Characterization of NH4-phlogopite (NH4) (Mg3) [AlSi3O10] (OH)2 and ND4-phlogopite (ND4) (Mg3) [AlSi3O10] (OD)2 using IR spectroscopy and Rietveld refinement of XRD spectra |
| |
| Authors: | D E Harlov M Andrut S Melzer |
| |
| Institution: | (1) GeoForschungsZentrum Potsdam, Telegrafenberg, 14473 Potsdam, Germany Fax: +49 331 2881402; email: dharlov@gfz.potsdam.de, DE;(2) Institute for Mineralogy and Crystallography, University of Vienna – Geozentrum, 1090 Vienna, Austria, AT |
| |
| Abstract: | A synthesis technique is described which results in >99% pure NH4-phlogopite (NH4) (Mg3) AlSi3O10] (OH)2 and its deuterium analogue ND4-phlogopite (ND4) (Mg3) AlSi3O10] (OD)2. Both phases are characterised using both IR spectroscopy at 298 and 77 K as well as Rietveld refinement of their X-ray powder
diffraction pattern. Both NH4
+ and ND4
+ are found to occupy the interlayer site in the phlogopite structure. Absorption bands in the IR caused by either NH4
+ or ND4
+ can be explained to a good approximation using Td symmetry as a basis. Rietveld refinement indicates that either phlogopite synthesis contains several mica polytypes. The
principle polytype is the one-layer monoclinic polytype (1M), which possesses the space group symmetry C2/m. The next most common polytype is the two-layer polytype (2M
1
) with space group symmetry C2/c. Minor amounts of the trigonal polytype 3T with the space group symmetry P3112 were found only in the synthesis run for the ND4-phlogopite. Electron microprobe analyses indicate that NH4-phlogopite deviates from the ideal phlogopite composition with respect to variable Si/Al and Mg/Al on both the tetrahedral
and octahedral sites, respectively, due to the Tschermaks substitution VIMg2++IVSi4+↔VIAl3++IVAl3+ and with respect to vacancies on the interlayer site due to the exchange vector XII(NH4)++IVAl3+↔XII□+IVSi4+.
Received: 30 August 1999 / Accepted: 2 October 2000 |
| |
| Keywords: | NH4-phlogopite ND4-phlogopite IR absorption spectra Ammonia-bearing sheet silicate minerals Nitrogen-bearing minerals |
| 本文献已被 SpringerLink 等数据库收录！ |
|
