Optical Absorption Spectra of Y2BaNi1−xZnxO5(0≤ x<1)

Abstract

Abstract The very different optical spectra found for the green coloured Y2BaNiO5 and the substituted brown-tobacco Y2BaNi1−xZnxO5 oxides have been explained taking account the different crystal structure which show these oxides. In this sense, Y2BaNiO5 shows orthorhombic symmetry, space group Immm, with the nickel situated in a distorted octahedral coordination giving rise to a site of D4h as local symmetry. The substituted Y2BaNi1−xZnxO5 which are isostructural crystallyze with orthorhombic symmetry, space group Pnma showing as main characteristic the existence of isolated distorted square pyramidal coordination for the nickle NiO5 which yeilds aproximately C4v as point symmetry.