Essai d'introduction dans un aéronosol calcaire de petite-Camargue de pins pignons (Pinus pinea L.) mycorhisés par Suillus collinitus

Two reforestation plots of Pinus pinea were set up (1988 and 1990) in "petite-Camargue" area. We measured the effects of controlled mycorhizal infection with Suillus collinitus and the effect of mineral nutrition in nursery on the survival rate and growth in plantation. Controlled mycorhization with Suillus collinitus n°2 increased plants growth in nursery and this increase is always observed 6 years after plantation. Mycorhization allowed the production of plants in relation with the marketing reglementation and reduced the mineral nutrition supply in nursery. / Deux plantations expérimentales (1988 et 1990) ont été effectuées pour mettre en évidence l'effet de la fertilisation en pépinière sur le comportement du Pin pignon dans un arénosol calcaire de petite Camargue. Dans les 2 essais, la mycorhization a eu un effet positif sur la croissance des plants en pépinière. Cet effet s'est maintenu au cours des 6 premières années de plantation. La mycorhisation contrôlée par Suillus collinitus a permis la production de plants conformes aux normes de commercialisation moyennant une utilisation réduite d'engrais

Growth, single-crystal structure, and magnetic properties of the double molybdate KYb(MoO4)2

International audienceCrystals of the rare earth double molybdate KYb(MoO4)2 were grown by spontaneous nucleation from a K2Mo4O13 flux. The typical crystals were colorless and elongated, well-developed plates. The material has been characterized by powder X-ray diffraction (PXRD), energy-dispersive X-ray spectrometry (EDS), and Raman spectroscopy methods. The structural properties have been investigated through single-crystal X-ray diffraction at room temperature. KYb(MoO4)2 crystallizes in the orthorhombic symmetry, space group Pbcn (No. 60), a = 5.0395(2), b = 18.2821(9), c = 7.8635(4) Å, and Z = 4. A complete ordering of the Yb3+ and Mo6+ cations has been found. The Yb3+ ions are located in distorted YbO8 antiprisms which form chains of edge-sharing, aligned along the c-axis while the Mo6+ ions are placed in a slightly deformed tetrahedral environment of oxygen atoms. Double bridge modes of the “Mo2O8 dimers” have been identified in the unpolarized Raman spectra. The temperature-dependent magnetic susceptibility of KYb(MoO4)2 follows a Curie–Weiss law with a Weiss constant of −52 K

The open-framework structure of KSbGe3O9 flux-grown crystals investigated by X-ray diffraction, vibrational spectroscopy, and DFT calculations

International audienceWe report on the preparation and the X-ray crystal structure of colorless KSbGe3O9, its vibrational properties (Raman and infrared studies), and density functional theory (DFT) calculations. KSbGe3O9, grown by the high-temperature flux method from K2Mo4O13 flux, is thermally stable at least up to 1200 ​°C and is isostructural to the benitoite BaTiSi3O9 (space group P6c2 (no. 188)). The hexagonal unit cell contains two formula units and the structure was refined to R1 ​= ​0.0324 from single-crystal X-ray diffraction data. KSbGe3O9 is characterized with only one crystallographically independent Ge atom involved in three-member units [Ge3O9]6- of regular germanate tetrahedra. The K+ ions are located in channels and, like SbV, are octahedrally surrounded by oxygen atoms. The KSbGe3O9 local structure and the planarity of Ge3O3 rings are also studied by a room-temperature vibrational investigation using non-polarized infrared and Raman spectroscopy. Both the infrared and Raman phonon modes have been assigned from the agreement observed between our experimental data and the corresponding DFT ones. In particular, two E’ (TO) modes (both IR and Raman active) characterize the planarity of the Ge3O3 ring in the ab plane

Thermal dependence of the mechanical properties of NiTiSn using first-principles calculations and high-pressure X-ray diffraction

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Les facteurs nutritionnels antepartum sont associés à l'infertilité/infécondité dans les élevages bovins laitiers: exemple de l'île de la Réunion

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Crystal structure, Raman characterization, and magnetic properties of the hydrate RbYb(MoO4)2, H2O

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