Phase transformations in methanol at high pressure measured by dielectric spectroscopy technique.

The dielectric response in methanol measured in wide pressure and temperature ranges (P < 6.0 GPa; 100 K < T < 360 K) reveals a series of anomalies which can be interpreted as a transformation between several solid phases of methanol including a hitherto unknown high-pressure low-temperature phase with the stability range P > 1.2 GPa and T < 270 K. In the intermediate P-T region P ≈ 3.4-3.7 GPa, T ≈ 260-280 K, a set of complicated structural transformations occurs involving four methanol crystalline structures. At higher pressures within the narrow range P ≈ 4.3-4.5 GPa methanol can be obtained in the form of fragile glass (T(g) ≈ 200 K, m(p) ≈ 80 at P = 4.5 GPa) by relatively slow cooling.