High Critical-Current Density Ba2YCu3O7 Thin Films Produced by Coevaporation of Y, Cu, and BaF2

1987 ◽  
Vol 99 ◽  
Author(s):  
P. M. Mankiewich ◽  
R. E. Howard ◽  
W. J. Skocpol ◽  
A. H. Dayem ◽  
A. Ourmazd ◽  
...  
Keyword(s):  
Thin Film ◽  
Critical Current ◽  
High Critical Current Density ◽  
High Quality ◽  
Residual Resistance ◽  
Substrate Interaction ◽  
Transmission Electron ◽  
Zero Resistance ◽  
Current Densities ◽  
Oxygen Addition

ABSTRACTHigh quality films of Ba2YCu3O7 have been made by coevaporation of Y, Cu, and BaF2 and subsequent annealing in oxygen. Addition of water vapor to the annealing gas at high temperatures has been found to greatly reduce the annealing time and, thus the substrate interaction. Transition temperatures (zero resistance) between 89–92 K are routinely obtained on SrTiO3 and cubic zirconia substrates. Critical current densities on SrTiO3 are as high as 106 A/cm2 at 81 K and routinely above 105 A/cm2 at 77 K. Transmission electron microscopy shows that on SrTiO3 the superconducting grains have an epitaxial orientation with respect to the substrate. Persistent current measurements in thin film rings demonstrate the absence of residual resistance in the superconducting state.

Semi-Coherent Yttria Inclusions Occurring Spontaneously in YBa2Cu3O6+× Films Grown by Dc Magnetron Sputtering

1992 ◽  
Vol 275 ◽  
Author(s):  
T. I. Selinder ◽  
Z. Han ◽  
U. Helmersson ◽  
J. Magnusson ◽  
P. Norling ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Magnetron Sputtering ◽  
Critical Current ◽  
Film Growth ◽  
Number Density ◽  
Dc Magnetron Sputtering ◽  
High Quality ◽  
Transmission Electron ◽  
Current Densities

ABSTRACTSemi-coherent Y2O3 (yttria) inclusions have been observed in high quality, c-axis oriented YBa2Cu3O6+×,(YBCO) Alms. The inclusions were studied by transmission electron microscopy (TEM), and were found to be embedded in the YBCO matrix without disturbing its structure seriously. Their number density is estimated to higher than 2 × 1016 cm−3 in epitaxial YBCO films, having transport critical current densities in excess of 1 × 106 A cm−2 at 77 K. Magnetization measurements indicate a possible correlation between a high density of yttria inclusions and high pinning strength. The effects of the inclusions on film growth and microstructure is discussed.

scholarly journals The Progress on Low-Cost, High-Quality, High-Temperature Superconducting Tapes Deposited by the Combustion Chemical Vapor Deposition Process

2001 ◽  
Vol 689 ◽  
Author(s):  
Shara S. Shoup ◽  
Marvis K. White ◽  
Steve L. Krebs ◽  
Natalie Darnell ◽  
Adam C. King ◽  
...  
Keyword(s):  
Chemical Vapor Deposition ◽  
High Temperature ◽  
Critical Current Density ◽  
Buffer Layer ◽  
Critical Current ◽  
Vapor Deposition ◽  
Low Cost ◽  
Chemical Vapor ◽  
High Critical Current Density ◽  
High Quality

ABSTRACTThe innovative Combustion Chemical Vapor Deposition (CCVD) process is a non-vacuum technique that is being investigated to enable next generation products in several application areas including high-temperature superconductors (HTS). In combination with the Rolling Assisted Biaxially Textured Substrate (RABiTS) technology, the CCVD process has significant promise to provide low-cost, high-quality lengths of YBCO coated conductor. The CCVD technology has been used to deposit both buffer layer coatings as well as YBCO superconducting layers. A buffer layer architecture of strontium titanate and ceria have been deposited by CCVD on textured nickel substrates and optimized to appropriate thicknesses and microstructures to provide templates for growing PLD YBCO with high critical current density values. The CCVD buffer layers have been scaled to meter plus lengths with good epitaxial uniformity along the length. A short sample cut from one of the lengths enabled high critical current density PLD YBCO. Films of CCVD YBCO superconductors have been grown on single crystal substrates with critical current densities over 1 MA/cm2. Work is currently in progress to combine both the buffer layer and superconductor technologies to produce high-quality coupons of HTS tape made entirely by the non-vacuum CCVD process.

