Physical properties data compilations relevant to energy storage :

Janz, George J.; Allen, C. B.; Bansal, Narottam P.; Murphy, Ryan; Tomkins, Reginald P. T.

doi:10.6028/nbs.nsrds.61p2

Cited by 208 publications

(81 citation statements)

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“…The σ e of ionic solids increases during melting, but is < 10 1/Ω cm 39 , so k e gives negligible contribution. The Z TCS of molecular and ionic solids are not high 39,59 , and are generally negative as mentioned before.…”

Section: Bulksupporting

confidence: 56%

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Thermal conductivity switch: Optimal semiconductor/metal melting transition

Kim

Kaviany

2016

Phys. Rev. B

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Scrutinizing distinct solid/liquid (s/l) and solid/solid (s/s) phase transitions (passive transitions) for large change in bulk (and homogenous) thermal conductivity, we find the s/l semiconductor/metal (S/M) transition produces largest dimensionless thermal conductivity switch (TCS) figure of merit Z TCS (change in thermal conductivity divided by smaller conductivity). At melting temperature, the solid phonon and liquid molecular thermal conductivities are comparable and generally small, so the TCS requires localized electron solid and delocalized electron liquid states.For cyclic phase reversibility, the congruent phase transition (no change in composition) is as important as the thermal transport. We identify XSb and XAs (X = Al, Cd, Ga, In, Zn) and describe atomic-structural metrics for large Z TCS , then show the superiority of S/M phonon-to electrondominated transport melting transition. We use existing experimental results and theoretical and ab initio calculations of the related properties for both phases (including the Kubo-Greenwood and Bridgman formulations of liquid conductivities). The 5p orbital of Sb contributes to the semiconductor behavior in the solid-phase bandgap and upon disorder and bond-length changes in the liquid phase this changes to metallic, creating the large contrast in thermal conductivity.The charge density distribution, electronic localization function, and electron density of states are used to mark this S/M transition. For optimal TCS, we examine the elemental selection from the transition-, basic-and semimetals and semiconductor groups. For CdSb, addition of residual Ag suppresses the bipolar conductivity and its Z TCS is over 7, and for Zn 3 Sb 2 it is expected to be over 14, based on the structure and transport properties of the better known β-Zn 4 Sb 3 . This is the highest Z TCS identified. In addition to the metallic melting, the high Z TCS is due to the electron-poor nature of II-V semiconductors leading to the significantly low phonon conductivity.

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Section: Bulksupporting

confidence: 56%

“…The thermal conductivity of Cu wire is affected by magnetic field, with experiment at 4.2 K recording thermal conductivity decrease and in proportionality under such fields (and Pure/Compound (H 2 O [35], c-Se [36], C 6 H 14 [37,38], NaF [39]) Passive Low Dimensionality…”

Section: Thermal Conductivity Switches (Tcs)mentioning

confidence: 99%

Thermal conductivity switch: Optimal semiconductor/metal melting transition

Kim

Kaviany

2016

Phys. Rev. B

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“…36,37; more data covering a wider temperature range are obtained by light scattering, and in particular by the forced Rayleigh scattering method; 39 A critical assessment of the different measurements of diffusion coefficients in molten salts is given in Ref. 38. Thermal conductivity is reported by Nunes et al 41 , and by Egorov and Revyakin; 42 ; fairly systematic data on electrical conductivity are listed in Janz and Lorenz.…”

