biostudies-literatureHenriques AUniversity Global Partnership NetworkCentro Nacional de Pesquisa em Energia e Materiais - CNPEMConselho Nacional de Desenvolvimento Científico e TecnológicoUK International Science Partnerships FundInstituto SerrapilheiraFundação de Amparo à Pesquisa do Estado de São Pauloe02379https://www.ebi.ac.uk/biostudies/studies/S-EPMC12376643biostudies-literatureUnknown12(31)Unraveling the underlying mechanisms at the origin of ultra-low thermal conductivity in pristine crystals is of central relevance to designing new functional materials. Here, a study of thermal conductivity κ(T) in an extended temperature range (1.5-400 K) is reported in the single-crystalline bismuthate perovskite BaBiO₃. The measured κ(T) shows an anomalous glass-like behavior with a ≈ T² dependence at low temperatures and a plateau in a wide temperature range from about 20 to 260 K, surprisingly recovering the expected downturn for a crystal only for T > 300 K. The measured room temperature κ ≈ 1.6 W m^-1 K^-1 agrees with the calculated value, including three-phonon and isotope disorder scattering. However, the departure of the experimental from the calculated κ(T) for T < 300 K, at the onset of the plateau, indicates that an additional scattering mechanism comes into play at lower temperatures. It is proposed that a tunneling two-level system associated with the BiO₆ octahedra rotation offers an additional phonon scattering mechanism and may explain the observed κ(T) suppression. The findings may have significant implications for the pairing mechanism and unconventional superconductivity of doped-BaBiO₃ aside from suggesting it as a candidate building block for functional heterostructures.Advanced science (Weinheim, Baden-Wurttemberg, Germany)Anomalous Glassy Thermal Conductivity in a Perovskite Bismuthate Induced by Structural Dynamic Instability.PMC123766432022/14202-3402919/2021-1402919/2021‐12022/14202‐3305726/2023-42013/08293‐42013/08293-4201149/2024‐9201149/2024-9305726/2023‐4B24000022021/00989‐92024/16100-9R-2401-469832024/00177‐22024/16100‐92022/01742-02024/00177-22022/01742‐0202421742019/17874‐02018/08845-32018/08845‐32019/17874-02021/00989-9202320192018/19420‐32018/19420-3Henriques AWirth SGutmann MJLima MSLBrito WHMartelli VNilsen GJfalseAnomalous Glassy Thermal Conductivity in a Perovskite Bismuthate Induced by Structural Dynamic Instability.Unraveling the underlying mechanisms at the origin of ultra-low thermal conductivity in pristine crystals is of central relevance to designing new functional materials. Here, a study of thermal conductivity κ(T) in an extended temperature range (1.5-400 K) is reported in the single-crystalline bismuthate perovskite BaBiO₃. The measured κ(T) shows an anomalous glass-like behavior with a ≈ T² dependence at low temperatures and a plateau in a wide temperature range from about 20 to 260 K, surprisingly recovering the expected downturn for a crystal only for T > 300 K. The measured room temperature κ ≈ 1.6 W m^-1 K^-1 agrees with the calculated value, including three-phonon and isotope disorder scattering. However, the departure of the experimental from the calculated κ(T) for T < 300 K, at the onset of the plateau, indicates that an additional scattering mechanism comes into play at lower temperatures. It is proposed that a tunneling two-level system associated with the BiO₆ octahedra rotation offers an additional phonon scattering mechanism and may explain the observed κ(T) suppression. The findings may have significant implications for the pairing mechanism and unconventional superconductivity of doped-BaBiO₃ aside from suggesting it as a candidate building block for functional heterostructures.2025-01-01T00:00:00Z2025 Aug2026-05-09T19:08:12.706Z2026-04-08T01:09:53.795ZS-EPMC123766434046425410.1002/advs.202502379