Influence of Thermal Treatment on YBa2Cu3O7-x Thick Films Prepared by Electrophoretic Deposition on Ni and Ag Substrates
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1001-M05-03
Influence of thermal treatment on YBa2Cu3O7-x thick films prepared by electrophoretic deposition on Ni and Ag substrates Laurent Dusoulier1,2, Samuel Denis2,3, Michel Dirickx2, Philippe Vanderbemden3, Marcel Ausloos4, Rudi Cloots1, and BÈnÈdicte Vertruyen1 1 Chemistry, University of LiËge/SUPRATECS, AllÈe de la chimie 3, B‚t B6a, LiËge, 4000, Belgium 2 CISS, Royal Military Academy, Brussels, 1000, Belgium 3 Engineering, University of LiËge/SUPRATECS, LiËge, 4000, Belgium 4 Physics, University of LiËge/SUPRATECS, LiËge, 4000, Belgium ABSTRACT We have studied the sintering parameters of YBa2Cu3O7-x (YBCO) coatings produced by electrophoretic deposition (EPD) on Ag and Ni substrates. The maximal sintering temperature is ~ 930∞C due to partial melting and chemical contamination for Ag and Ni substrates respectively. Increasing the sintering duration does not improve significantly the densification. When Ar sintering atmosphere is used, the coating density is strongly increased on Ag substrates while adhesion is poor on Ni substrates. The Ar-sintered YBCO coating deposited on planar Ag substrate displays a significant magnetic shielding effect for low frequency applied magnetic induction. INTRODUCTION High-temperature superconductors (HTS) have been the subject of intensive research since their discovery in 1986. Most potential applications require a critical current density Jc as high as possible, e.g. for resistanceless cables above 77 K. However there are some low-Jc applications [1-3], in particular magnetic shielding at very low frequencies [3-6]. For this application, substrates with large area and complex shape have to be coated with the superconducting ceramic. Electrophoretic deposition (EPD) is one of the few techniques able to meet these practical conditions. EPD allows a thickness control from hundred nm to mm and can be applied to a broad range of compounds: metals, ceramics, glasses or polymers [7-9]. EPD is based on the migration of charged particles between two electrodes when a voltage is applied. The coating grows on one electrode used as a substrate. The preparation of a stable suspension is an essential step in order to realise a homogeneous coating. In the case of an YBa2Cu3O7-x (YBCO) suspension in acetone (in presence of I2), particles are positively charged and the coating is formed on the negative electrode (cathode) [10]. A heat treatment is used to densify the thick film. In the present work we have studied the influence of the heat treatment parameters (temperature, duration and atmosphere) in order to maximize the density of coatings deposited on two different substrates, Ni and Ag. The coatings were mainly characterised by electron microscopy and magnetic shielding factor measurements.
EXPERIMENT Commercial spray-pyrolysed YBa2Cu3O7-x powder (Alfa-Aesar, 99.9%, ref. 39534) was used as purchased. Suspensions were prepared in technical acetone (100 ml) with iodine as an additive (0.2 g/l). YBCO powder (10 g/l) was dispersed for 15 s with an ultrasonic probe (dr. Hielser gmbH, UP
