Atomistic simulation of M2CuO2F2+δ(M = Ca,Sr)
Abstract
Atomistic simulations predict that fluorine ions occupy axial sites in Sr2CuO2F2 and Ca2CuO2F2 with minimal O/F disorder and that excess fluorine occupies the same interstitial site in Sr2CuO2F2 as in La2CuO4+δ; calculated solution energies of BaO in Sr2CuO2F2 are consistent with the formation of Sr1.4Ba0.6CuO2F2+δ, while the predicted energy and mode of solution of Na2O in Sr2CuO2F2 suggest (Na/K)xSr2–xCuO2F2 warrants investigation for possible high-Tc behaviour.