scholarly journals Reduction of Thermal Conductivity for Icosahedral Al-Cu-Fe Quasicrystal through Heavy Element Substitution

Materials ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5238
Author(s):  
Yoshiki Takagiwa ◽  
Ryota Maeda ◽  
Satoshi Ohhashi ◽  
An-Pang Tsai
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Specific Heat ◽  
Heavy Element ◽  
Phonon Thermal Conductivity ◽  
Element Substitution ◽  
Sample Composition ◽  
Chemical Disorder ◽  
Phonon Relaxation Time ◽  
Type Conduction

Icosahedral Al-Cu-Fe quasicrystal (QC) shows moderate electrical conductivity and low thermal conductivity, and both p- and n-type conduction can be controlled by tuning the sample composition, making it potentially suited for thermoelectric materials. In this work, we investigated the effect of introducing chemical disorder through heavy element substitution on the thermal conductivity of Al-Cu-Fe QC. We substituted Au and Pt elements for Cu up to 3 at% in a composition of Al63Cu25Fe12, i.e., Al63Cu25−x(Au,Pt)xFe12 (x = 0, 1, 2, 3). The substitutions of Au and Pt for Cu reduced the phonon thermal conductivity at 300 K (κph,300K) by up to 17%. The reduction of κph,300K is attributed to a decrease in the specific heat and phonon relaxation time through heavy element substitution. We found that increasing the Pt content reduced the specific heat at high temperatures, which may be caused by the locked state of phasons. The observed glass-like low values of κph,300K (0.9–1.1 W m−1 K−1 at 300 K) for Al63Cu25−x(Au,Pt)xFe12 are close to the lower limit calculated using the Cahill model.

Thermoelectric Properties of Ag1-xPbmSbTe2+m Compounds

2007 ◽  
Vol 336-338 ◽  
pp. 854-856
Author(s):  
Yong Gao Yan ◽  
Xin Feng Tang ◽  
Hai Jun Liu ◽  
Ling Ling Yin ◽  
Qing Jie Zhang
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Seebeck Coefficient ◽  
Spark Plasma Sintering ◽  
Thermoelectric Properties ◽  
M 10 ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Type Conduction

Ag1-xPbmSbTe2+m (m = 6, 10, 18; x = 0, 0.5, 0.75) compounds were prepared by melting-spark plasma sintering (SPS) process. The effects of m and x on the thermoelectric properties of the compounds were investigated. The results indicate that all samples are n-type conduction. For Ag1-xPb18SbTe20 (x = 0, 0.5, 0.75), the electrical conductivity decreases, whereas Seebeck coefficient increases, with increasing Ag concentration. For AgPbmSbTe2+m (m = 6, 10, 18), as m increases, the Seebeck coefficient slightly decreases and the electrical conductivity increases first, with a maximum at m =10, and then decreases. The thermal conductivity increases with increasing m.

Wärmeleitfähigkeit, elektrische Leitfähigkeit, Hall-Effekt, Thermospannung und spezifische Wärme von Ag2Se

1962 ◽  
Vol 17 (10) ◽  
pp. 886-889 ◽  
Author(s):  
Y. Baer ◽  
G. Busch ◽  
C. Fröhlich ◽  
E. Steigmeier
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Low Temperature ◽  
Specific Heat ◽  
Thermoelectric Power ◽  
Hall Coefficient ◽  
A Value ◽  
Price Formula ◽  
Elektrische Leitfähigkeit ◽  
Increasing Temperature

The thermal conductivity, electrical conductivity. Hall coefficient und thermoelectric power of Ag2Se have been measured between 80 and 600°K. In the low temperature semiconductor phase the thermal conductivity increases with increasing temperature due to the high amount of carrier contribution. The latter has been calculated using the Price formula. Agreement with experiment is satisfactory. The specific heat has been measured between 30 and 200°C. For the latent heat a value of (5.7 ± 0.5) cal/gr was determined in agreement with measurements of Bellati and Lussana 4. In addition to the transition at 133 °C an unknown new transition has been found at about 90 °C.

scholarly journals Влияние мультиплетных уровней Sm-=SUP=-3+-=/SUP=- и Eu-=SUP=-3+-=/SUP=- на теплоемкость мультиферроика BiFeO-=SUB=-3-=/SUB=-

2021 ◽  
Vol 63 (6) ◽  
pp. 763
Author(s):  
Р.Г. Митаров ◽  
С.Н. Каллаев ◽  
З.М. Омаров ◽  
О.М. Назарова ◽  
Л.А. Резниченко
Keyword(s):  
Thermal Conductivity ◽  
Heat Capacity ◽  
Rare Earth ◽  
Specific Heat ◽  
Temperature Dependence ◽  
Bismuth Ferrite ◽  
Rare Earth Ions ◽  
Phonon Thermal Conductivity ◽  
Additional Heat ◽  
Schottky Effect

The temperature dependence of the heat capacity of the multiferroics BiFeO3, Bi0.90Sm0.10FeO3, and Bi0.90Eu0.10FeO3 has been studied. It was found that the substitution of europium and samarium ions for bismuth ions in bismuth ferrite leads to the appearance of an additional heat capacity component due to transitions of 4f - electrons of rare earth ions to higher levels of the multiplet. A connection is established between the decrease in phonon thermal conductivity and the Schottky effect for the specific heat.

