White X-ray Nanodiffraction Study of Allotropic Phase Transformation of Hexagonal- into Monoclinic-Cu6Sn5

An allotropic phase transformation of CU
6
Sn
5
from a hexagonal
$(\eta)$
to monoclinic
$(\eta^{\prime})$
at 186–189 °C is scientifically interesting and technologically important to the microelectronic industry. As
$\eta^{\prime}$
lattice is crystallographically pseudosymmetrical with
$\eta^{\prime}$
the identifications of
$\eta$
and
$\eta^{\prime}$
and
$\eta$
-to-
$\eta^{\prime}$
transformation are extremely difficult via traditional analysis techniques. Herein, we conducted a study to characterize the allotropic phase transformation by Laue diffraction via synchrotron white X-ray nanodiffraction. The results showed that Laue diffraction analysis can well distinguish the two allotropic species
$(\eta$
and
$\eta^{\prime})$
in spite of the existence of pseudosymmetry in the η-Cu
6
Sn
5
lattice.