Cobalt-doped ZnO nanoparticles and PLD-deposited thin film forms: structure, optical properties and nature of magnetic anisotropy.

Cobalt-doped zinc oxide nanoparticles (NPs) were synthesized using a modified sol-gel method. Thereafter, the obtained powder was deposited on a Suprasil glass substrate by employing a pulsed laser deposition (PLD) technique. X-ray diffraction analysis with Rietveld refinement confirmed a hexagonal wurtzite ZnO phase belonging to the 6 space group for both samples in the NP and thin film forms.

Doubling of the Phase Transition Temperature of VO by Fe Doping.

Vanadium dioxide (VO) undergoes a fully reversible first-order metal-insulator transition from the M1 monoclinic phase (2/) to a high-temperature tetragonal phase (4/) at around 68 °C. Modulation of the phase transition of VO by chemical doping is of fundamental and technological interest. Here, we report the synthesis of highly crystallized Fe-doped VO powders by a carbo-thermal reduction process.

Structural and Spectroscopic Studies of NaCuCr(PO): A Noncentrosymmetric Phosphate Belonging to the α-CrPO-Type Compounds.

An electron and joint neutron and X-ray diffraction study of the synthetic copper/chromium phosphate NaCuCr(PO) (NaCuP) is reported. A noncentrosymmetric 2 space group belonging to the well-known α-CrPO type is observed contrary to what is reported in NaMCr(PO) (M = Co and Ni) phosphates. The structural model is validated by bond valence sum analysis and charge-distribution (CHARDI) calculations and supported by complementary infrared and Raman spectroscopy investigations.

Tuning the Cr/Cr Valence States in Purple Cr-Doped SnO Nanopowders: The Key Role of Cr Centers and Defects.

A low content of chromium (≤5 mol %) has been incorporated into a SnO cassiterite by a coprecipitation route in a basic medium, followed by an annealing step under an O flow at = 800 °C and = 1000 °C. Accurate UV-vis and EPR spectroscopy investigations show the coexistence of isolated Cr and Cr ions as well as ferromagnetic Cr-Cr and antiferromagnetic Cr-Cr interactions. The strong purple hue is related to the isolated Cr ions stabilized in a distorted octahedral site.

Oxygen vacancy ordering in SrFeCoO perovskite material.

SrFeCoO was synthesized by a solid-state reaction. Its structural study at room temperature using conventional X-ray as well as neutron powder diffraction, electron diffraction and high-resolution transmission electron microscopy is presented. An oxygen-vacancy ordering related to the "314" model known for the SrYCoO oxide is proposed despite neither an A-site ordering nor an A-site mismatch.

Effect of Co Substitution on the Crystal and Magnetic Structure of SrFeO: Stabilization of the "314-Type" Oxygen Vacancy Ordered Structure without A-Site Ordering.

A study of the structure-composition-properties correlation is reported for the oxygen-deficient SrFeCoO (x = 0.1-0.85) materials.

Tuning the Mn valence state in new Ca(0.66)Mn(2-x)Al(x)O4 (x≤ 0.4) oxides: impact on magnetic and redox properties.

New Ca(0.66)Mn(2-x)Al(x)O4 (x≤ 0.4) solid solutions crystallizing with the CaFe2O4-type structure (SG: Pnma) were synthesized for the first time by the glycine-nitrate process.

Optical contrast and cycling of bistable luminescence properties in Rb2KIn(1-x)CexF6 compounds.

Irradiation cycling was performed to evaluate the ageing of the redox process observed on cerium-doped Rb2KInF6 compounds. An on-off switch of monovalent indium luminescence is observed for the lowest cerium doped material, whereas a nice colourimetric contrast between a bluish-green and orange emission is generated for the material with the highest cerium content. Photoluminescent properties combined with X-ray diffraction, chemical analysis and magnetism measurements allowed an accurate characterization of the system.

Novel Mixed Cobalt/Chromium Phosphate NaCoCr2(PO4)3 Showing Spin-Flop Transition.

We describe the synthesis and the crystallographic and magnetic properties of a novel NaCoCr2(PO4)3 phosphate. A conventional solid-state reaction was used to obtain single-phase powders. A Rietveld analysis of powder X-ray diffraction data proposes an orthorhombic symmetry similar to α-CrPO4-type structure in space group Imma with the following unit cell parameters: a = 10.

Core-level photoemission spectra of Mo0.3Cu0.7Sr2ErCu2Oy, a superconducting perovskite derivative. Unconventional structure-property relationships.

Detailed studies of the electronic states for Mo(0.3)Cu(0.7)Sr(2)ErCu(2)Oy samples with different oxygen contents are presented here.

Understanding the relationships between structural features and optical/magnetic properties when designing Fe(1-x)Mg(x)MoO4 as piezochromic compounds.

Fe1-xMgxMoO4 compounds with x = 0, 0.25, 0.5, 0.

On the anomalous magnetic behavior and the multiferroic properties in BiMn2O5.

Sealed-tube synthesis of BiMn2O5 materials and their physical properties have rationally been reinvestigated depending on the reactants. The aim of the study was to characterize its potential multiferroic properties and to investigate the anomalous magnetic properties in relation to the expected ferroelectric properties. Rietveld refinement of the room temperature X-ray diffraction data shows the stability of the crystallographic structure with a Mn(3+)/Mn(4+) ratio far from 1 because of bismuth and oxygen deficiencies despite the sealed-tube synthesis.

Spin glass to superconducting phase transformation by oxidation of a molybdo-cuprate: Mo0.3Cu0.7Sr2TmCu2Oy.

A detailed study of the structure and properties for the as-prepared and oxygen annealed Mo0.3Cu0.7Sr2TmCu2Oy material is reported.

Grafting and thermal stripping of organo-bimetallic clusters on AU surfaces: toward controlled CO/RU aggregates.

The controlled stoichiometry of heterometallic carbonyl clusters make them attractive precursors for the stabilization of bare metal alloy clusters for magnetic applications. The mixed-metal molecular cluster [RuCo3(H)(CO)12] has been functionalized with the phosphane-thiol ligand Ph2PCH2CH2SH to allow subsequent anchoring on a gold surface. The resulting tetrahedral cluster [RuCo3(H)(CO)11(Ph2PCH2CH2SH)] (1) has been characterized by X-ray diffraction and the P-monodentate ligand is axially bound to a cobalt center and trans to the ruthenium cap.

Green coloration of Co-doped ZnO explained from structural refinement and bond considerations.

ZnO doped with Co2+ has been prepared by a Pechini process and investigated in terms of crystallographic structure and UV-visible properties. We emphasize for the first time a splitting of the ZnO band gap in two "sub-band gaps" (never clearly mentioned until now) which is fully interpreted basing on the iono-covalent nature of the O-Zn bonds. An anticipative approach of the potential structure relaxations was discussed from exchanged effective charge per bond calculated with the purely ionic Brown and Altermatt model.

Unraveling orbital ordering in La0.5Sr1.5MnO4.

Orbital ordering (OO) in the layered perovskite La0.5Sr1.5MnO4 has been investigated using the enhanced sensitivity of soft x-ray resonant diffraction at the Mn L edges.