High Temperature Thermoelectric Property of Sr-Filled Skutterudite SryCo4Sb12

2007 ◽  
Vol 336-338 ◽  
pp. 842-845
Author(s):  
Xue Ying Zhao ◽  
Xun Shi ◽  
Li Dong Chen ◽  
Sheng Qiang Bai ◽  
Wen Bing Zhang ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Chemical Composition ◽  
Seebeck Coefficient ◽  
Figure Of Merit ◽  
Thermoelectric Figure ◽  
Filled Skutterudite ◽  
Absolute Value ◽  
Homogeneous Chemical ◽  
Type Conduction

Sr-filled skutterudite compounds SryCo4Sb12 (y=0-0.20) were synthesized by melting method. XRD and EPMA results revealed that the obtained samples are single skutterudite phase with homogeneous chemical composition. The lattice parameters increase linearly with increasing Sr content in the range of y=0-0.20. The thermal conductivity, electrical conductivity and Seebeck coefficient were measured in the temperature range of 300-850K. The measurement of Hall effect was performed by Van de Pauw method at room temperature. The obtained Sr-filled skutterudite exhibits n-type conduction. The absolute value of the Seebeck coefficient of SryCo4Sb12 decreases with the increase of Sr content. The electrical conductivity increases with the increase of Sr content. The lattice thermal conductivity of SryCo4Sb12 is significantly depressed as compared with unfilled CoSb3. The maximum dimensionless thermoelectric figure of merit is 0.7 for Sr0.20Co4Sb12 at 850K. Further optimization of chemical composition would improve the thermoelectric performance.

scholarly journals Thermal Conductivity of Cu-Cr-Zr-Ti Alloy in the Temperature Range of 300–873 K

2012 ◽  
Vol 2012 ◽  
pp. 1-4 ◽  
Author(s):  
S. Chenna Krishna ◽  
N. Supriya ◽  
Abhay K. Jha ◽  
Bhanu Pant ◽  
S. C. Sharma ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Room Temperature ◽  
Ofhc Copper ◽  
Ti Alloy ◽  
Phonon Thermal Conductivity ◽  
Temperature Range ◽  
Transmission Electron

In the present investigation, thermal conductivity of Cu-Cr-Zr-Ti alloy was determined as the product of the specific heat (), thermal diffusivity (), and density () in the temperature range of 300–873 K. The experimental results showed that the thermal conductivity of the alloy increased with increase in temperature up to 873 K and the data was accurately modeled by a linear equation. For comparison, thermal conductivity was also evaluated for OFHC copper in the same temperature range. The results obtained were discussed using electrical conductivity and hardness measurements made at room temperature. Transmission electron microscopy (TEM) was done to understand the microstructural changes occurring in the sample after the test. Wiedemann-Franz-Lorenz law was employed for calculating electronic and phonon thermal conductivity using electrical conductivity. On the basis of studies conducted it was deduced that in situ aging may be one of the reasons for the increase in thermal conductivity with temperature for Cu-Cr-Zr-Ti alloy.

Electrical and thermal transport properties of the Y1 − x Mx CrO3 system

1986 ◽  
Vol 1 (5) ◽  
pp. 675-684 ◽  
Author(s):  
W.J. Weber ◽  
C.W. Griffin ◽  
J.L. Bates
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Seebeck Coefficient ◽  
Dopant Concentration ◽  
Strong Dependence ◽  
Divalent Metal Ions ◽  
Ionic Radii ◽  
Measured Activation ◽  
Small Polarons ◽  
Type Conduction

The effects of substituting divalent metal ions (Mg, Ca, Sr, Ba) for Y in YCrO3 were investigated by electrical conductivity, Seebeck coefficient, and thermal conductivity measurements. The electrical conductivity results were consistent with the hopping-type conduction of a temperature-independent concentration of small polarons, with measured activation energies of 0.18-0.26 eV. The Seebeck coefficient increased nearly linearly with temperature and indicated p-type conductivity. Both electrical conductivity and Seebeck coefficient results show a strong dependence on dopant size (ionic radius) and indicate that the highest carrier concentrations were associated with Ca as the dopant, which is attributed to the similar ionic radii of Ca2+ and Y3+. The thermal conductivity decreased slightly with temperature and dopant concentration.

scholarly journals Solid-State Synthesis and Thermoelectric Properties of Mg2+xSi0.7Sn0.3Sbm

2013 ◽  
Vol 2013 ◽  
pp. 1-4 ◽  
Author(s):  
Sin-Wook You ◽  
Il-Ho Kim ◽  
Soon-Mok Choi ◽  
Won-Seon Seo
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Solid State ◽  
Seebeck Coefficient ◽  
Solid Solutions ◽  
Solid State Synthesis ◽  
Sb Doping ◽  
Excess Mg ◽  
Bipolar Conduction ◽  
Type Conduction

Mg2+xSi0.7Sn0.3Sbm(0≤x≤0.2,m=0or 0.01) solid solutions have been successfully prepared by mechanical alloying and hot pressing as a solid-state synthesis route. All specimens were identified as phases with antifluorite structure and showed n-type conduction. The electrical conductivity of Mg-excess solid solutions was enhanced due to increased electron concentrations. The absolute values of the Seebeck coefficient varied substantially with Sb doping and excess Mg, which was attributed to the change in carrier concentration. The onset temperature of bipolar conduction was shifted higher with Sb doping and excess Mg. The lowest thermal conductivity of 1.3 W/mK was obtained for Mg2Si0.7Sn0.3Sb0.01. A maximumZTof 0.64 was achieved at 723 K for Mg2.2Si0.7Sn0.3Sb0.01.

Sign in / Sign up

Export Citation Format

Share Document