scholarly journals Manganese incorporation in synthetic hercynite

2015 ◽  
Vol 79 (3) ◽  
pp. 635-647 ◽  
Author(s):  
G. D. Bromiley ◽  
G. D. Gatta ◽  
T. Stokes
Keyword(s):  
Single Crystal ◽  
Absorption Spectroscopy ◽  
Structure Refinement ◽  
Tetrahedral Site ◽  
Silicate Melt ◽  
X Ray ◽  
Octahedral Sites ◽  
Partial Disorder ◽  
X Ray Absorption ◽  
Preferential Incorporation

AbstractManganese incorporation in synthetic hercynite, and partitioning between hercynite and silicate melt synthesized at 1.0 GPa, 1250°C, and at an fO2 buffered by Fe–FeO, has been studied by X-ray absorption spectroscopy and single-crystal X-ray structure refinement. Spectra indicate the presence of both Mn2+ and Mn3+ (and possibly also Mn4+) in synthetic hercynite and partitioning of Mn2+ into the melt phase, and Mn3+ into hercynite, respectively, under run conditions. X-ray refinement is consistent with partial disorder of Fe and Al across tetrahedral and octahedral sites. A higher than expected degree of Fe-Al disorder in the Mn-bearing hercynite can be explained by preferential incorporation of Mn2+ onto the tetrahedral site, and indicates that Fe-Al disorder in pure, stoichiometric hercynite cannot necessarily be used to determine closure temperatures in natural spinel. However, partitioning of Mn2+ and Mn3+ between melt and hercynite suggests that Mn incorporation in hercynite could be used as a measure of fO2 conditions in magmas during spinel crystallization.

H-bonding scheme in allactite: a combined single-crystal X-ray and neutron diffraction, optical absorption spectroscopy, FTIR and EPMA-WDS study

2016 ◽  
Vol 80 (5) ◽  
pp. 719-732 ◽  
Author(s):  
G. Diego Gatta ◽  
Ferdinando Bosi ◽  
Maria Teresa Fernandez Diaz ◽  
Ulf Hålenius
Keyword(s):  
Neutron Diffraction ◽  
Optical Absorption ◽  
Single Crystal ◽  
Absorption Spectroscopy ◽  
Structure Refinement ◽  
Site Occupancy ◽  
Optical Absorption Spectroscopy ◽  
Hydroxyl Groups ◽  
X Ray ◽  
Bonding Scheme

AbsatractThe crystal chemistry of allactite from Långban, Värmland (Sweden) was investigated by single-crystal X-ray and neutron diffraction, optical absorption spectroscopy, Fourier-transform infra-red spectroscopy (FTIR) and electron microprobe analysis by wavelength-dispersive spectroscopy (EPMA-WDS). The optical spectra indicate the presence of Mn in valence state 2+ only. Assuming 16 O atoms per formula unit, arsenic as As5+and the (OH) content calculated by charge balance, the resulting formula based on the EPMA-WDS data is (Mn2+6.73Ca0.13Mg0.12Zn0.02)∑7.00(As5+)2.00O16H8, very close to the ideal composition Mn7(AsO4)2(OH)8. In the unpolarized FTIR spectrum of allactite, fundamental (OH)-stretching bands are observed at 3236, 3288, 3387, 3446, 3484, 3562 and 3570 cm–1, suggesting that a number of OH environments, with different hydrogen bond strengths, occur in the structure. The neutron structure refinement shows that four independent H sites occur in allactite with full site occupancy, all as members of hydroxyl groups. The complex hydrogen-bonding scheme in the allactite structure is now well defined, with at least nine hydrogen bonds energetically favourable with mono-, bi- and trifurcated configurations.

Single-crystal polarized x-ray absorption spectroscopy. Observation and theory for thiomolybdate(2-)

1981 ◽  
Vol 103 (20) ◽  
pp. 6083-6088 ◽  
Author(s):  
Frank W. Kutzler ◽  
R. A. Scott ◽  
Jeremy M. Berg ◽  
Keith O. Hodgson ◽  
S. Doniach ◽  
...  
Keyword(s):  
Single Crystal ◽  
Absorption Spectroscopy ◽  
X Ray ◽  
X Ray Absorption ◽  
Spectroscopy Observation

An electronic structure study of La8−xSrxCu8O20−δ (8820) single crystal using polarized X-ray absorption spectroscopy

2004 ◽  
Vol 132 (3-4) ◽  
pp. 279-283
Author(s):  
S.K. Gaur ◽  
R.K. Singhal ◽  
N.L. Saini ◽  
S. Dalela ◽  
C.T. Chen ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Single Crystal ◽  
Absorption Spectroscopy ◽  
Structure Study ◽  
X Ray ◽  
X Ray Absorption

Study of Ga3+-Induced Hydrothermal Crystallization of an α-Quartz Type Ga1-xFexPO4 Single Crystal by in Situ X-ray Absorption Spectroscopy (XAS)

2012 ◽  
Vol 51 (21) ◽  
pp. 11811-11819 ◽  
Author(s):  
Manhal Souleiman ◽  
Olivier Cambon ◽  
Abel Haidoux ◽  
Julien Haines ◽  
Claire Levelut ◽  
...  
Keyword(s):  
Single Crystal ◽  
Absorption Spectroscopy ◽  
Hydrothermal Crystallization ◽  
X Ray ◽  
X Ray Absorption

scholarly journals Investigation on cation distribution and luminescence in spinel phase γ-Ga3−δO4 : Sm nanostructures using X-ray absorption spectroscopy

RSC Advances ◽  
2017 ◽  
Vol 7 (83) ◽  
pp. 52543-52554 ◽  
Author(s):  
Aditya Sharma ◽  
Mayora Varshney ◽  
Hyun-Joon Shin ◽  
Keun Hwa Chae ◽  
Sung Ok Won
Keyword(s):  
Absorption Spectroscopy ◽  
Cation Distribution ◽  
Spinel Phase ◽  
Luminescence Properties ◽  
X Ray ◽  
Octahedral Sites ◽  
Spectroscopic Investigations ◽  
X Ray Absorption

In this study, spectroscopic investigations are employed to quantify the Ga distribution over the tetrahedral/octahedral sites and to assimilate the luminescence properties in the barely reported γ-Ga2.67O4 : Sm nanoparticles.

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