Materials Science Lecture Notes

These flashcards cover key concepts from materials science, including definitions of various types of semiconductors, behaviors of materials under stress, and characteristics of polymers.

Creep

The slow, progressive, permanent deformation of a material under constant stress at high temperatures.

Intrinsic Semiconductor

A perfectly pure semiconductor where electrical conductivity is dictated solely by temperature, not impurities.

Extrinsic Semiconductor

A semiconductor that has been doped with impurities to increase its conductivity.

n-type Semiconductor

Doped with Group V elements to create an excess of negatively charged electrons.

p-type Semiconductor

Doped with Group III elements to create an excess of positively charged holes.

Soft Ferromagnet

A magnetic material with a narrow B-H hysteresis loop, easy to magnetize and demagnetize.

Hard Ferromagnet

A magnetic material with a wide B-H hysteresis loop, resists demagnetization.

Bohr Magneton

The fundamental unit of magnetic moment caused by the spin of a single electron.

Thermal Shock

Catastrophic fracturing of a brittle material caused by a rapid temperature drop.

Apparent Porosity

The percentage of a ceramic's volume consisting of open, interconnected pores that can absorb fluids.

True Porosity

The percentage of a ceramic's volume consisting of all pores, including closed ones.

Glass Transition Temperature (Tg)

The critical temperature where an amorphous solid transitions from hard and brittle to soft and rubbery.

Degree of Polymerization (DOP)

The average number of repeating monomer units chained together to form a polymer molecule.

Thermoplastics

Polymers made of long, independent chains held together by weak forces; they can be melted and reformed.

Thermosets

Polymers with a highly cross-linked structure that do not melt when heated but can burn or degrade.

Elastomers

Polymers with a lightly cross-linked network allowing them to uncoil and recoil like springs.

Tacticity (Stereoisomerism)

The arrangement of side-groups along a polymer backbone, including isotactic, syndiotactic, and atactic.

Crazing

Localized yielding in a polymer that resembles a cloudy crack but can still support a load.

Matrix Phase

The continuous binder material in a composite that holds shape and transfers applied stress.

Dispersed Phase

The discontinuous reinforcing material in a composite that bears the actual load and provides strength.