Energy-dispersive x-ray diffraction was employed to study pressure-induced phase transitions in ${\mathrm{Zn}}_{0.84}{\mathrm{Fe}}_{0.16}$Se, ${\mathrm{Zn}}_{0.9}{\mathrm{Cd}}_{0.1}$Se, and ${\mathrm{Zn}}_{0.76}{\mathrm{Mn}}_{0.24}$Se crystals up to 21.0, 23.3, and 24.3 GPa, respectively. Our result shows that the $B3\mathrm{}$ to $B1\mathrm{}$ structure transitions for these crystals occurred at 11.4$\pm$0.5, 9.5$\pm$0.3, and 9.6$\pm$0.5 GPa, respectively. Compared to the phase-transition pressure ${(P}_t)$ of ZnSe (14.4 GPa), a reduction of about 3–5 GPa is exhibited in these ternary compounds. This reduction in phase-transition pressure $\Delta P_t$ in the ternary compounds suggests that the fractional volume change, $\left(\Delta {V/V}_0\right)$, of the $B3-B1\mathrm{}$ phase admixture might be the source of this reduction. Our results indicate that $P_t$ (with respect to the phase transition pressure 14.4 GPa of ZnSe) is related to the fractional volume change $\left(\Delta {V/V}_0\right)$ by the expression $P_t$=[14.4003+0.1568$\left(\Delta {V/V}_0\right)$-0.0281$(\Delta {V/V}_0{)}^2$] GPa.

• Received 12 May 1997

DOI:https://doi.org/10.1103/PhysRevB.58.16