Grain properties, electrical conductors

Guo, X., Waser, R. Electrical properties of the grain boundaries of oxygen ion conductors Acceptor-doped zirconia and ceria. Prog. Mater. Sci. 2006, 51,151-210. 

You already know some of the physical properties of table salt. It is a white solid at room temperature. If you look at table salt under a magnifier, you ll notice that the grains of table salt are little crystals shaped like cubes. These crystals are hard, but when you press down on them with the back of a spoon, the crystals shatter. This shattering shows that the crystals are brittle. If sodium chloride is heated to a temperature of about 800°C, it melts and forms liquid salt. Solid sodium chloride does not conduct electricity, but melted sodium chloride does. Salt also dissolves easily in water. The resulting solution is an excellent conductor of electricity, as shown in Figure 4.2. 

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