Search results for "Diffraction"
showing 10 items of 1584 documents
Performance of a thermoelectric module based on n-type (La0.12Sr0.88)0.95TiO3-δ and p-type Ca3Co4-xO9+δ
2020
Here, we present the performance of a thermoelectric (TE) module consisting of n-type (La0.12Sr0.88)0.95TiO3 and p-type Ca3Co4-xO9+δ materials. The main challenge in this investigation was operation of TE module in different atmosphere conditions, since n-type has its optimum TE-performance at reducing, while p-type at oxidizing conditions. The TE module was exposed to two different atmospheres and demonstrated higher stability in N2 atmosphere than in air. The maximum electrical power output decreased after 40 h when the hot side was exposed to N2 at 600 °C, while only 1 h at 400 °C in ambient air was enough to oxidize (La0.12Sr0.88)0.95TiO3 followed by a reduced electrical power output. T…
Order-disorder evolution in solid solutions of the NLO material KTiOPO : K Rb TiOPO and K Rb TiOPO in the temperature range 293-973 K
2000
K0.88Rb0.12TiOPO4 and K0.465Rb0.535TiOPO4 solid solutions of the potassium titanyl phosphate (KTiOPO4, space group Pna21) family, are described at 293, 473, 673, 873 and at 973 K. Their high resolution structures are obtained by using accurate single-crystal X-ray diffraction techniques at high resolution, (sin A-1. Large anharmonic motion of alkaline ions increasing with temperature allows the evolution of the rubidium and potassium ions repartition in the two alkaline sites versus temperature. To describe this motion inducing ionic conductivity phenomenon and to determine accurately the order-disorder evolution, two alkaline site refinement models are developed and discussed. A thermodyna…
Apparent magic numbers in embedded Ti-O clusters
2003
Stable clusters constituted of four ${\mathrm{TiO}}_{2}$ entities have been evidenced in nanometer-sized spinel oxides by a combination of diffraction and x-ray-absorption experiments. Contrary to free clusters, the size of the embedded clusters is strongly determined by the constraints imposed by the surrounding matrix so that the magic number of four is in fact specific to the matrix and only then apparent.
Structural characterization of TiNxOy/TiO2 single crystalline and nanometric multilayers grown by LP-MOCVD on (110)TiO2
2001
TiO2/TiNxOy superlattices were grown by Low Pressure-Metal-Organic Vapor Phase Epitaxy (LP-MOVPE) technique at deposition temperatures ranking from 650 to 750°C. The growth was performed on top of TiO2(110) rutile substrates. Intense peaks observed in the X-rays rocking curves and θ-2θ diffraction patterns show the presence of crystalline epilayers. The TiNxOy layers were grown in a (200) cubic structure on the (110) quadratic TiO2 epilayer structure. Transmission electron microscopy confirmed the XRD results and showed the formation of periodic and well structured epilayers.
A wideband THz Time Domain Spectroscopy table-top system based on ultrafast pulsed laser: Model and experiments
2014
We present an analytical model carefully describing the time-frequency behavior of all the stages composing our whole Terahertz Time Domain Spectroscopy laser based system, from the THz pulses generation via Optical Rectification, to their detection through Electro-Optic Sampling technique, by way of diffraction, collecting and focusing effects. In order to prove the effectiveness of our work, we report on the comparison among the experimental waveforms and the simulation results.
Preparation of photocatalytic brookite thin films
2007
Pure brookite films were deposited from a brookite dispersion obtained by peptizing a mixture brookite–rutile prepared by thermolysis of TiCl4 in a HCl solution. The films were characterised by X-ray diffraction and Raman spectroscopy. The photoactivity of the samples was tested by using the photo-oxidation of 2-propanol in gas–solid regime as a probe reaction. The brookite films efficiently degraded 2-propanol under UV illumination.
Resonant Photoelectron Diffraction
2013
A layout of a resonant photoelectron diffraction, RESPED, experiment is described from the theoretical basis to the data acquisition and analysis procedures. The theory of the resonance between the directly emitted photoelectron of a selected valence band and the electron emitted by autoionization (Auger) of the same valence band is presented within a formal frame. The critical issue of the angular symmetry and distribution of the resonating electron is discussed in connection with the current computational protocols for photoelectron diffraction, PED, analysis. A few representative applications are presented, where RESPED is shown to overcome some limitations of conventional PED thanks to …
Recent Advances in 3D Structured Illumination Microscopy
2018
In structured illumination microscopy (SIM) the sample under investigation is illuminated using a structured illumination (SI) pattern. This SI pattern encodes high spatial frequencies of fine features within the sample, which usually are not transferred by the conventional three-dimensional (3D) optical transfer function (OTF) of the imaging system and fills the missing cone of frequencies in the OTF for better discrimination of the out-of-focus light. Thereby, SIM provides super-resolution (SR) performance beyond the diffraction limit and optical-sectioning (OS) capability with the use of data post-processing approaches. 3D structured patterns that include lateral and axial variations in …
Effect of Penetrating Irradiation on Polarization Reversal in PZT Thin Films
2006
Spatially non-uniform imprint behavior induced by X-ray synchrotron, electron, and neutron irradiation has been investigated in Pb(Zr,Ti)O3 thin films. The obtained effects have been explained as a result of acceleration of the bulk screening process induced by irradiation. It has been shown that the spatial distribution of the internal bias field is determined by the domain pattern existing during irradiation. The microstructural changes in the structural characteristics during fatigue cycling have been revealed by high resolution synchrotron X-ray diffraction experiments. Their correlation with the evolution of the switching characteristics has been revealed and discussed.
Towards automated diffraction tomography. Part II--Cell parameter determination.
2008
Automated diffraction tomography (ADT) allows the collection of three-dimensional (3d) diffraction data sets from crystals down to a size of only few nanometres. Imaging is done in STEM mode, and diffraction data are collected with quasi-parallel beam nanoelectron diffraction (NED). Here, we present a set of developed processing steps necessary for automatic unit-cell parameter determination from the collected 3d diffraction data. Cell parameter determination is done via extraction of peak positions from a recorded data set (called the data reduction path) followed by subsequent cluster analysis of difference vectors. The procedure of lattice parameter determination is presented in detail f…