Physico-chemical nanomaterials science

Cluster modeling of nanostructurization-driven reamorphization pathways in glassy arsenoselenides 
Shpotyuk O.1,2*, Hyla M.2, Boyko V.1  
1 O.G. Vlokh Institute of Physical Optics
23, Dragomanov str., Lviv, 79005, Ukraine
olehshpotyuk@yahoo.com
2 Jan Dlugosz University in Czestochowa
13/15, al. Armii Krajowej, Czestochowa, 42200, Poland

The melt-quenched and nanomilling-derived glassy g-As-Se probes are studied analyzing arrangement of diffuse peak-halos in their XRD patterns ascribed to intermediate- and extended-range ordering, respectively revealed through first and second sharp diffraction peaks (FSDP, SSDP). Straightforward interpretation of the observed changes is developed with modified microcrystalline approach, accepting diffuse halos as originated from superposition of inter-planar- and inter-atomic correlations due to quasi-crystalline remnants, the former contributing through broadened reflexes from quasi-crystalline planes (Bragg-diffraction contribution), and latter contributing through inter-atomic distances belonging to these planes and inter-molecular correlations (Ehrenfest-diffraction contribution). 
Balance in molecular-network entities in g-As-Se due to melt-quenching is disturbed at nanomilling, providing evidence on defects with unfavorable energies. Nanomilling destroys cage-like molecules, facilitating transferring towards chain-like network structures. Nanomilling-driven reamorphization results in increase in the FSDP position and width, occurring fragmentation impact on the correlation length of the FSDP-responsible entities. Destruction of intermediate-range ordering under nanomilling is accompanied by changes in extended-range order, revealed in high-angular shift in the SSDP position and broadening in the width. Milling-driven breakdown in intermediate-range ordering in g-As-Se is concomitant with destruction of most distant inter-atomic correlations belonging to remnants of quasi-crystalline planes contributing to the FSDP, whereas the longer inter-atomic correlations become dominant in extended-range ordering. Complete hierarchy of reamorphization scenarios in g-As-Se connected with cage-like molecules and most energetically favorable network-forming derivatives are examined with ab-initio quantum-chemical cluster modeling code CINCA [1].
1.	Shpotyuk O., Hyla M., Boyko V. Structural-topological genesis of network-forming nanoclusters in chalcogenide semiconductor glasses, J. Optoelectron. Adv. Mater.,2013.-15.-P. 1429-1437.