Journal articles: 'Ceramic oxide superconductors'

1

Rao, C. N. R. "High-temperature ceramic oxide superconductors." Sadhana 13, no. 1-2 (July 1988): 19–35. http://dx.doi.org/10.1007/bf02811956.

Full text

APA, Harvard, Vancouver, ISO, and other styles

2

Lee, Sang-Heon. "Electromagnetic Properties of Oxide Ceramic Superconductors." Journal of the Korean Physical Society 51, no. 3 (September 15, 2007): 1180. http://dx.doi.org/10.3938/jkps.51.1180.

Full text

APA, Harvard, Vancouver, ISO, and other styles

3

Li, Bin, and Ellen D. Williams. "Stability of the YBa2Cu3O7−x−Si interface." Journal of Materials Research 6, no. 8 (August 1991): 1634–40. http://dx.doi.org/10.1557/jmr.1991.1634.

Full text

Abstract:

Electron spectroscopies were used to study the reaction of Si and SiO2 layers with high-Tc superconductors at room temperature and under annealing conditions. The superconductor samples include YBa2Cu3O7 ceramic and thin film samples as well as GdBa2Cu3O7 ceramic samples. The results show that the Si overlayers withdraw oxygen from the superconductor and form an interfacial layer of Si oxide at room temperature. Annealing increases the reaction rate so that films as thick as 30 Å become completely oxidized following annealing above approximately 100 °C. Ba segregates to the surface from the bulk after Si oxidation when annealed at temperatures higher than 200 °C, while the rare earth element (Gd) does not segregate.

APA, Harvard, Vancouver, ISO, and other styles

4

Kothari, N. C. "Powder Metallurgy and Ceramic Copper Oxide Superconductors." Solid State Phenomena 8-9 (January 1991): 509–36. http://dx.doi.org/10.4028/www.scientific.net/ssp.8-9.509.

Full text

APA, Harvard, Vancouver, ISO, and other styles

5

Stephens, R. B. "Critical current limitations in ceramic oxide superconductors." Cryogenics 29, no. 3 (March 1989): 399–404. http://dx.doi.org/10.1016/0011-2275(89)90197-5.

Full text

APA, Harvard, Vancouver, ISO, and other styles

6

Ausloos, M., K. Durczewski, S. K. Patapis, Ch Laurent, and H. W. Vanderschueren. "Thermoelectric power of granular ceramic oxide superconductors." Solid State Communications 65, no. 5 (February 1988): 365–68. http://dx.doi.org/10.1016/0038-1098(88)90717-x.

Full text

APA, Harvard, Vancouver, ISO, and other styles

7

Nellis, W. J., and L. D. Woolf. "Novel Preparation Methods for High TcOxide Superconductors." MRS Bulletin 14, no. 1 (January 1989): 63–66. http://dx.doi.org/10.1557/s0883769400053938.

Full text

Abstract:

High Tc oxide superconductors can be prepared by a variety of novel metallurgical or ceramic processing techniques. For example, forming metallic precursors of YBa2Cu3 or REBa2Cu3, where RE is a rare earth element, followed by oxidation has yielded the corresponding ceramic oxide in pellet, wire, and thin film forms. Ceramic fabrication techniques (which often involve incorporating fine particles of the ceramic in a suitable vehicle) such as doctor-blade tape casting and screen printing have been utilized to synthesize both tapes and thin films. Due to intense worldwide effort to develop these ceramics into useable forms, many unique fabrication techniques have been employed, such as the melt-textured growth method of Jin et al. and dynamic compaction. In addition, it is likely that numerous laboratories, particularly industrial, are developing proprietary methods to fabricate wire and other forms but have not published these results due to the intensely competitive nature of this area. In this article, we review some of the methods reported so far for preparing high Tc ceramic superconductors, and we discuss one example of a proprietary method being developed at one of the author's (LDW) laboratories.Tapes of YBa2cu3O7-x fabricated using the doctor-blade tape casting technique were first displayed by AT&T Bell Laboratories scientists at the 1987 March meeting of the American Physical Society. This method involves mixing ceramic powder, a binder to provide green (unfired ceramic) strength, a plasticizer to provide flexibility, a dispersant to prevent particle agglomeration and a solvent. After mixing all these components together, the solution is poured into a “doctor blade” device which allows a controlled thickness of material to be deposited on a plastic film carrier that passes underneath the doctor blade.

APA, Harvard, Vancouver, ISO, and other styles

8

Lee, Sang Heon. "Measurement and Analysis of Magnetic Properties of YBa2Cu3O7-y Bulk Superconductor." Journal of Nanoelectronics and Optoelectronics 15, no. 1 (January 1, 2020): 122–26. http://dx.doi.org/10.1166/jno.2020.2671.

Full text

Abstract:

YBa2Cu3O7-y single crystal bulk high-temperature superconductor has high critical current density with large magnetic levitation and trapping magnetic forces. Despite its distinctive electromagnetic properties, the longtime heat treatment process of oxide high-temperature superconductor, a ceramic material, is widely considered as a factor that can degrade industrial applicability of superconductors seriously. For applications in power systems, metal-ceramic composites need to be fabricated to enhance magnetic performance. In this study, CeO2 was utilized as an additive to control Y211 particles and improve superconducting magnetic properties. The study achieved meaningful outcomes, given that it reduced the processing time by half (1/2) with the interior seeding technique, realized the effect of top seeding by positioning one additional seed layer on the top surface, and obtained a magnetic levitation force of 67.015 N. In order to improve the physical properties of superconducting materials, interior seeding technique was applied, and the effect of top seeding was obtained by placing one seed layer on the top surface. Therefore, when two seed layers were used to fabricate a specimen, it could improve physical properties of superconductors to the extent that both the top and bottom pellets could be used.

