Thermal Diffusivity and Conductivity of La0.7Ca0.3-xSrxMnO3 (x=0 to 0.10)

2012 ◽  
Vol 501 ◽  
pp. 319-323
Author(s):  
Hasan A. Alwi ◽  
Lay S. Ewe ◽  
Zahari Ibrahim ◽  
Noor B. Ibrahim ◽  
Roslan Abd-Shukor
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Grain Size ◽  
Transition Temperature ◽  
Thermal Diffusivity ◽  
Electrical Properties ◽  
Room Temperature ◽  
Electronic Contribution ◽  
Insulator Metal Transition ◽  
Thermal And Electrical Properties

We report the room temperature thermal conductivity κ and thermal diffusivity α of polycrystalline La0.7Ca0.3-xSrxMnO3 for x = 0 to 0.1. The samples were prepared by heating at 1220 and 1320oC. The insulator-metal transition temperature, TIM and thermal diffusivity increased with Sr content. Phonon was the dominant contributor to thermal conductivity and the electronic contribution was less than 1%. Enhancement of electrical conductivity σ and thermal diffusivity for x ≥ 0.08 was observed in both series of samples. The grain size of the samples (28 to 46 µm) does not show any affect on the thermal and electrical properties.

THERMAL AND ELECTRICAL PROPERTIES OF ARMCO IRON AT HIGH TEMPERATURES

1960 ◽  
Vol 38 (7) ◽  
pp. 887-907 ◽  
Author(s):  
M. J. Laubitz
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Thermal Expansion ◽  
Electrical Properties ◽  
High Temperatures ◽  
Curie Point ◽  
Armco Iron ◽  
Discontinuous Change ◽  
Thermal And Electrical Properties

Thermal and electrical conductivity, thermoelectric power vs. platinum, and thermal expansion of Armco iron were determined in the temperature range of 0 °C to 1000 °C. All these properties show a discontinuous change at the α–γ transition of iron, and a change in slope at the Curie point. These measurements were carried out as a contribution to a co-operative determination of thermal conductivity of Armco iron at high temperatures.

scholarly journals Enhanced Thermal and Electrical Properties of Polystyrene-Graphene Nanofibers via Electrospinning

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Yan Li ◽  
Harshit Porwal ◽  
Zhaohui Huang ◽  
Han Zhang ◽  
Emiliano Bilotti ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Electrical Properties ◽  
Physical Properties ◽  
Morphological Analysis ◽  
Composite Nanofibers ◽  
Fold Increase ◽  
Fiber Formation ◽  
Liquid Exfoliation ◽  
Thermal And Electrical Properties

Polystyrene- (PS-) graphene nanoplatelets (GNP) (0.1, 1, and 10 wt.%) nanofibers were successfully produced via electrospining of dimethyformamide- (DMF-) stabilized GNP and PS solutions. Morphological analysis of the composite nanofibers confirmed uniform fiber formation and good GNP dispersion/distribution within the PS matrix. The good physical properties of GNP produced by liquid exfoliation were transferred to the PS nanofibers. GNP modified PS nanofibers showed a 6-fold increase in the thermal conductivity and an increase of 7-8 orders of magnitude in electrical conductivity of the nanofibers at 10 wt.% GNP loading.

Grain size-induced enhancement of thermoelectric performance of Cu3Sb1−xInxSe4 materials

2021 ◽  
pp. 2151026
Author(s):  
Lin Bo ◽  
Wen-Ying Wang ◽  
Yong-Peng Wang ◽  
Lei Wang ◽  
Fu-Jin Li ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Grain Size ◽  
Ball Milling ◽  
Temperature Region ◽  
Hot Pressing ◽  
Room Temperature ◽  
Powder Processing ◽  
Thermoelectric Performance ◽  
In Doping

