Roles of Point Defects in Thermal Transport in Perovskite Barium Stannate

Abstract

Perovskite barium stannate (BaSnO3) is a promising candidate that can be used as transparent conducting oxide in optoelectronic devices and as the channel material in high-mobility oxide electronics. In this work, we calculate the lattice thermal conductivity and investigate the impact of point defects on thermal transport in BaSnO3 based on the phonon Boltzmann transport equations with interatomic force constants from first-principles calculations. In pristine BaSnO3, we find the contribution of acoustic phonons to thermal transport accounts for 54% at 300 K and the rest is attributed to the lower-frequency (27.5–50 THz) optical modes with relatively high group velocity. We show oxygen vacancies and impurities can cause noticeable reduction in thermal conductivity of BaSnO3, but the corresponding mechanisms differ in terms of scattering rates on different phonon modes. The thermal conductivity reduction due to oxygen vacancies at 300 K is mainly caused by the increased scattering of the acoustic phonons and the low-frequency optical phonons. Lanthanum and potassium impurities mainly increase the scattering of acoustic phonons, but antimony impurity lowers the thermal conductivity by increasing the scattering rate of dominant phonons, including both the acoustic modes and the low-frequency optical modes. The results and findings facilitate us to better understand the thermal transport mechanisms of perovskite oxides with an emphasis on the impact of oxygen vacancies and impurities on the thermal properties of BaSnO3.

Wide-range continuous tuning of the thermal conductivity of La0.5Sr0.5CoO3-δ films via room-temperature ion-gel gating

“…We emphasize that the thermal conductivity can be continuously tuned over this range, in a non-volatile fashion, at room temperature. It should be noted that the thermal conductivity of our as-deposited P-LSCO films (with x = 0.5 and δ ≈ 0.1, see Methods and the discussion below regarding the determination of δ ) is 4.6 ± 2.0 W m −1 K −1 , which is less than half the equivalent values for several unsubstituted ABO 3 perovskites (e.g., 11 W m −1 K −1 for SrTiO 3 50 , 13 W m −1 K −1 for BaSnO 3 51 , and 13 W m −1 K −1 for LaAlO 3 52 ). Also, prior experimental studies reported a bulk thermal conductivity of 6 W m −1 K −1 for single-crystal La 0.7 Sr 0.3 CoO 3 52 , 53 .…”

Microstructural Engineering of Solution-Processed Epitaxial La-Doped BaSnO3 Transparent Conducting Films

“…During the past 10 years, raising electron mobility has become the core issue in the study of epitaxial BSO thin films. − Alaan et al reported that the lattice scattering is increased with a larger site mismatch with the native Ba site, accompanied by the more pronounced local strain fields that would serve to limit the carrier mobilities. Therefore, the highest room-temperature carrier mobility was achieved by doping 8% La in Ba sites among all rare-earth cation-doped BSO thin films.…”

Unraveling the Oxygen Effect on the Properties of Sputtered BaSnO3 Thin Films

“…Such behavior has been attributed to the presence of shallow states near the conduction band. The existence of defect states within the band gap of BSO can apparently affect the conductivity, − but the importance and activity of such sub-band levels to the photoconductivity has been largely neglected, which is rather important for optoelectronic devices. Therefore, it is highly expected that the optoelectronic properties of BSO films with oxygen vacancies will be studied.…”