Glasslike vs. crystalline thermal conductivity in carrier-tuned Ba8Ga16X30 clathrates (X = Ge, Sn)

Abstract

The present controversy over the origin of glasslike thermal conductivity observed in certain crystalline materials is addressed by studies on single-crystal x-ray diffraction, thermal conductivity k(T) and specific heat Cp(T) of carrier-tuned Ba8Ga16X30 (X = Ge, Sn) clathrates. These crystals show radically different low-temperature k(T) behaviors depending on whether their charge carriers are electrons or holes, displaying the usual crystalline peak in the former case and an anomalous glasslike plateau in the latter. In contrast, Cp(T) above 4 K and the general structural properties are essentially insensitive to carrier tuning. We analyze these combined results within the framework of a Tunneling/Resonant/Rayleigh scatterings model, and conclude that the evolution from crystalline to glasslike k(T) is accompanied by an increase both in the effective density of tunnelling states and in the resonant scattering level, while neither one of these contributions can solely account for the observed changes in the full temperature range. This suggests that the most relevant factor which determines crystalline or glasslike behavior is the coupling strength between the guest vibrational modes and the frameworks with different charge carriers.

arXiv comment8 pages, 4 figures, 4 tables, submitted to Phys. Rev. B

References in corpus (5)

• Glass-Like Heat Conduction in High-Mobility Crystalline Semiconductors
• Structural, transport, and thermal properties of single crystalline type-VIII clathrate Ba8Ga16Sn30
• Four-well tunneling states and elastic response of clathrates
• Possible mechanism for achieving glass-like thermal conductivities in crystals with off-center atoms
• Tunable charge carriers and thermoelectricity of single-crystal Ba8Ga16Sn30

Cited by in corpus (21)

• Phonon-glass electron-crystal thermoelectric clathrates: Experiments and theory
• Impact of Rattlers on Thermal Conductivity of a Thermoelectric Clathrate: A First-Principles Study
• Quartic Anharmonicity of Rattlers and Its Effect on Lattice Thermal Conductivity of Clathrates from First Principles
• Cage-size control of guest vibration and thermal conductivity in Sr8Ga16Si30-xGex
• Kondo-like phonon scattering in thermoelectric clathrates
• Low-Energy Optical Phonon Modes in the Caged Compound LaRu2Zn20
• Optical conductivity of rattling phonons in type-I clathrate Ba${}_8$Ga${}_{16}$Ge${}_{30}$
• Significance of Off-Center Rattling for Emerging Low-lying THz Modes in type-I Clathrates
• NMR relaxation and rattling phonons in type-I Ba8Ga16Sn30 clathrate
• Optical conductivity from local anharmonic phonons
• Hopping Processes Explain T-linear Rise of Thermal Conductivity in Thermoelectric Clathrates above the Plateau
• Strong-Coupling Theory of Rattling-Induced Superconductivity
• Interacting Dipoles in Type-I Clathrates: Why Glass-like though Crystal?
• Anharmonic phonon renormalization and thermal transport in the type-I Ba${}_8$Ga${}_{16}$Sn${}_{30}$ clathrate from first principles
• Thermal conductivity in intermetallic clathrates: A first principles perspective
• Transport and thermodynamic properties under anharmonic motion in type-I Ba8Ga16Sn30 clathrate
• Ab initio computational study on the lattice thermal conductivity of Zintl clathrates [Si${}_{19}$P${}_4$]Cl${}_4$ and Na${}_4$[Al${}_4$Si${}_{19}$]
• Anharmonic lattice dynamics and thermal transport in type-I inorganic clathrates
• Glass-like Thermal-Transport in Symmetry-Broken Clathrates
• Anomalous infrared spectra of hybridized phonons in type-I clathrate Ba${}_8$Ga${}_{16}$Ge${}_{30}$
• Heavy-Electron Formation and Bipolaronic Transition in the Anharmonic Holstein Model