Effect of cubic and planar collective and localized modes on the specific heat of C60 fullerite for 0.2 ≤ T ≤ 300 K

Tewari, Surya P.; Silotia, Poonam; Bera, Kakoli

doi:10.1016/s0038-1098(98)00174-4

Cited by 10 publications

(11 citation statements)

References 17 publications

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“…According to the authors of [45], the discussed hydrophobic bonds are very important for particle absorption on the surface of multi-wall carbon nanotubes. These bonds are so strong, that they cause specific heat increase despite a small amount of C 60 (0.01%) and over two-fold lower values of specific heat for fullerenes [46][47][48] in reference to non-admixed synthetic ester.…”

Section: Synthetic Ester Modified By Fullerene C 60mentioning

confidence: 99%

Electro-Insulating Nanofluids Based on Synthetic Ester and TiO2 or C60 Nanoparticles in Power Transformer

Nadolny

Dombek

2018

Energies

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The article discusses thermal properties of synthetic ester admixed with nanoparticles. The analyzed thermal properties were: thermal conductivity λ, kinematic viscosity υ, density ρ, specific heat cp, and the thermal expansion factor β- all obtained by means of measurements. On the basis of these, the authors calculated the heat transfer factor α, which determines the ability of the liquid to heat transport. The authors used nanoparticles of fullerene C60 and titanium oxide TiO2. The analysis of the thermal properties was done for the temperatures of 25, 40, 60 and 80 °C. The authors analyzed the impact of nanoparticles C60 and TiO2 on thermal properties of synthetic ester. They proved that fullerene C60 in principle had no influence on heat transfer factor α of the ester, while titanium oxide TiO2 had some positive influence on the factor, the value of which increased about 1–3%.

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Section: Synthetic Ester Modified By Fullerene C 60mentioning

confidence: 99%

Electro-Insulating Nanofluids Based on Synthetic Ester and TiO2 or C60 Nanoparticles in Power Transformer

Nadolny

Dombek

2018

Energies

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“…[14], where all the molecules in a crystal were supposed to be in tunnelling states. However, the paper [13] accurately estimates the tunnelling frequency to be about 5.5 K, and the number of tunnelling degrees of freedom to be ∼ 4.8 × 10 −4 (N/60), where N is the number of carbon atoms in a crystal. Obviously, the number of the H oriented molecules is much bigger, and the above mentioned potential barrier between the H and P orientations is too high to provide such a low tunnelling frequency.…”

Section: Introductionmentioning

confidence: 96%

“…For example, the data on heat conductivity [5,6] show a maximum phonon mean free path of about 50 intermolecular spacings, what implies only a 0.02 fraction of scattering ("wrong") molecules. Besides, the negative thermal expansion [7,8] and the linear contribution to the specific heat [9,13] of the fullerite samples at helium temperatures are explained with the help 2 Strictly speaking, the term 'H (or P) configuration' is more adequate for describing a mutual orientation of two neighbouring molecules. Nevertheless, for every chosen pair of neighbouring molecules (let us denote them as A and B) with the fixed directions of allowed rotation axes, the mutual orientation depends strongly only on the rotation angle of one molecule (say, A).…”

Section: Introductionmentioning

confidence: 99%

On the orientational relief of the intermolecular potential and the structure of domain walls in fullerite C60

Khalack

Локтев

2003

Low Temperature Physics

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A simple planar model for an orientational ordering of threefold molecules on a triangular lattice modelling a close-packed (111) plane of fullerite is considered. The system has 3-sublattice ordered ground state which includes 3 different molecular orientations. There exist 6 kinds of orientational domains, which are related with a permutation or a mirror symmetry. Interdomain walls are found to be rather narrow.The model molecules have two-well orientational potential profiles, which are slightly effected by a presence of a straight domain wall. The reason is a stronger correlation between neighbour molecules in triangular lattice versus previously considered square lattice A considerable reduction (up to one order) of orientational interwell potential barrier is found in the core regions of essentially two-dimentional potential defects, such as a threedomain boundary or a kink in the domain wall. For ultimately uncorrelated nearest neighbours the height of the interwell barrier can be reduced even by a factor of 10 2 .

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“…Hydrophobic bonds are important from the point of view of particle absorption on the surface of carbon nanotubes [86]. These bonds are so strong that, despite the small concentration of fullerene in the analyzed liquids (0.1 g•L −1 ) and more than twice the lower values of specific heat [87][88][89], they manage to increase the specific heat of analyzed nanofluids.…”

Section: Thermal Properties Of Electro-insulating Liquids Modified Bymentioning

confidence: 99%

Effects of Nanoparticles Materials on Heat Transfer in Electro-Insulating Liquids

2018

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This paper discusses the effect of doping of electro-insulating liquids with nanoparticle materials on the thermal properties of the obtained nanoliquids and heat transport in the transformer. Mineral oil, synthetic ester, and natural ester were used as base liquids. The effectiveness of doping base liquids with nanoparticles was supported by ultraviolet-visible (UV/VIS) measurements. In turn, Attenuated Total Reflection Fourier Transform Infrared (ATR-FTIR) confirmed the absence of intermolecular interactions (i.e., hydrogen bonding). The influence of modification of electro-insulating liquids with fullerene C60 and titanium dioxide TiO2 nanoparticles on such thermal properties as thermal conductivity, specific heat, kinematic viscosity, density, and thermal expansion was investigated. Based on these properties and the theory of similarity, the cooling efficiency of the transformer filled with the analyzed nanofluids was determined. Nanofluids’ cooling effectiveness was compared with the cooling effectiveness of the base liquids. This comparison was supported by an analysis of Grashof, Prandtl, and Nusselt numbers. It has been shown that the modification of electro-insulating liquids with nanoparticles widely used in order to improve their dielectric properties, such as C60 and TiO2, does not have a significant influence on their thermal properties. The addition of fullerene C60 caused an increase in kinematic viscosity, which was compensated by the increase in specific heat. In the case of TiO2, the addition of this nanoparticle resulted in an increase in kinematic viscosity and a decrease in specific heat, which were balanced out by the increase in thermal conductivity. In summary, the heat exchange-capacity of liquids did not change due to doping with nanoparticles.

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Effect of cubic and planar collective and localized modes on the specific heat of C60 fullerite for 0.2 ≤ T ≤ 300 K

Cited by 10 publications

References 17 publications

Electro-Insulating Nanofluids Based on Synthetic Ester and TiO2 or C60 Nanoparticles in Power Transformer

Electro-Insulating Nanofluids Based on Synthetic Ester and TiO2 or C60 Nanoparticles in Power Transformer

On the orientational relief of the intermolecular potential and the structure of domain walls in fullerite C60

Effects of Nanoparticles Materials on Heat Transfer in Electro-Insulating Liquids

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