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Idar-Oberstein, Germany

Druon F.,University Paris - Sud | Velazquez M.,CNRS Laboratory of Condensed Matter Chemistry, Bordeaux | Veber P.,CNRS Laboratory of Condensed Matter Chemistry, Bordeaux | Janicot S.,University Paris - Sud | And 6 more authors.
Optics Letters | Year: 2013

We present, to the best of our knowledge, the first laser demonstration of an Yb-doped Gd2O3 cubic crystal. This crystal was obtained by the flux method using an original borate-based solvent, which was particularly well suited to the growth of rare earth sesquioxide crystals at half the working temperature of classical growth techniques. This flux method is a very interesting alternative for the production of laser sesquioxide crystals, not only because it provides access to new matrices of the cubic polymorph, but also because it permits high Yb3+-doping levels for these crystals. The first laser results of two highly Yb3+-doped sesquioxides, namely Gd2O3 and Y2O3, grown by this flux method are presented here, including the Ti:sapphire and diode pumping configurations. Laser efficiencies and emission spectra for these two crystals were studied and compared. © 2013 Optical Society of America.

Douissard P.-A.,European Synchrotron Radiation Facility | Cecilia A.,Karlsruhe Institute of Technology | Martin T.,European Synchrotron Radiation Facility | Chevalier V.,European Synchrotron Radiation Facility | And 6 more authors.
Journal of Synchrotron Radiation | Year: 2010

The efficiency of high-resolution pixel detectors for hard X-rays is nowadays one of the major criteria which drives the feasibility of imaging experiments and in general the performance of an experimental station for synchrotron-based microtomography and radiography. Here the luminescent screen used for the indirect detection is focused on in order to increase the detective quantum efficiency: a novel scintillator based on doped Lu2SiO5 (LSO), epitaxially grown as thin film via the liquid phase epitaxy technique. It is shown that, by using adapted growth and doping parameters as well as a dedicated substrate, the scintillation behaviour of a LSO-based thin crystal together with the high stopping power of the material allows for high-performance indirect X-ray detection. In detail, the conversion efficiency, the radioluminescence spectra, the optical absorption spectra under UV/visible-light and the afterglow are investigated. A set-up to study the effect of the thin-film scintillators temperature on its conversion efficiency is described as well. It delivers knowledge which is important when working with higher photon flux densities and the corresponding high heat load on the material. Additionally, X-ray imaging systems based on different diffraction-limited visible-light optics and CCD cameras using among others LSO-based thin film are compared. Finally, the performance of the LSO thin film is illustrated by imaging a honey bee leg, demonstrating the value of efficient high-resolution computed tomography for life sciences. © 2010 International Union of Crystallography.

Daniels J.E.,University of New South Wales | Jo W.,TU Darmstadt | Rodel J.,TU Darmstadt | Rytz D.,Fee GmbH | Donner W.,TU Darmstadt
Applied Physics Letters | Year: 2011

Diffuse x-ray scattering intensities from a single crystal of 0.96 (Bi 1/2 Na1/2 TiO3) -0.04 (BaTiO3) have been collected at room temperature with and without application of an electric field along the [100] direction. Distinct features in the diffuse scattering intensities indicate correlations on a nanometer length scale. It is shown that locally correlated planar-like structures and octahedral tilt-domains within the room temperature rhombohedral R3c phase are both electrically active and are irreversibly affected by application of an electric field of 4.3 kV/mm. The field dependence of these nanoscale structures is correlated with the relaxor behavior of the material by macroscopic permittivity measurements. © 2011 American Institute of Physics.

Cattoor R.,French National Center for Scientific Research | Cattoor R.,French German Research Institute of Saint Louis | Manek-Honninger I.,French National Center for Scientific Research | Rytz D.,Fee GmbH | And 2 more authors.
Optics Letters | Year: 2014

Wedemonstrate the first (to our knowledge) quasi-three-level conical refraction laser operating at 2 μm, with 1.6Wof output power at 2074 nm, using a holmium-doped KY(WO4)2 crystal. A maximum slope efficiency of 52% has been achieved, along the optic axis with respect to the absorbed pump power. Furthermore, lasing operation around the optic axis has been performed. In this case, a maximumoutput power of 3Whas been reached, with a slope efficiency better than 70%, which are the best performances ever reported on this material. © 2014 Optical Society of America.

Schneider D.,TU Darmstadt | Rodel J.,TU Darmstadt | Rytz D.,Fee GmbH | Granzow T.,Luxembourg Institute of Science and Technology LIST
Journal of the American Ceramic Society | Year: 2015

The direction-dependence of pyroelectric properties of (1 - x)Bi1/2Na1/2TiO3 - xBaTiO3 (BNT - 100xBT) is investigated, using single crystal samples with well-defined orientations for x = 0.036 and x = 0.063. The results are compared with those of temperature-dependent measurements of the ferroelectric and dielectric hysteresis. The depolarization temperature Td of each crystal composition is found to depend on crystal orientation, a fact that is explained by differences in the stability of respective domain configurations. A rationalization is offered for the observation that Td differs from the ferroelectric-relaxor transition temperature, depending on orientation. The hysteresis curves of BNT - 3.6BT are typical for a rhombohedral system with a ferroelectric-relaxor transition, with polarization reversal close to Td occurring in a multistep process that includes decay of ferroelectric domains into polar nanoregions and re-formation of domains. BNT - 6.3BT, a composition in the region of the morphotropic phase boundary, shows the same feature, but additionally is characterized by a field-induced transition between rhombohedral and tetragonal symmetry. This combination results in an effective piezoelectric coefficient of d33∗=1886 pm/V. © 2015 The American Ceramic Society.

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