1051-8223 (c) 2015 IEEE. Personal use is permitted, but republication/redistribution requires IEEE permission. See http://www.ieee.org/publications_standards/publications/rights/index.html for more information. This article has been accepted for publication in a future issue of this journal, but has not been fully edited. Content may change prior to final publication. Citation information: DOI 10.1109/TASC.2016.2542250, IEEE Transactions on Applied Superconductivity 2A-WT-P-01.04 1 Development of biaxially textured LZO film on cold- rolled metal substrate A. Vannozzi, A. Augieri, G. Celentano, A. Rufoloni, A. Mancini, V. Pinto, F. Rizzo, A. Angrisani Armenio, V. Galluzzi, F. Fabbri, and T. Petrisor Abstract—La 2 Zr 2 O 7 (LZO) film grown by chemical solution deposition (CSD) technique is a widely studied buffer layer for YBa 2 Cu 3 O 7-x film growth on rolling assisted biaxially textured (RABiT) substrate. Biaxially textured LZO film is epitaxially grown on a cube-textured metal substrate. In RABiT substrate, cube texture is obtained as primary recrystallization of heavily cold-rolled fcc metals and is normally developed before CSD film deposition to obtain an oriented film growth. In the present contribution, we show that biaxially textured LZO film can be grown by depositing the precursor solution directly on cold- rolled fcc metal substrate and performing a single heat treatment. In fact, we show that if the recrystallization temperature of the metallic substrate is lower than the nucleation temperature of the film, a biaxially textured film is obtained as a result of transient cube texture transfer. Biaxially textured LZO films grown on cold-rolled substrates are compared with films grown on recrystallized substrates. In particular, the growth of LZO on either pure Cu or Ni-based substrate was studied. Compared with LZO film grown on cube textured substrate, LZO grown on cold-rolled substrate shows similar structural properties and morphology. Moreover, films are well adherent without cracks or delamination, suggesting that grain boundary migration in the metallic substrate has no detrimental influence on the film. In some cases, secondary recrystallization of the substrate occurs, without affecting the quality of LZO film. Index Terms—Buffer layer, chemical solution deposition (CSD), coated conductor, cube-textured substrate, lanthanum zirconate, recrystallization. I. INTRODUCTION HEMICAL SOLUTION DEPOSITION (CSD) is a powerful and cost-effective technique for the realization of biaxially- textured template for YBa 2 Cu 3 O 7-x (YBCO) coated conductor. The main advantage of this technique is the use of a cheap, non-vacuum experimental set-up that is easily scalable to long Automatically generated dates of receipt and acceptance will be placed here; authors do not produce these dates. This work was supported by MIUR (Ministero dell’Istruzione, Università e Ricerca) in the framework of the FIRB-Futuro in Ricerca project SURE:ARTYST on chemical coated- conductor. (Corresponding author: Angelo Vannozzi.) A. Vannozzi, A. Augieri, G. Celentano, A. Rufoloni, A. Mancini, V. Pinto, F. Rizzo, A. Angrisani Armenio, and V. Galluzzi are with ENEA Frascati Research Centre, 00044 Frascati, Italy (e-mail: angelo.vannozzi@enea.it; andrea.augieri@enea.it; giuseppe.celentano@enea.it; alessandro.rufoloni@enea.it; antonella.mancini@enea.it; valentina.pinto@enea.it; francesco.rizzo@enea.it; achille.angrisaniarmenio@enea.it; valentina.galluzzi@enea.it). F. Fabbri is with ENEA Casaccia Research Centre, 00123 S. Maria di Galeria, Rome, Italy (e-mail: fabio.fabbri@enea.it). T. Petrisor is with the Technical University of Cluj-Napoca, 3400 Cluj- Napoca, Romania (e-mail: Traian.Petrisor@phys.utcluj.ro). lenghts production [1]. Among the compounds suitable as buffer layers for YBCO coated conductor, La 2 Zr 2 O 7 (LZO) was thoroughly studied by several groups during the last years [2]–[8]. The main advantages of LZO are the very low lattice mismatch with YBCO, the low conversion temperature and the possibility of using a reducing atmosphere such as Ar-H 2 during the heat treatment. LZO film growth by CSD is mostly used as buffer layer in Rolling Assisted Biaxially Textured (RABiT) substrate [9]. This technique permits to develop a suitable orientation on fcc metals by means of a thermo-mechanical process, basically consisting in a severe cold-rolling followed by a high- temperature heat treatment to develop the cube texture. As previously shown, LZO film grown on cube-textured copper substrate shows a very high degree of epitaxy [10]. Due to the high temperature reached during LZO conversion heat treatment, 1000 °C in the case of deposition on copper substrate, in many cases the substrate underwent secondary recrystallization [10]. Nevertheless, this phenomenon did not affect LZO film orientation. Moreover, grain boundary (GB) migration occurring during secondary recrystallization of copper had no detrimental influence on LZO film adhesion. These observations suggest that microstructural modifications of the substrate occurring during LZO conversion heat treatment do not inevitably cause film degradation. As a consequence, if this behavior holds also for the migration of primary recrystallization GBs, it may be conceived that biaxially textured LZO film could be obtained also by depositing the precursor solution directly on as-rolled substrate, i.e. on a substrate that has not yet developed the cube texture. In fact, the recrystallization process of cold- rolled fcc metal tapes is very rapid and occurs at relatively low temperatures, while further annealing only slightly modifies the microstructure during the so-called grain growth phase [11],[12]. In the case of pure copper, recrystallization occurs in the range 200–300 °C [13], and at these temperatures no LZO precursor decomposition can be observed [7]. Conversely, LZO film nucleation occurs in the temperature range 700–800 °C [2] and at these temperatures copper is fully recrystallized [10]. Therefore, in this case, cube texture formation in the substrate and LZO nucleation and crystallization occur in succession and are separated by a considerable temperature gap. This approach may be extended to other substrate choices, provided that the recrystallization process occurs before the nucleation of LZO. C