Nanocomposites and nanomaterials

Synthesis of uniform ZnCr2O4 spherical nanoparticles
Mykhailovych V.V.1, Kanak A.I.2, Mykhailovych M. P.2, Khalavka Y.B.2 
1 Physical, Technical and Computer Science Institute, Yuriy Fedkovych Chernivtsi National University, Kotsubinsky 2, Chernivtsi-58012, Ukraine
E-mail: mykhailovych.v@gmail.com
2 Department of General Chemistry and Material Science, Yuriy Fedkovych Chernivtsi National University, Kotsubinsky 2, Chernivtsi- 58012, Ukraine.

Spinel-type based nanomaterials and nanostructures [1] are some of the most promising materials of the present day since they possess valuable semiconductor, catalytic, photocatalytic, magnetic, piezoelectric and other properties. Due to the wide set of properties, this type of material is used in industrial areas, medicine, electronics industries, etc. Such a wide range of applications of these compounds is provided by the combination of two and trivalent metals in a compound with the general formula AB2O4, where A is a bivalent metal and B is a trivalent metal. 
One of the perspective spinel compounds is ZnCr2O4 nanoparticles since they exhibit almost all of the above-mentioned properties especially catalytic activity. However, in order to appear the significant catalytic activity, it is important to obtain the nanoparticles with uniform small size which provides a large specific surface contact. Therefore the focus of the current work is to synthesize the high uniform ZnCr2O4 spherical nanoparticles with an extremely small dimension. 
Synthesis of ZnCr2O4 spherical nanoparticles was performed with a sol-gel process [2] in the presence of tartaric acid, as this combustion agent provides the low temperature of flame (around 505 °C) which allows the formation of nanoparticles with a small size. Zinc nitrate and Chrome nitrate ware used as a metal precursor. The post auto-combustion treatment during 5 hours was the most effective for the exhibition of carbon impurities and for nanoparticle formation. Therefore during the research, it was obtained the ZnCr2O4 spherical nanoparticles with 6-8 nm in size, which shows the formations of a practically uniform product.

1.	Manjón F., Tiginyanu I., Ursaki V. AB2O4 Compounds at High Pressures // Materials Science.-2014.-13.- P. 53-73
2.	Zhao, Q., Yan, Z., Chen, C., Chen, J. Spinels: controlled preparation, oxygen reduction/evolution reaction application, and beyond.//Chemical reviews, -2017-117. – P. 10121-10211.