Structure And Properties Of Ceramics Flashcards
inorganic and nonmetallic materials
Ceramic
between metallic and non-metallic elements which the interatomic bonds are either totally ionic or predominantly ionic but having some covalent character
Ceramic
greek word keramikos, which means
Burnt stuff
crystal structures are generally more complex than those for metals
Ceramics
Two characteristics of the component ions on crystalline ceramic materials influence the crystal structure
magnitude of the electrical charge
sizes of the cations and anions
Why is it that some or the ceramics are predominantly ionic?
There crystal structure is electrically charged
Common ceramic materials are those in which there are equal numbers of cations and anions
AX Compound
Most common AX compound crystal structure
Rock salt
coordination number for both cations and anions is 6
Rock salt
coordination number is 8 for both ion types
Cesium chloride
AX structure is one in which the coordination number is 4
Zinc Blende
charges on the cations and anions are not the same
AmXp
Interstitial positions
Tetrahedral
Octahedral
Four atoms (three in one plane, and a single one in the adjacent plane) surround one type
Tetrahedral position
involves six ion spheres, three in each of the two planes
Octahedral position
AmBnXp types, which is found for magnesium aluminate or spinel (MgAl2O4)
Spinel structure
composed primarily of silicon and oxygen
Silicate
2 most common abundant element in Earth’s crust
Silica
Oxygen
most simple silicate material
Silicon dioxide or silica
three primary polymorphic crystalline forms of silica
Quartz
Cristobalite
Tridymite
Silica that exist as noncrystalline solid or glass having a high degree of atomic randomness, which is characteristic of the liquid
Fussed Silica or vitreous silica
oxides (B2O3, GeO2) may also form glassy structures
Network former
oxide additives
Network modifier
oxides, such as TiO2 and Al2O3, substitute for silicon and become part of and stabilize the network
Intermediate
addition _____________________ lowers the melting point and viscosity of a glass and makes it easier to form at lower temperatures
modifiers and intermediates
can be produced by the sharing of three oxygen ions in each of the tetrahedra
Layered silicate
ordinarily established by a second planar sheet structure having an excess of cations, which bond to these unbonded oxygen atoms from the Si2O5 sheet
Electroneutrality
basic structure is characteristic of the clays and other minerals
Sheet
Common clay mineral
Kaolinite
Common clay mineral
Kaolinite
made of a series of these double layers or sheets stacked parallel to each other and form small flat plates that are typically less than 1μm in diameter and nearly hexagonal
Crystal of kaolinite
Exist in 2 allopathic form
Carbon