Interfaces in high-Tc superconducting oxides

1989 ◽  
Vol 47 ◽  
pp. 178-179
Author(s):  
C. Barry Carter ◽  
Lisa A. Tietz
Keyword(s):  
Solid State ◽  
Grain Boundaries ◽  
Superconducting Phase ◽  
Solid State Reactions ◽  
High Angle ◽  
Phase Boundaries ◽  
High Tc ◽  
Superconducting Material ◽  
First Case ◽  
Superconducting Oxides

Interfaces in high-Tc superconducting oxides are influential during both the processing of bulk materials and the growth of thin epitactically aligned layers. In the first case, the formation of the superconducting phase involves the movement of phase boundaries during the solid-state reaction, while in the second, the phase boundary is formed as the superconducting material grows on the single-crystal substrate. Having formed the superconducting material, the superconducting phase will, in general, contain a large number of grain boundaries varying from the simple twin boundaries which can be produced during the cubic-to-tetragonal transformation, to low-angle grain boundaries, special high-angle grain boundaries, other high-angle grain boundaries and phase boundaries due to incomplete or on-going solid-state reactions. During the course of this presentation, recent results on these topics will be reviewed, paying particular attention to the more widely studied material, YBa2Cu3O6+x.The importance of grain boundaries in high-Tc superconducting oxides has been firmly established by the systematic analysis of Dimos et al who have shown that the misorientation of the grains in layers of YBa2Cu3O6+x which had been grown on polycrystalline SrTiO3 substrate varies with the relative misorientation between the grains.

The formation of copper aluminate by solid-state reaction

1991 ◽  
Vol 6 (9) ◽  
pp. 1958-1963 ◽  
Author(s):  
David W. Susnitzky ◽  
C. Barry Carter
Keyword(s):  
Solid State ◽  
Single Crystal ◽  
Microprobe Analysis ◽  
Electron Microprobe Analysis ◽  
Substrate Surface ◽  
Alumina Substrate ◽  
Solid State Reactions ◽  
Phase Boundaries ◽  
Copper Aluminate ◽  
Scanning Electron

Solid-state reactions between bulk samples of copper oxide and alumina have been studied using scanning electron microscopy and electron microprobe analysis. Both CuAl2O4 and CuAlO2 were found to form during reactions in air at 1100 °C between CuO powder and single-crystal alumina substrates. The relative position of the CuAl2O4 and CuAlO2 layers was observed to depend on the crystallographic orientation of the surface of the alumina substrate: CuAl2O4 formed in contact with (0001) alumina substrates while CuAlO2 formed when the alumina substrate surface was (110). Faceted Cu–aluminate/alumina phase boundaries were observed to develop when single-crystal alumina rods were reacted with CuO, although the interfaces invariably tended to be wavy.

Cs3NdSi8O19 und Cs6Nd2Si21O48: Zwei cäsiumhaltige Oxosilicate des Neodyms im Vergleich / Cs3NdSi8O19 and Cs6Nd2Si21O48: Two Caesium-containing Oxosilicates of Neodymium in Comparison

2009 ◽  
Vol 64 (11-12) ◽  
pp. 1329-1338 ◽  
Author(s):  
Marion C. Schäfer ◽  
Thomas Schleid
Keyword(s):  
Solid State ◽  
Coordination Sphere ◽  
Quaternary System ◽  
Three Dimensional ◽  
Single Layer ◽  
Solid State Reactions ◽  
Double Layers ◽  
Orthorhombic Space Group ◽  
Space Group ◽  
First Case

In the quaternary system Cs / Nd / Si / O, two new representatives, the phyllo-oxosilicate Cs3NdSi8O19 and the tecto-oxosilicate Cs6Nd2Si21O48, were synthesized by CsF-flux-supported solid-state reactions between Nd2O3 and SiO2. The first one, Cs3NdSi8O19 (orthorhombic, Cmcm (no. 63), a = 705.74(5), b = 2712.85(19), c = 1163.72(8) pm, Z = 4), is not isotypic to the related scandium compound Cs3ScSi8O19. The [SiO4]4− tetrahedra (d(Si4+ -O2−) = 156 -163 pm) in the structure of Cs3NdSi8O19 are connected via common corners to form corrugated, loop-branched double layers containing four- and eight-membered rings in the (010) plane and eight-membered rings along [001]. Each of the eight-membered ellipses emerging along [100] is additionally loopbranched by two four-membered chains. The oxosilicate double layers are cross-linked by vertexsharing via otherwise isolated [NdO6]9− octahedra (d(Nd3+-O2-)= 232 - 234 pm) to build up a three-dimensional framework. Also in between the oxosilicate double layers, the (Cs1)+ cations are located on the 8 f site. Each of the octagonal channels along [001] hosts one (Cs3)+ and two (Cs2)+ cations, which both reside at only partially occupied sites (8g and 8 f , respectively) and disorder, because otherwise too short Cs+ ・ ・ ・ Cs+ distances would occur. The second compound, Cs6Nd2Si21O48, crystallizes also in an orthorhombic space group (Pmmn (no. 59), a = 2189.24(15), b = 731.92(5), c = 1593.61(11) pm, Z = 2). Starting from a loop-branched single layer containing five- and eight-membered rings, a three-dimensional framework of vertex-shared [SiO4]4− tetrahedra (d(Si4+-O2−) = 149 - 164 pm) built up, in which the Si-O distances range from 149 to 164 pm within a broad range. In certain cavities, one kind of Nd3+, but four kinds of Cs+ cations (here, all sites with full occupation) are embedded. Also surrounded by only six O2− anions just like in the first case, the Nd3+ cations (d(Nd3+-O2−) = 233 - 237 pm) exhibit an unusually small, but not unknown coordination sphere for this relatively large lanthanoid(III) cation

