solid state chemistry

Question 1

what does CCP stand for

Answer 1

face centres unit cells

Question 2

what does HCP stand for

Answer 2

hexagonal close packed unit cell

Question 3

what is the packing of HCP

Answer 3

ABABAB

Question 4

what is the packing of CCP

Answer 4

ABCABC

Question 5

O sites share ____ with eachother

Answer 5

edges

Question 6

T+ sites share ____ with eachother

Answer 6

corners

Question 7

O sites share ____ with T-sites

Answer 7

faces

Question 8

T+ wites share ___ with T- sites

Answer 8

edges

Question 9

sketch a rock salt structure CCP

Answer 9

1:1 ratio, all O sites filled, all T sites empty

domino 5

Question 10

sketch a sphalerite structure CCP

Answer 10

all either T+ or T- sites filled, no O sites.

sphaleriTTTTTe

Question 11

sketch a antifluorite structure CCP

Answer 11

all T+ and T- sites filled, O sites empty

Question 12

sketch a Nickel Arsenide structrue HCP

Answer 12

O sites filled, T sites empty

Question 13

sketch a Wurtzite structure HCP

Answer 13

all T+ or T- sites filled, No O sites

Question 14

describe the spinel structure

Answer 14

AB2O4,
O2- anions are arranged in the face centred cubic formation, then A and B are inis in the T sites and B is in the O sites.

Question 15

why does B in spinel structure prefer the O sites ?

Answer 15

Due to the crystal field stabilisation energy.
put a metal through both T and O calculations, higher energy is preferred (O always).

Question 16

describe perovskite structure

Answer 16

ABO3
A is a large cation, B is small,

A at corners -> 1/8 atom ends up = 1 atom
B in centre -> 1 atom
O on faces -> 6 x 1/2 = 3 atoms

Question 17

how to find the nearest neighbor distance for BCC

Answer 17

d = root3/2 a
where a is the lattice constant

Question 18

how to find the nearest neighbor distance for FCC

Answer 18

d = a/root2
where a is the lattice constant

Question 19

what is the min cation size for CN6

Answer 19

0.414

Question 20

what is the min cation size for CN8

Answer 20

0.732

Question 21

what is the min cation size for CN4

Answer 21

0.225

Question 22

what is the general rule for ionic radii

Answer 22

they are addittive, cations and anions are in contact, so radii increase with CN

Question 23

differnce between intrinsic and extrinsic defects

Answer 23

intrinsic - occur naturally,
extrinsic - occur through controlled change (doping)

Question 24

what is the schottky defect (I)

Answer 24

a balanced pair of cation and anion vancancies

Question 25

what is the frenkel defect (I)

Answer 25

cation displaced to a usally vacant site

Question 26

what is a subsitiutional defect (E)

Answer 26

one atom is replaced by another atom

Question 27

what is vegards law

Answer 27

it assumes during subsitution that there is a linear chnage in the unit cells dimentions.

Question 28

What is a vacancy defect (E)

Answer 28

where an ion is missing from a structure creating a gap. eg during sub if a 2 Na ions are removed and replaced with 1 Ca ion (neutral overall) there will be a gap (vacancy defect)

Question 29

what is an interstitial defect

Answer 29

where an atom is located in a normally empty space .

Question 30

lower CN will give you ___ strength per bond

Answer 30

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