Intro to solid state chemistry

Question 1

Crystalline solid

Answer 1

a solid material whose constituents are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions

Question 2

Amorphous solid

Answer 2

a solid that lacks long-range order and doesn’t organise into a definite lattice pattern

Question 3

2D lattice counting: atoms in centre of cell

Answer 3

1

Question 4

2D lattice counting: atoms on edge of cell

Answer 4

1/2

Question 5

2D lattice counting: atoms at a corner of cell

Answer 5

1/4

Question 6

3D lattice counting: atoms in centre of cell

Answer 6

1

Question 7

3D lattice counting: atoms on edge of cell

Answer 7

1/4

Question 8

3D lattice counting: atoms at a corner of cell

Answer 8

1/8

Question 9

3D lattice counting: atoms on face of cell

Answer 9

1/2

Question 10

Packing efficiency formula

Answer 10

Natoms*Vatom / Vunit cell

Question 11

Laves Principles

Answer 11

regarding the packing of spheres

• space
• symmetry
• connection

Question 12

Two types of close packing

Answer 12

• Hexagonal close packing (hcp); ABABAB…
• Cubic close packing (ccp); ABCABC…

Question 13

Coordination no. of close packing

Answer 13

12

Question 14

Packing efficiency of close packing

Answer 14

74%

Question 15

Primitive cubic packing

(sites of atoms, packing efficiency, coordination number, points of contact)

Answer 15

• M at (0,0,0)
• 52% of volume occupied
• coordination no. = 6
• spheres in contact along cell edges

Question 16

Body centred cubic packing

(sites of atoms, packing efficiency, coordination number, points of contact)

Answer 16

• M at (0,0,0) and (1/2, 1/2, 1/2)
• 68% of volume occupied
• coordination no. = 8
• spheres in contact along body diagonal

Question 17

CsCl structure

Answer 17

Cl at (0,0,0)
Cs at (1/2, 1/2, 1/2)
two interpenetrating primitive cubic lattices

Question 18

Are Oh or Td holes bigger

Answer 18

Oh

Question 19

If there are n spheres, how many Oh holes are there?

Answer 19

n

Question 20

If there are n spheres, how many Td holes are there?

Answer 20

2n

Question 21

NaCl structure

Answer 21

• Na in all Oh holes of a CCP of Cl
• 6:6 coordination
• 2 interpenetrating CCP arrays

Question 22

Rutile

Answer 22

TiO ₂

• distorted HCP of O with Ti in half Oh holes
• edge and corner sharing TiO ₆ octahedra

Question 23

Fluorite

Answer 23

CaF ₂

• all tetrahedral holes in CCP
• Ca is surrounded by 8 F
• F is surrounded by 4 Ca
• 8:4 coordination

Question 24

NiAs

Answer 24

• all octahedral holes in HCP
• HCP of As with Ni in Oh holes
• As in trigonal prism of Ni
• 6:6 coordination
• Ni octahedra share faces

Question 25

Perovskite

Answer 25

ABO ₃ - ideal cubic structure - Ti octahedrally coordinated - Ca is 12 coordinated - Ti in Oh holes - corner sharing BO ₆ octahedra

Question 26

What are the allowed oxidation states in perovskite

Answer 26

3+ / 3+ 2+ / 4+ 1+ / 5+

Question 27

Ferroelectric Material

Answer 27

dielectric materials in which polarisation remains permanently, even after removing the applied electric field

Question 28

Crystal polymorphism

Answer 28

compound can crystallise into more than one crystal structure

Question 29

Spinel

Answer 29

AB ₂ O ₄ - Mg in MgO ₄ tetrahedra - Al in AlO ₆ octahedra - close packed O layers - A and B are in some of the Td and Oh holes

Question 30

Allowed Oxidation states of spinels

Answer 30

2+ / 3+ 1+ / 4+

Question 31

Most favourable conditions for radius ratio rules

Answer 31

- ions treated as hard spheres - cation-anion contact - no anion-anion contact - coordination no. is max possible

Question 32

Lattice energy

Answer 32

the change in internal energy when 1 mole of an ionic compound at 1 bar is formed from infinitely separated gaseous ions

Question 33

What is the madelung constant?

Answer 33

the sum of the partial madelung constants which represent the contributions of the individual ions to the total lattice energy

Question 34

How does Born-Lande Equation differ from Born-Mayer?

Answer 34

Born-Mayer uses density as measuring the repulsion term

Question 35

How does Born-Lande Equation differ from Kapustinkii?

Answer 35

Kapustinkii can be used to estimate lattice energy without the knowledge of the structure type (i.e. the madelung constant)

Question 36

How types of polycrystalline materials are formed

Answer 36

- conventional solid state reactions - precursor methods - hydrothermal / solvothermal methods - intercalation ion exchange

Question 37

How types of single crystals are formed

Answer 37

- single crystal growth from melt - single crystal growth from fluxes - floating zone furnace (large) crystal growth

Question 38

How thin films are formed

Answer 38

- chemical vapour deposition - sputtering

Question 39

Why is grinding needed in 'shake and bake'?

Answer 39

- produces an intimate mixture of reactants - reduces reactant particle size

Question 40

Why are high temperatures required for 'shake and bake'?

Answer 40

- generally leads to thermodynamically stable products

Question 41

What method is used to deduce crystal structures?

Answer 41

x-ray diffraction

Question 42

Solid oxide fuel cells: positives and negatives

Answer 42

+ve = clean and efficient energy generation, fuel flexibility, zero CO ₂ emissions -ve = device cost and reliability

Question 43

Solid oxide fuel cells: electrolyte used

Answer 43

YSZ Yttria-stabilised zirconia

Question 44

Isovalent Substitution

Answer 44

the ion that is substituting the original ion is of the same oxidation state as the ion replacing it

Question 45

Aliovalent Substitution

Answer 45

the ion that is substituting the original ion is of a different oxidation state than the ion it is replacing

Question 46

Two mechanisms for ionic conduction

Answer 46

- Vacancy-hopping oxide ion conductors - Interstitial oxide ion conductors

Question 47

Example of other ionic conductor

Answer 47

Layered materials containing mobile cations used in rechargeable battery materials

Question 48

Superconductors

Answer 48

a type of material that conducts electricity with zero energy loss or resistance when cooled to a certain temperature

Question 49

Example of molecular superconductors

Answer 49

Alkali fullerides, A ₃ C ₆₀

Question 50

Factors for elements replacing one another in doping

Answer 50

- Oxidation state (similar oxidation state is favourable) - Ionic radii (similar sizes is favourable) - Coordination preferences (geometry)