Abstract
Unusual cruciform patterns are found in the Sn/Te reaction couples reacted at 250 °C. The cruciform pattern is composed of porous SnTe reaction layers of very uniform thickness along the four sides, and no reaction phase was observed at the corners of the rectangular Te substrate. The reaction SnTe layer cracks at the corners due to its inherent grown stress. The unusual cruciform pattern results from the fast growth rate, and the porous and brittle natures of the SnTe reaction phase.