Week 4 3D lattice, Miller Index & X-ray diffraction

Question 1

what are the 3 types of cubic bravis lattice

Answer 1

primitive cubic lattice
body centred cubic lattice
face centred cubic lattice

Question 2

what is the Miller Index

Answer 2

way how crystal structures are labelled based on X-ray diffraction

Question 3

what are the steps to obtain the Miller index of a certain structure

Answer 3

> Find intercepts of the plane on the a,b,c axes in terms of the lattice constants
Take reciprocals of these numbers, reduce to the smallest ratio

Question 4

why is X-ray diffraction

Answer 4

the wavelength of the X-ray diffraction is about the same length as the lattice constant

Question 5

what is the interplanar spacing for Miller index(hkl) for cubic lattices equation

Answer 5

d(hkl) = a / [h^2 + k^2 + l^2]^1/2

Question 6

what are the two conditions for measuring interplanar spacing

Answer 6

> Must follow Bragg diffraction law nλ = 2dsinθ

>Planes must be correctly aligned to the incident/scattered beams for measuring angle

Question 7

what are the 3 steps for determining the density of solids

Answer 7

> Use X-ray to measure the lattice parameters
Add up the mass of atoms in a basis
Divide the mass by the volume of the primitive unit cell