White X-ray nanodiffraction study of allotropic phase transformation of hexagonal- Into monoclinic-Cu6Sn5

An allotropic phase transformation of Cu6Sn5 from a hexagonal (η) to monoclinic (η’) at 186?189 °C is scientifically interesting and technologically important to the microelectronic industry. As η’ lattice is crystallographically pseudosymmetrical with η, the identifications of η and η’ and η-to-η’ 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 (η and η’) in spite of the existence of pseudosymmetry in the η’-Cu6Sn5 lattice. ? 2021 IEEE.