Interesting aspects of the analysis of resistivity in Li 3+ irradiated Bi-2212 A. Sarkar a,b , S. Chattopadhyay a , Ravi Kumar c , Udayan De d, * a Department of Physics, University of Calcutta, 92 A.P.C. Road, Kolkata 700009, India b Department of Physics, Bangabasi Morning College, 19 R.C. Sarani, Kolkata 700009, India c Nuclear Science Centre, Aruna Asaf Ali Marg, P.B. 10502, New Delhi 110067, India d Variable Energy Cyclotron Centre, 1/AF Bidhannagar, Kolkata 700064, India Available online 22 January 2005 Abstract Differently heat treated and 55 MeV Li 3+ beam irradiated Bi 2 Sr 2 Ca 1 Cu 2 O 8+d (Bi-2212) high temperature supercon- ductors have been studied from the analysis of resistivity in the normal state as well as near the superconducting tran- sition. For all the unirradiated and irradiated samples the so-called linear temperature dependence of the normal state resistivity, in a wide temperature range, can well be understood within the variable range hopping (VRH) conduction scenario. Near and above the bulk superconducting transition, the fluctuation enhanced conductivity (paraconductiv- ity) analysis shows a noteworthy modification of the conduction process due to radiation induced defects. Ó 2004 Elsevier B.V. All rights reserved. PACS: 74.72.Hs; 61.80.x Keywords: Bi-2212 High T c superconductor; Radiation damage; Analysis of resistivity 1. Introduction Defects and disorder in high T c superconductors (HTSC) is one of the most discussed issues till date [1–3]. In such ceramic materials, there always exist some intrinsic defect centers like non-stoichio- metric oxygen, vacancy defects, grain boundaries etc. Interestingly, defects are sometimes helpful from both technological and theoretical purposes and hence controlled defect creation in HTSC oxi- des has drawn prime attraction [4]. Particularly a defective but still superconducting system offers a scope to understand the pristine system as well. Near the superconducting transition temperature of such HTSCs, a large enough temperature region is found where thermodynamic fluctuations domi- nate resistivity and several other temperature 0168-583X/$ - see front matter Ó 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.nimb.2004.12.056 * Corresponding author. Tel.: +91 33 2337 1230; fax: +91 33 2334 6871. E-mail address: ude@veccal.ernet.in (U. De). Nuclear Instruments and Methods in Physics Research B 230 (2005) 284–289 www.elsevier.com/locate/nimb