Transport Measurements on Superconducting YBa2Cu3O7-δ Thin Film Lines

1989 ◽  
Vol 169 ◽  
Author(s):  
B. H. Moeckly ◽  
D. K. Lathrop ◽  
G. F. Redinbo ◽  
S. E. Russek ◽  
R. A. Buhrman
Keyword(s):  
Magnetic Field ◽  
Thin Film ◽  
Critical Current ◽  
Weak Link ◽  
High Sensitivity ◽  
Weak Links ◽  
Microwave Response ◽  
Field Response ◽  
Current Densities ◽  
Iv Curves

AbstractCritical current densities, magnetic field response, and microwave response have been measured for laser ablated YBa2Cu3O7-δ thin film lines on MgO and SrTiO3 substrates. Films on SrTiO3 have critical current densities > 1 x 106 A/cm2 at 77K and show uniform transport properties in lines of all sizes. Films on MgO have critical current densities which range between 102 and 106 A/cm2 at 77K and show considerable variation from device to device on the same chip. Narrow lines on MgO with low critical current densities show Josephson weak link structure which includes RSJ-like IV curves, microwave induced constant voltage steps, and a high sensitivity to magnetic field. The presence of the Josephson weak links is correlated with small amounts of misaligned grains in films on MgO.

Low-Tc phase formation at the grain boundaries and electromagnetic granularity in (Bi,Pb)2Sr2Ca2Cu3Ox silver-sheathed tapes

1993 ◽  
Vol 51 ◽  
pp. 940-941
Author(s):  
Yi Feng ◽  
A. Umezawa ◽  
H. S. Edelman ◽  
D. C. Larbalestier
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Grain Boundaries ◽  
Critical Current ◽  
Ac Susceptibility ◽  
Transmission Electron ◽  
Heat Treated ◽  
Standard Powder ◽  
Current Densities ◽  
Powder In Tube

High resolution transmission electron microscopy (HRTEM) was performed on progressively heat treated Ag-clad (Bi,Pb)2Sr2Ca2Cu3Ox (2223) tapes and was correlated with their transport critical current densities, DC magnetization and AC susceptibility. HRTEM reveals the presence of a small number of half layers of the low Tc Bi2Sr2CaCu2Ox (2212) phase clustered at the numerous (001) twist grain boundaries. This residual 2212 phase produces electromagnetic granularity in a temperature range around 77K and thus directly controls the critical current.The Bi(Pb)-Sr-Ca-Cu-0 (BSCCO) Ag-clad tapes with the stoichiometric 2:2:2:3 starting composition were prepared by a standard powder-in-tube method. Sample A was heat treated at 817°C for 5 hours only. Sample B was first heat treated at 817°C for 24 hours, and then heat treated for 100 hours at the same temperature after two intermediate pressings. Sample C was heat treated at 830°C for 72 hours, and then heat treated for additional 196 hours after one intermediate pressing.

Spatial variations in composition in high-critical-current-density Bi-2223 tapes

2000 ◽  
Vol 15 (2) ◽  
pp. 285-295 ◽  
Author(s):  
T. G. Holesinger ◽  
J. F. Bingert ◽  
M. Teplitsky ◽  
Q. Li ◽  
R. Parrella ◽  
...  
Keyword(s):  
Critical Current Density ◽  
Critical Current ◽  
Current Density ◽  
Compositional Analysis ◽  
Structural Features ◽  
Spatial Variations ◽  
High Critical Current Density ◽  
Transmission Electron ◽  
Filament Structure ◽  
Considerable Range

A detailed compositional analysis of high-critical-current-density (Jc) (55 and 65 kA/cm2at 77 K) (Bi,Pb)2Sr2Ca2Cu3Oy(Bi-2223) tapes was undertaken by energy dispersive spectroscopy in the transmission electron microscope. Structural features were coupled with characteristic compositions of the Bi-2223 phase. The average of all compositional measurements of the Bi-2223 phase was determined to be Bi1.88Pb0.23Sr1.96Ca1.95Cu2.98Oy. However, spatial variations in the Bi-2223 composition and differing phase equilibria were found throughout the filament structure. In particular, a considerable range of Bi-2223 compositions can be found within a single tape, and the lead content of the Bi-2223 phase is significantly depressed in the vicinity of lead-rich phases. The depletion of lead in the Bi-2223 phase around the 3221 phases may be a current-limiting microstructure in these tapes.

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