Page 53 - Curriculum Visions Dynamic Book

ceramics to be used as resistors in electronic circuits and as heating elements in cookers and boilers.
Some ceramics, such as lead oxide (PbO) and ruthenium dioxide (RuO2), are among the best conductors. These materials are used as resistive films in microelectronic circuits.
The best conductors are based on mixtures of indium oxide (In2O3) and tin oxide (SnO2). They are also transparent. They are used for the liquid crystal displays (LCDs) now common on flat-screen computer monitors and TVs.
The conducting properties described above are all recent developments. But conducting ceramics have been used as heating elements for a long time. They are found in cooking hobs, for example. They are known as glass ceramic.
Sensors
Ceramics are used in a wide range of sensors. Thermistors are one example. A thermistor is a resistor that varies in resistance with temperature.
Thermistors can be used as safety cutout devices to stop overheating. Some toasters have them. Thermistors also appear as fuel-level sensors in gas tanks. Electricity flowing through a thermistor makes it warm up. If the thermistor
is in a full tank, the heat escapes from the thermistor faster than if it is partly exposed (if the tank is not completely full). The change in temperature of the thermistor causes a change in resistance, and it can be changed into a reading on a dashboard dial.
Carbon monoxide gas sensors also use ceramics. In this case the ceramic is tin oxide. In the presence of carbon monoxide tin oxide changes its conducting properties. That can trigger an alarm.
This kind of sensor can also detect other harmful gases. It is widely present in chemical laboratories.
Zirconia doped with calcium makes an oxygen sensor to detect the amount of oxygen flowing into a car engine. For the engine to work at peak performance, a specific amount of fuel has to mix with the oxygen. The sensor can detect the level, and the amount of air allowed into the engine
can be varied constantly. It also prevents too high a level
of air going right through the engine and harming the
(Above and below)
Liquid crystal displays are conducting ceramics.
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See Vol. 5: Glass for more on glass ceramic.