Structural correlations in Jahn-Teller systems of Mn3+ and Cu2+: unraveling local structures through spectroscopic techniques

Abstract

An experimental correlation study between the low-5 symmetry 3d orbital splitting pattern, Δe and Δt, determined by 6 optical spectroscopy, and the local distortion ρ, determined by X-ray 7 diffraction, for different Cu2+ and Mn3+ fluorides and chlorides is 8 presented. Single crystals of different dimensionalities were explored, 9 some of them studied under high-pressure conditions. The collection 10 of structural and spectroscopic data provides structural correlations 11 relating ρ and Δe and Δt in Cu2+ and Mn3+ systems, showing that Δe 12 (and Δt) scales with ρ. Such correlations can be used to estimate 13 local distortions of Cu2+ (or Mn3+) introduced as impurities in 14 different chloride and fluoride host lattices from spectroscopic data. 15 The results can be interpreted in the framework of the Jahn−Teller 16 theory and provide support for the proposed structural scenario. The 17 influence of the crystal anisotropy in the local structure is analyzed as 18 well and compared with transition metal ion systems having E⊗e Jahn−Teller (Cu2+, Mn3+) and singly orbital (Ni2+, Mn2+, Fe3+) 19 ground states in octahedral symmetry.