کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
8910390 | 1637495 | 2018 | 59 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
The relationship between Mn oxidation state and structure in triclinic and hexagonal birnessites
ترجمه فارسی عنوان
رابطه بین وضعیت اکسیداسیون مونومر و ساختار در بیرونی تری کلاینل و شش ضلعی
دانلود مقاله + سفارش ترجمه
دانلود مقاله ISI انگلیسی
رایگان برای ایرانیان
کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
علوم زمین و سیارات
ژئوشیمی و پترولوژی
چکیده انگلیسی
We explored these issues by synthesizing a host of cation-exchanged birnessite specimens whose long-range symmetrical character could be determined by X-ray diffraction without ambiguity. Through a combination of Fourier transform infrared spectroscopy (FTIR), extended X-ray absorption fine structure (EXAFS), and X-ray photoelectron spectroscopy (XPS), we have examined the relationships among structural symmetry, Mn oxidation state, and interlayer composition. Our results confirm prior models that as the concentration of Mn3+ increases, the departure from hexagonal symmetry also increases. Rietveld refinements indicate that the Jahn-Teller distortions associated with Mn3+ induce systematic variations in unit-cell parameters, particularly an increase in the a-axis and the β angle of the unit cell. Interlayer cation composition also controls structural distortions, and Ca-rich birnessites showed less deviation from hexagonality than did Na-, K-, and Ba-birnessites. Our linear combination fits of X-ray absorption spectra sometimes yielded misleading results, reinforcing the difficulty and importance of selecting appropriate standards.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Chemical Geology - Volume 479, 20 February 2018, Pages 216-227
Journal: Chemical Geology - Volume 479, 20 February 2018, Pages 216-227
نویسندگان
Florence T. Ling, Jeffrey E. Post, Peter J. Heaney, Eugene S. Ilton,