APA, Harvard, Vancouver, ISO, and other styles

9

Quanlu, L. "Preliminary experiments on metallisation of ceramic oxide superconductors." British Ceramic Transactions 100, no. 1 (January 2001): 41–42. http://dx.doi.org/10.1179/096797801681189.

Full text

APA, Harvard, Vancouver, ISO, and other styles

10

Bench, Michael W., and C. Barry Carter. "Pulsed-laser deposition growth of copper oxide on α-Al2O3 and MgO." Proceedings, annual meeting, Electron Microscopy Society of America 52 (1994): 528–29. http://dx.doi.org/10.1017/s0424820100170372.

Full text

Abstract:

Copper and its oxides are involved in many electronic materials applications. Cuprous oxide (Cu2O)is a semiconductor finding usage as a thin-film solar-cell material. The copper-oxide-based hightemperature superconductor materials have been extensively investigated. Also, the adhesion andbonding ofcopper to ceramic substrates is of interest for usage in electronic device packaging applications. For the case of alumina substrates, it has been demonstrated that the adhesion properties of thin copper wires is optimized for a ternary bonding environment at the interface. For the growth of oxidematerials, pulsed-laser ablation (PLA) is a viable means of growing films, and allows materials with a wide range of stoichiometrics to be produced. Indeed, this technique has found wide application inthe growth of high-temperature superconductors. In a previous study on PLA growth of CuO and Cu2O, Ogale etal. reported the growth of continuous epitactic Cu2O films on (100) MgO substrates at 700°C, whereas growth onto silicon and zirconia produced polycrystalline films.

APA, Harvard, Vancouver, ISO, and other styles

11

HUANG, C. Y., and M. RABINOWITZ. "SOME NEW ASPECTS OF SUPER-HIGH TEMPERATURE SUPERCONDUCTORS." Modern Physics Letters B 04, no. 09 (May 10, 1990): 567–84. http://dx.doi.org/10.1142/s0217984990000726.

Full text

Abstract:

We review some salient features of the recently observed experimental evidence of ceramic super-high temperature superconductivity (T c > 200 K ). Two theoretical estimates which are capable of accounting for super-high T c will be presented. For comparison, several reports on non-ceramic oxide super-high temperature superconductors will also be discussed.

APA, Harvard, Vancouver, ISO, and other styles

12

Day, P. "Structural Inorganic Chemistry of High Temperature Ceramic Superconductors." International Journal of Modern Physics B 01, no. 03n04 (August 1987): 745–53. http://dx.doi.org/10.1142/s0217979287001110.

Full text

Abstract:

Correlations are drawn between the structures of the two series of ternary Cu oxide superconductors determined by high resolution powder neutron diffraction. Similarities and differences are emphasised, and comparison is made with other Group 11 compounds containing layers of corner linked square planar MX 4 units, such as Wells’ Salt (CsAuCl3) .

APA, Harvard, Vancouver, ISO, and other styles

13

Leese, Rebecca J., Atanas Ivanov, and Hari Babu-Nadendla. "The Potential to Machine Superconductors with Electrochemical Machining." Journal of Multiscale Modelling 07, no. 01 (March 2016): 1640001. http://dx.doi.org/10.1142/s1756973716400011.

Full text

Abstract:

Superconductors (SCs), such as gadolinium barium copper oxide, are brittle ceramics which are very difficult to machine conventionally due to the easy propagation of cracks. The cracks formed during conventional machining destroy the superconductive properties of the material. As a result a new method to machine ceramic SCs is needed. In this paper, polarization experiments were conducted in various nonaqueous salt electrolytes to determine whether electrochemical machining (ECM) is a suitable method for machining gadolinium barium copper oxide with silver inclusions (GdBCO-Ag) for the first time. Sodium chloride in formic acid proved to be the best electrolyte for this application with higher dissolution rates and achieving a better surface finish. It was noted that GdBCO-Ag dissolved at higher rates in NaCl in formic acid than in other salt-solvent systems.

APA, Harvard, Vancouver, ISO, and other styles

14

Clarke, D. R. "Critical issues in ceramic microstructures." Proceedings, annual meeting, Electron Microscopy Society of America 54 (August 11, 1996): 640–41. http://dx.doi.org/10.1017/s0424820100165665.

Full text

Abstract:

As the number and variety of ceramic materials have grown so rapidly in the last few decades, ranging from silicon nitride structural ceramics to the perovskite superconductors to the ferroelectric oxides to semiconducting sensors, the number of scientific and technical issues has also grown rapidly. Many of the basic questions relate to the role the microstructures play in determining the observed physical behavior but increasingly it is not the geometric properties of the microstructure that are of central concern but rather compositional variations and associated electrical characteristics. These require the continued development of microscopy techniques to complement the tremendous advances in microstructural understanding that have already been made possible by microscopy in the past.Since the role of microscopy is such a broad one, only a few of the most generic problems in microstructure characterization will be described in this talk. The topics selected include the characterization of intergranular films in liquid-phase sintered ceramics, the charge distribution at interfaces and the associated space charge, the epitaxial growth of oxides on oxide substrates, and the use of fluorescence imaging to identify phases and non-destructively measure local strains.

APA, Harvard, Vancouver, ISO, and other styles

15

Burns, S. J. "Thermodynamics of the superconducting phase transformation in high Tc ceramics with magnetoelectric effects." Journal of Materials Research 4, no. 1 (February 1989): 33–38. http://dx.doi.org/10.1557/jmr.1989.0033.

