论文标题

氢化解剖酶的电子和超精细特性的实验和理论研究(TIO $ _2 $):缺陷相互作用和热稳定性

Experimental and theoretical study of electronic and hyperfine properties of hydrogenated anatase (TiO$_2$): defects interplay and thermal stability

论文作者

Zyabkin, D. V., Gunnlaugsson, H. P., Goncalves, J. N., Bharuth-Ram, K., Qi, B., Unzueta, I., Naidoo, D., Mantovan, R., Masenda, H., Olafsson, S., Peters, G., Schell, J., Vetter, U., Dimitrova, A., Krischok, S., Schaaf, P.

论文摘要

In this study we report on the results from emission $^{57}$Fe M${ö}$ssbauer Spectroscopy experiments, using dilute $^{57}$Mn implantation into pristine (TiO$_2$) and hydrogenated anatase held at temperatures between 300-700 K. Results of the electronic structure and local environment are complemented with ab-initio calculations.植入后,Fe $^{2+} $和fe $^{3+} $在原始剖析酶中观察到,后者展示了自旋静态放松。为氢化培养酶获得的光谱显示没有Fe $^{3+} $贡献,这表明氢充当供体。由于阈值较低,氢从晶格中扩散出来。因此,在$^{57} $ Fe 14.4 KeV状态的时间尺度上显示了动态行为。周围的氧气空缺有利于高旋转fe $^{2+} $状态。在室温下处理的样品显示了两个不同的氢运动过程。该运动始于间质氢,然后切换到共价结合的状态。氢外扩散受到批量缺陷的阻碍,这可能会导致两个过程重叠。补充UV-VIS和电导率测量结果表明,氢化后的电导率提高和较高的光学吸收。室温下的X射线光电子光谱表明,在573 K处氢化的样品显示出存在Ti $^{3+} $和Ti $^{2+} $状态。这可能意味着样品中存在大量的氧空位和-OH键。理论表明,在植入Mn(Fe)的剖析酶样品中,探针位于赤道空缺附近,作为下一个最邻居的伯爵,而亚稳态的氢构型负责退火行为。

In this study we report on the results from emission $^{57}$Fe M${ö}$ssbauer Spectroscopy experiments, using dilute $^{57}$Mn implantation into pristine (TiO$_2$) and hydrogenated anatase held at temperatures between 300-700 K. Results of the electronic structure and local environment are complemented with ab-initio calculations. Upon implantation both Fe$^{2+}$ and Fe$^{3+}$ are observed in pristine anatase, where the latter demonstrates the spin-lattice relaxation. The spectra obtained for hydrogenated anatase show no Fe$^{3+}$ contribution, suggesting that hydrogen acts as a donor. Due to the low threshold, hydrogen diffuses out of the lattice. Thus showing a dynamic behavior on the time scale of the $^{57}$Fe 14.4 keV state. The surrounding oxygen vacancies favor the high-spin Fe$^{2+}$ state. The sample treated at room temperature shows two distinct processes of hydrogen motion. The motion commences with the interstitial hydrogen, followed by switching to the covalently bound state. Hydrogen out-diffusion is hindered by bulk defects, which could cause both processes to overlap. Supplementary UV-Vis and electrical conductivity measurements show an improved electrical conductivity and higher optical absorption after the hydrogenation. X-ray photoelectron spectroscopy at room temperature reveals that the sample hydrogenated at 573 K shows presence of both Ti$^{3+}$ and Ti$^{2+}$ states. This could imply that a significant amount of oxygen vacancies and -OH bonds are present in the samples. Theory suggests that in the anatase sample implanted with Mn(Fe), probes were located near equatorial vacancies as next-nearest-neighbours, whilst a metastable hydrogen configuration is responsible for the annealing behavior.

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