Low thermal conductivity of the layered oxide (Na,Ca)Co_2O_4: Another example of a phonon glass and an electron crystal

Abstract

The thermal conductivity of polycrystalline samples of (Na,Ca)Co_2O_4 is found to be unusually low, 20 mW/cmK at 280 K. On the assumption of the Wiedemann-Franz law, the lattice thermal conductivity is estimated to be 18 mW/cmK at 280 K, and it does not change appreciably with the substitution of Ca for Na. A quantitative analysis has revealed that the phonon mean free path is comparable with the lattice parameters, where the point-defect scattering plays an important role. Electronically the same samples show a metallic conduction down to 4.2 K, which strongly suggests that NaCo_2O_4 exhibits a glass-like poor thermal conduction together with a metal-like good electrical conduction. The present study further suggests that a strongly correlated system with layered structure can act as a material of a phonon glass and an electron crystal.

5 pages 3 figures, to be published in Phys. Rev. B

References in corpus (1)

• Hole Localization in Underdoped Superconducting Cuprates Near 1/8th Doping

Cited by in corpus (13)

• La0.95Sr0.05CoO3: An efficient room-temperature thermoelectric oxide
• Thermal Conductivity, Thermopower, and Figure of Merit of La_{1-x}Sr_xCoO_3
• Topological Thermoelectricity in Metals
• Thermal Hall effect in a phonon-glass Ba${}_3$CuSb${}_2$O${}_9$
• Thermal conductivity of the thermoelectric layered cobalt oxides measured by the Harman method
• Chemical, Structural, and Transport Properties of Na1-xCoO2
• Thermoelectric properties of new Bi-chalcogenide layered compounds
• Topology of Triple-Point Metals
• Thermal conductivity of the A_xBO_2 type layered oxides Na_0.77MnO_2 and LiCoO_2
• Electronic thermal conductivity as derived by density functional theory
• Crystal-to-stripe reordering of sodium ions in NaxCoO2 (x>=0.75)
• High-temperature thermoelectric properties of the double-perovskite ruthenium oxide (Sr${}_{1-x}$La${}_x$)${}_2$ErRuO${}_6$
• Enhanced thermopower in an intergrowth cobalt oxide Li${}_{0.48}$Na${}_{0.35}$CoO${}_2$