A5071701943- Quantum, superfluid, helium dynamics
- Carbon Nanotubes in Composites
- Chemical Thermodynamics and Molecular Structure
- Thermal properties of materials
- High-pressure geophysics and materials
- Graphene research and applications
- Fullerene Chemistry and Applications
- Solid-state spectroscopy and crystallography
- Phase Equilibria and Thermodynamics
- Spectroscopy and Quantum Chemical Studies
- Molecular Spectroscopy and Structure
- Advanced NMR Techniques and Applications
- Thermal and Kinetic Analysis
- Spacecraft and Cryogenic Technologies
- Inorganic Fluorides and Related Compounds
- nanoparticles nucleation surface interactions
- Advanced Chemical Physics Studies
- Atomic and Subatomic Physics Research
- thermodynamics and calorimetric analyses
- Cold Atom Physics and Bose-Einstein Condensates
- Molecular spectroscopy and chirality
- Mechanical and Optical Resonators
- Thermodynamic properties of mixtures
- Hydrogen Storage and Materials
- NMR spectroscopy and applications
B. Verkin Institute for Low Temperature Physics and Engineering of the National Academy of Sciences of Ukraine
2012-2024
National Academy of Sciences of Ukraine
2009-2024
Włodzimierz Trzebiatowski Institute of Low Temperature and Structure Research
2020
Polish Academy of Sciences
2020
Physicotechnical Institute
1977-1994
Physico-Technical Institute
1968-1971
Abstract The thermal capacity of solid nitrogen in the temperature range 2.6 to 15°K is investigated using an adiabatic calorimeter original construction. analysis results this paper and literature data on allow information about character rotational motion molecules crystalline be obtained. so‐called orientation defects give a considerable contribution near (35.6°K) phase transformation. In high‐temperature β‐phase practically free rotation molecule occurs.
Abstract The coefficients of thermal expansion (13 to 139 °K), heat capacity (2 20 and velocity longitudinal transversal ultrasonic waves (88 190 °K) for solid CO 2 have been determined along the solid‐vapour equilibrium line. Heat constant volume, adiabatic isothermal compressibilities, Grüneisen Poisson were calculated using above data. contributions various types motion capacity, compressibility separated, parameters isolated orientational defects in crystalline determined. connection...
The specific heat at constant pressure C(T) of bundles single-walled carbon nanotubes (SWNTs) closed their ends has been investigated in the temperature interval 2–120 K. It is found that curve features near 5, 36, 80, and 100 experimental results on radial thermal expansion coefficient αR(T) SWNTs oriented perpendicular to sample axis have compared. curves exhibit a similar behavior T > 10 dependence Grüneisen γ(T) calculated. also feature 36 Above K practically independent (γ ≈ 4)....
The heat capacity of bundles closed-cap single-walled carbon nanotubes (SWNT) with one-dimensional chains nitrogen molecules adsorbed in the grooves has been first experimentally studied at temperatures from 2K to 40K using an adiabatic calorimeter. contribution C(T) total separated. In region 2-8K behaviour curve is qualitatively similar theoretical prediction phonon 1D krypton (Kr) atoms localized SWNT bundles. Below 3K dependence linear. Above 8K becomes steeper comparison case Kr atoms....
A simple adiabatic calorimeter has been built to investigate the heat capacity of small (≤1 cm3) samples carbon nanomaterials at temperatures ranging from 1 300 K. It enables (i) rapid mounting (ii) doping with gases directly in calorimeter, and (iii) cooling liquid helium temperatures. can be placed vessel a portable Dewar or cryostat. The fullerite sample is measured temperature range 1–30
The experimental studies of the heat capacity 1D chains xenon atoms adsorbed in outer grooves bundles closed single-walled carbon nanotubes CXe have been first made at temperature range 2–30 K with adiabatic calorimeter. data compared theory [A. Šiber, Phys. Rev. B 66, 235414 (2002)]. and theoretical curves are close below 8 K. Above curve CXe(T) exceeds one excess ΔCXe(T) increases monotonously temperature. We assume that caused mainly by increase distance between neighboring chain increasing
DSC and calorimetric studies of multi-walled carbon nanotubes (MWCNTs) with average diameters in the range 7, 9 18 nm were carried out. MWCNTs obtained by CVD method. The kinetic processes studied from room temperature to 550 °C a nitrogen flow using differential scanning calorimetry (DSC) on Perkin – Elmer — 8000. It was found that exo- endothermic peaks are not observed curves after water evaporation. This indicates all have small number defects, functional groups, other impurities. heat...
