Dependence of interconfiguration excitation energies on local environment, composition and temperature in EuA_2-xB_x compounds

The dependence of the energy released by removing an electron from the 4f{hook} level to the conduction band on environment, composition and temperature was deduced from Mossbauer measurements on EuA_2-xB_x compounds (A = Rh or Ir, B = Pt or Al). For each system, this energy is equal to α + βx - λm + T, where α, β and λ are constants. m is the number of B neighbors of an Eu ion. The sizes of the unit cells are consistent with the recoilless absorption data.