The fcc–bcc Bain path in In–Sn and related alloys at ambient and high pressure

Abstract

Experimental high-pressure structural studies on an In-Sn alloy containing 8 at.% Sn reveal an isostructural transition of a face-centered tetragonal phase at pressures above 15 GPa with a switch of the axial ratio from c/a>1 to c/a<1. Such tetragonal phases in binary alloys based on In and Sn are analyzed in relation to the Bain path, i.e. a transformation between a face-centered cubic (fcc) and a body-centered cubic (bcc) structure. Variation of the axial ratio c/a in these phases correlates with the average number of valence electrons per atom in an alloy. A common Bain path from fcc to bcc is discussed within a nearly-free-electron model of Brillouin-zone-Fermi-sphere interactions.

Structural Characterization, Optical Properties, and Phase Transitions of In1–xSnx Alloy Thin Films

“…However, the bands near point P gradually depart from nearly parallel as the energy band narrows from the α phase to the β phase. Therefore, the absorption peak resulting from interband transitions shows a red shift and weakens as predicted from Brillouin-zone–Fermi-sphere interactions . In addition, indium (in the α phase) and In 0.75 Sn 0.25 (in the β phase) have tetragonal face-centered cell (fct) structure, so they show similar electronic band structure.…”

“…%); that is, strong deviations from the Bain path occur at tetragonal phases (fct close to fcc) in the In–Sn alloys. (The linear transformation from fcc to bcc following direct deformation along the c axis can be represented by a straight line, which is called as the Bain path …”

“…Changes in the dielectric functions from In to sample S2 reversed those from sample S3 to sample S5, which is resulted from the anomalous evolution of the crystal structure of In−Sn alloy. 1,3 The optical properties showed unusual changes because of the extraordinary solid−solid phase transitions with increasing tin content until sample S2 (Sn content of 9 at. %); that is, strong deviations from the Bain path occur at tetragonal phases (fct close to fcc) in the In−Sn alloys.…”

“…The anomalous elastic, electronic, and optical properties of indium (In) and indium-based alloys have attracted much attention both in experimental and in theoretical studies. − Indium under ambient conditions crystallizes in a tetragonal structure that is a slight distortion of the face-centered cubic (fcc) structure with a c/a axial ratio of 1.076 of a tetragonal face-centered (fct) cell. The axial ratio of the In-type structure can be changed by alloying with neighboring elements, such as Sn, which results in an initial increase in c / a and then a jump from c / a > 1 (α phase) to c / a < 1 (β phase) at 15 at.…”

Structure stability in the simple element sodium under pressure

“…The electronic properties, however, can be significant in driving tetragonal Bain path as was demonstrated in Ref. [44].…”