Section: Introductionmentioning

confidence: 99%

Molecular Dynamics Simulations of Metal/Molten Alkali Carbonate Interfaces

et al. 2017

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Interfaces between molten carbonates M 2 CO 3 (M=Li, Na and K) and planar metal walls have been investigated by molecular dynamics based on a rigid-ions force field (Janssen and Tissen, Mol. Simul. 5, 83-98, (1990)). Simulations cover the temperature range 1200 K ≤ T ≤ 1500 K at a moderate (∼ 15 kbar) overpressure to compensate for a slight overestimate of the system volume by the force field model. Most of the simulations represent neutral electrodes, but shorter computations have been carried out for systems with a low surface charge distribution on the metal side of the interface. The results provide an intriguing view of the interplay among ion packing, oscillating screening, anisotropic correlations and ion dynamics at the interface. The mass and charge density profiles display prominent peaks at contact, and tend to their constant bulk values through several oscillations, whose amplitude decays exponentially moving away from the interface.Oscillations in the charge density profile, in particular, limit the value of the interfacial dipole, and increase the capacitance of the interface. Ion-ion correlations are enhanced in proximity of the metal surface, but retain the exponentially-decaying oscillatory form of their bulk counterpart.Diffusion is slower in the molecularly thin layer of ions next to the interface than in the bulk.The analysis of interfaces is completed by the computation of structural properties of bulk phases, and by the estimate of transport coefficients such as self-diffusion, electrical conductivity, and especially thermal conductivity, which is seldom computed by simulation. All together, the results of our simulations for homogeneous and inhomogeneous molten carbonates provide crucial insight on systems and properties relevant for advanced devices such as fuel cells, that, in turn, might play a prominent role in future power generation strategies.

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“…All subsequent effects in figure 8 belong to KNO 3 as can be recognized by comparison with literature data on phase transformations of KNO 3 [10][11][12][13] as well as with the DTA trace of pure KNO 3 in figure 9 (left). KNO 3 melts at 334°C [14]. Thus the peak at 328 °C (Fig.…”

Section: Assignment Of the Bandsmentioning

confidence: 99%

“…Due to the higher sensitivity of the DSC instrument also the transformation of γ-KNO 3 into the stable α-KNO 3 is visible at 67.4°C. The heat of fusion and the melting temperature of pure potassium nitrate have been measured by Janz [14] and Takahashi [15] Also the RAMAN spectra from the sample pans of the thermal analysis gave evidence that above the decomposition temperature of about 287°C a mixture of KNO 3 and K 2 SiF 6 is formed (Fig. 11).…”

Section: Assignment Of the Bandsmentioning

confidence: 99%

Crystal structure and thermal properties of a new double salt: K₂SiF₆·KNO₃

Rissom

Schmidt

Voigt

2007

Cryst. Res. Technol.

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A new double salt K 2 SiF 6 ·KNO 3 was found during determination of the solubility of K 2 SiF 6 in aqueous potassium nitrate solutions. Unit cell parameters (P6 3 /mmc, a = 5.6268(1) Å, c = 14.5186(6) Å, V = 398.09(2) Å³, Z = 2) and crystal structure have been determined. The compound is further characterized by RAMAN spectroscopy and X-ray powder diffraction. Thermal properties were studied using DTA, DSC and in situ high-temperature X-ray powder diffraction measurements. At 287 °C K 2 SiF 6 ·KNO 3 decomposes into its components KNO 3 and K 2 SiF 6 with an enthalpy of decomposition of about + 42 J·g -1 . Further thermal effects could be assigned to phase transformations of KNO 3 whereby earlier literature data have been reconfirmed.

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Physical properties data compilations relevant to energy storage :

Cited by 208 publications

References 0 publications

Thermal conductivity switch: Optimal semiconductor/metal melting transition

Thermal conductivity switch: Optimal semiconductor/metal melting transition

Molecular Dynamics Simulations of Metal/Molten Alkali Carbonate Interfaces

Crystal structure and thermal properties of a new double salt: K₂SiF₆·KNO₃

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Physical properties data compilations relevant to energy storage :

Cited by 208 publications

References 0 publications

Thermal conductivity switch: Optimal semiconductor/metal melting transition

Thermal conductivity switch: Optimal semiconductor/metal melting transition

Molecular Dynamics Simulations of Metal/Molten Alkali Carbonate Interfaces

Crystal structure and thermal properties of a new double salt: K2SiF6·KNO3

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Crystal structure and thermal properties of a new double salt: K₂SiF₆·KNO₃