SEEBECK EFFECT AND NEUTRON-DIFFRACTION OF NDSRBACU3O6- EFFECT OF ARGON ANNEALING(Z )

We have performed neutron-diffraction and thermopower experiments on t wo samples of NdSrBaCu3O6+z. One was a conventionally annealed sample at 450 degrees C in oxygen [O] and the other was heated in argon at 85 0 degrees C followed by oxygen annealing [AO]. The T-c of the sample [ O] was 68 K and that of [AO] was 78 K. The neutron data showed that th e [O] sample had a higher impurity level arising from Nd entering the Sr/Ba sites that may result in a decrease in the carrier density (p) w hich was also confirmed by our thermopower measurements. The increase in p and in-phase purity for the [AO] sample may account for the obser ved increase in T-c.