Superconducting samples of YBa2(Cu1-xMnx)(3)O7-delta with x = 0, 0.01, 0.01
5, 0.02, 0.025, 0.035, and 0.05 have been prepared and the temperature vari
ation of the Seebeck coefficient, S(T), has been measured over a temperatur
e region of 77 to 250 K. The observed features of the results are analyzed
in terms of the metallic diffusion model, the Nagaosa-Lee model, and a narr
ow band model. The physical parameters obtained are discussed. [S0163-1829(
99)03310-X].