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.