Composition dependent phase transition and its induced hysteretic effect in the thermal conductivity of WxMo1−xTe2

2017 ◽  
Vol 110 (21) ◽  
pp. 211904 ◽  
Author(s):  
Xue-Jun Yan ◽  
Yang-Yang Lv ◽  
Lei Li ◽  
Xiao Li ◽  
Shu-Hua Yao ◽  
...  
Keyword(s):  
Phase Transition ◽  
Thermal Conductivity ◽  
Hysteretic Effect

scholarly journals The origin of the lattice thermal conductivity enhancement at the ferroelectric phase transition in GeTe

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Đorđe Dangić ◽  
Olle Hellman ◽  
Stephen Fahy ◽  
Ivana Savić
Keyword(s):  
Phase Transition ◽  
Thermal Conductivity ◽  
Phase Transitions ◽  
Thermoelectric Materials ◽  
Ferroelectric Phase Transition ◽  
Lattice Thermal Conductivity ◽  
Ferroelectric Phase ◽  
Structural Phase ◽  
High Symmetry ◽  
Structural Phase Transitions

AbstractThe proximity to structural phase transitions in IV-VI thermoelectric materials is one of the main reasons for their large phonon anharmonicity and intrinsically low lattice thermal conductivity κ. However, the κ of GeTe increases at the ferroelectric phase transition near 700 K. Using first-principles calculations with the temperature dependent effective potential method, we show that this rise in κ is the consequence of negative thermal expansion in the rhombohedral phase and increase in the phonon lifetimes in the high-symmetry phase. Strong anharmonicity near the phase transition induces non-Lorentzian shapes of the phonon power spectra. To account for these effects, we implement a method of calculating κ based on the Green-Kubo approach and find that the Boltzmann transport equation underestimates κ near the phase transition. Our findings elucidate the influence of structural phase transitions on κ and provide guidance for design of better thermoelectric materials.

scholarly journals Variation of thermal conductivity of DPPC lipid bilayer membranes around the phase transition temperature

2017 ◽  
Vol 14 (130) ◽  
pp. 20170127 ◽  
Author(s):  
Sina Youssefian ◽  
Nima Rahbar ◽  
Christopher R. Lambert ◽  
Steven Van Dessel
Keyword(s):  
Phase Transition ◽  
Thermal Conductivity ◽  
Thermal Properties ◽  
Transition Temperature ◽  
Lipid Bilayer ◽  
Lipid Bilayers ◽  
Phase Transition Temperature ◽  
Temperature Gradients ◽  
Phase Behaviour ◽  
Gel Phase

Given their amphiphilic nature and chemical structure, phospholipids exhibit a strong thermotropic and lyotropic phase behaviour in an aqueous environment. Around the phase transition temperature, phospholipids transform from a gel-like state to a fluid crystalline structure. In this transition, many key characteristics of the lipid bilayers such as structure and thermal properties alter. In this study, we employed atomistic simulation techniques to study the structure and underlying mechanisms of heat transfer in dipalmitoylphosphatidylcholine (DPPC) lipid bilayers around the fluid–gel phase transformation. To investigate this phenomenon, we performed non-equilibrium molecular dynamics simulations for a range of different temperature gradients. The results show that the thermal properties of the DPPC bilayer are highly dependent on the temperature gradient. Higher temperature gradients cause an increase in the thermal conductivity of the DPPC lipid bilayer. We also found that the thermal conductivity of DPPC is lowest at the transition temperature whereby one lipid leaflet is in the gel phase and the other is in the liquid crystalline phase. This is essentially related to a growth in thermal resistance between the two leaflets of lipid at the transition temperature. These results provide significant new insights into developing new thermal insulation for engineering applications.

Effect of thermal conductivity of substrate on laser‐induced phase transition of MoTe 2

2019 ◽  
Vol 50 (5) ◽  
pp. 755-761 ◽  
Author(s):  
Zhirong Chen ◽  
Haiyan Nan ◽  
Zheng Liu ◽  
Xiaoya Wang ◽  
Xiaofeng Gu ◽  
...  
Keyword(s):  
Phase Transition ◽  
Thermal Conductivity

Giant room-temperature barocaloric effect at the electronic phase transition in Ni1−xFexS

2020 ◽  
Vol 7 (10) ◽  
pp. 2690-2695
Author(s):  
Jianchao Lin ◽  
Peng Tong ◽  
Xuekai Zhang ◽  
Zichen Wang ◽  
Zhao Zhang ◽  
...  
Keyword(s):  
Phase Transition ◽  
Thermal Conductivity ◽  
Room Temperature ◽  
High Thermal Conductivity ◽  
Electronic Phase ◽  
Electronic Entropy

The electronic entropy enhanced giant barocaloric effect along with high thermal conductivity in hexagonal Ni1−xFexS.

scholarly journals Study of the Comparative Effect of Sintering Methods and Sintering Additives on the Microstructure and Performance of Si3N4 Ceramic

Materials ◽  
2019 ◽  
Vol 12 (13) ◽  
pp. 2142 ◽  
Author(s):  
Liangliang Yang ◽  
Allah Ditta ◽  
Bo Feng ◽  
Yue Zhang ◽  
Zhipeng Xie
Keyword(s):  
Phase Transition ◽  
Thermal Conductivity ◽  
Fracture Toughness ◽  
Relative Density ◽  
Transition Rate ◽  
Bending Strength ◽  
Si3n4 Ceramic ◽  
Sintering Additives ◽  
The Difference ◽  
And Performance

The Si3N4 ceramics were prepared in this study by gas pressure sintering (GPS) and spark plasma sintering (SPS) techniques, using 5 wt.% Yb2O3–2 wt.% Al2O3 and 5 wt.% CeO2–2 wt.% Al2O3 as sintering additives. Based on the difference in sintering methods and sintering additive systems, the relative density, phase composition, phase transition rate, microstructure, mechanical properties, and thermal conductivity were comparatively investigated and analyzed. SPS proved to be more efficient than GPS, producing higher relative density, bending strength, hardness, and thermal conductivity of Si3N4 ceramic with both additive systems; however, the phase transition rate and fracture toughness were lower. Similarly, higher bending strength, hardness, and thermal conductivity were achieved with Yb2O3–Al2O3 than CeO2–Al2O3 in the case of GPS and SPS, and only the relative density, fracture toughness, and phase transition rate were lower.

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