Chapter 12 Flashcards
ceramics
means “burnt stuff,” indicating that desirable properties of these materials are normally achieved through a high-temperature heat treatment process called firing
cation
- metallic ionsare
- positively charged because they have given up their valence electrons to the nonmetallic ions
anion
negatively charged
rock salt crystal structure
- most common AX crystal structure
- coordination number for both cations and anions is 6
- two interpenetrating FCC lattices—one composed of the cations, the other of anions
cesium chloride crystal structure
- coordination number is 8
- anions are located at each of the corners of a cube, whereas the cube center is a single cation
zinc blende or sphalerite structure
- coordination number is 4
- all ions are tetrahedrally coordinated
tetrahedral position
four atoms (three in one plane, and a single one in the adjacent plane) surround one type
octahedral position
six ion spheres, three in each of the two planes
silicates
- materials composed primarily of silicon and oxygen, the two most abundant elements in Earth’s crust
- not considered ionic
silicon dioxide or silica (SiO2)
- most simple silicate material
- material is electrically neutral and all atoms have stable electronic structures
fused silica or vitreous silica
silica made to exist as a noncrystalline solid or glass having a high degree of atomic randomness, which is characteristic of the liquid
network formers
other oxides that form glassy structures
network modifiers
oxides that do not form polyhedral networks, their cations are incorporated within and modify the SiO4-4 network
intermediates
other oxides, such as TiO2 and Al2O3 although not network formers, substitute for silicon and become part of and stabilize the network
carbon
exists in two allotropic forms—diamond and graphite—as well as in the amorphous state
