Magnetism and Photomagnetism of Prussian Blue Analogue Nanoparticles Embedded in Porous Metal Oxide Ordered Nanostructures

International audienc

Sintesi di prodotti altamente fluorurati per applicazioni industriali nel campo dei lubrificanti dei cristalli liquidi

NICE-BU Sciences (060882101) / SudocSudocFranceF

Using Prussian blue analogue nanoparticles confined into ordered mesoporous silica monoliths as precursors of oxides

International audiencePowdered Prussian blue analogues (PBAs) and PBAs confined in ordered mesoporous silica monoliths were used as oxide precursors through thermal treatment under an oxidizing atmosphere. The study focuses on the transformation of the alkali cation-free CoCo PBA of chemical formula K0.1CoII4[CoIII(CN)6]2.7·20 H2O. The compounds were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), IR spectroscopy and small-angle X-ray scattering (SAXS), and the magnetic properties of the calcined samples were investigated. In both cases, powdered and confined PBAs, the coordination polymers are transformed into well-crystallized Co3O4 spinel oxide. In the case of the confined PBA, isolated Co3O4 single crystals confined within the ordered mesoporosity of the monoliths were evidenced by HRTEM. A preliminary study shows an effect of particle size and confinement on the magnetic properties of the confined oxide particles

Evidence of the Core–Shell Structure of (Photo)magnetic CoFe Prussian Blue Analogue Nanoparticles and Peculiar Behavior of the Surface Species

International audienc

Co, Fe and CoFe oxide nanoparticle assemblies within an ordered silica matrix: effects of the metal ions and synthesis pathway on the microstructure and magnetic properties

The magnetic properties of nanoparticle assemblies strongly depend on the structural and morphological characteristics of the individual nanoparticles as well as on their organization within the assembly. Here, we present the synthesis of cobalt and/or iron oxide nanoparticles within the ordered mesoporosity of a silica monolith by two different synthesis pathways (using either Prussian blue analogues or nitrate salts as a precursor). We describe the influence of the nature of the metal ion and of the synthesis pathway on the morphology of the nanoparticles. With respect to these observations, we present and discuss the temperature-dependent magnetic behaviors of the final nanocomposites

Epsilon-Fe 2 O 3 Nanocrystals inside Mesoporous Silicas with Tailored Morphologies of Rod, Platelet and Donut

International audienc

Macroscopic Magnetic Anisotropy Induced by the Combined Control of Size, Shape and Organization of NiFe Prussian Blue Analog Nanoparticles in an Ordered Mesoporous Silica Monolith

International audienceIntegration of coordination polymers and metal–organic frameworks into real applications requires a processing step at the nanoscale. However, their synthesis in the form of nanoparticles with controlled size, shape and organization remains a challenge faced by diverse scientific communities. Ordered mesoporous silica monolith with 2D‐hexagonal structure of the mesopores is used to form ferromagnetic NiFe Prussian blue analog (PBA) nanoparticles with anisotropic shape. The PBA nanowires formed within the nanochannels of the monolith are made of single chains of nanocrystals. Furthermore, when using an ordered mesoporous silica monolith instead of the more frequently used mesoporous powders a parallel organization of the pores is achieved over whole macroscopic fragments of the monolith. A 1×1×1 mm3 fragment of monolith exhibits a remarkably strong anisotropy in its magnetic properties, arising from unprecedented magnetic dipolar interaction along the chains of coordination nanocrystals, which is spread to the macroscopic scale thanks to the long‐range organization of the pores. As various confined chemistries can be developed within the ordered porosity of such monolith, this tool opens up new opportunities for the development of original nanostructured materials exhibiting anisotropy in their properties at the macroscopic scale

Transforming a Diamagnetic Ordered Mesoporous Silica Monolith into a Room Temperature Permanent Magnet through Multiscale Control of the Magnetic Properties

International audienc

A chemical model of intermediate states implied in the switching properties of CoFe Prussian blue analogues: how a cell parameter lengthening can cause a crystal field parameter increase

International audienceA series of CoFe Prussian blue analogues of chemical formula Rb2Co4 xZnx[Fe(CN)6]3.3 11H2O (x = 0, 1, 1.95 and 2.7) has been synthesized along which the MII/CoIII ions ratio at the Co site has been tuned. The long range order and the electronic structure of the Co ions have been investigated by combined powder X-ray diffraction and X-ray absorption spectroscopy (XAS) measurements. The cell parameter of the face-centered cubic structure lengthens as the MII/CoIII ions ratio increases without phase demixing. The study of the electronic structure of the Co ions by XAS shows that the coordination polyhedra of the CoII(HS) ions play an important role in the flexibility of the cubic structure. The variation of the cell parameter in the series of compounds is accompanied by the variation of the CoII-NC bond angle which allows the expansion or contraction of the cubic structure accompanying the electronic switch without phase demixing. Due to this structural re-arrangement, a lengthening of the cell parameter unusually produces an increase of the Co ion crystal field. Such a re-arrangement occurs in the course of the photo-induced electron transfer