Growth and structural and superconducting properties of Bi2Sr2Ca2Cu3O10 (Bi2223) crystals grown in cavities formed in solution-melt KCl

Undoped Bi2223 single crystals were obtained by free growth in gas cavities formed in solution-melt KCl. The crystals had a platelet-like shape with d imensions of up to 1 x 1 x 0.003 mm(3) and mirror surfaces. Chemical compos ition corresponded to Bi2.11Sr2.02Ca1.75Cu2.81Ox X-ray diffraction analysis showed that the best crystals contained (97 divided by 95)% Bi2223 phase, whereas the remaining crystals consisted of Bi2223 phase, interlayered with either Bi2212 or Bi4435 phase layers of different thickness. The critical temperature of all samples was T-c = (109 +/- 1) K. The resistivity ratios along different axes at 300 K were rho(a)/rho(b) less than or equal to 3 an d rho(c)/rho(ab) approximate to 10(4). In the best crystal, rho(ab) = 2.8 x 10(-4) Ohm x cm at T = 300 K. The Hall coefficient at T = 120 K was R-H = 1.5 x 10(-9) m(3)/C and the Hall concentration was n = 4.1 x 10(27) m(-3). (C) 1999 Published by Elsevier Science Ltd. All rights reserved.