Pigments and Phosphors Optical Displays

FIGURE 22.27 Mixed crystals of two semiconductors with different band gaps, CdS (yellow) and CdSe (black), show a range of colors, illustrating a decrease In the band gap energy as the composition of the mixture becomes richer in Se. 

The mechanical properties of solid materials are determined by their internal structure, which in turn depends on the nature of the chemical bonds created during synthesis and processing. 

Silicate ceramics are well suited for structural applications because of their strength, which originates in the partially ionic, strong silicon-oxygen bonds in the tetrahedral orthosilicate anion. This structural unit appears in naturally occurring minerals and clays, which are fashioned into ceramic pieces through sintering and densification processes. 

Nonsilicate ceramics derive comparable properties from other inorganic structural units. 

Oxide ceramics are made from oxides of numerous metals including beryllium, aluminum, calcium, and yttrium these metal-oxide bonds are essentially ionic. 

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