Ž . Physica C 303 1998 220–230 Effect of Sm BaCuO addition on the properties of melt 2 5 processed SmBa Cu O 2 3 y N.V.N. Viswanath a , T. Rajasekharan a, ) , Latika Menon b , N. Harish Kumar b , S.K. Malik b , G.K. Dey c , D.D. Upadhyaya d a Defence Metallurgical Research Laboratory, P.O. Kanchanbagh, Hyderabad, 500 058, India b Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400 005, India c Materials Science DiÕision, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085, India d Materials Processing DiÕision, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085, India Received 18 November 1997; revised 21 April 1998; accepted 28 April 1998 Abstract Ž . Ž . Melt processing of SmBa Cu O Sm-123 is done in argon atmosphere by the solid liquid melt growth SLMG route, 2 3 y Ž . with increasing concentration of insulating Sm BaCuO Sm-211 content. The effects of Sm-211 on the microstructure and 2 5 Ž . on the behaviour of current density J in high magnetic fields, are discussed. It is observed that as the Sm-211 c concentration is increased, the morphology of the trapped 211s change from acicular having a high aspect ratio to nearly spherical. The J increases for low additions of 211, but for high concentrations, the J drops drastically. The above data is c c explained on the basis of pinning from the 211 particles and the matrix. q 1998 Published by Elsevier Science B.V. All rights reserved. Keywords: Melt processing; Solid liquid melt growth route; SmBa Cu O 2 3 y 1. Introduction Ž . Melt textured REBa Cu O RE-123 supports 2 3 y Ž . high current density J because of its superior c w x microstructure 1–3 . The microstructure of such ma- terials contains parallel 123 grains in the ab-plane with reduced number of weak links in the direction Ž of the current flow, and insulating RE BaCuO RE- 2 5 . 211 particles distributed in the grains. The presence of crystallographic defects at the 123r211 interface enhances the flux pinning. The defects include twins, ) Corresponding author. Tel.: q91-40-4440051; Fax: q91-40- 4441439; E-mail: tr@dmrl.ernet.in wx stacking faults and dislocations 4. In the mi- crostructure of melt textured materials, some amount of 211 is left back due to incomplete peritectic reaction and liquid phase loss. If excess 211 is taken in the starting material, a large amount of it will be left back after the peritectic reaction, which would contribute to an increase in flux pinning. Murakami wx et al. 5 observed an increase in J with the intro- c duction of Y-211 particles in melt processed Y-123 wx material. McGinn et al. 6 observed a drop, and Jin wx et al. 7 had seen no change in J , with an increase c in the Y-211 concentration in melt processed Y-123. wx Lee et al. 8 gave a generalized explanation for the behaviour of J for increasing concentrations of c 0921-4534r98r$19.00 q 1998 Published by Elsevier Science B.V. All rights reserved. Ž . PII S0921-4534 98 00219-6