Pressure-induced phase transitions, amorphization and alloying in Sb 2 S 3 .

Despite the extensive and systematic studies of pressure-induced phase transitions in sesqui-chalcogenides, several puzzles still remain to be solved. Here, the complicated phase transitions, amorphization, and alloying behaviors of the binary semiconductor antimony trisulfide (Sb 2 S 3 ) were observed by performing in situ high-pressure angle-dispersive x-ray diffraction, Raman spectroscopy and resistance measurements. Upon compression, two phase transitions are observed in Sb 2 S 3 before it transforms into a high-density amorphous state (HDA). Notably, it is found that the pressure transmitting medium has a great effect on these changes. Then, Sb 2 S 3 shows an irreversible process after full decompression and a low-density amorphous state (LDA) can be obtained. Unexpectedly, a site-disordered Sb-S alloy can be formed via recompressing LDA. These results indicate that the Sb 3+ lone electron pair activity will be destroyed at high pressures, which may make Sb 2 S 3 a promising thermoelectric material at high pressures.