Structural properties and hyperfine characterization of Sn-substituted goethites

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• 作者：A.L. Larralde^a ; C.P. Ramos^b ; ¹ ; B. Arcondo^c ; A.E. Tufo^a ; C. Saragovi^b ; E.E. Sileo^a ; ^{sileo@qi.fcen.uba.ar}
• 关键词：Oxides ; Chemical synthesis ; Mö ; ssbauer spectroscopy ; Rietveld analysis
• 刊名：Materials Chemistry and Physics
• 出版年：2012
• 期刊代码：58_02540584
• 类别：ms
• 出版时间：16 April, 2012
• 卷：133
• 期：2-3
• 页码：735-740
• 文件大小：755 K

摘要

Tin-doped goethites obtained by a simple method at ambient pressure and 70 掳C were characterized by inductively coupled plasma atomic emission spectrometry, scanning electron microscopy, Rietveld refinement of powder X-ray diffraction data, and ⁵⁷Fe and ¹¹⁹Sn M枚ssbauer spectroscopy.

The particles size and the length to width ratios decreased with tin-doping. Sn partially substituted the Fe(III) ions provoking unit cell expansion and increasing the crystallinity of the particles with enlarged domains that grow in the perpendicular and parallel directions to the anisotropic broadening (1 1 1) axis. Intermetallic E, E鈥?and DC distances also change although the variations are not monotonous, indicating different variations in the coordination polyhedron. In general, the Sn-substituted samples present larger intermetallic distances than pure goethite, and the greatest change is shown in the E鈥?distance which coincides with the c-parameter.

¹¹⁹Sn M枚ssbauer spectroscopy revealed that Sn(II) is incorporated as Sn(IV) in the samples. On the other hand, Fe(II) presence was not detected by ⁵⁷Fe M枚ssbauer spectroscopy, suggesting the existence of vacancies in the Sn-doped samples. A lower magnetic coupling is also evidenced from the average magnetic hyperfine field values obtained as tin concentration increased.