X-RAY PHOTOELECTRON-SPECTROSCOPY STUDY OF (TL0.5PB0.5)SR2(CA1-XTHX)CU2OY SYSTEM FOR X=0.0-0.3

To reveal the correlation between the T(c) temperatures and the hole concentration in p-type cuprates superconductors, a series of samples of (Tl0.5Pb0.5)Sr2(Ca1-x(Th)x)Cu2O(y) (x = 0.0 - 0.3) were prepared and investigated by the X-ray photoelectron spectroscopy. The core-level of Cu did not show consistent variation while a slight shifting of T1 4f7/2,5/2 peaked up to high binding energy as Th dopant increased. This might be resulted from the decrease of the hole concentration in T1-O layer. The Sr core-level spectra demonstrated an evident and consistent variation which could be attributed to two lattice sites available for Sr atoms and the decrease of Ca atoms. Our results indicated that the T1-O layer might act as "hole reservoir", which had been already suggested by the band structure calculation.