Structural changes in ab-plane of Zn doped Bi-2212 HTSC single crystals

Single crystals of undoped and 1% Zn-doped Bi-2212 are grown by self-flux slow cooling method under similar growth conditions. Tc(ΔTc) are found to be 84 K (2 K) and 82 K (8 K) for undoped and doped samples respectively. Effect of Zn doping on structure and modulation is studied. Different change in the value of a- and b-axes are observed resulting in a transformation of structure from tetragonal to orthorhombic one. However, no effective change in modulation is there. Distortions are compared in c- and b-axes for undoped and doped samples. The asymmetry in position and intensity of satellite peaks has been discussed. The value of a in excess of b has been reported for the first time. These results are discussed in terms of valancy, coordinates and position of occupancy of Zn ions vis-à-vis those of Cu− ions in Cu-O plane of the structure.