Investigations for the growth of large underdoped Bi(2)Sr(2)CaCu(2)O(8+d) single crystals

In order to study superconducting physical properties by neutron scattering technique, the necessity to obtain large and high quality optimally doped Bi(2)Sr(2)CaCu(2)O(8+d) (Bi-2212) and underdoped Bi-2212 single crystals is prominent. Three routes have been investigated to reach this goal: synthesis under low oxygen pressure by travelling solvent floating zone technique (TSFZ), TSFZ synthesis of yttrium doped Bi(2)Sr(2)Ca(1-x)Y(x)Cu(2)O(8+d) and TSFZ synthesis under air followed by post-annealing treatments. With decreasing p(O(2)) from ambient pressure to 0.1 atm during the TSFZ growth, the superconducting transition temperature, T(c), transits from 87 K (slightly overdoped) to 93 K. On yttrium doped growth, a systematic study of Bi(2 )Sr(2)Ca(1-x)Y(x)Cu(2)O(8+d), where x=0-0.5, was undertaken to correlate the nominal yttrium composition with the yttrium crystal composition and to control the T(c) as a function of yttrium composition. 85 K underdoped Bi-2212 crystals with a size up to 220 mm(3) and a 5 K transition width, T(c), were obtained by post-annealing under p(O(2))=0.1 atm at 450 'C.