Full text

Abstract:

A second order phase transformation in a dielectric ceramic superconductor is shown to relate jumps in physical properties to the ratio of state variables, i.e., to the phase boundary, near the critical point. The major jumps in specific heat, compressibility, permittivity, permeability, and spinodal composition curvature, between the normal and superconducting phases, are found from the continuity of the entropy, volume, electromagnetic fields (with zero fields), and chemical equilibrium. The thermal expansion, pyroelectric effects, and the piezoelectromagnetic effects are important differences between ceramic and metallic superconductors. The most important conclusions from experimental measurements are that the lattice plays a minor role in the superconductor transformation while the magnetoelectric jump may be related to the jump in permeability, i.e., the Meissner effect, and the jump in permittivity. The oxygen miscibility gap which controls order/disorder transformations thermodynamically mandate that only metastable compositions are obtained in the metal oxide, so absolute stability of the system may never be achieved. An explicit criterion to suggest other superconductor systems is given from magnetoelectric materials, i.e., some of the pervoskites.

APA, Harvard, Vancouver, ISO, and other styles

16

Dufner, D. C., R. A. Mohan Ram, and A. Clearfield. "HREM studies of YBa2Cu3O7-δ prepared from low-temperature precursors." Proceedings, annual meeting, Electron Microscopy Society of America 47 (August 6, 1989): 192–93. http://dx.doi.org/10.1017/s0424820100152938.

Full text

Abstract:

Solid state reactions are the most commonly employed processes for the preparation of high-Tc superconducting ceramic oxides. However, there has been considerable effort expended to prepare the YBa2Cu3O7-δ (1-2-3) superconductor by low-temperature solution methods in order to obtain a more homogeneous oxide mixture resulting in products with superior superconducting properties. Proper processing of the precursors resulting in less preparation time, lower temperature of firing, higher critical current density, higher flux expulsion, etc., is expected.Our laboratory has been preparing low-temperature precursors by sol-gel and other methods. We employed the same methods for the preparation of 1-2-3 superconductors. The precursors were heated at 925°C for 12 hours in flowing oxygen. The resulting powder was found to be superconducting at 92.3K. Superconducting properties were measured by resistivity and impedance measurements.

APA, Harvard, Vancouver, ISO, and other styles

17

Zaluzec, N. J., D. G. Hinks, D. W. Capone, D. Shi, L. Soderholm, B. Dabrowski, J. Z. Liu, J. W. Downey, and D. J. Lam. "Incommensurate ordering in Ca-Sr-Bi-Cu oxide superconductors." Proceedings, annual meeting, Electron Microscopy Society of America 46 (1988): 872–73. http://dx.doi.org/10.1017/s0424820100106429.

Full text

Abstract:

High temperature superconductivity in non-rare earth ceramic oxides has been recently reported, however the structure and composition of the phase(s) has yet to be unequivocally identified. In the Ca-Sr-Bi-Cu Oxide system onset transition temperatures as high as 120 K have been reported, in both single and multiphase specimens. In this work we report on preliminary AEM-based studies of single and polycrystalline specimens of Ca-Sr-Bi-Cu Oxide superconductors.The superconducting material was prepared by mixing powders of Bi2O3, CaCO3, SrCO3, and CuO; and then processed by repeated grinding, heating in either flowing oxygen or air followed by furnace cooling as described in detail elsewhere. The superconducting phase(s) in the powder (∽0.5 x 20μm) specimens are dark, elongated layered crystals which exhibit pronounced basal plane cleavage similiar to graphite or clay based minerals. Larger nominally single crystal specimens (∽0.5 - 2 mm) are less regular in shape, however, all other macroscopic characteristics are essentially the same.

APA, Harvard, Vancouver, ISO, and other styles

18

Song, Yi, Yue Cao, Anupam Misra, and J. R. Gaines. "Superconducting (YBaCuO)–(CuO)–Ag composites." Journal of Materials Research 4, no. 4 (August 1989): 802–5. http://dx.doi.org/10.1557/jmr.1989.0802.

Full text

Abstract:

We have fabricated superconducting composites composed of Y1Ba2Cu3O7–δ, copper oxide, and metallic silver. Sharp superconducting transitions were observed well above the liquid nitrogen temperature. The normal state resistivity of these composites was much lower than that of the pure ceramic Y1Ba2Cu3O7–δ. The critical current density was measured and it was comparable to that of ceramic superconductors. A substantial improvement of the mechanical properties has been achieved over those of the ceramic Y1Ba2Cu3O7–δ material.

APA, Harvard, Vancouver, ISO, and other styles

19

Dufner, D. C., R. A. Mohan Ram, and A. Clearfield. "Imaging of BaCuO2 impurity in solution-grown YBa2Cu3O7−δ." Proceedings, annual meeting, Electron Microscopy Society of America 48, no. 4 (August 1990): 70–71. http://dx.doi.org/10.1017/s0424820100173480.

Full text

Abstract:

Solid state reactions are the most commonly employed processes for the preparation of high-Tc superconducting ceramic oxides. However, there has been considerable effort expended to prepare the YBa2Cu3O7−δ (1-2-3) superconductor by low-temperature methods in order to obtain a more homogeneous oxide mixture resulting in products with superior superconducting properties. In our investigations, TEM was used to characterize the microstructure of these materials as a function of various processing parameters.The precursors for the (1-2-3) superconductors were prepared by precipitating hydroxides of Y, Ba, and Cu and heating the precipitates at various temperatures in the 750-930°C range for 12-60 hours in flowing O2. Crystals for electron microscopy were crushed, suspended in acetone, and dispersed onto holey carbon grids. TEM characterization was carried out on the Philips 400T operating at 120kV or on the JEOL 2000FX at the Texas Center for Superconductivity at the University of Houston.In this work, one of the impurity phases was observed and identified as BaCuO2.

APA, Harvard, Vancouver, ISO, and other styles

20

Adem, E., L. Martínez, J. Richards, E. Orozco, J. Fuentes-Maya, J. L. Albarrán, A. Mendoza, et al. "The effect of electron irradiation in high-Tc oxide superconductors." Journal of Materials Research 3, no. 5 (October 1988): 807–10. http://dx.doi.org/10.1557/jmr.1988.0807.

