Pressure-temperature phase supercooled silicon

To obtain the complete phase behavior of supercooled silicon Vasisht et al. analyzed the interplay of various loci of extremal behavior, namely, the spinodal, temperature of density extrema, and temperature of compressibility extrema. Loci of temperature of maximum and minimum density (TMD and TMinD), temperature of maximum and minimum compressibility TMC and TMinC), and spinodal were evaluated by employing, in addition to the MD simulations, parallel tempering (PT) Monte Carlo simulations (at low temperature and pressures) and restricted ensemble Monte Carlo (REMC) simulations [95] (for locating the... 

Figure 23. The ph ase diagram of supercooled silicon in pressure temperature (P, T) plane obtained from simulations using the SW potential. The phase diagram shows the location of (i) the liquid-crystal phase boundary [115]—thick solid line, (ii) the liquid-gas phase boundary and critical point—line and a star, (iii) the liquid-liquid phase boundaiy and critical point—filled diamond and a thick circle, (iv) the liquid splnodal—filled circle (v) the tensile limit—open circle (vi) the density maximum (TMD) and minimum (TMinD) lines— filled and open squares, and (vii) the compressibility maximum (TMC) and minimum (TMinC) line—filled and open circle. Lines joining TMD and TMinD (dot-dashed), TMC and TMinC (solid), Spinodal (black dotted line) are guides to the eye.

Dynamics One of the biggest challenges in the study of supercooled silicon is that, with deep undercooling the system, not only becomes prone to rapid crystallization but also the relaxation times increase very rapidly. Vasisht et al. studied the relaxation times at different parts of the phase diagram and found that ap proaching the liquid liquid transition line (below the critical temperature) and the compressibility maxima line (above the critical temperature), the relaxation time increases in a non Arrhenius manner. In Fig. 25a, the relaxation time as a function of temperature at two different pressme values (above — P = 0 GPa and below — P = —1.88 GPa critical point) is shown. Figure 25b shows relaxation times as a function of pressure for three different temperatures values. 

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