Abstract: In this paper, the Tb_4d photoelectron spectra in compounds of BaTbO₃, Tb₄O₇ and TbFeO₃ were measured, and the characteristic levels of Tb³⁺ and Tb⁴⁺ were found to be 149.45 and 156.20 eVrespectivelyThe relationship between the intensity ratio (I) of the higher binding energy peak to the lower one and the content of Tb⁴⁺/Tb(z) is obtained for the first time, I= -0.98z²+2.15z(0≤z≤1), which can be used to determine the valence state of Tb ion in the "123" phase of Eu_1-xTb_xBa₂Cu₃O_7-δBy normal sintering method at atmosphere and high temperature, the pure "123" phase Can not be obtained, and it is also difficult to form Eu_1-xTb_xBa₂Cu₃O_7-δ samples containing pure Tb³⁺In the "123" phase of Eu_1-xTb_xBa₂Cu₃O_7-δ, the Tb ions are in a mixing valence state of Tb³⁺ and Tb⁴⁺, and when x = 0.3, Tb⁴⁺/Tb=0.61 The O_2p hole number in the Cu(2)-O(2) plane is decreased because of doping Tb⁴⁺, and this may be one of the reasons of destroying the superconductivity.

Key words: Eu-Tb-Ba-Cu-O, XPS, Tb ion valence state, Tb³⁺ content, Superconductivity