Introduction

We discussed several interesting and useful properties of solids in the previous chapter. Tailor-making materials of desired properties is an integral part of modern solid state chemistry and an account of the subject would be incomplete without reference to it. To do justice to any one class of materials or to any one type of application, we would have to deal extensively with materials design, devices and other technological details. Since this would be beyond the scope of this monograph, we shall briefly present a few of the selected materials applications.

An area of great technological relevance today is high-performance ceramics (Bowen, 1980; Katz, 1980; Sanders, 1984). The term ‘ceramic’ itself refers to an inorganic, nonmetallic material processed or consolidated at high temperatures. Some ceramic materials (e.g. cubic BN, SiC, Si3N4) are hard, oxidation-resistant and light. They can often be made from abundantly available raw materials and are less expensive than metals. The shortcomings of ceramics are that they are generally brittle and difficult to make in large complex shapes. Uniform submicron powders required for making high-technology ceramics are made by the sol-gel process or from the vapour phase. Fibres made of Si3N4, SiC or carbon are toughened by depositing metals or silicon around them; lithium aluminium silicate glass ceramics are reinforced with SiC fibre. Ceramic materials are used in heat engines (e.g. Si3N4), as materials of fabrication, as thermistors, as substrates for electronics (e.g. barium silicate) and in magnetic and other applications.