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Using calculated tables of the second-rank constitutive tensors for linear
bianisotropic media, some general electromagnetic properties of the media are discussed. We
consider enantiomorphism, crosscoupling tensors and nonreciprocity. The presented tables
obtained by group-theoretical methods and comprising 122 discrete point and 21 continuous
magnetic groups of symmetry can serve for investigation of some other physical properties of
the media. Also considered are the main distinctions of the tables from those published
Ferrobielastic twinning in quartz single crystals has been investigated in relation to
crystallographic orientation and crystal origin. By means of uniaxial compressive stress
experiments, complete volumetric transformation to the alternate Dauphiné twin state was
performed in X- and AT-cut samples of natural and synthetic quartz. Either polarized light or
synchrotron radiation X-ray topography was employed to observe the movement of twin
boundaries. The dependence of the coercive stress and the preferential orientation of twin
boundaries on the crystallographic orientation are explained in terms of the thermodynamic
potential of the Gibbs free energy. In relation to natural crystals, the stress levels related to
optical visualization and complete transformation to the alternate twin state were 50% and
30% lower for synthetic quartz. These results are qualitatively discussed by the pinning of
Dauphiné twin boundaries at randomly distributed impurity-related point defects which were
evaluated by infrared spectroscopy and ion coupled plasma spectrometry. The spontaneous
irreversibility of ferrobielastic twinning on unloading is confirmed.
(001) surfaces of indium phosphide (InP) single crystals have been deformed at room
temperature by a Vickers indenter. The indents formed were observed by transmission
electron microscopy (TEM) in plan views as well as in cross-sectional views obtained by
focused-ion beam (FIB) milling. The in-depth structure of the plastic zone has been
investigated as well as the dislocation arrangements. The polarity of the crystal was
determined by convergent beam electron diffraction (CBED) and the plastic anisotropy was
Composites made of iron and Cr doped magnetite are obtained by precipitation from the metallic
chlorides salts into a KOH solution heated under reflux. A KOH concentration of 14 mol l−1 is
required. The composition of the samples is determined by X-ray diffraction, TG measurements,
chemical analysis and Mössbauer spectrometry. The higher the chromium content, the smaller the
lattice parameter and the lower the metal ratio. For Cr/Fe ≤ 0.1, the chemical formula of the
composites can be written FeA/(Fe
. We show that only in-field
Mössbauer spectrometry at low temperature is suitable to estimate unambiguously both the
proportions of octahedral and tetrahedral iron sites in spinel and the valence of delocalised iron
state, if any. A peculiar A-site occupation by either vacancies or Cr3+ ions is observed. This is
probably due to the low temperature synthesis. The two phases, metal and spinel are found to be
intimately mixed within the nanometer sized particles. For Cr/Fe ratios higher than 0.1, hydroxide
phase is also present.
High power pulsed lasers are used to induce shock waves in Hastelloy X
targets coated with tungsten carbide of 70 μm and 50 μm thickness. In suitable
irradiation conditions, a debonding of the substrate/coating interface due to the
generation of tensile stresses is observed. Experimental results are analyzed with the use
of numerical simulations yielding the stress history at interface and its dependence on
laser pulse intensity up to 600 GW/cm2 with 1 ns and 3 ns durations under direct
irradiation, and 23 ns with water confinement. As a consequence of shock decay during
the propagation through the substrate, a strong variation of incident intensity results in a
small variation of tensile stress. This allows an accurate determination of the debonding
threshold which is found in the range of 1.0 to 1.3 GPa for short laser pulses (1 and 3 ns) and 0.5 to 0.6 GPa for long laser pulses (23 ns confined).
The microstructure of NdNiO3 thin films deposited on Si (100) has been
investigated by high resolution electron microscopy. Deposition at 250 °C
and 600 °C and several annealing at high temperature under oxygen pressure
were performed. Depending on the deposition temperature and annealing
conditions, different texture and microstructure were observed. Relationships
between microstructure and transport properties are discussed. The
differences of grain boundaries are suggested to be responsible for the
difference in transport properties of the films.
This article presents a binary classification method which is
used in defects detection. It's presented as recursives “boosting”
algorithms which allow us to obtain a precise discriminating function by
combination of hypothesis and rules with moderate accuracy. This approach
permits the study of random phenomena governed by nonparametric laws and a
direct decision for the observations classification and the determination of
frontiers in an observation space. The various analyses which will be
developed are illustrated by simulations making it possible to evaluate the
possibilities of the method.