Journal ArticleDOI
The mechanism of exsolution of hematite from iron-bearing rutile
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In this paper, annealing at temperatures between 475° and 600° C precipitation of an iron-rich phase occurs and the precipitation sequence involves two transitional stages before the formation of hematite, the equilibrium precipitate.Abstract:
Natural iron-bearing rutile, formed under low temperature hydrothermal conditions, is chemically homogeneous on an electron-microscope scale (at a resolution of about 10 A) On annealing at temperatures between 475° and 600° C precipitation of an iron-rich phase occurs The precipitation sequence involves two transitional stages before the formation of hematite, the equilibrium precipitate The first phase is coherent with the rutile structure and has the general characteristics of Guinier-Preston zones The second transitional phase is a monoclinic variant of the rutile structure and is partially coherent with the matrix Annealing experiments enable a Time-Temperature-Transformation (TTT) plot to be constructed for the exsolution process and the kinetics are interpreted in terms of the structural changes involved at each stage of the processread more
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Journal ArticleDOI
Rutile and its applications in earth sciences
TL;DR: Rutile is the most common naturally occurring titanium dioxide polymorph and is widely distributed as an accessory mineral in metamorphic rocks ranging from greenschist to eclogite and granulite facies but is also present in igneous rocks, mantle xenoliths, lunar rocks and meteorites.
Journal ArticleDOI
Colossal Dielectric Permittivity in (Nb+Al) Codoped Rutile TiO2 Ceramics: Compositional Gradient and Local Structure
TL;DR: In this paper, it was shown that a conventional surface barrier layer capacitor (SBLC) effect, while it contributes significantly to the observed colossal permittivity, is not the dominant effect, rather, there exists a subtle chemical compositional gradient inward from the pellet surface, involving the concentration of Ti3+ cations gradually increasing from zero at the surface without the introduction of any charge compensating oxygen vacancies.
Journal ArticleDOI
Niobian rutile from the McGuire granitic pegmatite, Park County, Colorado; solid solution, exsolution, and oxidation
TL;DR: In this article, a fine trellis-like pattern of minor lamellar Nb-bearing pseudorutile I was broken down to pseudomorphs consisting of microgranular nb-rich pseudoreutile II imbedded in niobian-ferrian "ferropseudobrookite" and then extensive oxidation converted the mineral assemblages to anatase + hematite + titanian-tungstenian ixiolite.
Journal ArticleDOI
Nanoscale distribution of Pb in monazite revealed by atom probe microscopy
Denis Fougerouse,Steven M. Reddy,David W. Saxey,Timmons M. Erickson,Timmons M. Erickson,Christopher L. Kirkland,William D.A. Rickard,Anne-Magali Seydoux-Guillaume,Anne-Magali Seydoux-Guillaume,Chris D. Clark,Ian S. Buick +10 more
TL;DR: In this paper, the authors investigated the nanoscale distribution of Pb in monazite from granulite facies rocks of the Sandmata Metamorphic Complex (Rajasthan, India) by atom probe microscopy.
Journal ArticleDOI
Microstructural, trace element and geochronological characterization of TiO 2 polymorphs and implications for mineral exploration
Diana Plavsa,Diana Plavsa,Steven M. Reddy,Andrea Agangi,Chris D. Clark,Andrew R.C. Kylander-Clark,Caroline Tiddy +6 more
TL;DR: In this article, a ternary diagram was constructed based on the systematic changes in chemistry of TiO2 polymorphs to provide a relatively fast and easy chemical discrimination of polymorphs in large volumes of reconnaissance data.
References
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Book
Electron Microscopy of Thin Crystals
TL;DR: Hirsch et al. as mentioned in this paper described further experiments on the preparation of thin film sections of embedded Backscatter Kikuchi diffraction in the SEM for identification of crystallographic thin films by electron microscopy.
Book
Fundamentals of Physical Metallurgy
TL;DR: In this article, the authors present a review of Free-Energy Composition Diagrams (FECD) and a comparison with Massive Transformations (MT) for fcc and hcp materials.
Book ChapterDOI
Exsolution in Silicates
P. E. Champness,G. W. Lorimer +1 more
TL;DR: The phase distribution of exsolved minerals often bears a marked resemblance, both in scale and morphology, to the phase distributions which have been observed in metallic alloys as discussed by the authors, and this similarity appears anomalous for the cooling rates of naturally occurring minerals are 104 to 106 times slower than those usually encountered in alloys.