Fig. 4: X-ray absorption analysis.
a XANES spectra of Ni-K edge collected on (111)-oriented LaNiO3−δ samples (as prepared, after 1h and 16h potential hold). The Ni-K edge spectra of Ni2+O and LiNi3+O2 were added as references. b Δμ spectra obtained by subtracting the as-prepared spectrum from the one after 16 h CA and 1 h CA, the latter multiplied by a factor of 10, showing similarity of spectral changes. c Fourier transform of the EXAFS of the Ni-K edge collected on (111)-oriented LaNiO3−δ samples. Data are shown as circles and EXAFS fits as lines. Fourier transforms were performed between 35 and 550 eV (above E0 = 8333 eV) with a cosine window covering the first and last 10% of the data range. Interatomic distances and fitting parameters are listed in Supplementary Tables 1, 2, 3, 4. d ΔEXAFS of Fourier-filtered data (0.0 - 4.5 Å) obtained by subtracting the as-prepared spectrum from the one after 16 h CA and 1 h CA, the latter multiplied by a factor of 3, showing similarity in spectral changes.
