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Atomic Arrangement of Merwinite, Ca3Mg[SiO4]2, an Unusual Dense-packed Structure of Geophysical Interest

Paul B. Moore, +1 more
- 01 Oct 1972 - 
- Vol. 57, pp 1355-1374
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TLDR
In this paper, the crystal cell data are: space group P\/a, a 73.254(21), b 5.253(il, c 9.328(17)A, p 91.90(15)', Z 4.061 for 23O0 independent reflections.
Abstract
Merwinite, Ca"MglSionlr, is an important and persistent phase in petrological systems crucial to mantle and crustal chemistry and to the cement and blast furnance industries. Despite numerous studies on its crystal chemistry, all reports recorded heretofore in the literature are erroneous in various details. The crystal cell data are: space group P\/a, a 73.254(21), b 5.253(il, c 9.328(17)A, p 91.90(15)', Z 4. The unit formula, CaoMgtSi0l", constitutes the asymmetric unit of the crystal structure with all atoms in general positions. Solution of the structure proceeded from Patterson and p-general syntheses, and led to ,B(hftl) 0.061 for 23O0 independent reflections.

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Citations
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An internally consistent thermodynamic data set for phases of petrological interest

TL;DR: In this paper, the thermodynamic properties of 154 mineral endmembers, 13 silicate liquid end-members and 22 aqueous fluid species are presented in a revised and updated data set.
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An enlarged and updated internally consistent thermodynamic dataset with uncertainties and correlations: the system K2O–Na2O–CaO–MgO–MnO–FeO–Fe2O3–Al2O3–TiO2–SiO2–C–H2–O2

TL;DR: In this paper, a revised and much enlarged version of the thermodynamic dataset given earlier (Holland & Powell, 1985) is presented, which includes data for 123 mineral and fluid end-members made consistent with over 200 P-T-XCO2-fO2 phase equilibrium experiments.
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Warm-white-light emitting diode utilizing a single-phase full-color Ba3MgSi2O8:Eu2+,Mn2+ phosphor

TL;DR: In this paper, a fabricated white-light emitting diode using a 400nm-emissive chip with a white light emitting Ba3MgSi2O8:Eu2+, Mn2+ phosphor shows warm white light and higher color stability against input power in comparison with a commercial GaN-pumped (Y1−xGdx)3(Al1−yGay)5O12:Ce3+osphor.
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White-light generation through ultraviolet-emitting diode and white-emitting phosphor

TL;DR: In this article, a white-light-emitting diodes are fabricated by using 375nm emitting InGaN chip with Sr3MgSiSi2O8:Eu2+ (blue and yellow) or Sr3mgSi2 O8: Eu2+, Mn2+(blue, yellow, and red).
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Full-color Ba3MgSi2O8:Eu2+, Mn2+ phosphors for white-light-emitting diodes

TL;DR: The Ba3MgSi2O8:mEu2+, Mn2+ phosphors show three emission colors: blue band of 440 nm, green band of 505 nm and red band of 620 nm as mentioned in this paper.
References
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Journal ArticleDOI

Phase transformations and the constitution of the mantle

TL;DR: In this article, the authors present a review of the constitution of the mantle between depths of 200 and 1200 km in the light of recent high pressure experimental investigations on silicates and on their germanate analogues, concluding that the rapid increase of seismic velocity around 350-450 km is caused mainly by the transformation of olivine into a spinel-like structure and by transformation of pyroxenes into a new kind of garnet structure characterized by octahedral coordination of a substantial proportion of silicon atoms.

Or fls--a fortran crystallographic least-squares program

TL;DR: A computer program to perform the least-squares refinement of crystal structure parameters based on x-rayor neutron-diffraction measurements is described and detailed instructions for its use are included.
Journal ArticleDOI

Progressive Metamorphism of Siliceous Limestone and Dolomite

Abstract: The metamorphism of siliceous dolomitic limestone is considered with the aid of a composition tetrahedron which suggests that the changes may be referred to thirteen steps or grades of increasing decarbonation, taking place at successively higher temperatures at any given pressure. At the temperature appropriate to each step a certain phase assemblage becomes unstable and each step is characterized by the disappearance of its appropriate phase assemblage. The survival of that phase assemblage in a rock is rigorously indicative of the fact that the step in question has not been attained. In most of the steps, to wit ten, the disappearance of its phase assemblage is accompanied by a more conspicuous phenomenon, the appearance of a new phase, a meta-morphic mineral, but this appearance of a new phase cannot be regarded as rigorously indicative of the accomplishment of the step since the new phase can be produced otherwise. Nevertheless, if certain additional conditions are fulfilled, the new phase will appea...
Journal ArticleDOI

Crystal structure of β-Mg2SiO4: crystal-chemical and geophysical implications

TL;DR: In this paper, the earth mantle phase transition from beta magnesium silicate crystal structure is discussed. And the implications of the phase transition on the structure of the earth's mantle are discussed.
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