Nanostructured surfaces
Calorimetric studies of MWCNTs at low temperatures
Barabashko M.S.1, Szewczyk D.2, Jeźowski A.2, Bagatski M.I.1, Sumarokov V.V.1, Kuznetsov V.L.3,4, Moseenkov S.I.4, Ponomarev A.N.5
1 B.Verkin Institute for Low Temperature Physics and Engineering of NAS of Ukraine, 47 Nauky Ave., Kharkiv, 61103, Ukraine
2 W. Trzebiatowski Institute of Low Temperature and Structure Research, Polish Academy of Sciences, P.O. Box 1410, 50-950, Wroclaw, Poland 
3 Boreskov Institute of Catalysis, 5 Lavrentiev Ave., 630090, Novosibirsk, Russia 
4 National Research Tomsk Polytechnic University, 30 Lenin Ave., 634050, Tomsk, Russia 
5 Institute of Strength Physics and Materials Science of SB RAS, 2/4 Academicheskii Ave., 634055, Tomsk, Russia
E-mail: barabasсhko@ilt.kharkov.ua

The specific heat of milled and oxidized multi-walled carbon nanotubes (MWCNTs) has been studied in the temperature range from 1.8 to 275 K on the PPMS by the thermal relaxation method. The initial MWCNTs with a controlled level of defects and low content of inorganic impurities were obtained by CVD method. The transmission electron microscopy (TEM), Raman spectroscopy, X-Ray Fluorescence method (XRF), the energy dispersive X-ray spectroscopy (EDS) were used for the determination of the elemental composition and morphology of MWCNTs [1,2]. The specific heat capacity of MWCNTs significantly depends of the diameter of the initial nanotubes at low temperatures. [3]. Effects of influence of grinding and oxidation on the behavior of the temperature dependence of the heat capacity of MWCNTs are qualitatively different for nanotubes with different diameters. The discussed features of the temperature dependence of the specific heat capacity of MWCNTs are, apparently, the manifestation of the size effect.
1. Kuznetsov V.L., Bokova-Sirosh S.N., Moseenkov S.I., Ishchenko A.V., Krasnikov D.V., Kazakova M.A., Obraztsova E.D. // Phys. Stat. Sol. (b), -2014.-251(12).- P. 2444- 2450. 
2. Bokova-Sirosh S.N., Kuznetsov V.L., Romanenko A.I., Kazakova M.A., Krasnikov D.V., Tkachev E.N., Yuzyuk Y.I., Obraztsova E.D. //J. Nanophotonics, -2016.- 10(1), P 012526 (1-10). 
3. Sumarokov V.V., Jeżowski A., Szewczyk D., Bagatski M.I., Barabashko M.S., Ponomarev A.N., Kuznetsov V.L., Moseenkov S.I. // Low Temp. Phys.-2019. - 45. -P. 347-403.