Lecture 04/07

Question 1

Describe ceramic materials

Answer 1

• Inorganic and nonmetallic
• 2+ elements
• Ranges from purely ionic to covalent

Question 2

What are the two characteristics that influence crystal structure?

Answer 2

• Magnitude of the electrical charge on each of the component ions
• Size of the cations and anions

Question 3

AX-Type Crystal Structures have?

Answer 3

Equal # of cations and anions

Question 4

What are the types of AX-type crystal structures and their coordination numbers?

Answer 4

• Rock Salt, 6
• Cesium Chloride, 8
• Zinc Blende, 4

Question 5

For AmXp-Type crystal structures, the charges on the cations and anions are?

Answer 5

Not the same

Question 6

AmBnXp-Type Crystals have more than one type of ?

Answer 6

Cation

Question 7

What is the ration of Si to O atoms in Silica?

Answer 7

1:2

Question 8

Silicate ceramics have a _ arrangement

Answer 8

Tetrahedron

Question 9

What are the three primary polymorphic crystalline forms of silica?

Answer 9

Quartz, cristobalite, and tridymite

Question 10

What is silica glass?

Answer 10

Glass having a high degree of atomic randomness

Question 11

Fused silica is?

Answer 11

Silicon with no added impurities

Question 12

Glasses commonly contain what impurity ions?

Answer 12

Na, Ca, Al, B

Question 13

Carbon can either be?

Answer 13

Diamond or graphite

Question 14

Describe diamond

Answer 14

• Metastable

- Strong covalent bonds due to sp3 hybridization

Question 15

Describe graphite

Answer 15

• Stable polymorph
• Carbon atoms are located at corners of sheets of hexagons
• Each atom’s 4th bonding electron is delocalized
• Interlayer bonds are perpendicular to the sheets and are weak van der waal

Question 16

Diffusion in ionic materials generally occurs by?

Answer 16

Vacancy mechanism

Question 17

The rate of diffusion in ionic materials is limited by?

Answer 17

Diffusion rate of the slowest-moving species

Question 18

What are the simpler crystal structures?

Answer 18

Rock salt
Cesium chloride
Zinc blende
Flourite
Perovskite

Question 19

Silicate ceramics include?

Answer 19

Crystaline silica
Layered silicated
Noncrystalline silica glass