Y2O3 inclusions in YBa2Cu3O7−δ thin films

Abstract

Nanoprecipitates in YBa2Cu3O7-δ (YBCO) thin films have been identified by high resolution electron microscopy (HREM) as Y2O3 inclusions; they correspond to two different types of epitaxial relationships namely [001] or [110] parallel to the YBCO c-axis. The [001] precipitates are situated near the YBCO surface, in the bulk and on the YBCO film/substrate interface. The [110] precipitates have only been observed at the surface. Literature data have been reinterpreted.

Microstructural characterization of thick YBa2Cu3O7−δ films on improved rolling-assisted biaxially textured substrates

“…The Y 2 O 3 particle was located at roughly the center of the film and was not associated with any defects extending up from the buffer layers. Smaller Y 2 O 3 particles noted as Type B, which have the Y 2 O 3 (110)// YBCO (001) relationship and generally appear near the top of the YBCO film surface, 19,21 were not observed in this study. In earlier work on thick YBCO films on RABiTS, 9 the stacking faults were shown to contain excess Cu-O and were identified to be Y248 intercalates based on the expanded c-axis lattice constant to 13.3 Å.…”

“…A closer view of the faults is shown in Fig. 1(b 19 and Catana et al 20 as Type A particles. The Y 2 O 3 particle was located at roughly the center of the film and was not associated with any defects extending up from the buffer layers.…”

Transport Properties of ${\rm YBa}_{2}{\rm Cu}_{3}{\rm O}_{7-\delta}$ Thin Films Near the Critical State

“…Then, the vortices behave as pancake vortices and work W is not the work corresponding to the motion of a vortex line with length d over distance , but that corresponding to the motion of a vortex line section with mean length over distance . The existence of superimposed rows of weak links could be due to the inclusions that have been observed in YBCO films [7], [8]. Although they are known to be coherent with the matrix, their presence induces strain and defects such as stacking faults, shearing planes and dislocations parallel to the a-b planes.…”

Epitaxially Induced Defects in Sr- and O-doped La2CuO4Thin Films Grown by MBE: Implications for Transport Properties

“…The deposition method used is neither a codeposition method nor a layer-by-layer deposition but consists of a block-wise deposition of the various elements that is aimed at forming the desired compound only during the deposition of the final block with a minimum of intermediary phases [23,24]. For the undoped `214' compound grown on STO, the probable interfacial stacking sequence is Sr-O -Ti-O -La-OCu-O -La-O (a similar stacking sequence was derived from high resolution electron micrography (HREΜ) images obtained on La2SrCu2 O8 films deposited on SrTiO3 [25]); this would indicate an "ideal" sequential layer-by-layer deposition procedure of 1 monolayer of La-O, followed by 1 monolayer of Cu-O and finally another monolayer of La-O before the entire sequence is repeated. Such a process sequence is not optimal because once the Cu-O monolayer has been deposited, '214' will start to form, leaving about half the deposited Cu-O as precipitates.…”