Electron-hole transport in (La0.9Sr0.1)0.98Ga0.8Mg0.2O3−δ electrolyte: effects of ceramic microstructure
2003; Elsevier BV; Volume: 48; Issue: 13 Linguagem: Inglês
10.1016/s0013-4686(03)00247-0
ISSN1873-3859
AutoresВ.В. Хартон, A.L. Shaula, N. P. Vyshatko, F.M.B. Marques,
Tópico(s)Electronic and Structural Properties of Oxides
ResumoThe oxygen ion transference numbers of a series of (La0.9Sr0.1)0.98Ga0.8Mg0.2O3−δ (LSGM) ceramics with different microstructures, prepared by sintering at 1673 K for 0.5–120 h, were determined at 973–1223 K by a modified Faradaic efficiency technique, taking electrode polarization into account. In air, the transference numbers vary in the range 0.984–0.998, decreasing when temperature or oxygen partial pressure increases. Longer sintering times lead to grain growth and to the dissolution of Sr-rich secondary phases and magnesium oxide, present in trace amounts at the grain boundaries, into the major perovskite phase. This is accompanied with a slight decrease of the total grain-interior resistivity and thermal expansion, while the boundary resistance evaluated from impedance spectroscopy data decreases 3–7 times. The electron-hole transport in LSGM ceramics was found to decrease when the sintering time increases from 0.5 to 40 h, probably indicating a considerable contribution of acceptor-enriched boundaries in the hole conduction. Due to reducing boundary area in single-phase materials, further sintering leads to higher p-type conductivity. The results show that, as for ionic conductivity, electronic transport in solid electrolytes significantly depends on ceramic microstructure.
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