Low temperature specific heat of KTaO3 from 0.3K

Bourgeal, S.; Villar, R.; Vieǐra, S.; Трепаков, В. А.

doi:10.1080/00150198808229440

Cited by 4 publications

(2 citation statements)

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“…At low temperature and for acoustic phonon dominated scenario, c V ∼ T 3 and λ ph is determined by the scattering with the impurities and is temperature independent, thus κ ∼ T 3 . Experimental findings on this materials also support such T 3 behavior of the specific heat [30]. Thus any departure from the said T 3 behavior of the thermal conductivity, especially in a regime where some other interacting degrees of freedom become active, indicates the presence of some new scattering mechanism which results in frequency and temperature dependence of the mean free path or the scattering rate.…”

Section: Introductionsupporting

confidence: 60%

Optical phonon contribution to the thermal conductivity of a quantum paraelectric

Bhalla¹,

Das²

2021

J. Phys.: Condens. Matter

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Motivated by recent experimental findings, we study the contribution of a quantum critical optical phonon branch to the thermal conductivity of a paraelectric system. We consider the proximity of the optical phonon branch to transverse acoustic phonon branch and calculate its contribution to the thermal conductivity within the Kubo formalism. We find a low temperature power law dependence of the thermal conductivity as T α , with 1 < α < 2, (lower than T 3 behavior) due to optical phonons near the quantum critical point. This result is in accord with the experimental findings and indicates the importance of quantum fluctuations in the thermal conduction in these materials.

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Section: Introductionsupporting

confidence: 60%

Optical phonon contribution to the thermal conductivity of a quantum paraelectric

Bhalla¹,

Das²

2021

J. Phys.: Condens. Matter

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“…Thermal vibration in the real KTaO 3 should further decrease the intensity in the reconstructed atom distribution leading to underestimated Ca occupations. However, the extent of underestimation was not more than 7% with the Debye temperature of 449 K of the pristine KTaO 3 .…”

Section: Resultsmentioning

confidence: 81%

Single-Crystal Model of Highly Efficient Water-Splitting Photocatalysts: A KTaO₃ Wafer Doped with Calcium Cations

et al. 2020

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Alkali tantalates, NaTaO3 and KTaO3, are known as highly efficient semiconductor photocatalysts for the overall water-splitting reaction when properly doped with foreign metal cations. Characterizing surface reaction sites is needed for further development. In this study, (001)-oriented KTaO3 wafers were doped with Ca cations thorough a solid-state reaction to provide platforms for surface science studies. X-ray diffraction showed a Ca-rich perovskite-structured surface layer that covers the Ca-poor or pristine KTaO3 substrate. The lattice of the surface layer was contracted and rotated relative to the substrate lattice. The heteroepitaxial junction of the surface layer on the substrate mimicked the core–shell structure that is found in real photocatalyst particles. Nanometer-scale islands spontaneously appeared on the surface to correct the lattice mismatch across the surface–substrate junction. X-ray fluorescence holography was applied to determine the local, atom-scale structure around Ca cations in the host lattice. Atom distributions reconstructed from Ca Kβ fluorescence holograms suggested that K and Ta cations were simultaneously exchanged with Ca cations. Local lattice deformation was quantitatively deduced around the Ca cations occupying the two different sites. The major features of real photocatalystsheteroepitaxial surface–bulk junctions, surface restructuring to correct lattice mismatches, and simultaneous cation exchangewere reproduced in the doped wafers. The ability of X-ray fluorescence holography to determine a local structure around doping cations was also demonstrated.

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Thermodynamic properties of BaCeO3 and BaZrO3 at low temperatures

Ahrens

Maier

2006

Thermochimica Acta

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Low temperature specific heat of KTaO3 from 0.3K

Cited by 4 publications

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Optical phonon contribution to the thermal conductivity of a quantum paraelectric

Optical phonon contribution to the thermal conductivity of a quantum paraelectric

Single-Crystal Model of Highly Efficient Water-Splitting Photocatalysts: A KTaO₃ Wafer Doped with Calcium Cations

Thermodynamic properties of BaCeO3 and BaZrO3 at low temperatures

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Low temperature specific heat of KTaO3 from 0.3K

Cited by 4 publications

References 0 publications

Optical phonon contribution to the thermal conductivity of a quantum paraelectric

Optical phonon contribution to the thermal conductivity of a quantum paraelectric

Single-Crystal Model of Highly Efficient Water-Splitting Photocatalysts: A KTaO3 Wafer Doped with Calcium Cations

Thermodynamic properties of BaCeO3 and BaZrO3 at low temperatures

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Single-Crystal Model of Highly Efficient Water-Splitting Photocatalysts: A KTaO₃ Wafer Doped with Calcium Cations