The ternary Cu3SbSe4 thermoelectric material with diamond-like structure exhibits good thermoelectric performance in the middle temperature region. In this study, the Cu3Sb[Formula: see text]In[Formula: see text]Se4 ([Formula: see text]= 0–0.03) materials were fabricated by melting-annealing-ball milling-hot pressing process. The influences of In-doping and grain size on the microstructure and thermoelectric properties of Cu3Sb[Formula: see text]In[Formula: see text]Se4 were evaluated. It is found that the electricity conduction at room temperature for Cu3Sb[Formula: see text]In[Formula: see text]Se4 sample was significantly increased to 6.1 × 103Sm[Formula: see text] due to the In-doping. Additionally, during the powder processing, a relatively low thermal conductivity for the refinement Cu3Sb[Formula: see text]In[Formula: see text]Se4-BM-72H sample was obtained. Benefiting from the enhanced electrical conductivity and the decreased thermal conductivity, the maximum zT value of 0.75 was achieved for Cu3Sb[Formula: see text]In[Formula: see text]Se4-BM-36H at 650 K.

Microstructure, Thermal and Electrical Properties of Ultrafine Aluminium

2011 ◽  
Vol 465 ◽  
pp. 326-329
Author(s):  
Kinga Rodak ◽  
Grzegorz Moskal ◽  
Andrzej Grabowski
Keyword(s):  
Electrical Conductivity ◽  
Thermal Diffusivity ◽  
Electrical Properties ◽  
Electrical Impedance ◽  
Laser Flash ◽  
Flash Method ◽  
Misorientation Distribution ◽  
Thermal And Electrical Properties ◽  
Ebsd Technique ◽  
Electron Back Scattered Diffraction

In article the influence of large effective deformation on microstructure, thermal diffusivity and electrical conductivity is described. The tested material was monocrystalline aluminum deformed by the cyclic extrusion compression (CEC) method. The evolution of misorientation distribution, sub(grain) size was determined by using electron back scattered diffraction (EBSD) technique. The second part of the study was to evaluation of thermal diffusivity by using the laser-flash method. The LFA 427 laser-flash facility were applied. The electrical properties as electrical impedance was made by impedance bridge RLC type. The obtained results show that with increase of deformation the insignificant decrease in thermal diffusivity and electrical conductivity occurred.

High thermal conductivity of pure dense SiC ceramics prepared via HTPVT

2019 ◽  
Vol 12 (03) ◽  
pp. 1950032 ◽  
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].

scholarly journals Effect of Grain Size and Film Thickness on the Thermoelectric Properties of Flexible Sb2Te3 Thin Films

2019 ◽  
Vol 2019 ◽  
pp. 1-7 ◽  
Author(s):  
Pornsiri Wanarattikan ◽  
Piya Jitthammapirom ◽  
Rachsak Sakdanuphab ◽  
Aparporn Sakulkalavek
Keyword(s):  
Thin Films ◽  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Grain Size ◽  
Film Thickness ◽  
Seebeck Coefficient ◽  
Thermoelectric Properties ◽  
Flexible Substrate ◽  
Rf Magnetron Sputtering ◽  
Mean Free Path

In this work, stoichiometric Sb2Te3 thin films with various thicknesses were deposited on a flexible substrate using RF magnetron sputtering. The grain size and thickness effects on the thermoelectric properties, such as the Seebeck coefficient (S), electrical conductivity (σ), power factor (PF), and thermal conductivity (k), were investigated. The results show that the grain size was directly related to film thickness. As the film thickness increased, the grain size also increased. The Seebeck coefficient and electrical conductivity corresponded to the grain size of the films. The mean free path of carriers increases as the grain size increases, resulting in a decrease in the Seebeck coefficient and increase in electrical conductivity. Electrical conductivity strongly affects the temperature dependence of PF which results in the highest value of 7.5 × 10−4 W/m·K2 at 250°C for film thickness thicker than 1 µm. In the thermal conductivity mechanism, film thickness affects the dominance of phonons or carriers. For film thicknesses less than 1 µm, the behaviour of the phonons is dominant, while both are dominant for film thicknesses greater than 1 µm. Control of the grain size and film thickness is thus critical for controlling the performance of Sb2Te3 thin films.

