| dc.description |
The relationships between the crystal structure modification, due to the doping element of Sn, and the critical temperature T<sub>c</sub> of Sn-doped YBa<sub>2</sub>Cu<sub>3-x</sub> Sn<sub>x</sub>O<sub>7-</sub> , with x = 0.0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, have been investigated by means of the peak shift and the peak broadening of the powder x-ray diffraction pattern. The profiles of x-ray diffraction peaks, due to crystal planes (006), (020), (021) and (200), were studied using the multi-peak fitting technique which is based on the Gaussian distribution function. It is interesting to note that the Sn-doped atoms effectively occupy the Cu2 sites in the CuO<sub>2</sub> layer. The critical temperature of the Y-123 phase depends more sensitively on the lattice parameters a and b, rather than on the c-axis parameter c. The samples used for this investigation underwent the same treatment to ensure the requirement for maintaining the same oxygen content, particle size and residual stress. In this way, we can make sure that the Sn doping basically causes the peak shift and the peak broadening. Based on our results, we conclude that Sn doping in YBCO leads to an increase of the lattice constants a and b. The greater the expansion in a and b, the lower the critical temperature that results. |