Solid state reactions in the formation of YBa2Cu3O7−δ high Tc superconductor powders

1989 ◽  
Vol 32-33 ◽  
pp. 1179-1182 ◽  
Author(s):  
G PAZPUJALT ◽  
A MEHROTRA ◽  
S FERRANTI ◽  
J AGOSTINELLI
Keyword(s):  
Solid State ◽  
Solid State Reactions ◽  
High Tc ◽  
High Tc Superconductor

Preparation of Bi-Pb-Sr-Ca-Cu-O Superconductor By Thermal Decomposition of an Edta Colloid

1990 ◽  
Vol 180 ◽  
Author(s):  
H.S. Koo ◽  
C.K. Chiang ◽  
Y.T. Huang ◽  
G.C. Tu
Keyword(s):  
Thermal Decomposition ◽  
Solid State ◽  
Solid State Reactions ◽  
Superconducting Properties ◽  
X Ray Diffraction ◽  
Microstructural Characteristics ◽  
High Tc ◽  
X Ray ◽  
Metal Nitrates ◽  
Zero Resistance

ABSTRACTHigh-Tc superconducting Bi-Pb-Sr-Ca-Cu oxide with zero resistance temperature at above lOOK has been synthesized via the use of ethylenediamine-tetra-acetate(EDTA) colloid and corresponding metal nitrates. Remarkable sinterability of the precursor requires shorter time to achieve superconducting phases than conventional solid-state reactions. Superconducting properties were measured electrically and magnetically. The thermal decomposition, X-ray diffraction and microstructural characteristics of the precursor and the sintered samples were also discussed.

STUDY OF HIGH-Tc SUPERCONDUCTING MATERIALS IN (Bi.Pb)-Sr-Ca-Cu-O SYSTEM

1989 ◽  
Vol 03 (04) ◽  
pp. 595-601 ◽  
Author(s):  
YUGUI WANG ◽  
XINPING JIAO ◽  
JINSONG WANG ◽  
NANLING WANG ◽  
GUCHANG HAN
Keyword(s):  
Solid State ◽  
Solid State Reaction ◽  
Magnetization Measurement ◽  
Superconducting Phase ◽  
Superconducting Materials ◽  
High Tc ◽  
Preliminary Results ◽  
Zero Resistance ◽  
Weak Pinning

The high-T c superconducting materials in (Bi.Pb)-Sr-Ca-Cu-O system with zero resistance temperature of 104 K have been made by solid state reaction. The system has been compared with BiSrCaCu 2 O y composition. The preliminary results show that Pb would make the superconducting polycrystalline grains grow smaller resulting in the separation of 100–110 K and 80 K superconducting crystalline grains and connectivity among the high-T c phase grains. By comparison, the proportion of superconducting phase is not increased in the Pb doped multiphase samples. The magnetization measurement indicates that all of them belong to the weak pinning superconductors.

Solid-State Reactions in Model Oxide Systems

1996 ◽  
Vol 453 ◽  
Author(s):  
Matthew T. Johnson ◽  
Paul G. Kotula ◽  
Ryan S. Thompson ◽  
C. Barry Carter
Keyword(s):  
Thin Films ◽  
Solid State ◽  
Reaction Rates ◽  
Oxide System ◽  
Solid State Reactions ◽  
Diffusion Control ◽  
Phase Boundaries ◽  
Oxide Systems ◽  
Fe Oxide ◽  
Kinetics Of

AbstractThe kinetics of thin-film solid-state reactions have been investigated in two model spinel forming oxide systems, NiO/Al2O3 and MgO/Fe2O3. In the NiO/Al2O3 system, thin-films of epitactic NiO were reacted with (0001), , and orientated Al2O3 (corundum). The kinetics of the spinel forming reaction for this system were found to be linear-parabolic in nature. Additionally, it was found that the kinetics of the spinel-forming reaction varied by nearly two orders of magnitude between the fastest and slowest diffusion couples. The substrate determines the orientation of the overlayers and thereby the structure of the phase boundaries. In the MgO/Fe-oxide system, thin films of epitactic Fe oxide were reacted with {001} MgO. The kinetics of this spinel forming reaction were parabolic in nature, indicative of diffusion control. In contrast to the N1O/Al2O3 system, the movement of phase boundaries are not the step controlling the reaction rate, but rather the diffusion of one of the cations across the reaction layer. In comparing the reaction rates for the two systems the activation energy for the formation of the spinel product in the MgO/Fe-oxide system was found to be almost a factor of 4 lower in comparison to the NiO/Al2O3 system.

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