Processing and phase stability of metal carboxylate-derived barium-yttrium-copper oxide thin films
Davison, William Watson
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Permalink
https://hdl.handle.net/2142/19284
Description
Title
Processing and phase stability of metal carboxylate-derived barium-yttrium-copper oxide thin films
Author(s)
Davison, William Watson
Issue Date
1990
Doctoral Committee Chair(s)
Buchanan, Relva C.
Department of Study
Materials Science and Engineering
Discipline
Ceramic Engineering
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Engineering, Materials Science
Language
eng
Abstract
The processing and phase stability of Ba$\sb2$YCu$\sb3$O$\sb{\rm 7-x}$ High T$\sb{\rm c}$ thin films are seen to be critical aspects of the successful fabrication of this material. Metal neodecanoates of barium, yttrium, and copper were synthesized and mixed into a homogeneous, precipitate-free solution, which was spin-cast onto ZrO$\sb2$ coated silicon wafers. A minimum heat treated temperature of 725$\sp\circ$C in N$\sb2$ was needed to decompose the BaCO$\sb3$ present in the films. A phase map of the stability of Ba$\sb2$YCu$\sb3$O$\sb{\rm 7-x}$ as a function of heat treatment temperature and ambient showed both the upper and lower temperature boundaries to increase with decreasing P$\sb{\rm O2}$, with the higher temperature boundary truncated at temperatures $>$800$\sp\circ$C from interdiffusion of the films with the substrate. The high temperature decomposition mechanism for the high P$\sb{\rm O2}$ condition was seen to be nucleation of BaCuO$\sb2$, followed by formation of BaY$\sb2$CuO$\sb5$, the accelerated formation of which was attributed to the small grain size ($$90 K was accounted for by the presence of the weak links in the film microstructure.
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