title: Glass-like phonon scattering from a spontaneous nanostructure in AgSbTe2.
abstract: Materials with very low thermal conductivity are of great interest for both thermoelectric and optical phase-change applications. Synthetic nanostructuring is most promising for suppressing thermal conductivity through phonon scattering, but challenges remain in producing bulk samples. In crystalline AgSbTe2 we show that a spontaneously forming nanostructure leads to a suppression of thermal conductivity to a glass-like level. Our mapping of the phonon mean free paths provides a novel bottom-up microscopic account of thermal conductivity and also reveals intrinsic anisotropies associated with the nanostructure. Ground-state degeneracy in AgSbTe2 leads to the natural formation of nanoscale domains with different orderings on the cation sublattice, and correlated atomic displacements, which efficiently scatter phonons. This mechanism is general and suggests a new avenue for the nanoscale engineering of materials to achieve low thermal conductivities for efficient thermoelectric converters and phase-change memory devices.
authors.affiliation: Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
authors.forename: J
authors.initials: J
authors.lastname: Ma
authors.forename: O
authors.initials: O
authors.lastname: Delaire
authors.forename: A F
authors.initials: AF
authors.lastname: May
authors.forename: C E
authors.initials: CE
authors.lastname: Carlton
authors.forename: M A
authors.initials: MA
authors.lastname: McGuire
authors.forename: L H
authors.initials: LH
authors.lastname: VanBebber
authors.forename: D L
authors.initials: DL
authors.lastname: Abernathy
authors.forename: G
authors.initials: G
authors.lastname: Ehlers
authors.forename: Tao
authors.initials: T
authors.lastname: Hong
authors.forename: A
authors.initials: A
authors.lastname: Huq
authors.forename: Wei
authors.initials: W
authors.lastname: Tian
authors.forename: V M
authors.initials: VM
authors.lastname: Keppens
authors.forename: Y
authors.initials: Y
authors.lastname: Shao-Horn
authors.forename: B C
authors.initials: BC
authors.lastname: Sales
mesh_terms: D016880:Anisotropy; D000965:Antimony / Q000737:chemistry; D004581:Electronics; D005898:Glass / Q000737:chemistry*; D049329:Nanostructures / Q000737:chemistry*; D010316:Particle Size; D060739:Phonons; D012834:Silver / Q000737:chemistry; D013499:Surface Properties; D013691:Tellurium / Q000737:chemistry; D013696:Temperature; D013814:Thermal Conductivity
chemical_list: D012834:Silver; D000965:Antimony; D013691:Tellurium