Page 100 - bukuneutron

with, A = h2 sin2 α + k2 sin2β + l2 sin2γ ,
a2 b2 c2

B= 2kl (cosβcosγ – cosα) + 2hl (cosγcosα – cosβ)
bc ac
2hk
+ ab (cosαcosβ – cosγ) and

C=1 – cos2α – cos2β – cos2γ + 2cosαcosβcosγ

Determination of crystalline structure using neutron
diffraction is the measurement of intensity of diffracted
neutron beam from every planes inside material upon
the interaction with the neutron beam. The object is ro-
tating while scanning in neutron diffraction instrument.
The intensity of neutron is picking at the scanning an-
gle where the reflection from the plane is maximised.
Therefore, scanning angle,θ, obtained from diffraction
experiment will provides lattice spacing,d, value ac-
cording to Equation 4.10.

nλ (4.10)
d=

2sin(θ)

Lattice spacing,d, in Equation 4.10 can be related
with any Bravais structure as described above. The
value of lattice spacing,d, is constant depending on the
element or type of materials. The value of diffracted
angle,θ, is different depending on the wavelength of
neutron or X-ray used in the measurement.

For example, Si has lattice constant, a=b=c= 0.543
nm, at plane, h=k=l=1, gives, d[111], characterised by
Equation 4.11.

87