scholarly journals Anomalous thermal conductivity and suppression of negative thermal expansion inScF3

2016 ◽  
Vol 94 (2) ◽  
Author(s):  
Ambroise van Roekeghem ◽  
Jesús Carrete ◽  
Natalio Mingo
Keyword(s):  
Thermal Conductivity ◽  
Thermal Expansion ◽  
Negative Thermal Expansion

Primary pyroelectric transition temperatures of binary nitrides (AlN, GaN and InN)

2019 ◽  
Vol 33 (05) ◽  
pp. 1950049
Author(s):  
Muralidhar Swain ◽  
Sushant K. Sahoo ◽  
Bijay K. Sahoo
Keyword(s):  
Thermal Conductivity ◽  
Thermal Expansion ◽  
Thermal Properties ◽  
Transition Temperature ◽  
Negative Thermal Expansion ◽  
Polarization Field ◽  
Piezoelectric Polarization ◽  
Polarization Mechanism ◽  
Prior Literature

The primary pyroelectric transition temperature of wurtzite nitrides (AlN, GaN and InN) has been explored theoretically from their thermal properties. The spontaneous and piezoelectric polarization modifies the thermal conductivity of nitrides. The thermal conductivity [Formula: see text] as a function of temperature including and excluding the polarization mechanism predicts a transition temperature [Formula: see text] between primary and secondary pyroelectric effects. Below [Formula: see text], thermal conductivity including polarization field [Formula: see text] is lesser than thermal conductivity excluding polarization field [Formula: see text]. This is due to negative thermal expansion in binary nitrides below [Formula: see text]; however, above [Formula: see text], [Formula: see text]. [Formula: see text] is significantly contributed by piezoelectric polarization above [Formula: see text] due to thermal expansion which is the reason for the secondary pyroelectric effect. The transition temperature [Formula: see text] for AlN, GaN and InN has been predicted as 100 K, 70 K and 60 K, respectively, which fit well with the prior literature studies. This report proposes that thermal properties’ study can reveal the role of acoustic phonons in pyroelectricity.

Ultralow thermal conductivity and negative thermal expansion of CuSCN

Nano Energy ◽  
2020 ◽  
Vol 73 ◽  
pp. 104822 ◽  
Author(s):  
Yupeng Shen ◽  
Fancy Qian Wang ◽  
Qian Wang
Keyword(s):  
Thermal Conductivity ◽  
Thermal Expansion ◽  
Negative Thermal Expansion

ANOMALOUS LATTICE PROPERTIES OF ZrNiSn CAUSED BY ELECTRON LOCALIZATION

1993 ◽  
Vol 07 (01n03) ◽  
pp. 383-386 ◽  
Author(s):  
F. G. ALIEV ◽  
V. V. PRYADUN ◽  
R. VILLAR ◽  
S. VIEIRA ◽  
J. M. CALLEJA ◽  
...  
Keyword(s):  
Phase Transition ◽  
Thermal Conductivity ◽  
Thermal Expansion ◽  
Seebeck Coefficient ◽  
Raman Spectra ◽  
Negative Thermal Expansion ◽  
Electron Interaction ◽  
Electron Localization ◽  
Conduction Electrons ◽  
Isostructural Phase Transition

Thermal transport (resistivity, Seebeck coefficient, thermal conductivity), thermal expansion and Raman spectra of the intermetallic ordered vacancy compound ZrNiSn was studied. Below T = 100 K an isostructural phase transition was observed. Analyzing ZrNiSn properties, we conclude that this transition is related to freezing of Ni atoms in some of equivalent positions. Conduction electrons, delocalized by increasing order at T < 100 K , show a new localization below 20K. In this range, an anomalous negative thermal expansion, possibly caused by electron-electron interaction was seen.

scholarly journals Current Status of Research on the Modification of Thermal Properties of Epoxy Resin-Based Syntactic Foam Insulation Materials

Polymers ◽  
2021 ◽  
Vol 13 (18) ◽  
pp. 3185
Author(s):  
Zhongyuan Zhang ◽  
Xiaohan Dai ◽  
Le Li ◽  
Songsong Zhou ◽  
Wei Xue ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Thermal Expansion ◽  
Thermal Properties ◽  
Epoxy Resin ◽  
Coefficient Of Thermal Expansion ◽  
Negative Thermal Expansion ◽  
Syntactic Foam ◽  
Research Field ◽  
Current Status ◽  
Insulation Materials

As a lightweight and highly insulating composite material, epoxy resin syntactic foam is increasingly widely used for insulation filling in electrical equipment. To avoid core burning and cracking, which are prone to occur during the casting process, the epoxy resin-based syntactic foam insulation materials with high thermal conductivity and low coefficient of thermal expansion are required for composite insulation equipment. The review is divided into three sections concentrating on the two main aspects of modifying the thermal properties of syntactic foam. The mechanism and models, from the aspects of thermal conductivity and coefficient of thermal expansion, are presented in the first part. The second part aims to better understand the methods for modifying the thermal properties of syntactic foam by adding functional fillers, including the addition of thermally conductive particles, hollow glass microspheres, negative thermal expansion filler and fibers, etc. The third part concludes by describing the existing challenges in this research field and expanding the applicable areas of epoxy resin-based syntactic foam insulation materials, especially cross-arm composite insulation.

Low thermal conductivity of the negative thermal expansion material, HfMo2O8

2007 ◽  
Vol 90 (15) ◽  
pp. 151906 ◽  
Author(s):  
Catherine A. Kennedy ◽  
Mary Anne White ◽  
Angus P. Wilkinson ◽  
Tamas Varga
Keyword(s):  
Thermal Conductivity ◽  
Thermal Expansion ◽  
Negative Thermal Expansion ◽  
Low Thermal Conductivity

Reduced Thermal Conductivity by Low-Frequency Optic Phonons that Give Rise to Negative Thermal Expansion: Opportunities for Thermoelectrics?

2007 ◽  
Vol 1044 ◽  
Author(s):  
Mary Anne White ◽  
Catherine A. Whitman
Keyword(s):  
Thermal Conductivity ◽  
Thermal Expansion ◽  
Electronic Properties ◽  
Thermoelectric Materials ◽  
Negative Thermal Expansion ◽  
Low Frequency ◽  
Acoustic Phonons ◽  
Low Thermal Conductivity ◽  
Efficient Coupling

AbstractWe have recently found that the negative thermal expansion (NTE) materials, ZrW2O8 and HfMo2O8, show exceptionally low thermal conductivity. We surmise that the mechanism is the efficient coupling of the low-frequency optic phonons that give rise to negative thermal expansion with the heat-carrying acoustic phonons. Although neither ZrW2O8 nor HfMo2O8 has suitable electronic properties for thermoelectric applications, perhaps the principle of reduced thermal conductivity by low-frequency optic phonons in NTE materials can be used to develop more efficient thermoelectric materials.

Sign in / Sign up

Export Citation Format

Share Document