Miruszewski Tadeusz, Dzierzgowski Kacper, Winiarz Piotr, Wachowski Sebastian, Mielewczyk-Gryń Aleksandra, Gazda Maria
Department of Solid State Physics, Faculty of Applied Physics and Mathematics, Gdańsk University of Technology, Narutowicza 11/12, 80-233 Gdańsk, Poland.
Materials (Basel). 2020 Feb 21;13(4):965. doi: 10.3390/ma13040965.
In this work, Fe-doped strontium titanate SrTiFeO, for x = 0-1 (STFx), has been fabricated and studied. The structure and microstructure analysis showed that the Fe amount in SrTiFeO has a great influence on the lattice parameter and microstructure, including the porosity and grain size. Oxygen nonstoichiometry studies performed by thermogravimetry at different atmospheres showed that the Fe-rich compositions (x > 0.3) exhibit higher oxygen vacancies concentration of the order of magnitude 10-10 cm. The proton uptake investigations have been done using thermogravimetry in wet conditions, and the results showed that the compositions with x < 0.5 exhibit hydrogenation redox reactions. Proton concentration at 400 °C depends on the Fe content and was estimated to be 1.0 × 10 mol/mol for SrTiFeO and 1.8 × 10 mol/mol for SrTiFeO. Above 20 mol% of iron content, a significant drop of proton molar concentrations at 400 °C was observed. This is related to the stronger overlapping of Fe and O orbitals after reaching the percolation level of approximately 30 mol% of the iron in SrTiFeO. The relation between the proton concentration and Fe dopant content has been discussed in relation to the B-site average electronegativity, oxygen nonstoichiometry, and electronic structure.
在本工作中，制备并研究了铁掺杂钛酸锶SrTiFeOₓ（x = 0 - 1，STFx）。结构和微观结构分析表明，SrTiFeOₓ中的铁含量对晶格参数和微观结构有很大影响，包括孔隙率和晶粒尺寸。在不同气氛下通过热重法进行的氧非化学计量研究表明，富铁成分（x > 0.3）表现出更高的氧空位浓度，数量级为10⁻¹⁰ cm⁻³。在潮湿条件下使用热重法进行了质子吸收研究，结果表明，x < 0.5的成分表现出氢化氧化还原反应。400℃时的质子浓度取决于铁含量，对于SrTiFeO₀.₅估计为1.0×10⁻⁵ mol/mol，对于SrTiFeO₀.₈估计为1.8×10⁻⁵ mol/mol。铁含量高于20 mol%时，观察到400℃时质子摩尔浓度显著下降。这与SrTiFeOₓ中铁含量达到约30 mol%的渗流水平后Fe和O轨道更强的重叠有关。已结合B位平均电负性、氧非化学计量和电子结构讨论了质子浓度与铁掺杂剂含量之间的关系。
