ScienceAsia 29 (2003): 031-035 |doi: 10.2306/scienceasia1513-1874.2003.29.031

Structural Changes and Suppression of Superconductivity in Two Re1-2_xPr_xCa_xBa₂Cu₃O_7- HTSC’s (Gd, Dy) Due to Pr Doping

Nipaphat Charoenthai^a, Ramanathan Suryanarayanan^b, Srisuda Varamit^c, Pongtip Winotai^a and I-Ming Tang^c,d,*

ABSTRACT: The structural changes and the suppression of superconductivity in the Gd- and Dy- “123” HTSC’s due to the equal substitution of Pr and Ca were studied. The onset temperatures (T_c’s) of the codoped Gd_1-2xPr_xCa_xBa₂Cu₃O_7- and Dy_1-2xPr_xCa_xBa₂Cu₃O_7- HTSC’s were measured by AC susceptibility measurements. The Tc’s and rates of decrease of dT_c/dx due to Pr substitution for both series exhibited rare earth size effects. It was found that the lattice distortion defined D = (b-a)/(b+a), where a and b are the lattice parameters in the basal plane, decreases systematically as the doping is increased. A mixed (d+s)-wave symmetry model is used to explain the behaviors of both the T_c's and rates of decrease of dT_c/dx as Pr⁴⁺ ions are doped into the two “123” HTSC's.

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a Department of Chemistry, ^cDepartment of Physics and ^dCenter for Nanoscience, Faculty of Science, Mahidol University, Bangkok 10400, Thailand
b Laboratoire de Physico-Chimie des Solides, UMR 8648, CNRS, Batiment 414, University Paris-Sud, 91405 Orsay, France
d Institute of Science & Technology for Research & Development, Mahidol University,
Nakhon Pathom 73170, Thailand

* Corresponding author, Email: scimt@mahidol.ac.th

Received 8 May 2002, Accepted 22 Jul 2002