Far-infrared spectra of synthetic dioctahedral muscovite and muscovite-tobelite series micas: Characterization and assignment of the interlayer I-Oinner and I-Oouter stretching bands

Abstract

Far-infrared spectroscopy and X-ray powder diffraction Rietveld structure refinement for the hydrothermal synthetic muscovite series, (a) KAl 3 (Si 3-y Ge y )O 10 (OH,OD) 2 , (b) KGa 3 (Si 3-y Ge y )O 10 (OH,OD) 2 , and (c) K(Al 3-x Ga x )Ge 3 O 10 (OH,OD) 2 , where x = 0.0-3.0, y = 0.0-3.0, and the muscovite-tobelite series, (d) [K 1-A (NH 4 ,ND 4 ) A ]Al 3 Si 3 O 10 (OH,OD) 2 , where A = 0.0-1.0, indicate that there is a complete solid-solution in each series. In the 200-50 cm -1 far-infrared region, four kinds of bands are observed: two bands due to octahedral deformation coupled with OH deformational vibrations between 240 and 130 cm -1 , an in-plane tetrahedral torsional band between 175 and 130 cm -1 , an interlayer I-O inner stretching band, and an I-O outer stretching band. The weak and broad 140 cm -1 band is assigned to K-O inner stretching and the strong broad 110 cm -1 band to K-O outer stretching in muscovite. The broad 175 cm -1 band is (NH 4 /ND 4 )-O inner stretching and the 140 cm -1 broad strong band is (NH 4 /ND 4 )-O outer stretching in tobelite. With increasing Ga→Al substitution, the I-O inner and I-O outer stretching bands shift to lower frequency, while with increasing Ge→Si substitution, the I-O inner stretching band shifts to higher frequency; the I-O outer stretching bands do not change as a function of composition.

Rare earth element stripping from kaolin sands via mild acid treatment

“…Natural kaolinite sources usually contain kaolinite as a major phase and also several other side phases. For raw material from AKW, the most likely ones are α‐quartz, orthoclase feldspar, muscovite, and gorceixite 25–28 . Multiple separation steps are required to separate the different phases and to purify the single phases prior to the usage.…”

“…The program package STOE WinXPOW was used to process the raw data for phase analysis performed in Jana2006 22,23 . Literature data for kaolinite, 24 quartz, 25 orthoclase feldspar, 26 muscovite, 27 and gorceixite 28 were used to identify the most probable phases occurring in RK1 and RK2. This selection of phases is based on the knowledge provided by AKW.…”

“…For raw material from AKW, the most likely ones are α-quartz, orthoclase feldspar, muscovite, and gorceixite. [25][26][27][28] Multiple separation steps are required to separate the different phases and to purify the single phases prior to the usage. The raw material at AKW is treated in a magnetic separation process, whereby the purer stream is separated from the magnetic impure side stream.…”

“…33 The powder diffraction pattern of the residue samples (RK1 and RK2) are shown in Figure 1. Beside Al 2 Si 2 O 5 [OH] 4 (kaolinite) 24 itself, major expected side phases like SiO 2 (α-quartz), 25 KAlSi 3 O 8 (orthoclase feldspar), 26 and KAl 2 (AlSi 3 O 10 )(F,OH) 2 (muscovite) 27 are denoted. Due to an XRF analysis provided by AKW (see Tables S3-S6) that contained Ba and phosphate as minor components we added BaAl 3 (PO 4 )(PO 3 OH)(OH) 6 (gorceixite) 28 as an additional and most-probable phase in the XRD phase analysis.…”

“…Dependent on the conditions, these cyanobacteria were able to absorb 84.2-91.5, 69.5-83.4, 68.6-83.5, 44.7-70.6, and 47.2-F I G U R E 2 X-ray diffraction (XRD) data of RK1 (right) and RK2 (left) derived from a 14-h measurement in a capillary. Calculated diffractograms based on structure data of feldspar 26 and muscovite 27 are drawn with negative intensities. The main phase, kaolinite (star), and non-overlapping reflections of the minor phases, feldspar (triangle) and muscovite (diamond), are marked in the (a-d) diffractograms.…”