A HIGH-PRESSURE STUDY OF THALLIUM

High-pressure experiments on metallic thallium have been carried out u sing a diamond-anvil cell for pressures up to 32 GPa. A hexagonal clos e packed-->face-centred cubic (f.c.c.) phase change takes place around 4 GPa. Fitting of the experimental data to the Murnaghan and Birch eq uations of state has been used to obtain values for the bulk moduli an d their pressure derivatives for the two phases. Extrapolation of the high-pressure data for the f.c.c. phase to low pressure has been used to obtain an estimate of the pressure to about 0.23 GPa in nanosized m etastable f.c.c. thallium inclusions formed in aluminium by ion implan tation.