Disorder in sub-lattices

These substances have more sites then ions. This led to high conductivity values, which led to the name super ionic conductors. The disorder can concern the cation lattice (cation conductors) or the anion lattice (anion conductors). The transfer numbers t+ and t determine the classification with 1 for cation conductors or t 1 for anion conductors. Because of the usually small size of the cation compared to the anions, cation conductors are dominant. 

The super ionic conductivity can occur after a phase transformation at a characteristic transformation temperature. A representative example is Agl. The material has considerable conductivity already at room temperature. The large iodide ions form a lattice in which the much smaller Ag ions can move via interstitials. At this temperature the stable form of silver iodide is the sphalerite lattice (see Chapter 2). 

The high conductivity of Agl in the super ionic conducting state can be extended to lower temperatures by substitutions in the cation lattice. The best-known example is the RbAgJj. 

Similar properties were observed for Cu-ion conductors. An example of higher transition temperature is Bi20j with a transition temperature of 729 °C. 

With the development of lithium batteries, lithium conducting solid electrolytes were intensively investigated. The representative compound is LijN. Another super ionic conductor is LijP while LijAs shows metallic conductivity. Other Li ions conducting solid 

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