Andrew Putnis

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A selection of recent results illustrating the application of off-axis electron holography to the study of magnetic microstructure in closely-spaced nanoparticles and nanowires is reviewed. Examples are taken from the characterization of FeNi nanoparticle chains, Co nanoparticle rings, two-dimensional arrays of naturally occurring magnetite crystals in(More)
Models of crystal growth have been defined by comparing macro­ scopic growth kinetics with theoretical predictions for various growth mechanisms!,2. The classic Burton-Cabrera-Frank (BCF) theory' predicts that spiral growth at screw dislocations will dominate near equilibrium. Although this has often been observed2,,, such growth is sometimes inhibited4,5,(More)
Edges on the basal face of uranyl-sheet minerals control dissolution and crystal-growth processes because of their higher interaction with the aqueous solution than the less reactive basal face. A basal face is parallel to the structural unit of a uranyl-sheet mineral and dominates its crystal morphology. Edges terminate a structural unit and define the(More)
To investigate the acquisition mechanism of high and stable natural remanent magnetization (NRM) in rocks of the Russell Belt, Adirondack Mountains, New York, we examined the exsolution microstructures and compositions of magnetic minerals using three samples with different magnetic properties. The samples contain titanohematite with ilmenite lamellae,(More)
Four calcium,aluminum-rich inclusions from four carbonaceous chondrites-Allende, Acfer 082, Acfer 086, and Acfer 094-were studied by transmission electron microscopy. All inclusions contained at least two of the oxides periclase (MgO), rutile (TiO2), calcium oxide (CaO), and corundum (Al2O3). The oxides (50 to 200 nanometers in size) were found inside and(More)
Structural phase transformations in Ni(7)S(6) and Cu(7)S(4) have been observed dynamically by in situ experiments in a transmission electron microscope. In this way it is possible to demonstrate the possibility of two fundamentally different types of behavior: (i) the ideal transformation from the stable high-temperature form to the stable low-temperature(More)
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