Nanocomposites and nanomaterials

Electrophysical phenomena in the system of sealed nanoparticles based on zirconia under impact of external influences of electromagnetic nature
Shylo A.V. 1, Doroshkevich A.S. 1,2, Danilenko I.A.1, Konstantinova T.E.1 
1 Materials Science Department, Donetsk Institute for Physics and Engineering named after O.O. Galkin of the NAS of Ukraine, Nauki ave, 46, Kyiv-03028, Ukraine
e-mail:art.shylo@gmail.com
2Joint Institute for Nuclear Research, 141980, str. Joliot-Curie, 6, Dubna, Russia

There are many coordination-unsaturated chemical bonds on the surface of nanoparticles. Therefore, for the principle of electroneutrality, a nanoparticle adsorbs ions from surrounding atmosphere. That is, nanoparticle is covered with a double layer of OH-groups. These OH-groups can easily both be sorbed and desorbed from a surface of nanoparticles. By applying external influences (for example, magnetic or electric field) it is possible to change chemical activity of a surface of nanoparticles. 
Used the method of impedance spectroscopy it is shown that during processing by a pulsed magnetic field (PMF) (H = 105-106 A/m), formation of a frequency-independent part on a spectrum of impedance is observed. It can indicate a reducing of concentration of charge carriers inside nanoparticles. Based on the thermogravimetric data, it is established that energy of chemical bond of adsorbate molecules with surface of nanoparticles is reduced from 3.25 kJ/mol to 1.72 kJ/mol during explanation by PMF. That is, the activation energy of desorption of adsorbate molecules on surface of ZrO2 nanoparticles depends on a number of free charge carriers in near-surface zone of nanoparticles. 
It is shown that application of an external electric field (5-150 V / mm) to a system of sealed nanoparticles leads to accumulation of an electric charge with a density of up to 187 μF / g. The effect has a dimensional nature. The influence of level of hydration, geometric shape of a sample, the degree of compaction of nanoparticles, the magnitude and duration of charging on a level of charge of the system is shown. 
The authors are thankful for the H2020-MSCA-RISE-2015 Programme and project n691010 HUNTER for financial support of their work.
This work was supported by grant number 16-33-50010 Project of RFBR.