Preparation and characterization of yttrium barium(2) copper(3) oxygen(7-x) high critical transition...

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" Preparation and characterization of yttrium barium(2) copper(3) oxygen(7-x) high critical transition temperature superconductor "
M. A.-R. Redwan

Document Type	:	Latin Dissertation
Language of Document	:	English
Record Number	:	1112462
Doc. No	:	TLpq230729704
Main Entry	:	M. A.-R. Redwan
Title & Author	:	Preparation and characterization of yttrium barium(2) copper(3) oxygen(7-x) high critical transition temperature superconductor\ M. A.-R. Redwan
College	:	King Fahd University of Petroleum and Minerals (Saudi Arabia)
Date	:	1991
student score	:	1991
Degree	:	M.S.
Page No	:	196
Abstract	:	Superconductor samples of YBa2Cu3O7-x were prepared by two different methods. Measurements using XRD, SEM, EPMA, and four probe method indicated single phased samples with orthorhombic structure and transition temperature of 92 K. Samples were further studied by XPS and UPS techniques, where representative clean surfaces were prepared by in-situ scraping. Valence band spectra show low density of states at Fermi level and strongly hybridized O 2p and Cu 3d states. The position, shape, and satellite emission of Cu 2p indicate a mixture of Cu and Cu valencies. The O 1s two components are intrinsic and the 531 eV peak is related to oxygen hole states (O). Ba core levels show a two component structure, suggesting two principal Ba-O configurations due to oxygen vacancies. The position and shape of Y doublets indicate weak Y-O interactions. Annealling in UHV causes an increase in O vacuncies and a reduction of Cu valency. Water exposure causes the formation of hydroxides at the surface, while oxygen exposure has no significant effect.
Subject	:	Condensation
	:	Pure sciences