Solid-state synthesis, dewetting, and magnetic and structural characterization of interfacial FexSn1-x layers in Sn/Fe(001) thin films

The phase formation sequences in 9Sn/91Fe(001) and 25Sn/75Fe(001) bilayers during thin-film solid-state reactions up to 800 degrees C were investigated using X-ray diffraction, the torque method, and scanning electron microscopy. In both samples, FeSn2, FeSn, alpha-Fe1-xSnx, Fe5Sn3, alpha-Fe, and beta-Sn were sequentially formed at the initiation temperatures T-in(i) similar to 150 degrees C, similar to 300 degrees C, similar to 550 degrees C, similar to 600 degrees C, and similar to 700 degrees C, respectively. Low-temperature transformations were predicted at temperatures T-K(1) similar to 150 degrees C and T-K(2) similar to 300 degrees C, which are absent in the phase equilibrium diagram of the Fe-Sn system. Solid-state dewetting of the 9Sn/91Fe(001) and 25Sn/75Fe(001) bilayers started at temperatures above 550 degrees C. Overall, this work sheds new light on general chemical mechanisms governing the synthesis of intermetallic phases in Sn/Fe(001) thin films, the phase transformations, and the evolution of the dewetting process of FexSn1-x films. Graphic abstract

Automated summary

This study investigated the phase formation sequences in 9Sn/91Fe(001) and 25Sn/75Fe(001) bilayers during thin-film solid-state reactions, revealing the sequential formation of various intermetallic phases at different initiation temperatures. It also identified low-temperature transformations not present in the phase equilibrium diagram of the Fe-Sn system and observed solid-state dewetting of the bilayers at temperatures above 550 degrees C. Overall, this work provides new insights into intermetallic phase synthesis and transformations in Sn/Fe(001) thin films.