formula Bi1.7−x AlxPb0.3Sr2Ca2Cu3 Oy
(x = 0.0, 0.1, 0.2 and 0.3) have been studied by means of ultrasonic pulse transmission (UPT) technique at 1 MHz (300 K). The
elastic moduli of the specimens are computed and corrected to zero porosity. The observed variation of elastic constants with
aluminium substitution has been explained on the basis of the strength of interatomic bonding. The applicability of heterogeneous
metal mixture rule for estimating elastic constants and transition temperature has been tested. 相似文献
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Haiqian Wang Zhiqiang Mao Ling Zhou Menghua Cheng Guien Zhou Zhaojia Chen 《Applied Physics A: Materials Science & Processing》1990,50(6):519-521
Differently heat-treated samples with the nominal composition Bi1.6Pb0.3Sb0.1Sr2Ca2Cu3O
y
were studied by resistance and ac susceptibility measurements in the temperature range 77 K<T<200 K. The X-ray diffraction patterns at room temperature were also investigated. The experimental results show that repeated quenchings can depress the formation of the 80 K phase, and enhance the formation of the 110 K phase. 相似文献
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J.-H. Park J.-S. Bae B.-E. Jun B.-C. Choi J.-H. Jeong 《Applied Physics A: Materials Science & Processing》2007,86(1):63-65
Bi3.25La0.75Ti3-yNbyO12 (y=0.0, 0.03, 0.09, 0.15, 0.21) were synthesized using the solid-state reaction method. The effects of Nb doping on ferroelectric properties were studied through dielectric and P-E measurements. The value of Pr increases with increasing Nb content. Bi3.25La0.75Ti3-yNbyO12 ceramics exhibit a maximum remanent polarization of Pr=27 μC/cm2 at an Nb content of y=0.09. These results indicate that Nb doping can improve the ferroelectric properties of BLT ceramics. The Curie temperature, Tc, decreased with increasing Nb-content, and the ferroelectric phase transition of BLTNy is a second-order transition without thermal hysteresis. PACS 77.55.+f; 77.80.-e; 77.22.Jp 相似文献
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K. Konstantinov S. Karbanov V. Vassilev 《Zeitschrift für Physik B Condensed Matter》1990,81(2):151-154
The effect of Sb superconducting materials with nominal composition Bi1.6Pb0.4–x
Sb
x
Sr2Ca2Cu3O
y
(x=0.01–0.14) and Bi1.5Pb0.5–x
Sb
x
Sr2Ca2Cu3O
y
(x=0.025–0.12) has been investigated. These materials were subjected to DTA, ICP emission spectrometry, SEM, XRD and electric resistance measurements. It was found that the introduction of Sb raises the melting temperature of the material, it also raisesT
c
(up to 110K) at several defined stoichiometric ratios. A certain lack of correspondence between the 2223 phase volume and theT
c
value was noticed and a possible explanation has been proposed. 相似文献
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T. Rentschler C. Schulz P. Zoller S. Lsch E. Raff W. Wischert S. Kemmler-Sack P. Kessler H. Lichte T. Nissel R. P. Huebener 《Annalen der Physik》1994,506(2):71-76
From a study of the influence of the Ca: Pb ratio on the superconducting properties of Bibased ceramics of 2223 type it follows that as a second parameter the employed gas atmosphere must be taken into consideration. In case of air preparation good intragrain and intergrain properties are obtained for Ca rich samples (e.g. Bi1.8Pb0.2Sr1.9Ca2.1 Cu3Oz); whereas for Pb rich materials (e.g. Bi1.7Pb0.5Sr1.9Ca1.9 Cu3Oz) improved conditions are encountered by employment of an Ar/O2 (8%) atmosphere during synthesis. Independently, the transition temperature is situated near 108 K. 相似文献
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We have systematically investigated the doping effect on the Bi2Sr2Ca2Cu3Oy superconductive material. After entering into the crystal lattice, Pb and/or Sb atoms cause not only variations of the temperature condition during the sample preparation process, but also variations of structures and superconductivity. By analyzing the experimental results, we have come to the conclusion that the Pb and/or Sb atoms enter into the Bi-O planes, preferably occupy the sites of Bi ions, regulate the crystal structures and the distribution of oxygen ions in Bi-O planes and nearby lattice sites, thus benefiting the formation of the high-Tc phase and improving the superconductivity. 相似文献
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Effect of Metal Substitution in BSCCO Ceramic Superconductors 总被引:1,自引:0,他引:1
The fabrication, electrical, and optical properties of ceramic Bi2-xMxSr2Ca2Cu3Oy (where M=Al or Ni and x=0.3) superconductors are described. Resistivity measurements reveal that when Al is partially substituted at the bismuth site in the BiSrCaCuO compound, T
c decreases to 77 K and the nickel-substituted compound shows a T
c of 70 K, compared to the undoped ceramic BiSrCaCuO samples with T
c of 85 K. Infrared reflectance measurements, which cover the 50-4000 cm–1 range, find that the reflectance from the ceramic samples decreases in the metal-doped samples. The observed phonon modes in the infrared conductivity spectra (obtained by Kramers-Kronig analysis) decrease in strength and some features are completely smeared out. Furthermore some of the modes are observed to shift slightly in the frequency on doping, the change in the T
c and vibrational modes is attributed to destabilization of 2223 phase. 相似文献