Full text

Abstract:

A superconductor ceramic oxide with the Y1Ba2Cu3O7−x phase and exhibiting a transition temperature at Tc ≍92K, was irradiated at room temperature with 1 MeV electrons. It was found that the irradiation produces a sharp drop in the Tc value from 92 K down to ∼40K. The irradiated sample suffered a change from metallike character to semiconductorlike behavior at T > Tc. It is also shown that after irradiation the twin boundaries on the material become irregular.

APA, Harvard, Vancouver, ISO, and other styles

21

Kotula, Paul G., and C. Barry Carter. "The measurement of thin-film reaction layers with high-resolution FESEM." Proceedings, annual meeting, Electron Microscopy Society of America 53 (August 13, 1995): 330–31. http://dx.doi.org/10.1017/s0424820100138026.

Full text

Abstract:

Thin-film reactions in ceramic systems are of increasing importance as materials such as oxide superconductors and ferroelectrics are applied in thin-film form. In fact, reactions have been found to occur during the growth of YBa2Cu3O6+x on ZrO2. Additionally, thin-film reactions have also been intentionally initiated for the production of buffer layers for the subsequent growth of high-Tc superconductor thin films. The problem is that the kinetics of ceramic thin-film reactions are not well understood when the reaction layer is very thin; that is, when the rate-limiting step is a phase-boundary reaction as opposed to diffusion of the reactants through the product layer. In this case, the reaction layer is likely to be laterally non-uniform. In the present study, the measurement of thin reaction-product layers is accomplished by first digitally acquiring backscattered-electron images in a high-resolution field-emission scanning electron microscope (FESEM) followed by image analysis. Furthermore, the problem of measuring such small thicknesses (e.g., 20-500nm) over lengths of interfaces longer than 3mm is addressed.

APA, Harvard, Vancouver, ISO, and other styles

22

Powers, M. "The role of specimen morphology in the preparation of High-TC superconductors for Transmission Electron Microscopy." Proceedings, annual meeting, Electron Microscopy Society of America 48, no. 4 (August 1990): 66–67. http://dx.doi.org/10.1017/s0424820100173467.

Full text

Abstract:

It is vital in TEM investigations, especially for high resolution studies, that specimen quality be optimized and the information desired in a particular TEM analysis often prescribes the method of specimen preparation required. We have found that the morphology of a bulk superconductor sample can significantly influence the ultimate success of the preparation technique utilized.Methods employed for the production of electron transparent foils of ceramic oxide superconductors include mechanical grinding, cleavage, jet polishing, ultramicrotomy and ion milling. Grinding and cleavage are both low cost, quick and easy specimen preparation techniques. However, because of the layered crystal structures of these materials, they display a marked tendency to cleave along (001) planes, and hence the range of crystallographic orientations available with these methods is restricted. With grinding in particular, mechanical deformation can be a problem while with cleavage, transparent areas are confined to the vicinity of particle edges.

APA, Harvard, Vancouver, ISO, and other styles

23

Dravid, Vinayak P., Yun-Yu Wang, and Hong Zhang. "Electron spectroscopy of ceramics." Proceedings, annual meeting, Electron Microscopy Society of America 51 (August 1, 1993): 944–45. http://dx.doi.org/10.1017/s0424820100150551.

Full text

Abstract:

High resolution, analytical and conventional TEM techniques/analyses have had considerable impact on ceramic science and engineering. Recently, the focus is shifted to the use of less traditional such as transmission EELS and novel techniques such as electron holography, STM, AFM etc.. In this contribution we illustrate the power and potential for transmission EELS in high spatial/energy resolution analysis of charge carriers in ceramic superconductors. Traditionally, optical and x-ray spectroscopies have been successfully utilized to probe the electronic structure of solids. The oxide superconductors, however, are marred by inhomogeneity of structure, chemistry and consequently the electronic structure. Thus, though very powerful, dedicated EELS has its limitations. Furthermore, these compounds possess highly anisotropic crystal and electronic structure. As an alternative, we have demonstrated that our 200 keV Hitachi HF-2000 cFEG TEM offers adequate energy, momentum transfer (q) and spatial resolution (< 0.5 eV at zero loss, ∼ 0.10Å-1 and < 1-2 nm, respectively) to realistically address these issues.

APA, Harvard, Vancouver, ISO, and other styles

24

Lau, S.-F., A. B. Rosenthal, N. P. Pyrros, J. A. Graham, and H. N. Gheng. "Studies of weight changes and oxygen diffusion in oxide superconductors." Journal of Materials Research 6, no. 2 (February 1991): 227–31. http://dx.doi.org/10.1557/jmr.1991.0227.

Full text

Abstract:

In sintering and annealing of ceramic superconductors, diffusion of oxygen and sample weight changes are two important parameters to understand. In this work, we have undertaken to make weight loss measurements at different temperatures. At 400–600 °C, the weight loss data can be simply interpreted via one diffusion process. The Arrhenius activation energy is found to be ca. 23 kcal/mole. At 500 °C, the isotropic diffusion constant was found to be 9.5 × 10−12 cm2/s. Above 600 °C, the weight loss curves become complex and indicate the occurrence of two diffusion processes. The oxygen loss and the oxygen uptake data are interpreted via our present knowledge of this system.

APA, Harvard, Vancouver, ISO, and other styles

25

Eagles, D. M. "Analysis of hall data in ceramic samples of 90 K oxide superconductors." Physica C: Superconductivity 153-155 (1988): 701–2. http://dx.doi.org/10.1016/s0921-4534(88)80045-5.