scholarly journals Phonon hydrodynamics and ultrahigh–room-temperature thermal conductivity in thin graphite

Science ◽  
2020 ◽  
Vol 367 (6475) ◽  
pp. 309-312 ◽  
Author(s):  
Yo Machida ◽  
Nayuta Matsumoto ◽  
Takayuki Isono ◽  
Kamran Behnia
Keyword(s):  
Thermal Conductivity ◽  
Thermal Diffusivity ◽  
Wide Temperature Range ◽  
Room Temperature ◽  
Phonon Dispersion ◽  
High Conductivity ◽  
Temperature Range ◽  
A Value ◽  
Out Of Plane ◽  
Intimate Link

Allotropes of carbon, such as diamond and graphene, are among the best conductors of heat. We monitored the evolution of thermal conductivity in thin graphite as a function of temperature and thickness and found an intimate link between high conductivity, thickness, and phonon hydrodynamics. The room-temperature in-plane thermal conductivity of 8.5-micrometer-thick graphite was 4300 watts per meter-kelvin—a value well above that for diamond and slightly larger than in isotopically purified graphene. Warming enhances thermal diffusivity across a wide temperature range, supporting partially hydrodynamic phonon flow. The enhancement of thermal conductivity that we observed with decreasing thickness points to a correlation between the out-of-plane momentum of phonons and the fraction of momentum-relaxing collisions. We argue that this is due to the extreme phonon dispersion anisotropy in graphite.

scholarly journals Synthesis of AG Nanocrystal/Few-Layer Graphite Nanoplatelet Composites

2018 ◽  
Vol 27 (2) ◽  
pp. 096369351802700
Author(s):  
Shasha li ◽  
Nailiang Liu ◽  
Changqing Fang
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Grain Size ◽  
Electroless Plating ◽  
Organic Materials ◽  
Treatment Results ◽  
Plating Method ◽  
Distinct Boundary ◽  
Electroless Plating Method

The present study focuses on improving the combination of graphite nanoplatelet (GNP) with other organic materials without reducing its properties. An Ag nanocrystal was synthesized by electroless plating method under sonication at 40 °C, which was coated densely onto few-layer GNP and hexagon-slice GNP that was found during GNP treatment. Results illustrated that the Ag nanocrystal had uniform grain size and distinct boundary covered onto GNP. The thermal conductivity of the Ag nanocrystal /few-layer GNP (Ag/GNP) composite was superior to that of the GNP material. In addition, the Ag/GNP composite exhibited excellent electrical conductivity.

Reinvestigation the Thermal and Electrical Transport Properties of Tl7Sb2

2013 ◽  
Vol 802 ◽  
pp. 284-288
Author(s):  
Anek Charoenphakdee ◽  
Adul Harnwangmuang ◽  
Tosawat Seetawan ◽  
Chesta Ruttanapun ◽  
Vittaya Amornkitbamrung ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Transport Properties ◽  
Electrical Transport ◽  
Room Temperature ◽  
Lattice Parameter ◽  
Electronic Contribution ◽  
Electrical Transport Properties ◽  
Space Group ◽  
Crystal System ◽  
Thallium Compounds

The authors examined the thermal and electrical transport properties of Tl7Sb2 at temperatures ranging from room temperature to 400 K. The crystal system of Tl7Sb2 is cubic with the lattice parameter a = 1.16053 nm and the space group is Im3m. The polycrystalline samples were prepared by melting stoichiometric amounts of thallium and antimony. Although, usually the thermal conductivity of thallium compounds is very low (<1 Wm-1K-1), that of Tl7Sb2 was relatively high (~13 Wm-1K-1 at room temperature). This is because of the large electronic contribution to the thermal conductivity.

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