CRYSTAL-CHEMICAL STUDY BY XANES OF TRIOCTAHEDRAL MICAS: THE MOST CHARACTERISTIC LAYER SILICATES

2002 ◽  
Vol 16 (11n12) ◽  
pp. 1673-1679 ◽  
Author(s):  
F. TOMBOLINI ◽  
A. MARCELLI ◽  
A. MOTTANA ◽  
G. CIBIN ◽  
M. F. BRIGATTI ◽  
...  
Keyword(s):  
Tetrahedral Site ◽  
Chemical Study ◽  
Crystal Chemical ◽  
Single Crystal Xrd ◽  
Octahedral Sheet ◽  
Tetrahedral Sheet ◽  
Structural Probe ◽  
Fe Substitution ◽  
Mg Substitution ◽  
The Ideal

A crystal-chemical study of trioctahedral micas previously characterized by single-crystal XRD has been performed by XANES spectroscopy at the Si and Al K edges. XANES, being a local structural probe, can investigate distortion and modification of the tetrahedral sheet with increasing Fe for Mg substitution in the octahedral sheet. Comparison of XANES spectra allows determining the size of the tetrahedral site occupied by either Si or Al. The Si-O distance remains essentially unchanged whereas the Al-O distance appears to increase. The behavior may be interpreted as a tilt of the tetrahedra, initially rotated to match the ideal mica geometry, with increasing Fe substitution in the octahedral sheet.

scholarly journals A Synthesis and Crystal Chemical Study of the Fast Ion Conductor Li7–3xGaxLa3 Zr2O12 with x = 0.08 to 0.84

2014 ◽  
Vol 53 (12) ◽  
pp. 6264-6269 ◽  
Author(s):  
Daniel Rettenwander ◽  
Charles A. Geiger ◽  
Martina Tribus ◽  
Peter Tropper ◽  
Georg Amthauer
Keyword(s):  
Chemical Study ◽  
Crystal Chemical ◽  
Ion Conductor ◽  
Fast Ion Conductor ◽  
Fast Ion

scholarly journals Fedorite from Murun Alkaline Complex (Russia): Spectroscopy and Crystal Chemical Features

Minerals ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 702
Author(s):  
Ekaterina V. Kaneva ◽  
Roman Yu. Shendrik ◽  
Tatiana A. Radomskaya ◽  
Ludmila F. Suvorova
Keyword(s):  
Crystal Structure ◽  
Emission Spectra ◽  
Chemical Study ◽  
Double Layers ◽  
Water Molecules ◽  
Crystal Chemical ◽  
Alkaline Complex ◽  
Deformation Parameters ◽  
First Time ◽  
Red Coloration

Fedorite is a rare phyllosilicate, having a crystal structure characterized by SiO4-tetrahedral double layers located between continuous layers formed by edge-sharing (Ca,Na)-octahedra, and containing interlayer K, Na atoms and H2O molecules. A mineralogical-petrographic and detailed crystal-chemical study of fedorite specimens from three districts of the Murun alkaline complex was performed. The sequence of the crystallization of minerals in association with fedorite was established. The studied fedorite samples differ in the content of interlayer potassium and water molecules. A comparative analysis based on polyhedral characteristics and deformation parameters was carried out. For the first time, EPR, optical absorption and emission spectra were obtained for fedorite. The raspberry-red coloration of the mineral specimens could be attributed to the presence of Mn4+ ions.

Potassium and Rubidium Benzoyltrifluoroacetonates: A Crystal Chemical Study and Thermal Properties

2020 ◽  
Vol 61 (3) ◽  
pp. 439-448
Author(s):  
D. V. Kochelakov ◽  
E. S. Vikulova ◽  
N. V. Kuratieva
Keyword(s):  
Thermal Properties ◽  
Chemical Study ◽  
Crystal Chemical

Single-crystal X-ray diffraction, EMPA, FTIR and X-ray photoelectron spectroscopy study of narsarsukite from Murun Massif, Russia

2017 ◽  
Vol 81 (2) ◽  
pp. 339-354 ◽  
Author(s):  
E. Schingaro ◽  
E. Mesto ◽  
M. Lacalamita ◽  
F. Scordari ◽  
E. Kaneva ◽  
...  
Keyword(s):  
Single Crystal ◽  
Photoelectron Spectroscopy ◽  
Chemical Study ◽  
Structural Disorder ◽  
Crystal Chemical ◽  
X Ray Diffraction ◽  
Unit Cell Parameters ◽  
X Ray ◽  
Cell Parameters ◽  
Alkaline Massif

AbstractA crystal chemical study of narsarsukite from the Murun alkaline massif, Russia has been carried out combining single-crystal X-ray diffraction, electron microprobe analyses, micro-Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS). The narsarsukite single crystals are tetragonal (space group I4/m) with unit-cell parameters: 10.7140(1) ≤ a ≤ 10.7183(2) Å and 7.9478(1) ≤ c ≤ 7.9511(1) Å. The XPS analysis showed that Fe occurs in the mineral as Fe3+, whereas the FTIR spectrum showed that the sample studied is anhydrous. The average crystal chemical formula of the Murun narsarsukite is: Na2.04K0.01(V0.015+Ti0.74Zr0.01Al0.01Fe0.223+Mg0.01)1.00Si4.00(O10.74F0.23OH0.03)11.00. Structural disorder at octahedral and interstitial sites was modelled and also discussed in consideration of the main substitutional mechanism Ti4+ + O2– ↔ Fe3+ + (F–, OH–) active in the structure of the mineral.

Ferrierite from Tapu, Coromandel Peninsula, New Zealand, and a crystal chemical study of known occurrences

1986 ◽  
Vol 50 (355) ◽  
pp. 63-68 ◽  
Author(s):  
T. Sameshima
Keyword(s):  
New Zealand ◽  
Cell Volume ◽  
Chemical Study ◽  
Refractive Indices ◽  
Crystal Chemical ◽  
Optical Orientation ◽  
Mineral Vein ◽  
Using Data ◽  
Optical Sign ◽  
Andesite Lava

AbstractFerrierite has been found at Tapu, Coromandel Peninsula, New Zealand, as a mineral vein with calcite in altered hornblende andesite lava of the Miocene Beeson's Island Volcanics. The ferrierite is low in SiO2 (63.67%) and high in Al2O3 (13.75%), MgO (3.48%), and BaO(2.35%). The large a axis and cell volume (a 19.236(4), b 14.162(6), c 7.527(3) Å, V 2050 Å3) are consistent with the low SiO2, high Al2O3, high MgO chemistry. Optical orientation and optical sign (a = Z, b = X, c = Y, 2V(-)55°) of the mineral are different from those of the Lake Kamloops ferrierite reported by Graham (1918). Refractive indices α 1.487, γ 1.489, and density 2.136 were measured. Cleavage observed on (100) is perfect and on (001) is imperfect. Using data from eighteen occurrences so far reported including the Tapu mineral, the crystal chemistry of ferrierite has been studied.

A crystal chemical study on the superconductivity and compressibility of LnFePnO (Pn= P, As) superconductors

2015 ◽  
Vol 632 ◽  
pp. 303-306
Author(s):  
Huaiyong Li ◽  
Zhijian Wu ◽  
Shihong Zhou ◽  
Siyuan Zhang ◽  
Xipeng Pu ◽  
...  
Keyword(s):  
Chemical Study ◽  
Crystal Chemical
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