Full text

APA, Harvard, Vancouver, ISO, and other styles

26

Chela-Flores, J., P. Martin, and J. J. Rodriguez Nuñez. "A NEW EFFECT ON THE CRITICAL TEMPERATURE IN NON RARE EARTH CERAMIC SUPERCONDUCTORS." International Journal of Modern Physics B 02, no. 05 (October 1988): 1079–84. http://dx.doi.org/10.1142/s0217979288000937.

Full text

APA, Harvard, Vancouver, ISO, and other styles

27

KHAN, M. N., S. AL-DALLAL, and A. MEMON. "THE PROPERTIES OF RBa2(Cu1−xAgx)3O7 SUPERCONDUCTORS." International Journal of Modern Physics B 04, no. 13 (October 1990): 1993–2003. http://dx.doi.org/10.1142/s0217979290000991.

Full text

Abstract:

We present superconducting properties and structural analysis of R Ba 2( Cu 1−x Ag x)3 O 7 (with R = Y , Eu and Gd) ceramic compounds. Transition temperatures improve with a small amount of Ag. Results of powder X-ray diffraction (indicate no detectable substitution of Ag into the R Ba 2( Cu 0.999 Ag 0.001)3 O 7 oxide system. We also found that no superconductivity was observed above 10 K for R Ba 2( Cu 0.4 Ag 0.6)3 O 7 compounds. The superconductivity is discussed in relation to the results of X-ray diffraction study.

APA, Harvard, Vancouver, ISO, and other styles

28

Stoneham, Marshall, John Harding, and Tony Harker. "The Shell Model and Interatomic Potentials for Ceramics." MRS Bulletin 21, no. 2 (February 1996): 29–35. http://dx.doi.org/10.1557/s0883769400046273.

Full text

Abstract:

In a classification of solids according to their bonding character (into metals, ceramics and glasses, polymers, and semiconductors), the ceramic class includes an enormous range of industrially important materials. From the archetypal ionic solids through oxides to silicates, and to covalently bonded materials such as SiC, they exhibit a rich variety of structures and properties. They occur as structural materials, either on their own or as composites such as SiC/Al2O3. They are important functional materials, such as fast-ion conductors as electrolytes in fuel cells (for example ZrO2/Y2O3 for hydrogen combustion) or batteries (β-alumina in the sodium-sulfur battery), ferroelectric materials such as BaTiO3 and piezoelectrics such as PZT—a solid solution of PbTiO3 and PbZrO3. The high-temperature superconductors (for example, YBa2Cu3O7) are ceramics above the superconducting transition temperature. The products of corrosion and oxidation are ionic materials, and the properties of oxide coatings are vital to the survival of high-temperature alloys in gas turbines or fuel-element claddings in nuclear reactors.To understand the behavior of ceramic materials, and to optimize their production, processing, and application, it is often necessary to model their behavior at an atomic level. In some cases this is obvious. Ionic diffusion in a solid electrolyte is a self-evidently atomic process. In other cases the need for atomistic simulation is less clear. Oxidation, for example, is a subtle blend of atomic diffusion (often along grain boundaries), metal-ceramic bonding, stress relief, and grain growth. The course of oxidation can be spectacularly affected by impurities and alloying, and this can only be understood by considering the atomicscale processes involved.

APA, Harvard, Vancouver, ISO, and other styles

29

Mogare, K. M., I. Landau, N. Guérin, B. Trusch, M. Wagner, T. Locherer, M. Jansen, and J. Hulliger. "Ceramic Tl-oxide based superconductors reinvestigated by magnetic separation technique and SQUID measurements." Solid State Sciences 13, no. 10 (October 2011): 1879–84. http://dx.doi.org/10.1016/j.solidstatesciences.2011.07.023.

Full text

APA, Harvard, Vancouver, ISO, and other styles

30

Mosqueira, J., A. Pomar, O. Cabeza, J. Maza, and Fe´lix Vidal. "Measurements of the heat transfer to liquid nitrogen from ceramic copper-oxide superconductors." Physica B: Condensed Matter 194-196 (February 1994): 973–74. http://dx.doi.org/10.1016/0921-4526(94)90816-8.

Full text

APA, Harvard, Vancouver, ISO, and other styles

31

Maley, Martin P., Michael E. McHenry, and Jeffrey O. Willis. "Magnetic-history-dependent critical currents in granular high-temperature superconductors: Dependence on defect structures and morphology." Proceedings, annual meeting, Electron Microscopy Society of America 47 (August 6, 1989): 186–87. http://dx.doi.org/10.1017/s0424820100152902.

Full text

Abstract:

Critical current densities, Jc’s, in conventional low temperature superconductors are controlled by defect structures that provide pinning for the magnetic flux lattice. High critical current densities and strong pinning have been observed in single crystals of the new oxide, high temperature superconductors (HTS) and have been ascribed to the presence of twin planes and to stoichiometry variations in the YBCO compound. Neutron irradiation studies have shown that intragranular Jc’s in YBCO can be strongly enhanced by the point defects introduced by irradiation. However, transport Jc’s determined by intergranular current transfer have remained dissappointingly low in bulk ceramic HTS materials. This has suggested a model of strongly superconducting grains separated by “weak links” that behave as Josephson tunnel junctions.The extraordinarily small superconducting coherence length ζo ∼ 10 A° in the HTS make them considerably more sensitive to small scale defects. Grain boundaries that act as pinning centers in conventional superconductors thus become barriers to current flow in the HTS.

APA, Harvard, Vancouver, ISO, and other styles

32

DOMINEC, J., P. VAŠEK, P. SVOBODA, V. PLECHÁČEK, and C. LAERMANS. "ELASTIC MODULI FOR THREE SUPERCONDUCTING PHASES OF Bi-Sr-Ca-Cu-O." Modern Physics Letters B 06, no. 16n17 (July 1992): 1049–54. http://dx.doi.org/10.1142/s0217984992001885.

