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 La₂CuO_4+δ; calculated solution energies of BaO in Sr₂CuO₂F₂ are consistent with the formation of Sr_1.4Ba_0.6CuO₂F_2+δ, while the predicted energy and mode of solution of Na₂O in Sr₂CuO₂F₂ suggest (Na/K)_xSr_2–xCuO₂F₂ warrants investigation for possible high-T_c behaviour.