Inorganic Final: Alloys, Conductors, and Insulators

2 basic types of alloys

substitutional and interstitial

what happens when 2 metals are heated together or a metal is mixed with a nonmetal

1. an ionic compound may form
2. an interstitial alloy may form
3. a substitutional alloy may form
4. a simple mixture results

for semiconductors, what happens to conductivity as temp increases?

it increases

small band gap

semi conductors

large band gap

insulators

semiconductor ex

Gallium arsenide

for intrinsic semiconductors, what happens to conductivity as you increase temp?

it increases

who was the first to liquify He?

Heike-Kamerlingh-Onnes

Who was first to liquified H and made deware glass?

Dewar

most ___ are conductors

metals

if you get the metals below 4K, you get ____ . Why?

superconductors bc you are lowering the lattice vibrations

types of extrinsic semiconductors

N-type(negative) an p-type(positive)

semiconductivity that arises from the dopant atoms having more e- than the parent atoms

n-type extrinsic semiconductors

semiconductivity that arises from the dopant atoms have fewer e- than the parent atoms

p-type extrinsic semiconductors

ex of p-type

aresenic doped with gallium

ex of n-type

gallium doped with aresnic

in p-type, dopant atoms provide a ____

narrow empty acceptor band just above the highest filled band of the parent species

what effect does doping have on the conductivity of semiconductors or even insulators?

it increases it

ex of substitutional alloys

Cu/Ni, Cu/Au, K/Rb, K/Cs, and Rb/Cs

in substitutional alloys what can happen?

one atom may replace another at random in the lattic

if two metals are completely __ with each other they can form a continous range of _ _.

miscible/ solid solutions

in a interstitial alloy….

atoms are much smaller and fill up holes in the latice

in a random substitutional alloy…

a metal is substituted randomly thoughout the lattice

in an ordered substitutional alloy…

a metal is sunstituted in an ordered way througout the lattice

for a random substitutional alloy or an ordered substitutional alloy to occur what 3 things must happen?

1. both metals have to similar in size
2. both metals must have the same crystal structure
3. the chemicals properties of the metals must be similar ( # of valence e- needs to be the same)

Alnico

Fe, Al, Ni, Co fridge magnets

Brass

Cu and Zn plumbing and hardware

Bronze

Cu, Zn,Sn bells and medals

Cast iron

Fe C

Dental amalgam

Hg, Ag, Sn

Gold

Au, Ag, Cu

Nichrome

Ni, Fe, Cr electrical wire

Pewter

Sn, Sb, Pb tableware

Solder

Pb, Sn joining metal

Spiegeleisen

Fe, Mn, C safes armor

Stainless Steel

Fe, Cr, Ni

Steel

Fe C

Sterling Silver

Ag, Cu

White gold

Au, Pd

What are the 2 types of semiconductor?

extrinsic and intrinsic

What lead to the discovery of superconductivity?

Onnes liquifying He

What else di Onnes discover?

that metal (like Hg and Pb) became superconductor near absolute zero

a superconductor has _____ electrical resistance

zero or almost zero

what happens a critical temp?

resistance drops and superconductivity occurs

what do superconductive alloys require to achieve and maintain their super conductivity?

liquid He

conductance involves two e- or a ___ ___ at the same time

cooper pair

what is formed by compounds of formula ABO3

perovskite structures

what do the oxidation state of A and B add up to in a perovskite stucture?

6

What type of superconductors exist?

metal or ceramic

Who discovered the first known superconductor above the boiling point of nitrogen?

Wu, Chu, and Ashburn in 1987

three apparent facts of warm (or ceramic) superconductors

1. many contain copper
2. they are all related to the perovskite structures
3. the oxygen deficiency seems to be critical