Terahertz Proton Motions in Proton-Conducting Electrolyte of Solid Oxide Fuel Cell

We measure the THz conductivity in the proton-conducting solid electrolyte, BaZr _0.8 Y _0.2 O _3-δ , with THz time-domain spectroscopy at high temperature. Observed sub-THz conductivity reflects the breaking and reforming hydrogen bonding, which is related to the proton hopping between neighboring oxygen atoms. Our results will open a new evaluation technique of the proton-conducting electrolyte of fuel cell.