Transport Properties of the Mixed-Conducting SrFe1.2Co0.3Ox期刊界 All Journals 搜尽天下杂志传播学术成果专业期刊搜索期刊信息化学术搜索

Transport Properties of the Mixed-Conducting SrFe1.2Co0.3Ox

Authors:	B Ma U Balachandran

Affiliation:	(1) Energy Technology Division, Argonne National Laboratory, Argonne, Illinois 60439

Abstract:	Single phase SrFe_1.2Co_0.3O_x sample with layered crystal structure was prepared using a solid state reaction method. Electrical conductivity and apparent oxygen diffusion coefficients of the SrFe_1.2Co_0.3O_x sample were measured as functions of temperature in atmospheres of various oxygen partial pressures $({\text{P}}_{{\text{O}}_{\text{2}} } )$ . Total and ionic conductivities were determined by using the conventional four-probe and electron blocking four-probe methods, respectively. The apparent oxygen diffusion coefficient was derived from the time-dependent conductivity relaxation data of the reequilibrium process after abruptly changing the $({\text{P}}_{{\text{O}}_{\text{2}} } )$ in the surrounding atmosphere. Several atmospheres of different $({\text{P}}_{{\text{O}}_{\text{2}} } )$ were established by the use of premixed gas cylinders. The conductivity of SrFe_1.2Co_0.3O_x increases with increasing temperature and $({\text{P}}_{{\text{O}}_{\text{2}} } )$ . At 900°C in air, the total conductivity and ionic conductivity are 10 and 8S · cm^-2, respectively. The ionic transference number ( 0.8 in air) does not have strong temperature dependence. The activation energy increases with decreasing $({\text{P}}_{{\text{O}}_{\text{2}} } )$ . In air, the activation energy has a low value of 0.37 eV. The apparent oxygen diffusion coefficient was $\approx 2 \times 10^{ - 6} {\text{ cm}}^{\text{2}} \cdot {\text{s}}^{{\text{ - 1}}}$ at 950°C over a wide range of ${\text{P}}_{{\text{O}}_{\text{2}}} (1 \leqslant {\text{P}}_{{\text{O}}_{\text{2}}} \leqslant 10^{ - 18} {\text{atm}})$ .

Keywords:	mixed-conductor oxygen permeation diffusivity ceramic membrane Sr-Fe-Co oxide
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