The conversion of beta-Sn into PtSn4 during in situ heating of thin fi
lms of Pt and Sn has been observed by high-resolution electron microsc
opy (HREM). In situ heating of the metal films in the transmission ele
ctron microscope (TEM) allows the establishment of orientation relatio
nships between the unreacted Sn film and the intermetallic phases form
ed during the reactions. Initial observations reveal the formation of
PtSn4 in the [110] orientation where the (002) fringes of PtSn4 are or
iented parallel to the (011) fringes of beta-Sn. This observation sugg
ests that the (002) planes of PtSn4 are formed by the doubling of the
(011) planes of beta-Sn during the transformation, rather than the (02
0) planes of beta-Sn as previously reported.