Full text

Abstract:

We have measured the absolute values of longitudinal and transversal sound velocities in ceramic samples of Bi 2 Sr 2 Ca n-1 Cu n O 2n+4 (n=1, 2,3). We have compared various methods of calculation of "true" elastic moduli of matrix material. We used best of them to find the elastic moduli, sound velocities and Debye temperatures of the material. The calculated elastic moduli are low in a comparison with other oxide superconductors. The velocities and Debye temperatures increase with increasing n.

APA, Harvard, Vancouver, ISO, and other styles

33

Phillips, J. C. "Universal non-Landau, self-organized, lattice disordering percolative dopant network sub-Tc phase transition in ceramic superconductors." Proceedings of the National Academy of Sciences 106, no. 37 (September 8, 2009): 15534–37. http://dx.doi.org/10.1073/pnas.0908634106.

Full text

Abstract:

Ceramic superconductors (cuprates, pnictides, etc.) exhibit universal features in both Tcmax and in their planar lattice disordering measured by EXAFS, as reflected by three phase transitions. The two highest temperature transitions are known to be associated with formation of Jahn–Teller pseudogaps and superconductive gaps, with corresponding Landau order parameters, but no new gap is associated with the third transition below Tc, and its origin is mysterious. It is argued that the third subTc transition is a dopant glass transition, which is remarkably similar to topological transitions previously observed in chalcogenide and oxide alloy network glasses (like window glass).

APA, Harvard, Vancouver, ISO, and other styles

34

Weber, J. K. R., P. C. Nordine, K. C. Goretta, and R. B. Poeppel. "Effects of oxygen pressure on the structure of Y–Ba–Cu–O materials formed by containerless melting and solidification." Journal of Materials Research 9, no. 7 (July 1994): 1657–60. http://dx.doi.org/10.1557/jmr.1994.1657.

Full text

Abstract:

YBa2Cu3Ox ceramic superconductors were levitated, laser-beam melted, and undercooled in pure oxygen, dry air, and pure argon atmospheres. Solidified material from this containerless melting was examined by electron microscopy and x-ray diffraction analysis. The solubility of yttrium oxide in the melt was found to depend on ambient oxygen pressure such that complete dissolution was readily achieved in argon, but not in oxygen. The material formed in argon could be deeply undercooled and resolidified to produce a fine-grained and chemically homogeneous material. Use of ambient oxygen pressure to control the product morphology is discussed.

APA, Harvard, Vancouver, ISO, and other styles

35

Scheel, H. J., and F. Licci. "Crystal Growth of High Temperature Superconductors." MRS Bulletin 13, no. 10 (October 1988): 56–61. http://dx.doi.org/10.1557/s0883769400064204.

Full text

Abstract:

The discovery of high temperature superconductivity (HTSC) in oxide compounds has confronted materials scientists with many challenging problems. These include the preparation of ceramic samples with critical current density of about 106 A/cm2 at 77 K and sufficient mechanical strength for large-scale electrotechnical and magnetic applications and the preparation of epitaxial thin films of high structural perfection for electronic devices.The main interest in the growth of single crystals is for the study of physical phenomena, which will help achieve a theoretical understanding of HTSC. Theorists still do not agree on the fundamental mechanisms of HTSC, and there is a need for good data on relatively defect-free materials in order to test the many models. In addition, the study of the role of defects like twins, grain boundaries, and dislocations in single crystals is important for understanding such parameters as the critical current density. The study of HTSC with single crystals is also expected to be helpful for finding optimum materials for the various applications and hopefully achieving higher values of the superconducting transition temperature Tc than the current maximum of about 125 K. It seems unlikely at present that single crystals will be used in commercial devices, but this possibility cannot be ruled out as crystal size and quality improve.

APA, Harvard, Vancouver, ISO, and other styles

36

Goyal, A., E. D. Specht, D. P. Norton, M. Paranthaman, F. A. List, C. Park, D. K. Christen, and D. M. Kroeger. "Texture and Grain Boundaries in Epitaxial Oxide Multilayers, Including Superconductors, on Biaxially Textured Metal Substrates." Microscopy and Microanalysis 3, S2 (August 1997): 565–66. http://dx.doi.org/10.1017/s1431927600009715.

Full text

Abstract:

A new technique, referred to as rolling-assisted-biaxially-textured-substrates (RABiTS) has recently been proposed by Goyal et al., to fabricate long-range, biaxially textured substrates with suitable metal/ceramic surfaces for epitaxial growth of electronic devices [1]. Using standard thermomechanical processing, long lengths of flexible, biaxially oriented substrates with smooth surfaces (rms∼50nm) are obtained [1]. Epitaxial metal and/or oxide layers which can serve both as a chemical as well as a structural buffer are deposited on the biaxially textured metal. The metal with a suitable set of epitaxial, multi-layers comprises the substrate which is expected to have many potential applications, including superconductivity, photovoltaics and ferroelectrics [1].When high temperature superconductors are deposited on a set of epitaxial multilayers on biaxially textured RABiT substrates, extremely high critical current densities, approaching 106 A/cm2 at 77K have been obtained [2].

APA, Harvard, Vancouver, ISO, and other styles

37

Crubellati, R. O., P. N. Smichowski, D. A. Batistoni, G. Polla, and E. Manghi. "Precise determination of oxygen content in high Tc ceramic oxide superconductors based on previous chemical analysis." Solid State Communications 75, no. 2 (July 1990): 101–4. http://dx.doi.org/10.1016/0038-1098(90)90350-k.

Full text

APA, Harvard, Vancouver, ISO, and other styles

38

Dominguez, J. E., L. Fu, and X. Q. Pan. "TEM Study of the Effect of the Sapphire Substrate Surface Orientation on the Microstructure of Tin Dioxide Films." Microscopy and Microanalysis 7, S2 (August 2001): 1220–21. http://dx.doi.org/10.1017/s1431927600032177.

