Zhang Xi, Zhang Yuqiao, Wu Liao, Tsuruta Akihiro, Mikami Masashi, Cho Hai Jun, Ohta Hiromichi
Research Institute for Electronic Science, Hokkaido University, N20W10, Kita, Sapporo 001-0020, Japan.
Graduate School of Information Science and Technology, Hokkaido University, N14W9, Kita, Sapporo 060-0814, Japan.
ACS Appl Mater Interfaces. 2022 Jul 27;14(29):33355-33360. doi: 10.1021/acsami.2c08555. Epub 2022 Jul 12.
Thermoelectric energy conversion technology has attracted attention as an energy harvesting technology that converts waste heat into electricity by means of the Seebeck effect. Oxide-based thermoelectric materials that show a high figure of merit are promising because of their good chemical and thermal stability as well as their harmless nature compared to chalcogenide-based state-of-the-art thermoelectric materials. Although several high- thermoelectric oxides ( > 1) have been reported thus far, the reliability is low due to a lack of careful observation of their stability at elevated temperatures. Here, we show a reliable high- thermoelectric oxide, BaCoO. We fabricated BaCoO epitaxial films by the reactive solid-phase epitaxy method (NaCoO) followed by ion exchange (Na → Ba) treatment and performed thermal annealing of the film at high temperatures and structural and electrical measurements. The crystal structure and electrical resistivity of the BaCoO epitaxial films were found to be maintained up to 600 °C. The power factor gradually increased to ∼1.2 mW m K and the thermal conductivity gradually decreased to ∼1.9 W m K with increasing temperature up to 600 °C. Consequently, the reached ∼0.55 at 600 °C in air.
热电能量转换技术作为一种通过塞贝克效应将废热转化为电能的能量收集技术，已引起人们的关注。具有高优值的氧化物基热电材料很有前景，因为与基于硫族化物的先进热电材料相比，它们具有良好的化学和热稳定性以及无害的性质。尽管迄今为止已经报道了几种高热电氧化物（>1），但由于缺乏对其在高温下稳定性的仔细观察，其可靠性较低。在此，我们展示了一种可靠的高热电氧化物BaCoO。我们通过反应性固相外延法（NaCoO）制备了BaCoO外延薄膜，随后进行离子交换（Na→Ba）处理，并在高温下对薄膜进行热退火以及结构和电学测量。发现BaCoO外延薄膜的晶体结构和电阻率在高达600°C时保持不变。随着温度升高至600°C，功率因数逐渐增加至约1.2 mW m K，热导率逐渐降低至约1.9 W m K。因此，在空气中600°C时，优值达到约0.55。
