Ž . Physica C 319 1999 169–180 Correlation of magnetic and magneto-optical properties with microstructure analysis in melt-textured ž / Nd Sm Gd Ba Cu O 0.33 0.33 0.33 2 3 y A. Das 1 , M.R. Koblischka ) , M. Jirsa 2 , M. Muralidhar, S. Koishikawa, N. Sakai, M. Murakami SuperconductiÕity Research Laboratory, DiÕision 3, International SuperconductiÕity Technology Center, 1-16-25 Shibaura, Minato-ku, Tokyo 105-0023, Japan Received 29 March 1999; received in revised form 13 April 1999; accepted 27 April 1999 Abstract Ž . Ž . Magnetic properties of the melt-processed ternary superconductor Nd Sm Gd Ba Cu O ‘‘NSG’’ with 0.33 0.33 0.33 2 3 y non-homogeneously distributed NSG-211 particles were investigated by means of magnetic and magneto-optical measure- ments. Flux distributions obtained by means of magneto-optic imaging after zero field-cooling and field-cooling were analyzed in order to understand the flux penetration behavior of this compound. The current-carrying length-scale was determined from the reverse leg of the magnetization hysteresis loops and compared to the actual dimensions of the sample. This was done both on the whole sample and on three individual domains to which the sample was subsequently divided. Magnetization hysteresis loops of all samples exhibited a strongly developed secondary peak in the temperature range 30 K FT F77 K. The critical current and pinning force densities derived from these data were normalized to the values at the peak position, J and F , respectively, and analyzed as a function of applied field reduced both to the respective peak max max field and irreversibility field. q 1999 Published by Elsevier Science B.V. All rights reserved. PACS: 74.60 Ec; 74.60 Ge; 74.60 Jg Ž . Keywords: Magnetic and magneto-optical properties; Nd Sm Gd Ba Cu O ; Melt-textured superconductor 0.33 0.33 0.33 2 3 y 1. Introduction Ž . Ž Light rare earth LRE Ba Cu O where LRE 2 3 y . denotes Nd, Eu, Sm, Gd superconductors melt- ) Corresponding author. Fax: q81-3-3454-9284; E-mail: koblischka@istec.or.jp 1 Present address: Solid State Physics Laboratory, Delhi 110054, India. 2 On leave from Institute of Physics, ASCR, Na Slovance 2, CZ-182 21 Praha 8, Czech Republic. processed in low oxygen partial pressure exhibit a high irreversibility field, B , accompanied by a irr large critical current density, J , in intermediate c Ž . fields, at the maximum of the secondary fishtail peak. At T s 77 K, B ) 7 T and J usually ap- irr c proaches the order of magnitude of 10 9 Am y2 at the w x peak position 1,2 . A characteristic feature of the LRE-123 superconductors is the existence of a solid solution between the LRE atoms and Ba, which leads to the formation of a LRE-rich phase with weaker superconducting properties. Using the oxygen-con- 0921-4534r99r$ - see front matter q 1999 Published by Elsevier Science B.V. All rights reserved. Ž . PII: S0921-4534 99 00295-6