Question

Ceramics exhibit a greater range of electrical conductivity than any other class of materials. Explain why this is the case and provide some examples to illustrate this statement. Include discussion of the temperature dependence of conductivity for your examples.

Answer 1

There is a wide range of band gap in ceramics and moreover impurities are doped and achieve desired properties leading to it's wide range of electrical conductivity. The way of incorporation of impurities and the amount of impurities added determine the conductivity. Thus based of the stoichiometric composition, the ceramic may be ferro electric or superconductor or instulator or a good electrical conductor. Glass, tiles, pottery, porcelain, bricks, cement, diamond, and graphite, are all cermics with varied properties.Bi4Ti3O12, Silicon Carbide, ITO indium Tin Oxide, clay

Examples :

1)Bi₄Ti₃O_{12 is a ferroelectric material. Sr is doped in it. Below 380degrees the material has less conductivity where as at temperatures above 380 degrees the conductivity increases.}

2)SiC has high electric and thermal conductivity and remains stable upto 1500 degrees.

3)ITO is a very good electrical conductor and its conductivity increases with increase in temperature.

4)clay is an insulator and has very large bandgap and increase in temperature is not sufficient to promote electrons to the conduction band.