Journal of Physical Studies 24(4), Article 4707 [7 pages] (2020) DOI: https://doi.org/10.30970/jps.24.4707 THERMOCHROMIC PROPERTIES OF NANO- AND MICROCOMPOSITES BASED ON (NH2(C2H5)2)2CuCl4 CRYSTALS V. Kapustianyk1 , Yu. Chornii1 , S. Semak2  1Ivan Franko National University of Lviv, Department of Physics, 50, Drahomanov St., Lviv, UA–79005, Ukraine, 2Ivan Franko National University of Lviv, Scientific-Technical and Educational Center of Low-Temperature Studies, 50, Drahomanov St., Lviv, UA–79005, Ukraine Received 01 November 2020; in final form 18 November 2020; accepted 24 November 2020; published online 21 December 2020

The absorption spectra of [NH$_2$(C$_2$H$_5$)$_2$]$_2$CuCl$_4$ (DEACC) nanocrystals and microcrystals incorporated into the polymer matrices were investigated. The main attention was devoted to the size effects manifestation in the spectral properties of the nano- and microcomposites based on DEACC crystals. It has been found that contrary to the case of the initial bulk crystals undergoing the first order thermochromic phase transition, the composites with the nanocrystals of average size 160 nm are characterized only by continuous change of color. Polymer-based microcomposites with an average microcrystal size of 20 $μ$m were found to possess the thermochromic properties similar to those in a bulk crystal, although their discontinuous thermochromic phase transition was shifted to higher temperatures (316 K) compared to the case of the bulk crystal (311 K). Besides, these microcomposites are characterized by a more diffused hysteresis loop observed on the temperature dependence of the absorption coefficient at the constant wavelength reflecting the hysteresis of the phase transition temperature. The significant effect of the polymer matrix on the phase transition temperature and nature was also detected. Indeed, the polysterene-based microcomposites with an average microcrystal size of 200 $μ$m were found to possess the thermochromic properties similar to those in a bulk crystal, although their discontinuous thermochromic phase transition was more considerably shifted toward higher temperatures (337 K) compared to the case of the bulk crystal. It was suggested that the ‟rigid” polystyrene matrix more significantly affects the geometry of the anionic [CuCl$_4$]$^{2-}$ complex than the ‟softer” latex matrix.

Key words: nanostructured materials, phase transitions, optical spectroscopy, thermochromic effect

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1. D. R. Bloomquist, M. R. Pressprich, R. D. Willett, J. Am. Chem. Soc. 110, 7391 (1988);
   Crossref
2. V. B. Kapustianik et al., in Proceedings of 1994 IEEE International Symposium on Applications of Ferroelectrics (University Park, PA, USA, 1994), p. 801;
   Crossref
3. D. R. Bloomquist, R. D. Willett, H. W. Dodgen, J. Am. Chem. Soc. 103, 2610 (1981);
   Crossref
4. V. B. Kapustyanyk, Yu. M. Korchak, J. Appl. Spectrosc. 67, 1045 (2000);
   Crossref
5. S. A. Roberts, D. R. Bloomquist, R. D. Willett, H. W. Dodgen, J. Am. Chem. Soc. 103, 2603 (1981);
   Crossref
6. V. Kapustianyk, S. Semak, P. Demchenko, I. Girnyk, Yu. Eliyashevskyy, Phase Transit. 91, 715 (2018);
   Crossref
7. V. Kapustianyk, S. Semak, M. Panasyuk, M. Rudko, V. Rudyk, Phase Transit. 92, 396 (2019);
   Crossref
8. V. B. Kapustianyk et al., J. Appl. Spectrosc. 86, 590 (2019);
   Crossref
9. J. H. Davies, The Physics of Low-Dimensional Semiconductors: an Introduction (Cambridge University Press, Cambridge, 1998).
10. T. Ohno, D. Suzuki, H. Suzuki et al, KONA 22, 195 (2004);
    Crossref
11. E. K. Akdogan et al., J. Appl. Phys. 97, 084305 (2005);
    Crossref
12. V. Kapustianyk et al., J. Phys.: Conf. Ser. 79, 012005 (2007);
    Crossref
13. V. Kapustianyk et al., J. Alloys Compd. 493, 26 (2010);
    Crossref
14. I. V. Kityk et al., Mater. Lett. 27, 233 (1996);
    Crossref
15. F. Ramtolli, G. Saccinni, Cryst. Res. Technol. 37, 1325 (2002);
    Crossref
16. V. Rudyk et al., Ferroelectrics 330, 19 (2006);
    Crossref
17. I. Oral, H. Guzel, G. Ahmetli, Polym. Bull. 67, 1893 (2011);
    Crossref
18. W. Simchareona, T. Amnuaikita, P. Boonmea, W. Taweepredab, W. Pichayakorna, Procedia Chem. 4, 308 (2012);
    Crossref