Synergy in Photomagnetic/Ferromagnetic Sub-50 nm Core-Multishell Nanoparticles

Abstract

Based on nickel hexacyanidochromate and cobalt hexacyanidoferrate Prussian blue analogues, two series of photomagnetic/ferromagnetic sub-50 nm core multishell coordination nanoparticles have been synthesized in a surfactant-free one-pot multistep procedure with good control over the dispersity (10% standard deviation) and good agreement with the targeted size at each step. The composition and the valence state of each shell have been probed by different techniques that have revealed the predominance of Co(II)-NC-Fe(III) pairs in a series synthesized without alkali while Co(III)-NC-Fe(II) photoswitchable pairs have been successfully obtained in the photoactive coordination nanoparticles by control of Cs(+) insertion. When compared, the photoinduced behavior of the latter compound is in good agreement with that of the model one. Exchange coupling favors a uniform reversal of the magnetization of the heterostructured nanoparticles, with a large magnetization brought by a soft ferromagnetic shell and a large coercivity due to a harder photomagnetic shell. Moreover, a persistent increase of the photoinduced magnetization is observed for the first time up to the ordering temperature (60 K) of the ferromagnetic component because of a unique synergy.

Core–shell nanoparticles: synthesis and applications in catalysis and electrocatalysis

“…For example, Fe 3 O 4 @Ag/SiO 2 /Au microspheres were prepared starting from Fe 3 O 4 (prepared via solvothermal method) and using reduction, sol-gel process and interfacial growth chemistry. In their recent report, 242,243 Catala et al demonstrated a surfactant-free one-pot multistep procedure to obtain core-multishell magnetic/ photomagnetic co-ordination NPs specifically composed of facecentered-cubic Prussian blue analogs (PBAs) of the general formula A I xM II [M 0III (CN) 6 ] (2+x)/3 , [where A is an alkali-metal cation and M II and M 0III are transition-metal ions]. The synthetic procedure involved precipitation (to make the CaCO 3 core) followed by layer-by-layer assembly of astralen with polyallylamine hydrochloride (PAH) and finally deposition of Ag-NPs by means of the silver mirror reaction.…”

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

“…Scheme of the unit cell for (a) an alkali-cation-free PBA, and (b) a PBA containing two alkali cations per cell. compounds, many efforts have thus been devoted to produce PBAs in various shapes and sizes: nanoparticles, [32][33][34][35][36][37][38][39] core-shell particles, [40][41][42] films [43][44][45] and wires, [46,47] thus also making them key compounds in the field of molecular nanomaterials.…”

High-pressure neutron scattering of the magnetoelastic Ni-Cr Prussian blue analog

“…Moreover, NiCrPB strain coupled heterostructures with ≤10 nm layers that show a seemingly opposite response to strain are actually in a different size regime than the ≈ 100 nm structures for both NiCrPB strain and magnetism. 44 Notably, nanoparticles of NiCrPB showed slightly different response to pressure than the "bulk" material, but a surfactant was used that might modify the surface anisotropy as well as the effective mulk modulus. 45 Using our model of NiCrPB, each system must be approached individually to properly identify the magnetic ground state of the constituent particles even though the coordination polymer repeat unit might be identical.…”