  The generic 1-bond:2-mode percolation type Raman signal inherent to the short
bond of common (A,B)C semiconductor mixed crystals with zincblende (cubic)
structure is exploited as a sensitive mesoscope to explore how various
ZnSe-based systems engage their pressure-induced structural transition (to
rock-salt) at the sub-macroscopic scale with a focus on ZnCdSe. The Raman
doublet, that distinguishes between the AC- and BC-like environments of the
short bond, is reactive to pressure: either it closes (ZnBeSe, ZnSeS) or it
opens (ZnCdSe), depending on the hardening rates of the two environments under
pressure. A partition of II-VI and III-V mixed crystals is accordingly
outlined. Of special interest is the closure case, in which the system
resonantly stabilizes ante transition at its exceptional point corresponding to
a virtual decoupling, by overdamping, of the two oscillators forming the Raman
doublet. At this limit, the chain-connected bonds of the short species (taken
as the minor one) freeze along the chain into a rigid backbone. This reveals a
capacity behind alloying to reduce the thermal conductivity.
