6 research outputs found
Extended defects in natural diamonds: Atomic Force Microscopy investigation
Surfaces of natural diamonds etched in high-pressure experiments in H2O, CO2
and H2O-NaCl fluids were investigated using Atomic Force Microscopy. Partial
dissolution of the crystals produced several types of surface features
including the well-known trigons and hillocks and revealed several new types of
defects. Besides well-known trigons and dissolution hillocks several new types
of defects are observed. The most remarkable ones are assigned to anelastic
twins of several types. The observation of abundant microtwins, ordering of
hillocks and presence of defects presumably related to knots of branched
dislocations suggests importance of post-growth deformation events on formation
of diamond microstructure. This work confirms previous reports of ordering of
extended defects in some deformed diamonds. In addition, the current work shows
that natural diamonds deform not only by dislocation mechanism and slip, but
also but mechanical twinning. The dominant mechanism should depend on
pressure-temperature-stress conditions during diamond transport from the
formation domain to the Earth surface.Comment: Submitted to special issue (1st European Mineralogical congress,
Frankfurt, Germany, September 2012) of European Journal of Mineralogy. 21
page, 9 figure
Electron-Beam Domain Patterning in Sr0.61Ba0.39Nb2O6 Crystals
The characteristics of electron-beam domain writing (EBDW) on the polar and nonpolar surfaces of the field-cooled (FC) and zero-field cooled (ZFC) Sr0.61Ba0.39Nb2O6 (SBN) crystals are presented in the range of accelerating voltage U from 10 to 25 kV. The exposure characteristics of the domain diameter d and length Ld (when writing on the polar and nonpolar surfaces, respectively) were measured. With increasing exposure time, d tends to a saturation value, whereas Ld grows linearly, the frontal velocity Vf being of 40 μm/s. At U = 25 kV the achieved d and Ld are of 7 and 40 µm, respectively. The observed peculiar features of EBDW—specifically the domain widening with exposure times and the effect of the polarization state of the crystal on the domain stability—are accounted for by the relaxor features inherent to this material. The effects of electron-beam (EB) irradiation on the local hysteresis loops is evidence of a domain fixation
One-Step Synthesis of Functional Sulfonated Polynaphthoylenebenzimidazoles for Biosensing Applications
Polynaphthoylenebenzimidazoles containing functional sulfo groups were synthesized by a one-step method in a sulfuric acid medium with oleum. A polymer-analogous transformation of these polymers with aqueous solutions of metal salts (K, Ca, and Cr) was carried out. Their chemical structure was characterized by FTIR, NMR, and elemental analysis. Polymer salt coatings were deposited on QCM sensor surfaces by electron beam-induced vacuum deposition. The morphology of the coatings was characterized by AFM. It was shown that the coatings formed from a series of polymer salts have different adsorption activity in acetaminophen–water solution compared to distilled water. The QCM results indicate that sensor signal correlates with polymer coating thickness, morphology, and its chemical composition