Diversity of Molecular–Network Conformations in the Over-Stoichiometric Arsenoselenides Covering a Full Thioarsenides Row As4Sen (0 ≤ n ≤ 6)

Molecular network conformations in the over-stoichiometric arsenoselenides of canonical As_xSe_100-x system (40 ≤ x ≤ 100) covering a full row of thioarsenide-type As₄Se_n 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) <i>polymorphic</i> and <i>polyamorphic</i> transitions initiated by decomposition of the <i>thioarsenide</i>-type As₄Se_n 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) <i>thioarsenide</i> phases. Straightforward interpretation of decomposition reactions accompanying induced crystallization and amorphization (reamorphization) in the arsenoselenides is achieved, employing disproportionality analysis of <i>thioarsenide</i>-type molecular network conformations within the reconstructed clustering map. The preference of network clustering at the boundaries of the As₄Se_n 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 As₄Se₅ molecular-crystalline species; polyamorphism in mechanoactivated As₄Se_n alloys (2 ≤ n ≤ 6); breakdown in the glass-forming ability of melt-quenching-derived arsenoselenides in the vicinity of tetra-arsenic biselenide As₄Se₂ composition; plastically and normally crystalline polymorphism in tetra-arsenic triselenide As₄Se₃-based <i>thioarsenides</i>, and so on.