Full text

Abstract:

Tin dioxide (SnO2) has been extensively studied and used as gas sensors to detect toxic gases such as CO, NOxand flammable gases like H2.[l] Recently, considerable researches have focused on thin film sensors due to their high performance as well as their integration compatibility with semiconductor technology for making microsensors and sensor arrays. [2] The performance of thin film sensors is remarkably influenced by the way they were fabricated.[3] Among various deposition techniques, pulsed laser deposition (PLD) has shown great prominence in the deposition of a wide variety of oxide thin film materials such as high Tc superconductors, semiconductors and dielectrics. in this work we present our experimental results on tin dioxide films deposited using pulsed laser ablation on sapphire (α -Al2O3) substrates with different surface orientations.Tin oxide films with a thickness of 100 nm were deposited on the (1012) and (0001) sapphire by pulsed laser ablation of ceramic SnO2 targets.

APA, Harvard, Vancouver, ISO, and other styles

39

Laurent, Ch, S. K. Patapis, M. Laguesse, H. W. Vanderschueren, A. Rulmont, P. Tarte, and M. Ausloos. "Thermoelectric power and magneto Seebeck-effect near the critical temperature of granular ceramic oxide superconductors Y1Ba2Ca3O7−y." Solid State Communications 66, no. 4 (April 1988): 445–50. http://dx.doi.org/10.1016/0038-1098(88)90874-5.

Full text

APA, Harvard, Vancouver, ISO, and other styles

40

Ausloos, M., Ch Laurent, H. W. Vanderschueren, A. Rulmont, and P. Tarte. "Porosity, magnetic field, and anisotropy effects on resistivity and thermoelectric power of classical and substituted ceramic oxide superconductors." Physica C: Superconductivity 153-155 (June 1988): 1351–52. http://dx.doi.org/10.1016/0921-4534(88)90316-4.

Full text

APA, Harvard, Vancouver, ISO, and other styles

41

Ponnusamy, D., and K. Ravi-Chandar. "Extrusion of superconducting wires of YBa2Cu3O7−x." Journal of Materials Research 8, no. 2 (February 1993): 268–73. http://dx.doi.org/10.1557/jmr.1993.0268.

Full text

Abstract:

High Tc superconductors need to be fabricated into desirable configurations such as wires for practical applications. Toward this objective, the plastic extrusion process was applied to the fabrication of wires and rods of YBa2Cu3O7−x. The ceramic oxide powder is combined with several organic additives to form a slurry which is extruded by forcing it through a small aperture. This is subjected to a sequence of heat treatments for drying, binder burn-out, and sintering. The critical current density of these wires ranges from 800 A/cm2 to 1500 A/cm2 depending upon the diameter and the current-carrying capacity is uniform over long lengths of up to 140 cm. This process was also applied to fabrication of larger cross-sectional area rods and hollow cylinders, capable of carrying up to 245 A. The mechanical properties of these wires were also investigated.

APA, Harvard, Vancouver, ISO, and other styles

42

Navrotsky, Alexandra. "Thermochemistry of New, Technologically Important Inorganic Materials." MRS Bulletin 22, no. 5 (May 1997): 35–41. http://dx.doi.org/10.1557/s0883769400033182.

Full text

Abstract:

The past decade has seen exciting advances in the discovery, improved synthesis and processing, and molecular level engineering of new inorganic materials having specialized electronic, ceramic, and structural applications. Many such materials share two common characteristics: They are complex in structure and composition (think for example of oxide superconductors), and they must be prepared by a series of steps under carefully controlled conditions (consider the intricacies of zeolite synthesis for example). The use of low-temperature aqueous synthesis conditions, with appropriate attention to pH, inorganic and organic structure-directing agents, and subsequent drying and calcination protocols has led to a wealth of new and often metastable crystalline polymorphs, to amorphous materials, and to fine powders with particles of nanoscale dimensions. Methods such as sol-gel synthesis, chimie douce (soft chemistry), hydrothermal synthesis, chemical vapor deposition, and various beam-deposition and epitaxy techniques produce a wealth of materials not constrained to be in chemical equilibrium with their surroundings and not representing the state of lowest free energy. Modern materials chemists almost have their pet Maxwell Demon to select atoms at will and cause them to assemble in a structure of controllable dimensions. The wealth of possible new structures formed begins to mimic the riches of organic chemistry. In this field, the fact that all complex organic and biochemical molecules are metastable under ambient conditions with respect to a mixture of carbon dioxide, water, and other simple gases is irrelevant except in a conflagration.Liberation of ceramic science from the tyranny of high-temperature equilibrium is thus leading to new materials synthesized more quickly, at lower cost, and under environmentally more friendly conditions. There is of course a price to pay. First the synthetic procedures are more complex than traditional “mix, grind, fire, and repeat” ceramic processing. Second and more importantly, very little is known about the long-term stability of the materials formed, about their degradation during use, and about materials compatibility. Two examples of such problems are the potential corrosion of high Tc YBCO superconductors by ambient H2O and CO2, and the collapse to inactive phases of complex zeolitic and mesoporous catalysts under operating conditions. Chemical reactions in metastable materials are governed by an intertwined combination of thermodynamic driving forces and kinetic rates. For this rich landscape of new materials, neither the depths of the valleys nor the heights of the mountains are known. Often one cannot even tell which way is energetically downhill.

APA, Harvard, Vancouver, ISO, and other styles

43

Goyal, Amit, M. Parans Paranthaman, and U. Schoop. "The RABiTS Approach: Using Rolling-Assisted Biaxially Textured Substrates for High-Performance YBCO Superconductors." MRS Bulletin 29, no. 8 (August 2004): 552–61. http://dx.doi.org/10.1557/mrs2004.161.

