Pulse method for simultaneous measurement of electric thermopower and heat conductivity at low temperatures

Maldonado, O.

doi:10.1016/0011-2275(92)90358-h

Cited by 86 publications

(59 citation statements)

References 7 publications

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“…The thermal conductivity was measured under high vacuum (10 -6 Torr) under a steady state not only at room temperature, but also as a function of temperature, starting from cryogenic temperatures, specifically 2 K. The control software uses a special algorithm to optimize measurements parameters, such as heat pulse duration, heater current, and frequency. A more detailed description of the PPMS measuring method can be found in the literature [11,31]. The obtained core-shell powders, namely (Al 2 O 3 @AlN) and (SiO 2 @Si 3 N 4 ), and their composites were characterized by means of scanning electron microscopy (SEM) Nova NanoSEM 200, which was used for detailed observation of the surface microstructures of fillers and obtained composites.…”

Section: Measurement Methodsmentioning

confidence: 99%

Functional composites with core–shell fillers: I. Particle synthesis and thermal conductivity measurements

Rybak

Gąska

2015

J Mater Sci

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Filled epoxy composites are broadly used in electronic and power devices as an electrical insulation. It is of importance to achieve efficient heat dissipation in such devices due to fact that thermal properties have a strong influence on their proper operation. For this reason, the modification of standard filler materials, such as silica or alumina, can give a promising solution. In this work, a novel core-shell material has been proposed and manufactured by means of a carbothermal reduction and nitridation process. The obtained fillers are made of a standard material which is covered by the high thermally conductive shell. The synthesized fillers were characterized by means of X-ray diffraction, and scanning electron microscopy coupled with elemental analysis. The composite samples based on epoxy resin filled with the manufactured coreshell fillers have been investigated in order to determine their effective thermal conductivity. The obtained composite samples exhibited a significant improvement in the thermal conductivity, represented by a 63 % relative increase. The obtained results show the potential for the novel core-shell fillers to be applied for the electrical insulation with the enhanced thermal conductivity.

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Section: Measurement Methodsmentioning

confidence: 99%

Functional composites with core–shell fillers: I. Particle synthesis and thermal conductivity measurements

Rybak

Gąska

2015

J Mater Sci

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“…To fully characterize the figure of merit, these three properties were simultaneously measured for each sample over the selected temperature range of interest, that is, 77 K to 320 K (system capability is 4.2 K to 475 K). To alleviate offset error voltages and increase the density of data points, a slow ac-technique was used with a heater pulse period of 720 s. [17] The pulse shape was monitored, in situ, to determine temperature stabilization, and the sample chamber was maintained at a pressure less than 10 À5 Torr for the entire measurement run. Samples were mounted in the standard four-probe configuration for both the electrical and thermal conductivity, and the heater current was adjusted for an average temperature gradient of 1 K. The sample stage and radiation shield were made of gold-coated copper to minimize radiation effects and maintain temperature uniformity.…”

Section: Physical Measurementsmentioning

confidence: 99%

Structure and Thermoelectric Properties of the New Quaternary Bismuth Selenides A1−xM4−xBi11+xSe21 (A=K and Rb and Cs; M=Sn and Pb)—Members of the Grand Homologous Series Km(M6Se8)m(M5+nSe9+n)

et al. 2001

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Several members of the new family A(1-x)M(4-x)Bi(11+x)Se21 (A = K, Rb, Cs; M = Sn, Pb) were prepared by direct combination of A2Se, Bi2Se3, Sn (or Pb), and Se at 800 degrees C. The single-crystal structures of K(0.54)Sn(3.54)Bi(11.46)Se21, K(1.46)Pb(3.08)Bi(11.46)Se21, Rb(0.69)Pb(3.69)Bi(11.31)Se21, and Cs(0.65)Pb(3.65)Bi(11.35)Se21 were determined. The compounds A(1-x)M(4-x)Bi(11+x) Se21 crystallize in a new structure type with the monoclinic space group C2/m, in which building units of the Bi2Te3 and NaCl structure type join to give rise to a novel kind of three-dimensional anionic framework with alkali-ion-filled tunnels. The building units are assembled from distorted, edge-sharing (Bi,Sn)Se6 octahedra. Bi and Sn/Pb atoms are disordered over the metal sites of the chalcogenide network, while the alkali site is not fully occupied. A grand homologous series Km(M6Se8)m(M(5+n)Se(9+n)) has been identified of which the compounds A(1-x)M(4-x)Bi(11+x)Se21 are members. We discuss here the crystal structure, charge-transport properties, and very low thermal conductivity of A(1-x)M(4-x)Bi(11+x)Se21.

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“…A consolidated pellet (diameter = 5.10 AE 0.04 mm, thickness 1.12 AE 0.04 mm, and density of 4.04 AE 0.2 g cm À3 ) was adhered between two goldplated copper disks with silver epoxy (Tra-Bond 2902) and fixed on the thermal transport stage. While r and thermal conductivity 60,61 were determined from the geometry dimensions and the electrical resistance and thermal conductance, respectively, S was measured from the voltage drop by applying a temperature gradient. The thermal conductivity was corrected assuming an emissivity of one due to blackbody radiation.…”

Section: Measurements Of Transport Propertiesmentioning

confidence: 99%

Metal phosphides as potential thermoelectric materials

et al. 2017

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There still exists a crucial need for new thermoelectric materials to efficiently recover waste heat as electrical energy. Although metal phosphides are stable and can exhibit excellent electronic properties, they have traditionally been overlooked as thermoelectrics due to expectations of displaying high thermal conductivity. Based on high-throughput computational screening of the electronic properties of over 48 000 inorganic compounds, we find that several metal phosphides offer considerable promise as thermoelectric materials, with excellent potential electronic properties (e.g. due to multiple valley degeneracy). In addition to the electronic band structure, the phonon dispersion curves of various metal phosphides were computed indicating low-frequency acoustic modes that could lead to low thermal conductivity. Several metal phosphides exhibit promising thermoelectric properties. The computed electronic and thermal properties were compared to experiments to test the reliability of the calculations indicating that the predicted thermoelectric properties are semi-quantitative. As a complete experimental study of the thermoelectric properties in MPs, cubic-NiP 2 was synthesized and the low predicted lattice thermal conductivity (B1.2 W m À1 K À1 at 700 K) was confirmed. The computed Seebeck coefficient is in agreement with experiments over a range of temperatures and the phononic dispersion curve of c-NiP 2 is consistent with the experimental heat capacity. The predicted high thermoelectric performance in several metal phosphides and the low thermal conductivity measured in NiP 2 encourage further investigations of thermoelectric properties of metal phosphides.

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Pulse method for simultaneous measurement of electric thermopower and heat conductivity at low temperatures

Cited by 86 publications

References 7 publications

Functional composites with core–shell fillers: I. Particle synthesis and thermal conductivity measurements

Functional composites with core–shell fillers: I. Particle synthesis and thermal conductivity measurements

Structure and Thermoelectric Properties of the New Quaternary Bismuth Selenides A1−xM4−xBi11+xSe21 (A=K and Rb and Cs; M=Sn and Pb)—Members of the Grand Homologous Series Km(M6Se8)m(M5+nSe9+n)

Metal phosphides as potential thermoelectric materials

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