The heat capacity at constant pressure of fullerite C60 has been investigated using an adiabatic calorimeter in a temperature range from 1.2 to 120 K. Our results and literature data have analyzed interval 0.2 300 contributions the intramolecular lattice vibrations into separated. contribution vibration becomes significant above 50 Below 2.3 K experimental dependence is described by linear cubic terms. limiting Debye T→0 estimated (Θ0 = 84.4 K). In 30 curve describes rotational tunnel...
Abstract The heat capacity of solid tetrafluoromethane has been measured in the temperature range 2 to 20 °K. analysis results this paper and literature data on allow make conclusions about character motion molecules crystalline CF 4 . An “extra” near phase transformation T λ = 76.09 °K is due orientational disordering. dependence Δ C or well described by logarithmic function ∼ lg ∼|– | λ|.
The heat capacity at constant pressure CP of 1D-chains methane molecules adsorbed in the grooves on outer surface bundles closed single-walled nanotubes was measured temperature range from 2 to 60 K for first time. behavior dependence below 12 indicates presence a Schottky-type anomaly originated tunneling between lowest energy levels rotational spectra A, T, and E nuclear-spin species molecules. feature observed vicinity 14 is presumably caused by an orientational phase transition, which...
Measurements of heat capacity at constant pressure thermally reduced graphene oxide (trGO) and graphite (GtO) were performed in the temperature range from 1.8 to 275 K by thermal relaxation method. Above 15 K, specific values trGO GtO are close each other within 20%. Below 10 ratio increases with decreasing reaches 5 2 K. It was found that dependence is a complex character. There ranges which either linear or T2.5.
The heat capacity of Kr–nCH4 solid solutions with the concentrations n=1; 5; 10% and solution Kr–1% CH4–0.2% O2 is studied at 0.7–8 K. contributions Crot to due rotation CH4 molecules are estimated. deviations measured from values corresponding equilibrium distribution nuclear spin modifications dependent on correlation between characteristic times conversion calorimetric experiment. effects temperature, impurities, clusters upon rate studied. It shown that hybrid mechanism proposed by...
The heat capacity C of fullerite doped with deuteromethane (CD4)0.4(C60) has been investigated in the temperature interval 1.2–120 K. contribution ΔCCD4 CD4 molecules to isolated. It is shown that at T ≈ 120 K rotational motion octahedral voids C60 lattice weakly hindered. When lowered 80 K, changes from hindered rotation libration. In range = 1.2–30 described quite accurately by sum contributions translational and librational vibrations tunneling molecules. ΔCCD4(T) dominant below 5 effect...
The low-temperature heat capacity of cryocrystals containing impurity clusters is investigated theoretically and experimentally. Such defects might essentially enrich the low-frequency part phonon spectrum by introducing both localized delocalized vibrations. effect types vibrations on temperature dependence analyzed. disordered solid solution Kr–Ar (Ar concentration ∼25%) studied as an example light, weakly coupled impurities thermodynamic characteristics a system. mass defect such induces...
The heat capacity of the interstitial solid solution (CH4)0.4C60 has been investigated in temperature interval 1.4–120 K. contribution CH4 molecules to separated. contributions and CD4 solutions (CH4)0.40C60 (CD4)0.40C60 have compared. It is found that above 90 K character rotational motion changes from libration hindered rotation. In 14–35 capacities are satisfactorily described by translational vibrations, as well tunnel rotation for equilibrium distribution nuclear spin species. isotope...
The heat capacity of the solid solutions (CD4)0.05Kr0.95 and (CD4)0.05Kr0.948(O2)0.002 are investigated in temperature interval 0.7–1.6 K. contribution to from rotational subsystem is separated out. Conversion between A T nuclear spin species CD4 detected. It shown that unconcentrated methane isotopes krypton rate conversion larger for deuteromethane molecules than molecules.