THEORETICAL STUDY ON INTERMEDIATE VALENCE FLUCTUATION IN EUROPIUM SULPHIDE (EuS)

Europium chalcogenides receive greater interest because of their interesting properties such as valence transition, semiconductor to metallic transition and structural phase transition etc. In this paper, the charge transfer in Europium Sulphide (EuS) is analyzed by experimental and theoretical X-ray diffraction (XRD) data. The direction and amount of charge transfer are inferred by plotting and comparing the structure factors of the components. The charge transfer parameter thus obtained is 0.29 electron from Eu to S which confirms the intermediate valence fluctuation. Further, the charge transfer in EuS, EuSe and EuTe, is found to be decreasing with the increase of lattice constant and energy gap which correlates the valency and lattice size.