HIGH-PRESSURE PHASE-TRANSITIONS IN ZN1-XMXSE (M=CD, FE, AND MN)

Energy-dispersive x-ray diffraction was employed to study pressure-ind uced phase transitions in Zn0.84Fe0.16Se, Zn0.9Cd0.1Se, and Zn0.76Mn0. 24Se crystals up to 21.0, 23.3, and 24.3 GPa, respectively. Our result shows that the B3 to B1 structure transitions for these crystals occu rred at 1 1.4 +/- 0.5, 9.5 +/- 0.3, and 9.6 +/- 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. T his reduction in phase-transition pressure Delta P-t in the ternary co mpounds suggests that the fractional volume change, (Delta V/V-o), of the B3-B1 phase admixture might be the source of this reduction. Our r esults indicate that P-t (with respect to the phase transition pressur e 14.4 GPa of ZnSe) is related to the fractional volume change (Delta V/V-o) by the expression P-t = [14.4003 + 0.1568 (Delta V/V-o)-0.0281( Delta V/V-o)(2)] GPa. [S0163-1829(98)05426-5].