Publications by authors named "O Toulemonde"
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.
View Article and Find Full Text PDFVanadium 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.
View Article and Find Full Text PDFAn 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.
View Article and Find Full Text PDFA 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.
View Article and Find Full Text PDFArticle Synopsis
- The study focuses on creating Co-doped and Fe-doped La(Ga,Al)O perovskite materials using the Pechini method to induce a color change with temperature, related to spin crossover (SCO) phenomena.
- In the case of Fe-doped samples, iron remains in a high-spin state even at low temperatures, while Co-doped compounds exhibit a transition from low-spin to high-spin states as temperature rises, confirmed through various analytical methods.
- The findings suggest that Co-doped LaGaCoO can function as thermal sensors with low cobalt concentrations and highlight the influence of electronic bonding on the stabilization of spin states in these materials.