Search results for "Microscopy"
showing 10 items of 3390 documents
Magnetization reversal of the domain structure in the anti-perovskite nitride Co3FeN investigated by high-resolution X-ray microscopy
2016
We performed X-ray magnetic circular dichroism (XMCD) photoemission electron microscopy imaging to reveal the magnetic domain structure of anti-perovskite nitride Co3FeN exhibiting a negative spin polarization. In square and disc patterns, we systematically and quantitatively determined the statistics of the stable states as a function of geometry. By direct imaging during the application of a magnetic field, we revealed the magnetic reversal process in a spatially resolved manner. We compared the hysteresis on the continuous area and the square patterns from the magnetic field-dependent XMCD ratio, which can be explained as resulting from the effect of the shape anisotropy, present in nano…
Ptychographic imaging and micromagnetic modeling of thermal melting of nanoscale magnetic domains in antidot lattices
2020
CA extern Antidot lattices are potential candidates to act as bit patterned media for data storage as they are able to trap nanoscale magnetic domains between two adjacent holes. Here, we demonstrate the combination of micromagnetic modeling and x-ray microscopy. Detailed simulation of these systems can only be achieved by micromagnetic modeling that takes thermal effects into account. For this purpose, a Landau-Lifshitz-Bloch approach is used here. The calculated melting of magnetic domains within the antidot lattice is reproduced experimentally by x-ray microscopy. Furthermore, we compare conventional scanning transmission x-ray microscopy with resolution enhanced ptychography. Hence, we …
Structural characterization of TiO2/TiN O (δ-doping) heterostructures on (1 1 0)TiO2 substrates
2003
Abstract TiO2/TiNxOy δ-doping structures were grown on the top of (1 1 0)TiO2 rutile substrates by low pressure metal-organic vapor phase epitaxy (LP-MOVPE) technique at 750 °C. The samples were analyzed by high resolution transmission electron microscopy (HRTEM), electron energy loss spectroscopy (EELS) and X-ray diffraction techniques (rocking curves and φ-scans). The presence of satellites in the (1 1 0)TiO2 rocking curve revealed the epitaxial growth of 10 period δ-doping structures. The thickness of the TiO2 layers, 84 nm, was deduced from the satellites period. HRTEM observations showed around 1.5 nm thick δ-doping layers, where the presence of nitrogen was detected by EELS. The analy…
Stable and simple quantitative phase-contrast imaging by Fresnel biprism
2018
Digital holographic (DH) microscopy has grown into a powerful nondestructive technique for the real-time study of living cells including dynamic membrane changes and cell fluctuations in nanometer and sub-nanometer scales. The conventional DH microscopy configurations require a separately generated coherent reference wave that results in a low phase stability and a necessity to precisely adjust the intensity ratio between two overlapping beams. In this work, we present a compact, simple, and very stable common-path DH microscope, employing a self-referencing configuration. The microscope is implemented by a diode laser as the source and a Fresnel biprism for splitting and recombining the be…
A procedure for slicing and characterizing soft heterogeneous and irregular-shaped tissue
2020
Abstract This paper presents a slicing technique useful to prepare precise and repeatable samples from organs which are irregularly shaped and highly heterogeneous for mechanical testing and advanced microscopy observation. The suggested technique does not seem to influence the internal microstructure and it is employed here for testing specimens cut from different region of the meniscal tissue. Fast Fourier Transform analysis is used to quantify characteristic features of the microstructure (collagen fibers orientation, pore size) after slicing prior mechanical testing. Uniaxial (relaxation) tests are performed on dog-bone meniscal samples. Stress relaxation testing results on samples cut …
The interdependence of structural and electrical properties in TiO2/TiO/Ti periodic multilayers
2013
International audience; Multilayered structures with 14-50 nm periods composed of titanium and two different titanium oxides, TiO and TiO2, were accurately produced by DC magnetron sputtering using the reactive gas pulsing process. The structure and composition of these periodic TiO2/TiO/Ti stacks were investigated by X-ray diffraction and transmission electronic microscopy techniques. Two crystalline phases, hexagonal close packed Ti and face centred cubic TiO, were identified in the metallic-rich sub-layers, whereas the oxygen-rich ones comprised a mixture of amorphous TiO2 and rutile phase. DC electrical resistivity rho measured for temperatures ranging from 300 to 500 K exhibited a meta…
Induced crystallographic changes in Cd1−xZnxO films grown on r-sapphire by AP-MOCVD: the effects of the Zn content when x ≤ 0.5
2020
High-resolution X-ray diffraction, scanning electron microscopy and transmission electron microscopy techniques were used to investigate, as a function of the nominal Zn content in the range of 0–50%, the out-of-plane and in-plane crystallographic characteristics of Cd1−xZnxO films grown on r-plane sapphire substrates via atmospheric pressure metal–organic chemical vapor deposition. The study is conducted to search for knowledge relating to the structural details during the transition process from a rock-salt to a wurtzite structure as the Zn content increases in this CdO–ZnO system. It has been found that it is possible to obtain films exhibiting a single (001) cubic orientation with good …
Two-phase dielectric polar structures in 0.1NBT-0.6ST-0.3PT solid solutions
2018
Abstract In this work we address the peculiarities of the macroscopic responses in ternary 0.1Na0·5Bi0·5TiO3-0.6SrTiO3-0.3PbTiO3 (0.1NBT-0.6ST-0.3PT) solid solutions. These solid solutions exhibit a spontaneous first order relaxor to normal ferroelectric phase transition. The phase transition is accompanied by a broad dielectric relaxation which expands over 10 orders of magnitude in frequency just above the phase transition temperature. The temperature dependence of polarization shows that non-zero net polarization persists above the phase transition temperature. Below the phase transition temperature, it is not possible to describe the temperature dependence of polarization with a power l…
Real space observation of two-dimensional Bloch wave interferences in a negative index photonic crystal cavity
2008
We report here the direct observation of two-dimensional (2D) Bloch wave interferences in a negative index photonic crystal by using optical near-field microscopy techniques. The photonic crystal is formed by a defectless honeycomb lattice of air holes etched in III-V semiconductor slab. A scanning near-field optical microscope is used to visualize spatially, as well as spectrally, the light distribution inside the photonic crystal. The recorded near-field spectra and maps presented here unambiguously demonstrate the Bloch wave interferences within the photonic crystal. Then, the spectral and spatial evolution of these interferences allows us to recover experimentally the 2D band diagram of…
Formation of translucent nanostructured zirconia ceramics
2021
Abstract In this work the mechanisms that affect the optical transparency of nanostructured translucent ZrO2 ceramics are studied. The translucent ceramic samples were obtained from a low agglomeration nanosized powder at low pressure and low temperature sintering. Even low pressures cause structural changes and defect creation in the nanocrystals. Annealing was used to study the grain formation, structure and impact of defects. Significant changes in translucency were observed with increase in pore size. In order to further understand the defect creation, the obtained ceramics were doped with Er3+ ions and studied optically. Photoluminescence studies revealed a change in the ratio of green…