Solid State

•solid spheres

• radius is identical for atoms of the same element

•packing tight together as tight as possible

• forms upon the lattice

• the second layer of atoms fits into the gaps on the first layer

•simple cubic

•vertical pattern, of AAAA

•coordination no of 6, as each atom has 6 nearest neighbours

•related by octahedrsl symmetry

•sits on top of the first layer

•repeat unit of ABABAB

•where each atom has 8 nearest neighbours, with a coodination no of 8

• e.g. Fe

•most efficent for each atom, to have 6 nearest neighbours in one plane

•2 simple regular lattices, that achieve the highest density.

•both have a coordination no of 12

•both based on their symmetry

•hcp

ccp

•Mg, Zn, Be

•Ca, Ni, Pt, Cu, Au, Al

•hcp

•ccp

• hexagonal packing as it is 100% efficient

•ccp leaves 26% vacant

• but ccp still the most efficient packing of spheres.

•allows smaller molecules to penetrate the lattic

•in ionic systems

•where the larger ions adopt one of the lattices, and smaller ions fit inbetween

•sites can either be tetrahedral or octaherdral

there are twice as many tetrahedral sites as ions in the lattice.

1 2r

2 r+h

•chloride ions form cubic packed lattice and

sodium ions in full octahedral interstitial sites

•overall charge neutrality must be obeyed.

1 all

2 1/2

3 1/3

4 all

5 1/2

1 NaCl

2 CdCl2

3 CrCl3

4 Na2O

5 ZnS

1 all

2 1/2

3 1/3

4 1/2, zinc blende

1 FeS

2 CdI2

3 FeCl3

4 ZnS, wurtzite

•simplest repeat unit of a structure, that imparts all the necessary info to expand structure in all directions to generate the crystal called unit cell

•

•between adjoining cells

•2 cells in the centre

• one on edge by four cells

• one on the corner by 8 cells

•positions within a cell should be known

•size of cations and anions

• ions pack to minimise replusion

•alot of smaller negative charges to pack around it

•so replusion is minimised

•xray diffraction, as the ions pack in a crystal

• by 3D array of points (atoms)

•smallest piece of the crystal required to show a repeating a pattern.

•is the long range pattern that is shownh by repeating the unit cell

•starts with a layer of identical spheres

•2nd layer sits in the gaps of the first layer

•3rd layer falls directly on too of first layer

•ABABAB layer

• start with a layer of identical spheres

• 2nd layer, spheres in the dips forming AB layer.

•3rd layer, places spheres into remaining gaps of the first layers

•forms ABC layer, particles per unit cell.

•particle in centre of a celland one at each corner

• as there are 2 particles per unit cell

•unit cell= one in the middle

• 8x(1/8ths) at corners

• perovskite is a unite cell

•contains titanium at the centre

•6 oxygen, centre of faces

• 8 Ca, at the corners

•by multiplying no. of ions by their occupancy

• 1Tix1= Ti

•6Ox1/2= 3O

•8Ca x 1/8=Ca

so the formula is CaTiO3

• Ca at the centre, O ions are half way down each of the 12 edges

•titanium ions occupy each of 8 corners

so formula is the same

•14 distinct families of unit cell

where the basic catergories have unit cell edge lengths (a, b, c) and internal angles (gamma, alpha, beta), α, β, and γ

1 cubic

2 tetragonal

3 orthorhombic

4 monoclinic

5 triclinic

6 trigonal

7 hexagonal

1 cubic

2 tetragonal

3 monoclinic

4 orthorhombic

5 rhombohedral

6 hexagonal

7 triclinic

• conductuing

• insulating

• semiconducting

• electrons free to move throughout solid

•electrons localised

•conductivity variable, and temp related

• a molecular orbital is formed

•atomic orbitals combine for form molecular orbitals.

Li ground state is 1s2 2si

1 li

2 li2

3 li3

4 lin

•filled band and empty with a band gap too high in energy for electrons to cross

•electrons can cross the small band

• ntype semiconductors contain electrons in the 'empty' band

•p type semicondutors have 'vacancies' in full band

•addition of elements to tetravalent silicon, that have more or less than 4 valence electrons.

• by doping it wih As (5 valence electrons), giving the n type semiconductor, electron rich.

•doping with boron, 3 valent electrons gives p type semi conductor, electron deficient.

•n type semiconductor

• schottky

•frenkel

• twinning

twinning

frenkel defect

schottky

simple cube

body centered cubic

face centered

simple tetragonal

body centered tetragonal

orthorhombic

rhombohedral

simple monoclinic

simple hexagonal

triclinic

cubic

tetragonal

monoclinic

orthorhombic

rhombohedral

hexagonal

triclinic