Full text

Abstract:

AbstractThis article provides an overview of the fabrication of epitaxial, biaxially aligned buffer layers on rolling-assisted biaxially textured substrates (RABiTS) as templates for YBCO films carrying high critical current densities.The RABiTS technique uses standard thermomechanical processing to obtain long lengths of flexible, biaxially oriented substrates with smooth surfaces.The strong biaxial texture of the metal is conferred to the superconductor by the deposition of intermediate metal and/or oxide layers that serve both as a chemical and a structural buffer.Epitaxial YBCO films with critical current densities exceeding 3 106A/cm2at 77K in self-field have been grown on RABiTS using a variety of techniques and demonstrate magnetic-field-dependent critical current values that are similar to those of epitaxial films on single-crystal ceramic substrates.The RABiTS architecture most commonly used consists of a CeO2 (sputtered)/YSZ (sputtered)/Y203 (e-beam)/Ni-W alloy.The desired texture of the base metal has been achieved in 100 m lengths and 10cm widths.Scaleable and cost-effective techniques are also being pursued to deposit the epitaxial multilayers.The results discussed here demonstrate that this technique is a viable route for the fabrication of long lengths of high-critical-current-density wire capable of carrying high currents in magnetic fields and at temperatures accessible by cooling with relatively inexpensive liquid nitrogen (up through the 77K range).

APA, Harvard, Vancouver, ISO, and other styles

44

Domínguez-Rodríguez, Arturo, and Diego Gómez-García. "The Future of Research in Ceramics in the XXI Century." Key Engineering Materials 663 (September 2015): 127–32. http://dx.doi.org/10.4028/www.scientific.net/kem.663.127.

Full text

Abstract:

This lecture will outline the past, present and future of research in ceramics. The concept of “ceramic material” has evolved along the time and it hás broadened remarkably for the last decades from traditional clay-based materials to new systems: the term includes now high-performant capacitors, superconductors, highly-efficient oxides, carbides and nitrides of transition metals. The search of new materials has made that their processing and characterization become more technically sophisticated and it has encouraged the development of new techniques and more accurate scientific instruments, altogether providing a wider updated database. The landscape for ceramics research has changed dramatically for the past 15 years, and research in this field is now in a crossroad: in this lecture the emerging areas in ceramic science will be discussed, based upon a workshop held in March 2012 in USA on this regard.

APA, Harvard, Vancouver, ISO, and other styles

45

Clarke, D. R. "Critical Issues In Ceramic Microstructures." Microscopy Today 5, no. 7 (September 1997): 14–15. http://dx.doi.org/10.1017/s1551929500056546.

Full text

Abstract:

As the number and variety of ceramic materials have grown so rapidly in the last few decades, ranging from silicon nitride structural ceramics to the perovskite superconductors to the ferroelectric oxides to semiconducting sensors, the number of scientific and technical issues has also grown rapidly. Many of the basic questions relate to the role the microstructures play in determining the observed physical behavior, but increasingly it is not the geometric properties of the microstructure that are of central concern but rather compositional variations and associated electrical characteristics.

APA, Harvard, Vancouver, ISO, and other styles

46

JEFFERY, MARK, CHARLES GREEN, SOMDEV TYAGI, and R. GILMORE. "QUANTUM NETWORK SIMULATIONS OF HIGH Tc CERAMIC SUPERCONDUCTORS." International Journal of Modern Physics B 02, no. 06 (December 1988): 1399–405. http://dx.doi.org/10.1142/s0217979288001220.

Full text

Abstract:

Microwave absorption measurements of the high T c ceramic superconductors reveal reproducible features in weak magnetic fields. These features are qualitatively explained by a quantum network model of these superconducting oxides. The ceramic superconductors are modeled as a set of one-dimensional wires weakly coupled at random nodes. The magnetoconductance, magnetization and susceptibility are computed from the network S-matrix.

APA, Harvard, Vancouver, ISO, and other styles

47

Lung, C., D. Marconi, M. Pop, and A. V. Pop. "Resistance of High-Tc Superconductors: Review Article." Studia Universitatis Babeș-Bolyai Physica 65, no. 1-2 (December 30, 2020): 87–96. http://dx.doi.org/10.24193/subbphys.2020.09.

Full text

Abstract:

"The origin of resistance and its relation to the superconducting mechanism remain a profound, unsolved mystery. Currently, model parameters used to fit normal state properties are specific and vary arbitrarily from one doping. This short review illustrates the electrical resistivity of ceramic high temperature superconductors copper oxides. The article gives a summary of the prevailing arguments of researchers to relate the material to ceramic HTS compounds. Keywords: superconductivity, HTC ceramic compounds, resistivity. "

APA, Harvard, Vancouver, ISO, and other styles

48

Cava, Robert J. "Oxide Superconductors." Journal of the American Ceramic Society 83, no. 1 (January 2000): 5–28. http://dx.doi.org/10.1111/j.1151-2916.2000.tb01142.x.

Full text

APA, Harvard, Vancouver, ISO, and other styles

49

Lee, Sang Heon, and Yong Choi. "Electromagnetic properties of metal oxide doped ceramic oxide superconductor." Physics of Metals and Metallography 115, no. 13 (December 2014): 1300–1302. http://dx.doi.org/10.1134/s0031918x14130146.

Full text

APA, Harvard, Vancouver, ISO, and other styles

50

Cerezo, A., C. R. M. Grovenor, R. M. Hoyle, and G. D. W. Smith. "Atom probe analysis of a ceramic oxide superconductor." Applied Physics Letters 52, no. 12 (March 21, 1988): 1020–22. http://dx.doi.org/10.1063/1.99232.

Full text

APA, Harvard, Vancouver, ISO, and other styles

Journal articles on the topic 'Ceramic oxide superconductors'

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles