I want to shortly introduce my group.

 

We are working in B.Verkin Institute for Low Temperature Physics & Engineering, National Academy of sciences of Ukraine. Our scientific interests are thermal and sorption properties of fullerite (C60) single-walled carbon nanotubes and graphene.

 

STAFF

Group leader

Dolbin Aleksander Vitoldovich

Educational background, institutional affiliations

 2012 - Doctor of Physics and Mathematics, 2004-  Senior Researcher, head of the group for dilatometric studies of B.Verkin Institute for Low Temperature Physics and Engineering of the National Academy of Sciences of Ukraine 2000-2004 Researcher, Department of Thermal properties of Molecular Crystals B.Verkin Institute for Low Temperature Physics and Engineering of the National Academy of Sciences of Ukraine 1996-2000 STC "Institute for Single Crystals" (Researcher) 1993-1996 National Tecnical University (KhPI) (Graduate Ph.D. in Engineering Science) 1985-1993 National Tecnical University (KhPI) (Graduated With Honors)

Research Experience

1. Investigation of the sorptive characteristics of the carbon nanomaterials.

2. The dilatometric investigations of thermal expansion of carbon nanotubes (pure and doped with gases), fullerites and solid gases.

3. Computer simulation of physical processes in high electric and magnetic field.

 

Vinnikov Nikolay A., Ph.D. in Physics and Mathematics in 2010. Graduated from National Tecnical University (KhPI) in 2005. Since 2007 - a junior researcher at the Institute for Low Temperature Physics & Engineering of the National Academy of Sciences of Ukraine, participant of the group for dilatometric research. An author and co-author of over 30 scientific publications. His main scientific publications are concerned with the thermal and sorption properties of carbon nanotubes. An expert in low temperature physics.

 

Esel’son Valentin Borisovich, Ph.D. in Physics and Mathematics. Graduated from Kharkov State University in 1970. Since 1968 - a researcher at the Institute for Low Temperature Physics & Engineering of the National Academy of Sciences of Ukraine. He is a author and co-author of about 65 scientific publications, has 3 author’s certificates for inventions. His main publications are concerned with low temperature physics, in particular the thermal, mechanical and dielectric properties of solid hydrogen’s (H2, D2), thermal expansion and adsorption properties of fullerite C60 and carbon nanotube, experimental equipment.

 

 Selected publications

1. A. V. Dolbin, V. B. Esel'son, V. G. Gavrilko, V. G. Manzhelii, N. A. Vinnikov, I. I. Yaskovets, I. Yu. Uvarova, N. A. Tripachko, and B. A. Danilchenko. Hydrogen sorption by the bundles of single-wall carbon nanotubes, irradiated in various gas media. Low Temp. Phys. 39, 610 (2013)

2. A. V. Dolbin, V. B. Esel’son, V. G. Gavrilko, V. G. Manzhelii, N. A. Vinnikov, S. N. Popov, and B. Sundqvist. Quantum phenomena in the radial thermal expansion of bundles of single-walled carbon nanotubes doped with 3He. A giant isotope effect Low Temp. Phys. 37, 544 (2011)

3. A. V. Dolbin, V. B. Esel'son, V. G. Gavrilko, V. G. Manzhelii, N. A. Vinnikov, S. N. Popov. Kinetics of 4He gas sorption by fullerite C60. Quantum effects. Low.Temp.Phys. 36,1091 (2010)

4. A. V. Dolbin, V. B. Esel'son, V. G. Gavrilko, V. G. Manzhelii, N. A. Vinnikov, S. N. Popov and B. Sundqvist. Quantum effects in the radial thermal expansion of bundles of single-walled carbon nanotubes doped with 4He. Low.Temp.Phys. 36, 635 (2010)

5. A. V. Dolbin, V. B. Esel'son, V. G. Gavrilko, V. G. Manzhelii, S. N. Popov, N. A. Vinnikov and B. Sundqvist. The low-temperature radial thermal expansion of single-walled carbon nanotube bundles saturated with nitrogen. Low Temp. Phys. 36, 365 (2010)

6. A. V. Dolbin, V. B. Esel'son, V. G. Gavrilko, V. G. Manzhelii, S. N. Popov, N. A. Vinnikov and B. Sundqvist. The effect of sorbed hydrogen on low temperature radial thermal expansion of single-walled carbon nanotube bundles. Low Temp. Phys. 35, 939 (2009)

7. A. V. Dolbin, V. B. Esel’son, V. G. Gavrilko, V. G. Manzhelii, N. A. Vinnikov, S. N. Popov, N. I. Danilenko and B. Sundqvist. Radial thermal expansion of pure and Xe-saturated bundles of single-walled carbon nanotubes at low temperatures. Low Temp. Phys. 35, 484 (2009)

 

EXPERIMENTAL EQUIPMENT

All dilatometric measurements carry out with low temperature (2-100K) high-sensivity capacitance dilatometer. Datailed its construction and measuring technique is described in paper. But in the recent years we principially modernized dilatometer and whole dilatometric complex. Now the sensivity of the dilatometer is 10-9 cm (!). We can measure thermal expansion of cilindrical samples ~10 mm in diameter and up to 10 mm high.

Sorption - desorption experiments could be carry out using low-temperature (2-300K) and high-temperature (300 – 1100K) desorption gas analyzer. The investigation technique and the setup design are detailed in paper

 

MOST IMPORTANT RESULTS

At present the development, property investigations and commercial applications of new carbon nanosystems are among the top priority trends of the world science and science-based technologies. Recently the authors have obtained fundamentally novel results pointing to a quantum character of carbon nanosystems at low temperatures. They are as follows.

 

For fullerite C60:

1. A negative thermal expansion of fullerite has been observed at low temperatures, which suggests the tunnel origin of the rotational states of C60 molecules. Impurities introduced into the voids of the C60 lattice affect drastically both the magnitudes and the sign of the thermal expansion of the system (1).

2. Quantum diffusion of 3He, 4He, Ne atoms and H2 molecules in C60 has been detected by investigating the sorption – desorption kinetics of gases at low temperature [2 3]. The method was a direct measurement of the pressure of these gases contacting a C60 powder in a closed volume.

3. An isotopic effect has been detected in the investigation of the thermal expansion of C60 doped with methane and deuteromethane. The effect is caused by the tunnel rotation of the CH4 and CD4 molecules in the octahedral interstitials of the C60 lattice [4].

 

For single-walled carbon nanotubes (SWNT):

4. The low temperature coefficient of the thermal expansion of bundles of single-walled carbon nanotubes in the radial direction has been measured for the first time [5]. Negative values of the thermal expansion were observed be low 5.5 K. This novel phenomenon is a manifestation of the lowest-frequency part of the vibrational spectrum of nanotubes at low temperatures. The spectrum is characterized by a negative Gruneisen coefficient, which is typical of bending vibrations of two – dimensional systems. As the temperature increases above 5.5 K, the negative values of the thermal expansion typical for two-dimensional systems change into positive ones characteristics of three-dimensional objects.

5. Saturation of nanotube bundles with gas impurities triggers an intensive increase in the radial thermal expansion of bundles of carbon nanotubes, which is attributed to the influence of the gas impurity molecules on the bending vibrations of the system. Because of the geometrical features of SWNT bundles, their saturation with an impurity leads to the formation of one-dimensional chains of the impurity molecules in the grooves of the bundles. This structural reordering of the impurity molecules produces a peak in the temperature dependence of the radial thermal expansion coefficient [6].

6. Experimental evidence has been obtained for the first time which suggests tunneling of 4He and 3He atoms in bundles of single-walled carbon nanotubes [7 8]. This results in a considerable increase in the magnitudes of the negative radial thermal expansion of the 4He-SWNT and 3He-SWNT systems at T<3.7 and 7K, respectively. An unexpectedly large isotopic effect has been observed due to the higher probability of tunneling of 3He atoms.

 

For Graphene Oxide and Reduced Graphene Oxide (GO and RGO). In the investigations of samples, kindly provided by Ana Benito.

7.  Sorption and the subsequent desorption of 4He, H2, Ne, N2, CH4 and Kr gas impurities in a graphene oxide (GO) powder and its modification reduced with glucose (RGO-Gl) and hydrazine (RGO-Hz) have been investigated in temperature interval 2-290 K. The highest effect upon the sorptive properties of the samples was observed in Hz-reduced GO: the total sorptive capacity of RGO-Hz was three to six times higher than that of GO. It is possible that the O2-containing groups were removed in the process of Hz-reduction, which opened the layer spacings for sorption. This assumption is supported by the increased activation energies of RGO-Hz in comparison with GO and RGO-Gl. The Gl-reduction of GO had a little effect on the sorptive properties of the RGO-Gl sample.

8. The measured characteristic times of saturating the GO, RGO-Gl and RGO-Hz samples with impurity particles were used to obtain the temperature dependences of the diffusion coefficients for the impurities specified. It is assumed that the behavior of the temperature dependences of the diffusion coefficients for the investigated impurities in the GO, RGO-Gl and RGO-Hz samples is determined by the competition of the thermally activated and the tunneling mechanisms of diffusion, the contribution of the latter mechanisms being dominant at low temperatures. The tunneling mechanism may account for the weak temperature dependence of the times of impurity sorption at the lowest temperatures of the experiment.

The results obtained point to the importance of the influence of quantum effects upon the structure and properties of new carbon nanomaterials. The above results lead us to expect that a controllable introduction of impurities (including quantum ones) will enable modification of the properties of carbon nanosystems in a wide temperature interval.

 

CONTACT INFORMATION

 

Me:

Dr. Nikolay A. Vinnikov

B.Verkin institute for low temperature physics & engineering,  National Academy of sciences of Ukraine,

 47, Lenin Ave., Kharkov,61103,  Ukraine.

Phone: +38-(057)-341-0979

E-mail: nikolasviltpe@gmail.com, vinnikov@ilt.kharkov.ua

 

Group Leader:

Dr. Alexander Dolbin

 B.Verkin institute for low temperature physics & engineering,  National Academy of sciences of Ukraine,

 47, Lenin Ave., Kharkov,61103,  Ukraine.

Phone: +38-(057)-341-0979

Fax. +38-(057)-340-3370, +38-(057)-345-0593

E-mail: dolbin@ilt.kharkov.ua  

Web pages: http://dolbin.org.ua/en/ ; http://www.ilt.kharkov.ua/bvi/structure/depart_r/d09/dolbin_e.html

 

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