Absence of Ni on the outer surface of Sr doped La2NiO4 single crystals†
Abstract
A combination of surface sensitive techniques was used to determine the surface structure and chemistry of La2−xSrxNiO4+δ. These measurements unequivocally showed that Ni is not present in the outermost atomic layer, suggesting that the accepted model with the B-site cations exposed to the environment is incorrect.