Accession Number : ADA322090
Title : 'Thin Film Multilayer High Tc Structures with Enhanced Superconductor Properties'.
Descriptive Note : Final rept. 1 Sep 92-31 Aug 96,
Corporate Author : FLORIDA INTERNATIONAL UNIV MIAMI DEPT OF ELECTRICAL AND COMPUTER ENGINEERING
Personal Author(s) : Larkins, Grover L., Jr
PDF Url : ADA322090
Report Date : FEB 1997
Pagination or Media Count : 6
Abstract : Room Temperature Poling at + 10Volts (positive on the silver top electrode) of BTO in Bi-layer Structures led to changes in the Resistance vs. Temperature Curves of the 123 of the same sort as Poling above the Curie Temperature. Epitaxy has been achieved with 123 deposition parameters of 790C in 200 millitorr of flowing O2 and BTO deposition at 700C in 100 millitorr of flowing O2. Note: All deposition temperatures quoted were measured with an optical pyrometer. The resultant bi-layers showed good epitaxy with clean x-ray diffraction spectra and superconductive transitions which were approximately 1K to 2K wide with an onset at 89K to 90K and T sub c sub(zero resistance) of 87K to 89K for un-poled (virgin) samples. Deposition of the BTO at temperatures in excess of about 725C resulted in dirty x-ray spectra with an unexplained peak at 36.5 degrees. T sub c s of these films were considerably reduced from the conditions described above and often possessed a 'two-step' transition which was quite broad beginning at 89K and ending at about 60K. This was taken to be indicative of the presence of non-stoichiometric phases (mixed phase or oxygen deficient material).
Descriptors : *HIGH TEMPERATURE, *RESISTANCE, *SUPERCONDUCTORS, *THIN FILMS, EXPERIMENTAL DATA, GRAPHS, STRUCTURES, X RAY DIFFRACTION, EPITAXIAL GROWTH, ROOM TEMPERATURE, OXYGEN, DEPOSITION, X RAY SPECTRA, MIXING, TRANSITIONS, FLOW, CURIE TEMPERATURE, SILVER, SUPERCONDUCTIVITY, OPTICAL PYROMETERS.
Subject Categories : Solid State Physics
Electrical and Electronic Equipment
Electricity and Magnetism
Distribution Statement : APPROVED FOR PUBLIC RELEASE