Highly Conductive Grain Boundaries

A quantitative interpretation of grain boundary contributions to the overall impedance of polycrystals with highly resistive grain boundaries can be problematic (see 

---

Polycrystals with Highly Conductive Grain Boundaries... 

Conventional impedance spectroscopy does not allow a separation of grain boundary and bulk contributions in samples with highly conductive grain boundaries (cf. Sec. 3.2). The two microelectrode configurations sketched in Fig. 17a, however, can be applied i) to easily check whether highly conductive grain boundaries exist and ii) to quantitatively determine the bulk conductivity obuik and the grain boundary conduc-... 

Fig. 7.49 The equivalent circuit of the brick layer model . The validity is dependent on the local behaviour of the intersections of the grain boundaries. The approximation used in what follows refers to the broken connecting line. Then the highly conducting grain boundary paths (e.g. space charge zones) are blocked by the perpendicular boundary (e.g. core region). The factors 4 and 1/2 refer to the number of grain boundary contributions per grain (4 parallel and 2 serial half grain boundaries) according to Ref. [256].

---