title: Excess vibrational modes and high thermoelectric performance of the quenched and slow-cooled two-phase alloy Cu0.2Ag2.8SbSeTe2.
abstract: In this article we examine the low-temperature specific heat of slow-cooled Cu(0.2)Ag(2.8)SbSeTe(2) and the thermoelectric performance of quenched samples. We find that the low-temperature specific heat is dominated by two Einstein terms of approximate energies of 2.5 and 5 meV. The specific-heat behavior is consistent with the amorphous low-temperature thermal conductivity behavior and validates the glassy nature of the structure. We performed the synthesis of quenched samples in an attempt to eliminate the presence of micro-cracks, whose existence presumably enhances electronic scattering. We find that quenching eliminates the presence of micro-cracks but does not result in an improvement of the figure of merit. Specifically, the highest ZT obtained in the quenched samples (ZT = 1.5), though very competitive, is still significantly less that the ZT obtained in the slow-cooled samples (ZT = 1.75).
authors.affiliation: Department of Physics and Astronomy, Clemson University, Clemson, SC, USA.
authors.forename: F R
authors.initials: FR
authors.lastname: Drymiotis
authors.forename: S
authors.initials: S
authors.lastname: Lindsey
authors.forename: J
authors.initials: J
authors.lastname: Capps
authors.forename: J C
authors.initials: JC
authors.lastname: Lashley
authors.forename: D
authors.initials: D
authors.lastname: Rhodes
authors.forename: Q R
authors.initials: QR
authors.lastname: Zhang
authors.forename: C
authors.initials: C
authors.lastname: Nucklos
authors.forename: T B
authors.initials: TB
authors.lastname: Drye
mesh_terms: D000497:Alloys / Q000737:chemistry*; D003080:Cold Temperature; D003300:Copper / Q000737:chemistry*; D004553:Electric Conductivity; D017097:Electric Impedance; D004581:Electronics / Q000379:methods; D006358:Hot Temperature; D046529:Microscopy, Electron, Transmission / Q000379:methods; D008956:Models, Chemical; D012643:Selenium / Q000737:chemistry*; D012834:Silver / Q000737:chemistry*; D013691:Tellurium / Q000737:chemistry*; D013696:Temperature; D013814:Thermal Conductivity; D014732:Vibration
chemical_list: D000497:Alloys; D012834:Silver; D003300:Copper; D012643:Selenium; D013691:Tellurium