We have studied the thermopower S of La1.4-xNd0.6SrxCuO4 as a function
of temperature and the hole concentrations x. At the LTO-LTT phase tr
ansition anomalies of S occur, which weaken with increasing x. In the
LTT phase S becomes negative in a narrow hole concentration range arou
nd x similar or equal to 1/8, which gives evidence for a particular ro
le of this hole concentration.