The effect of amorphization on the local structure of arsenic chalcogenides

The effect of amorphization on the symmetry of the local environment of chalcogen atoms in As₂S₃, As₂Se₃, and As₂Te₃ compounds has been investigated by ¹²⁹Te(¹²⁹I) Mössbauer spectroscopy. Three states of triply coordinated tellurium atoms are indistinguishable in the Mössbauer spectra of crystalline As₂Te₃. Amorphization of As₂Te₃ decreases the local symmetry of triply coordinated states of Te atoms and leads to the formation of doubly coordinated states in -As-Te-Te-As- chains. In the structure of crystalline As₂S₃ and As₂Se₃, two states of doubly coordinated chalcogen atoms X in -As-X-As- chains manifest themselves in the broadening of the Mössbauer spectra. Amorphization of As₂S₃ and As₂Se₃ is not accompanied by a change in the local symmetry of doubly coordinated chalcogen atoms in -As-X-As- chains; however, doubly coordinated states of S and Se atoms in -As-X-X-As chains are formed in the amorphous material.