[19p-D62-1~17] 22.1 Joint Session M "Phonon Engineering"

3:00 PM - 3:15 PM JST(6:00 AM - 6:15 AM UTC)English Presentation

[19p-D62-8] Effect of Capping Layers on CeO₂-based Electrochemical Thermal Transistors

〇(D)Hyeonjun Kong¹, Jason Tam², Zhiping Bian¹, Mitsuki Yoshimura¹, Ahrong Jeong³, Bin Feng², Yuichi Ikuhara², Yusaku Magari³, Hiromichi Ohta³ (1.IST-Hokkado U., 2.U. Tokyo, 3.RIES-Hokkaido U.)

Keywords:

Thermal transistor,Thermal conductivity,Redox treatment

An electrochemical thermal transistor is a device capable of reversibly switching the thermal conductivity (κ) of the active oxide layer through electrochemical redox reactions. Our research group has demonstrated thermal transistor characteristics for several active oxide materials, including SrCoO_x (2 < x < 3), LaNiO_3−δ, and CeO_2−δ. We focus on CeO_2−δ because it shows a wide κ switching width of 9.5 W/mK and an on-to-off κ ratio of 4.8. An interesting feature of our CeO2-based thermaltransistors is that reduced off-state comprises partially reduced CeO_2−δ and fully oxidized CeO₂ domains. Reduced CeO_2−δ exhibits significant oxide ion (O²⁻) conductivity similar to rare-earth element (Gd, Sm)-doped CeO₂. If oxygen gas is supplied externally, O^2- conduction occurs instrad of electrochemical reduction. To prevent external O²⁻ conduction, we used a SrCoO_2.5 capping layer, which grows heteroepitaxially on CeO₂. Additionally, we used 10% Gd-doped CeO₂ (GDC) as the active layer for its large O²⁻ conductivity. The GDC layer (100 nm) was fully reduced after applying an electron concentration of 2 × 10²² cm⁻³ with the SrCoO_2.5 layer (10 nm) cap, following Faraday’s laws of electrolysis. Without the capping layer, reduction did not occurred. These results confirm that the SrCoO_2.5 layer effectively suppresses external oxygen supply in CeO₂-based thermal transistors.