摘要:

YBaCuO superconducting thin films are prepared by using a plasma‐enhanced metalorganic chemical vapor deposition. An rf discharge plasma is used to decompose the metalorganic chelate precursors. Optimization of the film deposition conditions is studied using optical emission spectroscopy. The rf process is also applied to decompose silicon compounds for preparation a SiO2insulating film on the YBa2Cu3O7bulk superconductor.

ISSN:0094-243X    

DOI:10.1063/1.40207

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Good quality crystals were grown from a non stoichiometric melt of Y‐Pr‐Ba‐Cu‐D. (AIP)

ISSN:0094-243X    

DOI:10.1063/1.40208

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

We report successful preparation of thin films of Y1Ba2Cu3O7−&dgr;(YBC) using the technique of laser ablation on single crystal (001) SrTiO3. X‐ray diffraction (XRD) pattern of the as deposited film showed thec‐axis to be perpendicular to the substrate. The critical current was estimated to be 9×106A/cm2(H∥c) and 4×108A/cm2(H⊥c) at 12K as determined from magnetic hysteresis measurements. Intial base pressure in addition to oxygen pressure and substrate temperture is found to be important to achieve correct stoichiometry and high critical currents.

ISSN:0094-243X    

DOI:10.1063/1.40210

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

AG sheathed highTcsuperconducting tapes of Bi‐2212 were fabricated using the powder in tube method. X‐ray diffraction studies of the as cold‐worked (drawn and rolled) samples show some preferential (OO1) alignment, but very broad peaks indicative of servere damage. Annealing removes the damage and greatly enhances the degree of orientation. Superoconducting properties were also found to be extremely sensitive to cold‐work and heat treatment conditions.

ISSN:0094-243X    

DOI:10.1063/1.40211

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

This paper contains a discussion of the glass ceramic processing methods and the important parameters which must be understood to control microstructure through the use of this process. Initial results of thermal analysis and high temperature diffraction analysis of glass crystallization, as well as high temperature diffraction analysis of the peritectic melting of the Bi‐2212 phase are included.

ISSN:0094-243X    

DOI:10.1063/1.40212

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

This paper presents a series of investigations of glass forming properties and crystallization behavior in both the Y2O3‐BaO‐CuO‐B2O3and Y2O3‐BaO‐CuO‐P2O5systems. The melting temperatures for the glasses of varied compositions ranged from 1000 °C to 1400 °C. Different heat treatment temperatures were used ranging from 700 °C to 940 °C. A series of stoichiometries were studied to determine the glass forming limits. The crystallized phases were analyzed by means of XRD and SEM. The progressive development of 123 phase from the supersaturated glasses further proved the feasibility of obtaining sudperconducting materials by using the glass‐ceramic route. A study of the interface reaction between 123 and the glasses revealed that it is possible to crystallize the 123 phase from the glasses by a surface induced crystallization technique.

ISSN:0094-243X    

DOI:10.1063/1.40213

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Glass‐ceramic processing of Bi‐system superconductors has been improved through the addition of intermediate glass formers. The intermediate glass formers used here are Ga and In. The Ga and Ga/In additions did produce Bi2Sr2Cu1O6and Bi2Sr2CaCu2O8. TheTx‐Tgdifference for the Ga and Ga/In glasses were 73 K and 89 K respectively. The molar ratios used were 1:1 (2223:Ga) and 1:.9:.1 (2223:Ga:In).

ISSN:0094-243X    

DOI:10.1063/1.40214

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Samples near the stoichiometry Y1Ba4Cu2Oxwere prepared with and without the presence of carbonate. XRD and wet chemical analysis were performed to determine carboinate content. A compound with the the stoichiometry of Y1Ba4Cu2(CO3)O7±&dgr;was stabilized when the precursor BaCO3was used. The absence of carbonate yielded the Y1Ba4Cu3O8.5±&dgr;compound. Electrical measurements indicated no superconductivity properties in the 10–298 K temperature range for the 142 oxycarbonate and the 143.

ISSN:0094-243X    

DOI:10.1063/1.40215

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Ruddlesden‐Popper (R‐P) type compounds in the parent La‐Cu‐O system have been reported to exist up to then=7 series member of Lan+1CunO3n+1[1]. La2CuO4is the first member of the series and LaCuO3, then=∞ member. The other members of the series can be regarded as combinations of these two end members.The crystal structure of La2CuO4has been well characterized but the structural information of the other members of this series is lacking in the literature. An atomistic computer simulation was performed to predict the equilibrium structures for the first five members of this series. XRD patterns were then calculated to aid in analyzing the experimentally prepared samples of higher order phases.The ability to synthesize structurally stable bulk compounds of the Lan+1CunO3n+1homologous series using a solid state and nitrate preparation technique has been investigated. Samples with starting stoichiometries corresponding to series members were reacted in both air and oxygen atmospheres. Results indicate bulk structural instability of series members higher thann=1.

ISSN:0094-243X    

DOI:10.1063/1.40216

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Recent progress in developing high‐temperature superconductors has enhanced the economic viability of energy applications such as power systems, motors, material processing and handling, refrigeration, transportation, and power electronics. This paper discusses the technical and economic issues associated with these applications.

ISSN:0094-243X    

DOI:10.1063/1.40217

出版商:AIP    

年代:1991

数据来源: AIP