The doping routes and distribution of holes in layered cuprates: A novel bond-valence approach

Abstract

Abstract In the present contribution a general view on the charge balance and doping in superconducting and related layered cuprates is developed. For a quantitative discussion the concept of bond valence as formulated by Brown and Altermatt is utilized. When summing up the excess positive charge above +2 for Cu and -2 for the in-plane O in one CuO2 unit, that is focusing on the ‘net holes’ shared by Cu and O in the CuO2 planes, all the contributions from the in-plane Cu-O bonds are counteracted arid only the bonds from Cu to the apical O and from the in-plane O to the nearest-neighbour cations in the layers above and below the CuO2 plane have net effects on the resulting hole concentration parameter p (CuO2). From this observation, three distinct ways of hole doping the CuO2 planes are defined. Representative examples of each doping route are discussed in terms of bond-valence analysis based on existing crystallographic data. Furthermore, bond-valence calculations were utilized to estimate the dist...