Interplay between Cu and Fe Valences in BaR(Cu0.5Fe0.5)2O5+δ Double Perovskites with R=Lu, Yb, Y, Eu, Sm, Nd, and Pr

Properties of perovskite-like phases LnBaCuFeO5 + δ (Ln = La, Pr)

“…The unit cell parameters calculated for the structures of the LnBaCuFeO 5 + δ (Ln = La, Pr) ferrocuprates agree well with the data available in the literature [10][11][12] and are close to those obtained in our earlier works [7,9].…”

Copper doped lanthanum strontium ferrite for reduced temperature solid oxide fuel cells

“…Fe(II) can be formed in significant amounts in LSF at oxygen partial pressures below about 1Â10 À6 atm (0.1 Pa) [12]. Fe(V) has been reported by Linden et al for greater than 1.0 atm (10 5 Pa) atmosphere oxygen partial pressures in ReBaCu 0.5 Fe 0.5 O 3Àd [8]. These authors also suggested that excess oxygen existed at atmospheric pressures and that the excess oxygen was associated with Fe sites and that iron is oxidize to either Fe(IV) or less likely Fe(V) in preference to formation of Cu(III).…”

“…LSCuF materials can be considered derivatives of either LaCuO 3 or LaFeO 3 and the Sr doped materials La 1Àx Sr x CuO 3 and La 1Àx Sr x FeO 3 tetragonally distorted perovskites [7][8][9][10][11]. La(III) is the largest rare earth ion and is most similar in size to the Ba(II) ion.…”

Chemical lattice strain in nonstoichiometric oxides: an overview

“…Hence, the oxygen release from RBaFeCuO 6– δ is accompanied by Fe 4+ → Fe 3+ reduction, causing much lower ionic radius changes and much lower expansion. 249,250 The absence of contraction of the unit cell parameter c with δ in RBaFeCuO 6– δ (ref. 251) might be related to the crystal structure of these oxides, where corner-sharing strongly elongated CoO 5 and already squashed FeO 5 pyramids 252 have little opportunity to shift towards oxygen-depleted rare-earth layers.…”

“…S5 †). [249][250][251] The oxidation state of Cu 2+ forces iron in RBaFeCuO 6-d to assume higher oxidation states at d > 0.5 than in RBaFe 2 O 6-d . Hence, the oxygen release from RBaFeCuO 6-d is accompanied by Fe 4+ / Fe 3+ reduction, causing much lower ionic radius changes and much lower expansion.…”