Polycrystals with Highly Conductive Grain Boundaries

3 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- 

In the quantitative interpretation, the resistance obtained with a microelectrode atop a grain shall be considered first. Fig. 19a displays a cross section of the potential distribution obtained for the 60-grain model sample. As in the case of a homogeneous material without grain boundaries, most of the voltage drops in a very small 

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