Pressure effect on thermal-induced crystallization of amorphous selenium up to 5.5Â GPa

Thermal stability of bulk melt-quenched amorphous selenium (a-Se) has been investigated with a multi-anvil apparatus in a pressure range of 0.5-5.5 GPa. An anomalous pressure effect on thermal-induced crystallization of a-Se is observed through in situ temperature measurements. In the lower-pressure range (0.5-2.0 GPa), the onset crystallization temperature (Tx) increases largely with increasing pressure. However, in the higher-pressure range of 2.0-5.5 GPa, Tx does not increase but remains almost constant when pressure is applied. The results are briefly discussed with regard to the various pressure effects on amorphous solids and may be explained by considering that two different crystallization mechanisms are probably involved in the two pressure regions.