Abstract
Thin films of YBa{sub 2}Cu{sub 3}O{sub 7-x} (YBCO) are significant in fundamental studies of oxide superconductors and for prospective electronic applications based on superconductors operating at 77 K. Synthesis of YBCO thin films is complex and a large part of this thesis has been devoted to elaborating various techniques in forming YBCO thin films. It was observed that synthesis of YBCO films exhibiting high zero-resistivity temperatures (T{sub c}) {>=} 88 K and elevated critical current densities (J{sub c}) {>=} 10{sup 6} A/cm{sup 2} at 77 K was possible under widely different conditions of film growth. For the BaF{sub 2}-based method, various substrate materials were investigated. Among perovskite related substrates with low losses in the high frequency regime, LaA10{sub 3} was found to yield YBCO films exhibiting the highest quality electrical properties. A study of YBCO film interaction with sapphire substrates was performed. It was suggested that the YBCO film on sapphire consists of weakly coupled superconducting grains. Compositional effects of Y, Ba and Cu for MOCVD-YBCO films were examined with respect to morphology, structure, resistivity, as susceptibility and J{sub c}(T). High T{sub c}`s and J{sub c}`s were observed for an anomalous large compositional range of Cu in off-compositional YBCO films.
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Citation Formats
Hudner, J.
Superconducting thin films of YBa{sub 2}Cu{sub 3}O{sub 7-x}.
Sweden: N. p.,
1993.
Web.
Hudner, J.
Superconducting thin films of YBa{sub 2}Cu{sub 3}O{sub 7-x}.
Sweden.
Hudner, J.
1993.
"Superconducting thin films of YBa{sub 2}Cu{sub 3}O{sub 7-x}."
Sweden.
@misc{etde_10112467,
title = {Superconducting thin films of YBa{sub 2}Cu{sub 3}O{sub 7-x}}
author = {Hudner, J}
abstractNote = {Thin films of YBa{sub 2}Cu{sub 3}O{sub 7-x} (YBCO) are significant in fundamental studies of oxide superconductors and for prospective electronic applications based on superconductors operating at 77 K. Synthesis of YBCO thin films is complex and a large part of this thesis has been devoted to elaborating various techniques in forming YBCO thin films. It was observed that synthesis of YBCO films exhibiting high zero-resistivity temperatures (T{sub c}) {>=} 88 K and elevated critical current densities (J{sub c}) {>=} 10{sup 6} A/cm{sup 2} at 77 K was possible under widely different conditions of film growth. For the BaF{sub 2}-based method, various substrate materials were investigated. Among perovskite related substrates with low losses in the high frequency regime, LaA10{sub 3} was found to yield YBCO films exhibiting the highest quality electrical properties. A study of YBCO film interaction with sapphire substrates was performed. It was suggested that the YBCO film on sapphire consists of weakly coupled superconducting grains. Compositional effects of Y, Ba and Cu for MOCVD-YBCO films were examined with respect to morphology, structure, resistivity, as susceptibility and J{sub c}(T). High T{sub c}`s and J{sub c}`s were observed for an anomalous large compositional range of Cu in off-compositional YBCO films. This was shown to be related to the formation of Cu-rich precipitates embedded within a c-Axis oriented stoichiometric YBCO film matrix. Thermal critical current behavior at zero field in thin films of YBCO fabricated by various methods has been studied by three techniques: transport measurements on patterned microbridges, dc magnetization hysteresis loops using the Bean model and non-linear ac susceptibility analysis. Absolute critical current values obtained form the two former techniques when measured on the same YBCO film were observed to differ about a factor of two.}
place = {Sweden}
year = {1993}
month = {Dec}
}
title = {Superconducting thin films of YBa{sub 2}Cu{sub 3}O{sub 7-x}}
author = {Hudner, J}
abstractNote = {Thin films of YBa{sub 2}Cu{sub 3}O{sub 7-x} (YBCO) are significant in fundamental studies of oxide superconductors and for prospective electronic applications based on superconductors operating at 77 K. Synthesis of YBCO thin films is complex and a large part of this thesis has been devoted to elaborating various techniques in forming YBCO thin films. It was observed that synthesis of YBCO films exhibiting high zero-resistivity temperatures (T{sub c}) {>=} 88 K and elevated critical current densities (J{sub c}) {>=} 10{sup 6} A/cm{sup 2} at 77 K was possible under widely different conditions of film growth. For the BaF{sub 2}-based method, various substrate materials were investigated. Among perovskite related substrates with low losses in the high frequency regime, LaA10{sub 3} was found to yield YBCO films exhibiting the highest quality electrical properties. A study of YBCO film interaction with sapphire substrates was performed. It was suggested that the YBCO film on sapphire consists of weakly coupled superconducting grains. Compositional effects of Y, Ba and Cu for MOCVD-YBCO films were examined with respect to morphology, structure, resistivity, as susceptibility and J{sub c}(T). High T{sub c}`s and J{sub c}`s were observed for an anomalous large compositional range of Cu in off-compositional YBCO films. This was shown to be related to the formation of Cu-rich precipitates embedded within a c-Axis oriented stoichiometric YBCO film matrix. Thermal critical current behavior at zero field in thin films of YBCO fabricated by various methods has been studied by three techniques: transport measurements on patterned microbridges, dc magnetization hysteresis loops using the Bean model and non-linear ac susceptibility analysis. Absolute critical current values obtained form the two former techniques when measured on the same YBCO film were observed to differ about a factor of two.}
place = {Sweden}
year = {1993}
month = {Dec}
}