Page 98 - bukuneutron
P. 98
ment. The main advantageous of diffraction devices
utilising neutron is its high penetrating power compared
to X-Ray. Therefore, large sample can be used in neu-
tron diffraction technique. Two applications such as
the measurement of crystalline structure and residual
stress of solid materials is discussed.
4.4.1 Measurement of Crystalline Structure
Crystalline structure of solid materials is characterised
by lattice constant and each angle in between the lat-
tice constant. In general, there are 14 crystal structure
as defined as Bravais lattices. These lattice structure
is shown in Figure 4.5.
Bravais lattice is divided into seven crystal system
namely, cubic, tetragonal,orthombic, hexagonal trigo-
nal, monoclinic and triclinic. These crystal structure is
determined by neutron diffraction pattern. Each crystal
system has specific geometry or dimension as define
by lattice constant,a,b, and c with the orthogonal angle
given by α, β and γ.
Lattice constant of crystalline structure for each Bra-
vais lattice has specific relationship with planes spac-
ing,d, which is describe in Equation 4.1. The rela-
tionship between lattice constant with lattice planes for
crystalline structure such as Cubic, Rhombohedral, Tetrag-
onal, Hexagonal, Orthorombic, Monoclinic and Triclinic
as describe by Bravais lattice is given as follows,
85
