Effect of high‐energy mechanical milling on the medium‐range ordering in glassy As‐Se

Abstract

Effect of high‐energy mechanical milling on glassy AsxSe100 − x (5 ≤ x ≤ 75) is recognized with X‐ray powder diffraction analysis applied to their diffuse halos ascribed to intermediate—and extended‐range structural ordering, which are revealed respectively in the first sharp diffraction peak (FSDP) and principal diffraction peak (PDP). Straightforward interpretation of the results is developed within modified microcrystalline approach, treating diffuse halos as superposition of broadened Bragg‐diffraction reflexes from remnants of inter‐planar correlations, supplemented by inter‐atomic Ehrenfest‐diffraction reflexes from most prominent inter‐atomic and inter‐molecular correlations between cage‐like molecules (such As4Se4 and/or As4Se3). Milling is shown to be ineffective in glassy arsenoselenides near Se (x < 20), while causing increase in the FSDP width for glasses with 20 ≤ x ≤ 40 due to destroyed inter‐planar ordering. Remnants of cage‐like molecules in over‐stoichiometric As‐rich AsxSe100 − x glasses (40 ≤ x ≤ 75) disappear under milling, promoting formation of higher polymerized structural network. This milling‐driven reamorphization results in a drastic increase in the FSDP position and fragmentation impact on the correlation length of the FSDP‐responsible entities. Breakdown in intermediate‐range ordering in these glasses is accompanied by changes in their extended‐range ordering revealed in high‐angular shift and broadening of the PDP. This effect is concomitant with the disappearance of distant inter‐atomic correlations between quasi‐crystalline planes in the milled arsenoselenide glasses at a cost of prolonged correlations dominating in their extended‐range ordering.

High-Energy Mechanical Milling-Driven Reamorphization in Glassy Arsenic Monoselenide: On the Path of Tailoring Special Molecular-Network Glasses

“…The XRPD patterns collected from unmilled g-AsSe ( Figure 1 ) demonstrate diffuse halos attributed to the FSDP, SSDP, and TDP at ~16.03°2θ, ~29.77°2θ, and ~52.64°2θ, respectively (see Table 1 ), corresponding to scattering vectors positioned at Q FSDP ~1.138 Ǻ −1 (with width Δ Q FSDP ~0.229 Ǻ −1 ), Q SSDP ~2.096 Ǻ −1 (Δ Q SSDP ~0.419 Ǻ −1 ), and Q TDP ~3.617 Ǻ −1 (Δ Q TDP ~0.624 Ǻ −1 ). As was shown in our preliminary research [ 13 ], a similar arrangement of peak-halos was also detected in the reduced X-ray structure factor derived from these XRPD profiles.…”

“…The macroscopic room-temperature density of this MQ-derived alloy ρ = 4.490 g⋅cm −3 (measured in ethanol by the Archimedes displacement method) and glass-transition temperature T g = 166 °C (the mid-onset point on the differential scanning calorimetry curve obtained with 10 °C/min heating rate using TA Instrument Q20 calorimeter) show good correlation with known glassy counterpart g-AsSe [ 8 , 9 , 10 , 11 , 12 ]. The mean inter-atomic spacing d s m = 3.79 Å calculated from atomic density ρ was close to the maximum among over-stoichiometric arsenoselenides g-As x Se 100−x (χ > 40) [ 13 ].…”

“…The glassy arsenic monoselenide g-AsSe was prepared by the conventional MQ route [ 10 , 11 , 12 , 13 ]. The melt-rocking technological operation [ 16 ] was employed to prepare the homogeneous g-AsSe specimens.…”

“…Under such conditions, the energy transferring to fine-powdered g-AsSe estimated over specific grinding work in the Pulverisette 6 mill [ 17 , 18 , 19 ] was estimated to approach ~320 kJ/g. The high-energy MM under these conditions is known to ensure effective mechanochemical activation in a rich family of chalcogenide-type compounds [ 6 , 13 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 ].…”

“…A great plethora of amorphous materials such as glassy arsenoselenides g-As-Se possess principally different conformations associated with molecular and network entities [ 8 , 9 , 10 , 11 , 12 ], their functionalization being defined by system escape towards preferential atomic arrangement. It was found in a group of As-rich over-stoichiometric thioarsenides g-As x Se 100−x (χ > 40) that molecular-to-network transition could be initiated mechanochemically by treatment in a high-energy ball mill [ 13 ], allowing tailoring of advanced amorphous substances with guided properties.…”