Interfacial reaction products and film orientation in YBa2Cu3O7−x on zirconia substrates with and without CeO2 buffer layers

Abstract

Thick film (1.2 μm) YBCO superconductors grown by pulsed laser deposition on unbuffered and CeO2-buffered single crystal (001)-oriented yttria-stabilized zirconia (YSZ) substrates have been investigated. YBCO and YSZ react to form BaZrO3 (BZO), whereas YBCO and CeO2 react to form BaCeO3. Reaction phases were examined by θ-2θ and four-circle x-ray diffraction and high resolution electron microscopy. Three orientation relationships identified for the unbuffered films were (i) (001)YBCO ‖ (011)BZO ‖ (001)YSZ with [110]YBCO ‖ [100]BZO ‖ [100]YSZ, (ii) (001)YBCO ‖ (001)BZO ‖ (001)YSZ with [110]YBCO ‖ [100]BZO ‖ [100]YSZ, and (iii) (001)YBCO ‖ (001)BZO ‖ (001)YSZ with [100]YBCO ‖ [100]BZO ‖ [100]YSZ. The results suggest that for films grown at typical deposition temperatures, YBCO epitaxy is established before the interfacial reaction occurs. The presence of BaCeO3 in buffered films grown at high temperatures (790 °C) was confirmed by θ-2θ scans and selected area diffraction patterns.