jp409962x_si_001.zip (14.35 MB)
Ab Initio Calculation of Proton Transport in DyPO4
dataset
posted on 2014-03-13, 00:00 authored by Isaac
M. Markus, Nicole Adelstein, Mark Asta, Lutgard C. De JongheProton mobilities in xenotime-structured
DyPO4 have
been investigated through first-principles calculations based on electronic
density functional theory. The calculated mobility is shown to be
highly anisotropic, consistent with the tetragonal symmetry of the
xenotime crystal structure. Due to the presence of one-dimensional
channels along the c-axis, the hopping rate is significantly
enhanced along this direction. Specifically, the activation energy
for hopping along the a- and b-axes
is computed to be 0.45 eV away from aliovalent dopant impurities,
while the calculated energy barrier within the channels that run along
the c-axis is 0.15 eV. The corresponding hopping
rates along the c-axis channels are more than 2 orders
of magnitude larger than those calculated previously for the monoclinic
monazite-structured LaPO4 compound. The effects of aliovalent
dopants on proton migration have also been investigated, considering
the case of Ca2+ substitution for Dy3+. These
calculations reveal a dopant-proton binding energy of approximately
0.4 eV and an increase in the hopping barriers near the dopant by
up to 0.2 eV. These dopant effects were found to be relatively localized,
with minimal changes to the energetics of the protons obtained more
than approximately 5 Å away from the aliovalent impurity.