Abstract
We investigated the nitridation of reduced BaTiO3, BaTiO2.60H0.08, corresponding to an oxyhydride with a large concentration of O defects (>10%). The material is readily nitrided under flowing N2 gas at temperatures between 400 and 450 °C to yield oxynitrides BaTiO2.6Nx (x = 0.2−0.22) with a slightly tetragonally distorted perovskite structure, a ≈ 4.01 and c ≈ 4.02 Å, and Ti partially remaining in the oxidation state III. The tetragonal structure was confirmed from Raman spectroscopy. 14N MAS NMR spectroscopy shows a single resonance at 270 ppm, which is typical for perovskite transition metal oxynitrides. However, largely different signal intensity for materials with very similar N content suggests N/O/vacancy ordering when prolonging nitridation times to hours. Diffuse reflectance UV-VIS spectroscopy shows a reduction of the intrinsic band gap to 2.4–2.45 eV compared to BaTiO3 (~3.2 eV). Mott-Schottky measurements confirm n-type conductivity and reveal a slight negative shift of the conduction band edge from –0.59 V (BaTiO3) to ~–0.65 eV.
Highlights
SketchSketchofofmaterial materialconversions: conversions: hydride reduction of BaTiO to O-deficient an O-deficient
Chen, Z.; Lu, C.; Slabon, A.; Department of Materials and Environmental Chemistry, Stockholm University, SE-10691 Stockholm, Sweden; Institute of Inorganic Chemistry, RWTH Aachen University, Landoltweg 1, DE-52074 Aachen, Germany; Abstract: We investigated the nitridation of reduced BaTiO3, BaTiO2.60 H0.08, corresponding to an oxyhydride with a large concentration of O defects (>10%)
The particle ticle morphology of BaTiO3 is retained in BaTiO2.60 H0.08 0.32 (BTOH) (Figure 4b)
Summary
Sketchofofmaterial materialconversions: conversions: hydride reduction of BaTiO to O-deficient an O-deficient. H/vacancy disordered oxyhydride (exemplified as H/vacancy disordered BaTiO2.5 H0.125 ) which is nitridized with mental nitrogen 2.5 N0.25 with an ordered (orthorhombic) N/vacancy arment). O, H, N and vacancies are depicted as grey, red, green, blue, and white-blue circles, rerangement). O, H, N and vacancies are depicted as grey, red, green, blue, and white-blue circles, spectively
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