کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1298401 | 1498351 | 2010 | 8 صفحه PDF | دانلود رایگان |
![عکس صفحه اول مقاله: Space–charge theory applied to the grain boundary impedance of proton conducting BaZr0.9Y0.1O3 − δ Space–charge theory applied to the grain boundary impedance of proton conducting BaZr0.9Y0.1O3 − δ](/preview/png/1298401.png)
The specific grain interior and grain boundary conductivities, obtained from impedance spectroscopy and the brick layer model, are reported for BaZr0.9Y0.1O3 − δ as a function of pO2 and temperature. pO2-dependencies were indicative of dominating ionic and p-type electronic conduction for the grain interior under reducing and oxidizing conditions, respectively, while the grain boundaries showed an additional n-type electronic contribution under reducing conditions. Transmission electron microscopy revealed enrichment of Y in the grain boundary region. These findings indicate the existence of space–charge layers in the grain boundaries. A grain boundary core–space–charge layer model is therefore applied to interpret the data. Using a Mott–Schottky approximation, a Schottky barrier height of 0.5–0.6 V and an effective grain boundary width of 8–10 nm (= 2× space–charge layer thickness) is obtained at 250 °C in wet oxygen. Finite-element modelling of the complex impedance over a grain boundary with a space–charge layer depletion of protons yields a distorted semicircle as observed in the impedance spectra.
Journal: Solid State Ionics - Volume 181, Issues 5–7, 11 March 2010, Pages 268–275