American Chemical Society, Journal of Physical Chemistry C, 35(118), p. 20112-20121, 2014
DOI: 10.1021/jp5048425
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We have investigated the diffusion dynamics of protons in hydrated 4.2% Ca-doped LaPO4, a candidate electrolyte for proton-conducting intermediate temperature fuel cells. The macroscopic and microscopic dynamics have been studied using electrochemical impedance spectroscopy (EIS) and quasi-elastic neutron scattering (QENS), respectively. The conductivity of the bulk hydrated sample was determined in the temperature range of 500–850 °C by EIS and showed a clear signature of proton conductivity with an activation energy of about 1.0 eV. The QENS experiment revealed a fast dynamical process below 500 °C that was not observed by EIS. The activation energy of the fast proton diffusion is 0.09 eV in the temperature range from 150 °C to 500 °C.