Diversity of Molecular-Network Conformations in the Over-Stoichiometric Arsenoselenides Covering a Full Row AsSe (0 ≤ ≤ 6).

Molecular network conformations in the over-stoichiometric arsenoselenides of canonical AsSe system (40 ≤ x ≤ 100) covering a full row of thioarsenide-type AsSe entities (0 ≤ n ≤ 6) are analyzed with ab initio quantum-chemical modeling employing cluster-simulation code CINCA. Native (melt-quenching-derived) and nanostructurization-driven (activated by nanomilling) and transitions initiated by decomposition of the -type AsSe cage molecules and incorporation of their remnants into a newly polymerized arsenoselenide network are identified on the developed map of molecular network clustering in a binary As-Se system. Within this map, compositional counter lines corresponding to preferential molecular or network-forming tendencies in the examined arsenoselenides are determined, explaining that network-crystalline conformations prevail in the boundary compositions corresponding to n = 6 and n = 0, while molecular-crystalline ones dominate inside the rows corresponding to n = 4 and n = 3. A set of primary and secondary equilibrium lines is introduced in the developed clustering map to account for inter-phase equilibria between the most favorable (regular) and competitive (irregular) phases. Straightforward interpretation of decomposition reactions accompanying induced crystallization and amorphization (reamorphization) in the arsenoselenides is achieved, employing disproportionality analysis of -type molecular network conformations within the reconstructed clustering map. The preference of network clustering at the boundaries of the AsSe row (at n = 6 and n = 0) disturbs inter-phase equilibria inside this row, leading to unexpected anomalies, such as absence of stable tetra-arsenic triselenide AsSe molecular-crystalline species; polyamorphism in mechanoactivated AsSe alloys (2 ≤ n ≤ 6); breakdown in the glass-forming ability of melt-quenching-derived arsenoselenides in the vicinity of tetra-arsenic biselenide AsSe composition; plastically and normally crystalline polymorphism in tetra-arsenic triselenide AsSe-based , and so on.