Lithium diffusion in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>Li</mml:mi><mml:mi>Mn</mml:mi><mml:mi mathvariant="normal">P</mml:mi><mml:msub><mml:mrow><mml:mi mathvariant="normal">O</mml:mi></mml:mrow><mml:mn>4</mml:mn></mml:msub></mml:math> detected with <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msup><mml:mi>μ</mml:mi><mml:mo>±</mml:mo></mml:msup><mml:mi>SR</mml:mi></mml:math>
Jun Sugiyama, Ola Kenji Forslund, Elisabetta Nocerino, Nami Matsubara, Konstantinos Papadopoulos, Yasmine Sassa, Stephen P. Cottrell, A. D. Hillier, Katsuhiko Ishida, Martin Må̊nsson, J. H. Brewer
Abstract
Positive-and negative-muon spin rotation and relaxation ( SR) was first used to investigate fluctuations of nuclear magnetic fields in an olivine-type battery material, LiMnPO 4 , in order to clarify the diffusive species, namely, to distinguish between a + hopping among interstitial sites and Li + ions diffusing in the LiMnPO 4 lattice. Muon diffusion can only occur in + SR, because the implanted -forms a stable muonic atom at the lattice site, and therefore any change in linewidth measured with -SR must be due to Li + diffusion. Since the two measurements exhibit a similar increase in the field fluctuation rate with temperature above 100 K, it is confirmed that Li + ions are in fact diffusing. The diffusion coefficient of Li + at 300 K and its activation energy were estimated to be 1.4(3) 10 -10 cm 2 /s and 0.19(3) eV, respectively. Such combined SR measurements are thus shown to be a suitable tool for detecting ion diffusion in solid-state energy materials.