An inexpensive nonlinear medium for intense ultrabroadband pulse characterization

The ability of pellets made up of compressed iron iodate nanocrystals to frequency-double the whole visible spectrum is demonstrated. We suggest their use for complete characterization of intense ultrabroadband laser pulse

Phase Decomposition and Chemical Inhomogeneity in Nd2-xCexCuO4

Extensive X-ray and neutron scattering experiments and additional transmission electron microscopy results reveal the partial decomposition of Nd2-xCexCuO4 (NCCO) in a low-oxygen-fugacity environment such as that typically realized during the annealing process required to create a superconducting state. Unlike a typical situation in which a disordered secondary phase results in diffuse powder scattering, a serendipitous match between the in-plane lattice constant of NCCO and the lattice constant of one of the decomposition products, (Nd,Ce)2O3, causes the secondary phase to form an oriented, quasi-two-dimensional epitaxial structure. Consequently, diffraction peaks from the secondary phase appear at rational positions (H,K,0) in the reciprocal space of NCCO. Additionally, because of neodymium paramagnetism, the application of a magnetic field increases the low-temperature intensity observed at these positions via neutron scattering. Such effects may mimic the formation of a structural superlattice or the strengthening of antiferromagnetic order of NCCO, but the intrinsic mechanism may be identified through careful and systematic experimentation. For typical reduction conditions, the (Nd,Ce)2O3 volume fraction is ~1%, and the secondary-phase layers exhibit long-range order parallel to the NCCO CuO2 sheets and are 50-100 angstromsthick. The presence of the secondary phase should also be taken into account in the analysis of other experiments on NCCO, such as transport measurements.Comment: 15 pages, 17 figures, submitted to Phys. Rev.

Thermodynamic investigations on the Zr-Au system

We report on Lire discovery of two new intermetallics, Zr3Au2 and ZrAu, and we stated precisely the formation types and temperatures of the eight intermediate phases in the system. The enthalpies of formation of seven compounds have been measured by direct reaction calorimetry with reference to the pure metals in their solid states

Contribution to the study of the Ce-Zr-Au system

The equilibrium phase diagram of the Ce-Zr-Au system was studied by differential thermal analysis, X-ray diffraction and electron probe microanalysis along the isopletic section at 50 at. % Au. Our main result concerns the discovery of a new ternary phase and a ternary invariant. The polymorphic transitions of the ZrAu phase, previously reported, was confirmed and we precised the melting and the polymorphic transition temperatures of the CeAu phase. A schematic representation of the isopletic section is given

Development and characterization of nanocomposite materials

International audienc

Non linear optical imaging and polarization response of Fe(IO3)3 nanocrystals

International audienc