Properties of YBa 2 Cu 3 O y -textured superconductor foams J.G. Noudem a, * , E. Guilmeau a , D. Chateigner a , S. Lambert a , E.S. Reddy b , B. Ouladdiaf c , G.J. Schmitz d a CRISMAT-ENSICAEN, CNRS/UMR 6508, 6 Bd Mar echal Juin, 14050 CAEN Cedex, France b IRC in Superconductivity, University of Cambridge, Madingley Road, Cambridge CB 30 HE, UK c ILL, 6, rue J. Horowitz, BP 156 - 38042 Grenoble Cedex 09, France d ACCESS Materials & Processes, Intzestr. 5, D-52072 AACHEN, Germany Abstract Usingthecombinationofstandardceramicprocessingandaninfiltrationtechnique,singledomainsuperconductor foam of Y123 has been prepared. In this report we present magneto-transport measurements of these foams. The investigationsrevealsuperconductingpropertiesbeingsimilartothoseofbulkmeltprocessedmaterials.Themagnetic hysteresis vs field measurements show a high anisotropy of the critical current density up to J ab c =J c c  7, in good agreement with the observation of a strong texture as determined from neutron diffraction measurements. Ó 2004 Elsevier B.V. All rights reserved. Keywords: YBaCuO foam; Magneto-transport properties; Neutron diffraction; Texture Recently, a superconducting material being pro- cessed as a foam structure has been reported [1]. This newmorphologyseemstobeanalternative3Dstructure to solve the mechanical handling for the 2D fabric materials[2]andmaybeagoodcandidateforincreasing interfacial flux pinning if the pores can be made suffi- ciently small. Many other prospects are related to the foam structure like e.g. more efficient heat transfer, faster oxygenation and less related microcracking, pos- sibilityofreinforcementandofinterlockingconnections etc. One of the central questions is whether this novel superconductor structure is similar to YBCO bulk material in terms of microstructure, superconducting properties and performances. The details of the preparation process of Y211 foam as a starting precursor are reported elsewhere [1]. The resulting Y123 have the nature of a foam while dem- onstrating microstructural features of a single domain bulksample(insetFig.2).ThefinalY123foamstructure is favorable to coolant connectivity (liquid nitrogen bath) during quenching process due to its large surface area. Magnetization, resistivity and texture (D1B-ILL) measurementshavebeenperformed.Fig.1(inset)shows the resistive transition of a typical Y123 foam sample. The qðT Þ curvesforthe ab-planesand c-axisorientations exhibit a narrow superconducting transition (DT  1:5 K) with T c (onset) 91.5Kand T c ðq ¼ 0Þ 90K.At300 K, we can deduce an anisotropy ratio q c c =q ab c  8. The zero field cooled magnetization curve (Fig. 1) shows a narrowtransition,withanonsetat92K,comparableto the qðT Þ curves. But one can observe a saturation of magnetizationat70Kshowinganarrowjumpprobably due to the degradation of thin 123 struts with time duringexposuretoatmosphereusuallyobservedonthin or thick films. The magnetic J c values are estimated for both directions.Acriticalcurrentdensityof J ab c  40kA/cm 2 at 0 T can be deduced for current parallel to the ab- planes. A J c c  15 kA/cm 2 is obtained for currents par- alleltothe c-axis,leadingtoananisotropyfactor J ab c =J c c ofabout7at2T. Texture data (Fig. 2) show very strong intensity variations when the sample is rotated relative to the * Corresponding author. Tel.: +33-231-45-29-15; fax: +33- 231-45-95-16-00. E-mail address: noudem@ismra.fr (J.G. Noudem). 0921-4534/$ - see front matter Ó 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.physc.2004.03.098 Physica C 408–410 (2004) 655–656 www.elsevier.com/locate/physc