Experimental Realization of Microelectrode Measurements

Mainly, two kinds of microelectrodes are used in order to realize local electrical measurements on ceramics  

Two further techniques to realize microelectrodes should be mentioned. Thin metal wires have been embedded into relatively soft ionic crystals such as AgCl and 

AgBr by the aid of thermal treatment [312, 313], These wires can, for example, be used as local potential probes. Moreover, very fine metal wires have been welded on oxide surface [314, 315], 

In several studies, large contact electrodes at the periphery of a sample have been used to feed the current. As sketched in Fig. 27, a connection line is deposited in order to connect microelectrodes and contact electrodes in some cases the ends of such thin connection lines are regarded as the microelectrodes. However, such a setup can be very problematic since experimental results are, in many cases, determined by the current between the two large contact electrodes rather than by the current between the microelectrodes. 

This can be understood from the electrode configuration shown in Fig. 27b extended electrodes on two sides of a square sample are used as current feed electrodes and very thin, highly conductive lines connect these contacts and circular microelectrodes on top of the sample. In the case of a single crystal, the resistance between two circular microelectrodes Rme is given by (ubuik me)-1, whereas the resistance between the two contact electrodes reads (owk j with being the sample height. The 

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