Effect of the annealing process on the microstructure of La2Zr2O7 thin layers epitaxially grown on LaAlO3 by metalorganic decomposition

Carmen Jiménez (1) , Tristan Caroff (1, 2) , L. Rapenne (1) , Stéphanie Morlens (2) , Elena Santos (1) , Philippe Odier (2) , François Weiss (1)

1 LMGP - Laboratoire des matériaux et du génie physique
2 CRETA - Consortium de Recherches pour l'Emergence des Technologies Avancées

La2Zr2O7 (LZO) films have been grown by Metalorganic Decomposition (MOD) to be used as buffer layers for coated conductors. A characteristic feature of LZO thin films deposited by MOD is the formation of nanovoids in an almost single crystal structure of LZO pyrochlore phase. Annealing parameters (heating ramp, temperature, pressure...) were varied to establish their influence on the microstructure of the LZO layers. XRD and TEM were used for sample characterisation. The epitaxial pyrochlore phase was obtained for annealing temperatures higher that 850°C whatever the other annealing conditions. However, the film microstructure, in particular, nanovoids shape and size, is strongly dependent on heating ramp and pressure during annealing. When using low heating ramp, percolation of voids creates diffusion channels for oxygen which are detrimental for the substrate protection during coated conductor fabrication. From this point of view high heating rates are more adapted to the growth of LZO layers.

Mots clés: Methods of deposition of films and coatings; Film growth and epitaxy; .Superconducting wires fibers and tapes; Superconducting wires fibers and tapes; Transmission electron microscopy (TEM); Nucleation and growth

Domaines: Matériaux

Carmen Jiménez, Tristan Caroff, L. Rapenne, Stéphanie Morlens, Elena Santos, et al.. Effect of the annealing process on the microstructure of La2Zr2O7 thin layers epitaxially grown on LaAlO3 by metalorganic decomposition. Journal of Crystal Growth, 2009, 311, pp.3204. ⟨10.1016/j.jcrysgro.2009.03.021⟩. ⟨hal-00395314⟩