Journal of Physical Studies 22(2), Article 2703 [7 pages] (2018) DOI: https://doi.org/10.30970/jps.22.2703 PECULIARITIES OF DOMAIN STRUCTURE AND THE FORMATION PROCESS OF NANO- AND MICROCRYSTALS ON THE SURFACE OF [NH2(CH3)2]Al0.8Cr0.2(SO4)2×6H2O SINGLE CRYSTALS N. A. Loboda{1,2}, V. B. Kapustianyk{1,2}, Yu. I. Eliyashevskyy{1}, B. Ya. Kulyk{1}, R. Ya. Serkiz{1}, Z. Czapla{3,4}, R. V. Bilyak{1} 1Physical Department, Ivan Franko National University of Lviv 50, Drahomanov St., Lviv, UA-79005, Ukraine, e-mail: kapustianyk@yahoo.co.uk 2Scientific-Technical and Educational Center of Low-Temperature Studies, Ivan Franko National University of Lviv, 50, Drahomanov St., Lviv, UA-79005, Ukraine 3Department of Physics, Opole University of Technology, 75, Ozimska St., Opole, PL-45370, Poland 4Institute of Experimental Physics, University of Wroclaw, 9, pl. M. Borna, Wroclaw, PL-50204, Poland

This article studies the peculiarities of the ferroelastic domain structure in [NH$_2$(CH$_3$)$_2$]Al$_{0.8}$Cr$_{0.2}$(SO$_4$)$_2\times$6H$_2$O solid solutions. The domain structure was investigated using optical, atomic force and scanning electron microscopy. It has been shown that the investigated crystals predominately grow in a polydomain ferroelastic state. According to the data of the energy-dispersive X-ray analysis, in the case of a polydomain as-grown crystal, the neighbouring domains are characterized by different contents of chromium -- 17.6\% and 20\% respectively. This means that due to different signs of mechanical stress in the two groups of domains, they will be characterized by noticeably different levels of metal ion substitution. Therefore, it has been found that the thermodynamic conditions of growth are highly stress-dependent and allow a variation of the Cr distribution within the sample volume. The peculiarities of the formation of the specific nano- and microcrystalline structure on the single crystal surface were also investigated. It has been found that if the humidity of the atmospheric air is relatively high, the nanocrystals of a distorted hexagonal shape appear on the surface, growing to the sizes of a few tens micrometers during 72 hours.A model describing the nature and dynamics of this process is proposed.

PACS number(s): 75.85.+t, 77.84.-s, 81.07.-b

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