GeSe2 under pressure

Experimentally, the crystallization and the amorphization of binary amorphous systems under pressure have already been the subjects of many studies [73-81]. In 1965, Prewitt and Young [73] found two new crystalline phases of Germanium and Silicium disulfides at T=300 K under pressure. Later, Shimada and Dachille [74] studied the crystallization of amorphous GeSe2 under pressure and found that three different crystalline phases exist depending on temperature and pressure. They also quoted that the crystallization was inhibited for temperatures lower than T=573 K. 

The GeSe2 system has also been the subject of X-ray diffraction study under pressure in the liquid phase [77]. It was found that under compression the connectivity of the liquid changes from a 2D to 3D. The 2D structure is characterized by a mixture of ES and CS tetrahedra, while the 3D one is only made by CS tetrahedra. This conversion from a mixture of ES/CS to a full CS network is accompanied by a breakdown of the IRO, completely lost above 2.5 GPa. 

Fig. 12.17 The pressure-volume equation of state for GeSe2 glass under compression where V is the volume at pressure P and Vo is the volume under ambient conditions. The measured data from Mei et al. [79] blackfilled circles with vertical error bars) are compared to the results obtained from FPMD in the present work (filled red squares) [61] and in the work by Durandurdu and Drabold [83] blue diamond). The measured and simulated data are fitted to a second-order Birch-Mumaghan equation of state solid green and dashed blue curve respectively)...

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