Barroso, Margarida ; Dai, Mian ; Bubeck, Cora ; Scavini, Marco ; Cuello, Gabriel J. ; Zhang, Hongbin ; Weidenkaff, Anke ; Widenmeyer, Marc (2024)
Investigation of O/N ordering in perovskite-type oxynitrides La1−xYxTa(O,N)3 on long-range & short scale.
In: Inorganics, 12 (3)
doi: 10.3390/inorganics12030090
Artikel, Bibliographie

Kurzbeschreibung (Abstract)

Oxynitrides such as LaTa(O,N)3 are attractive materials as photoelectrodes for photoelectrocatalytic solar water splitting. The potential anionic ordering in their perovskite-type structure has been shown to impact the materials’ properties. Given the importance attributed to it, the present study reports a detailed experimental analysis supported by simulations of the anionic ordering of La1−xYxTa(O,N)3. The influence of O/N and yttrium content on the anionic order was assessed. Neutron diffraction analysis was performed on four different nominal compositions—LaTaON2, LaTaO2N, La0.9Y0.1TaON2, and La0.9Y0.1TaO2N—at 10 K and 300 K to study potential long-range ordering. Neutron pair distribution function (PDF) analysis was performed on all samples at 10 K and on non-Y-substituted samples at 300 K to evaluate short-range ordering. There was no evidence of long-range O/N order in any of the compounds. In contrast, at a short range (1.5 Å ≤ r < 6 Å), a Pnma (a−b+a−) tilting pattern and local cis-ordering of the anions were seen. The latter faded rapidly, leaving the Pnma tilting pattern in a 6 Å ≤ r ≤ 11 Å range. At higher distances, the PDF analysis agreed with the Imma (a−b0a−) O/N disordered long-range structure. As the O/N content changed, not much difference in behavior was observed. Yttrium substitution introduced some disorder in the structure; nonetheless, it showed marginal influence on octahedral tilting and anionic ordering.

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