Fig. 1: Schematic representation of the structural relationship between bcc and B2 structures, illustrated for a 1:1 stoichiometric solid solution.
From: Short-range order stabilizes a cubic iron alloy in Earth’s inner core
In both cases, the structure consists of two simple cubic lattices. P(Si) is the probability of finding a Si atom on a given lattice site. When Fe and Si are randomly distributed across all cubic sublattice sites with equal probability (P(Si) = 0.5), the crystallographic structure is bcc (a). Conversely, when Si occupies one of the two simple-cubic sublattices and Fe the other, as shown in (c), the crystal is isostructural with the B2 phase. Intermediate configurations with 0 < P(Si) < 1, shown in (b), retain the B2 crystal symmetry and are called B2-like.
