LaTiO2N nanopowders (NPs) with low surface defect density via nitridation of flame made NPs retaining simple perovskite structure

Yoshiyuki Abe; Richard M Laine

doi:10.1039/d1dt03687d

LaTiO₂N nanopowders (NPs) with low surface defect density via nitridation of flame made NPs retaining simple perovskite structure

Dalton Trans. 2022 Jan 25;51(4):1571-1579. doi: 10.1039/d1dt03687d.

Authors

Yoshiyuki Abe^{1

2}, Richard M Laine¹

Affiliations

¹ Department of Materials Science and Engineering, University of Michigan, Ann Arbor, MI 48109-2136, USA. talsdad@umich.edu.
² Ichikawa Research Center, Sumitomo Metal Mining Co., Ltd, Nakakokubun, Ichikawa, Chiba 272-8588, Japan. yoshiyuki.abe.r3@smm-g.com.

PMID: 34990504
DOI: 10.1039/d1dt03687d

Abstract

This work introduces a novel route to perovskite LaTiO₂N nanopowders (NPs) via nitridation of perovskite LaTiO₃ NPs in an NH₃ gas flow at 1050 °C/NH₃/15 h, in which a simple perovskite structure (ABX₃) is retained during nitridation. The LaTiO₃ NP is formed with a trace of a second phase in a precursor oxide NP (LTO-4/3) produced using liquid-feed flame spray pyrolysis (LF-FSP) of a metallo-organic ethanol solution with La/Ti = 4/3. The characterization of the resulting powders allows for a comparison with LaTiO₂N NPs synthesized by the nitridation of the La₂Ti₂O₇ precursor oxide NP (LTO-1) with a perovskite slab structure (A₂B₂X₇) also prepared by LF-FSP of a La/Ti = 1 solution. Williamson-Hall plots suggest that the as-produced LaTiO₂N from LTO-1 offers a quite small but effective crystallite size of 16-18 nm with almost no lattice spacing fluctuations, while LaTiO₂N from LTO-4/3 presents a larger effective crystallite size of 50-52 nm with some lattice spacing fluctuations. UV-vis diffuse reflectance analysis reveals that, unlike LaTiO₂N from LTO-1, the spectra of LaTiO₂N from LTO-4/3 show a quite low absorption background above the wavelength of the optical absorption edge (∼580 nm), suggesting good crystallinity with a very low surface defect density. Both oxynitride NPs appear to offer utility as inorganic pigments with different colours, while LaTiO₂N NPs from LTO-4/3 have advantages for various applications, including potential as a visible-light-driven water splitting photocatalyst.