Synthesis, properties, application of nanosized powders of oxides and hydroxides. Cluster model of water state on their surface

The work is devoted to the development of the physicochemical foundations of the processes of obtaining powders of oxides and hydroxides, including aluminum, magnesium, calcium, and silicon with a given shape, size, impurity and phase composition, low thermal conductivity, etc., by methods of pyrolysis of a polymer matrix and hydrothermal treatment element-containing precursors, as well as the creation of a mechanism that allows describing the phase transformations of powders of oxides and hydroxides and reveals the role of water clusters with a low heat of vaporization in phase transformations.

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Lattice Thermal Conductivity Modelling of a Diatomic Nanoscale Material

Nanoscience &Nanotechnology-Asia ◽

10.2174/2210681209666190423142040 ◽

2020 ◽

Vol 10 (5) ◽

pp. 602-609

Author(s):

Adil H. Awad

Keyword(s):

Thermal Conductivity ◽

Lattice Thermal Conductivity ◽

Phonon Scattering ◽

Correction Term ◽

Nanoscale Material ◽

New Approach ◽

Two Samples ◽

Conductivity Modelling ◽

Callaway Model

Introduction: A new approach for expressing the lattice thermal conductivity of diatomic nanoscale materials is developed. Methods: The lattice thermal conductivity of two samples of GaAs nanobeam at 4-100K is calculated on the basis of monatomic dispersion relation. Phonons are scattered by nanobeam boundaries, point defects and other phonons via normal and Umklapp processes. Methods: A comparative study of the results of the present analysis and those obtained using Callaway formula is performed. We clearly demonstrate the importance of the utilised scattering mechanisms in lattice thermal conductivity by addressing the separate role of the phonon scattering relaxation rate. The formulas derived from the correction term are also presented, and their difference from Callaway model is evident. Furthermore their percentage contribution is sufficiently small to be neglected in calculating lattice thermal conductivity. Conclusion: Our model is successfully used to correlate the predicted lattice thermal conductivity with that of the experimental observation.

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High thermal conductivity of pure dense SiC ceramics prepared via HTPVT

Functional Materials Letters ◽

10.1142/s1793604719500322 ◽

2019 ◽

Vol 12 (03) ◽

pp. 1950032 ◽

Cited By ~ 2

Author(s):

Yuchen Deng ◽

Yaming Zhang ◽

Nanlong Zhang ◽

Qiang Zhi ◽

Bo Wang ◽

...

Keyword(s):

Thermal Conductivity ◽

Silicon Carbide ◽

Grain Size ◽

Phase Composition ◽

Room Temperature ◽

Vapor Transport ◽

Physical Vapor Transport ◽

Growth Substrate ◽

Sic Ceramics ◽

Evolution Of Microstructure

Pure dense silicon carbide (SiC) ceramics were obtained via the high-temperature physical vapor transport (HTPVT) method using graphite paper as the growth substrate. The phase composition, the evolution of microstructure, the thermal diffusivity and thermal conductivity at RT to 200∘C were investigated. The obtained samples had a relative density of higher than 98.7% and a large grain size of 1[Formula: see text]mm, the samples also had a room-temperature thermal conductivity of [Formula: see text] and with the temperature increased to 200∘C, the thermal conductivity still maintained at [Formula: see text].

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Role of Compressive Viscosity and Thermal Conductivity on the Damping of Slow Waves in Coronal Loops with and Without Heating–Cooling Imbalance

Solar Physics ◽

10.1007/s11207-021-01764-x ◽

2021 ◽

Vol 296 (1) ◽

Author(s):

Abhinav Prasad ◽

A. K. Srivastava ◽

T. J. Wang

Keyword(s):

Thermal Conductivity ◽

Slow Waves ◽

Coronal Loops

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Microscopic Insights into Water Adsorption in Carbon Nanopore – The Role of Acidic and Basic Functional Groups and their Configurations

Physical Chemistry Chemical Physics ◽

10.1039/d1cp02308j ◽

2021 ◽

Author(s):

Lumeng Liu ◽

Wenmao Zeng ◽

Shiliang Johnathan Tan ◽

Meng Liu ◽

Duong Do

Keyword(s):

Functional Groups ◽

Porous Carbon ◽

Water Adsorption ◽

Water Clusters ◽

Pivotal Role

Functional groups (FGs) in porous carbon play a pivotal role in water adsorption by nucleating water clusters followed by their coalescence, the process for which is the precursor for the...

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Role of electron–phonon coupling in thermal conductivity of metallic nanofluids

Journal of Physics D Applied Physics ◽

10.1088/1361-6463/ab3aac ◽

2019 ◽

Vol 52 (48) ◽

pp. 485302 ◽

Cited By ~ 1

Author(s):

Dong-Xing Song ◽

Yu-Feng Zhang ◽

Wei-Gang Ma ◽

Xing Zhang

Keyword(s):

Thermal Conductivity ◽

Phonon Coupling ◽

Electron Phonon Coupling

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Internal melt figures in ice by rapid adiabatic compression

Journal of Glaciology ◽

10.3189/s0022143000003890 ◽

1994 ◽

Vol 40 (134) ◽

pp. 132-134

Author(s):

R.E. Gagnon ◽

C. Tulk ◽

H. Kiefte

Keyword(s):

Phase Transformations ◽

Grain Boundaries ◽

Single Crystals ◽

Adiabatic Compression ◽

Air Bubbles ◽

Water Ice ◽

Deep Focus ◽

And Behavior ◽

First Time

AbstractSingle crystals and bicrystals of water ice have been adiabatically pressurized to produce, and clearly illustrate, two types of internal melt figures: (1) dendritic figures that grow from nucleation imperfections on the specimen’s surface, or from air bubbles at grain boundaries, into the ice as pressure is elevated; and (2) compression melt fractures, flat liquid-filled disks, that nucleate at imperfections in the crystal and grow with the application of pressure eventually to sprout dendritic fingers at the periphery. The transparency of the ice permitted visualization of the growth and behavior of the figures, and this could be an important tool in understanding the role of phase transformations in deep-focus earthquakes. Correlation between figure size and pressure is noted for the first time.

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Microstructure and magnetic properties of Nd-Fe-B-(Re, Ti) alloys

Nukleonika ◽

10.1515/nuka-2015-0008 ◽

2015 ◽

Vol 60 (1) ◽

pp. 29-33

Author(s):

Mariusz Hasiak

Keyword(s):

Magnetic Properties ◽

Phase Composition ◽

Volume Fraction ◽

Magnetic Characteristics ◽

Ti Alloys ◽

Wide Range ◽

Magnetically Hard ◽

Ti Addition ◽

Microstructure And Magnetic Properties

Abstract The microstructure and magnetic properties of nanocomposite hard magnetic Nd-Fe-B-(Re, Ti) materials with different Nd and Fe contents are studied. The role of Re and Ti addition in phase composition and volume fraction of the Nd-Fe-B phase is determined. All samples are annealed at the same temperature of 993 K for 10 min. Mössbauer spectroscopy shows that the addition of 4 at.% of Re to the Nd8Fe78B14 alloy leads to creation of an ineligible amount of the magnetically hard Nd2Fe14B phase. Moreover, the microstructure and magnetic characteristics recorded in a wide range of temperatures for the Nd8Fe79−xB13Mx (x = 4; M = Re or Ti) alloys are also analyzed.

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