Cs. Gopinath et al., OXIDATION-STATE OF MERCURY IN HGBA2(CA0.86SR0.14)(2)CU3O8-RAY PHOTOELECTRON-SPECTROSCOPY(DELTA STUDIED BY X), Physical review. B, Condensed matter, 52(14), 1995, pp. 9879-9881
Hg 4f core levels of HgBa2(Ca0.86Sr0.14)(2)Cu3O8+delta(Hg-1223) and Hg
O were measured by x-ray photoelectron spectroscopy in order to demons
trate the oxidation state of mercury ions in the superconducting oxide
. The binding energy of the Hg 4f(7/2) level is found to be at 99.9 eV
in HgO and 101.0 and 103.4 eV in Hg-1223. This result reveals that th
e oxidation state of Hg is definitely more than +2 and it exists in a
mixed-valent state. The creation of charge carriers in Hg-1223 is disc
ussed in terms of a charge transfer between Hg-O-delta and Cu-O layers
.