Search results for "Microscopy"
showing 10 items of 3390 documents
Crystalline microstructure of sepiolite influenced by grinding
2005
The crystalline microstructure of ground sepiolite has been investigated. A reference sample of sepiolite and products of its comminution by dry grinding were studied through X-ray diffraction pattern analysis, specific surface measurements by nitrogen adsorption and complementary analysis of field emission scanning electron microscope images. A statistical model of polycrystals was applied to describe and determine the crystalline microstructure of the studied specimens. The model parameters characterizing the microstructure were prevalent crystallite shape, volume-weighted crystallite size distribution and second-order crystalline lattice strain distribution, and they were determined for …
Addressing subphthalocyanines and subnaphthalocyanines features relevant to fluorescence imaging
2018
International audience; A series of new synthetic subphthalocyanines bear structural features aimed at allowing either fluorescence activation or a bathochromic shift of the absorption band towards the near-infrared window, relevant to optical imaging. X-ray diffraction studies of four subphthalocyanines are reported. Spectrofluorimetric studies on subnaphthalocyanines and activatable subphthalocyanine pro-fluorophores are reported.
Towards metal chalcogenide nanowire-based colour-sensitive photodetectors
2018
Financial support provided by Scientific Research Project for Students and Young Researchers Nr. SJZ/2016/6 realized at the Institute of Solid State Physics, University of Latvia is greatly acknowledged. Authors are grateful to Reinis Ignatans for XRD measurements.
Growth and characterization of self-assembled Cd1−xMgxO (0 ≤ x ≤ 1) nanoparticles on r-sapphire substrates
2014
In this work, the growth of isolated Cd1−xMgxO nanoparticles on r-sapphire substrates is extended to the entire range of Mg content (0 ≤ x ≤ 1) using the spray pyrolysis method. The sizes of the Cd1−xMgxO nanoparticles were in the ranges 4–6 nm and 15–30 nm (with a nanoparticle density of 1010 cm−2). The composition of the nanoparticles was determined using transmission electron microscopy energy dispersive X-ray analysis (TEM-EDAX), while the compound formation was confirmed using X-ray photoelectron spectroscopy. A systematic decrease in the a lattice parameter of Cd1−xMgxO on increasing the Mg content substantiated the successful incorporation of Mg2+ ions into the cubic CdO lattice. Sin…
Three‐Component Self‐Assembly Changes its Course: A Leap from Simple Polymers to 3D Networks of Spherical Host–Guest Assemblies
2021
Angewandte Chemie / International edition 60(21), 12132 - 12142 (2021). doi:10.1002/anie.202103178
Mechanical and structural characterizations of gamma- and alpha-alumina nanofibers
2015
Abstract We investigate the applicability of alumina nanofibers as a potential reinforcement material in ceramic matrix compounds by comparing the mechanical properties of individual nanofibers before and after annealing at 1400 °C. Mechanical testing is performed inside a scanning electron microscope (SEM), which enables observation in real time of the deformation and fracture of the fibers under loading, thereby providing a close-up inspection of the freshly fractured area in vacuum. Improvement of both the Young's modulus and the breaking strength for annealed nanofibers is demonstrated. Mechanical testing is supplemented with the structural characterization of the fibers before and afte…
A multi-technique, micrometer- to atomic-scale description of a synthetic analogue of chukanovite, Fe-2(CO3)(OH)(2)
2014
International audience; A synthetic analogue of chukanovite Fe-2(CO3)(OH)(2) is formed during experimental work on iron-clay interactions simulating the cooling of containers in radioactive waste repositories. Despite its small size and the mixture with other minerals it is undoubtedly identified by X-Ray Diffraction, Fourier Transform Infrared Spectroscopy, Scanning Electron Microscopy and Transmission Electron Microscopy. For the first time, the structural characterisation of a synthetic chukanovite is carried out thanks to the combination of Automated Diffraction Tomography and Precession Electron Diffraction. Refinement results and comparison with literature data show that the structure…
Zinc Chalcogenide Seed-Mediated Synthesis of CdSe Nanocrystals: Nails, Chesses and Tetrahedrons
2015
Systematically shape-controlled synthesis of colloidal semiconductor nanocrystals (NCs) has attracted increasing attention recently for both fundamental and technological interest. The study on the synthesis of colloidal CdSe NCs has given rise to well-developed methods for producing diverse shapes such as rods, wires, cubs and discs. In the current study, we demonstrate the shape evolution of CdSe NCs by using a seed-mediated approach by control reaction temperature and injection methods. The synthesis utilizes small (2.0–3.0 nm) zinc chalcogenide NCs with zincblende structure as seeds for subsequent growth, which results in distinct shapes of nail-shaped, tetrahedron-shaped, chess piece-s…
3D Electron Diffraction: The Nanocrystallography Revolution
2019
Crystallography of nanocrystalline materials has witnessed a true revolution in the past 10 years, thanks to the introduction of protocols for 3D acquisition and analysis of electron diffraction data. This method provides single-crystal data of structure solution and refinement quality, allowing the atomic structure determination of those materials that remained hitherto unknown because of their limited crystallinity. Several experimental protocols exist, which share the common idea of sampling a sequence of diffraction patterns while the crystal is tilted around a noncrystallographic axis, namely, the goniometer axis of the transmission electron microscope sample stage. This Outlook review…
Electric and dielectric properties of nanostructured stoichiometric and excess-iron Ni–Zn ferrites
2013
In this paper, we report a study of the effect of excess iron on structural, microstructural, electric and dielectric properties of the nanostructured Ni–Zn ferrites Ni1−xZnxFe2+zO4−δ of different compositions with x = 0, 0.3, 0.5, 0.7, 1 and z = 0, 0.1. The structural and microstructural properties are estimated from x-ray diffraction and atomic force microscopy (AFM) data. The average grain size, evaluated from AFM topographical analysis, is found to be below 70 nm. The samples exhibit low values of dielectric constant and dielectric loss and a high resistivity. Contrary to earlier conclusions regarding microstructured Ni–Zn ferrites, in nanostructured Ni–Zn ferrites sintered at relativel…