Nonstoichiometry and defect structure of the perovskite-type oxides La1−xSrxFeO3−°

Electrical conductivity and thermopower of (1 − x) BiFeO3– xBi0.5K0.5TiO3(x = 0.1, 0.2) ceramics near the ferroelectric to paraelectric phase transition

“…27,28,32 P-type (in air) and n-type (reducing conditions) semiconductor behaviour has previously been reported for several related Fe-containing perovskites, including La 1Àx Sr x FeO 3Àd [33][34][35] and LnFeO 3 (Ln = Pr, Nd, Sm, Eu and Gd). 36,37 In these materials the electronic conductivity is strongly linked to polaron hopping and the oxidation state of Fe, which is strongly dependent on the partial pressure of oxygen ( p(O 2 )).…”

“…[33][34][35][36][37] The electrical conductivity of these materials has previously been modelled with success by a mass action type treatment of point defect equilibria. A mass action type model adapted for 0.8BFO and 0.9BFO is introduced here based on the approach presented by Mizusaki et al 35 for LaFeO 3 .…”

Oxygen permeation modelling of perovskites

“…The oxygen nonstoichiometry of La~_ySryCrO3, Lal_ySryFeO3 and Lal_ySryCoO3 can all be described with the same point defect model [11][12][13][14] when the Sr content is small. Lal_ySryMnO3 behaves slightly different.…”

“…1, experimental data of the nonstoichiometry of the Lao.7sSro.2sCrO3, Lao.9Sro.lFeO3, Lao.9Sro.tCoO3 and Lao.sSro.2MnO3 perovskites [11][12][13][14][15] are compared with the nonstoichiometry calculated from the model parameters given in table 1. Close agreements are seen between the experimentally determined and calculated nonstoichiometry for the Cr, Mn, Fe and Co-perovskites.…”

“…In this case, the oxygen partial pressure dependence of their ionic conductivity should be known. Assuming a vacancy diffusion mechanism, the ionic conductivity can be calculated form data of oxygen nonstoichiometry [11][12][13][14][15] and vacancy diffusion coefficients [ 16,17 ]. This gives a new analytical expression which describes the oxygen permeation current density as a function of the oxygen partial pressure gradient.…”