Applications for High-a Ceramics

There are many applications for ceramics that have metallike conductivity. We will look at two examples  

Components with / in the range 10 -10 0 are the major requirements of the electronic industry. These are fabricated from electronically conducting ceramics with o in the range 10 -10 S/na. Resistance is not an intrinsic property of a material. It is influenced by the specimen configuration, i.e., its thickness and length. The relationship between R and a is 

FIGURE 30.8 Temperature dependence of the electrical conductivity of several electronically conducting oxides. 

Increase the aspect ratio (length to width) of the conductive layer by patterning 

Thin-film resistors usually make use of the first approach. For example, thin films (-10 nm thick) of indium tin oxide (ITO) are deposited onto glass, or sometimes steatite, substrates by sputtering or chemical vapor deposition (CVD). After deposition the films are patterned to achieve a large aspect ratio. If the substrate is in the form of a rod a spiral groove is cut into the film. 

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