Marc Verelst

Unprecedented Ferromagnetic Interaction in Homobinuclear Erbium and Gadolinium Complexes: Structural and Magnetic Studies

Inthelattercaseoneoxygenatom(O2,O2)isterminallyboundtotherelatederbiumions(Er,Er)andthesecondoxygen(O1,O1) is involved in a monoatomic bridge between the twolanthanideions.Eachofthetworemaininganionschelatesametalion(ErandEr).AsaresultoftheinversioncentertheEr(O1,O1)Er doublebridgingnetworkisperfectlyplanar.ThesecondbridgethroughtheatomsO4,Er,O5,O4,Er,and O5 is not planar. The dihedral angle between the twoplanes Er(O1, O1)Er and Er(O4, O4)Er is equal to81.58(4) whereas the erbium ions are separated by4.0093(2)a. The coordination of each lanthanide ion iscompletedtoninebytwowatermoleculesandonebidentatechelating carboxylato group. It should be noted that thephenolic OH function of the ligand is not involved in anycoordination sphere. The bridging network present in 1 isoriginal for salicylate bridges but not unprecedented if weconsidertheacetatebridges.Analmostidenticalcorehasyetbeen observed in the structure of [Ce

Investigations of the reduction behavior of iron-impregnated alumina gels (Fe/AlOOH) and the formation of Fe0–Al2O3 metal-ceramic composites

Fe/AlOOH gels calcined and reduced at different temperatures have been investigated by a combined use of Mossbauer spectroscopy, x-ray diffraction, and electron microscopy in order to obtain information on the nature of the iron species formed as well as the various reduction processes. Calcination at or below 1070 K mainly gives reducible Fe3+ while calcination at higher temperatures gives substitutional Fe3+ in the form of Al2-xFexO3. The Fe3+ species in the calcined samples are, by and large, present in the form of small superparamagnetic particles. Crystallization of Al2O3 from the gels is catalyzed by Fe2O3 as well as FeAl2O4. Fe (20 wt. %)/AlOOH gels calcined at or below 870 K give FeAl2O4 when reduced in hydrogen at 1070 K or lower and a ferromagnetic Fe0-Al2O3 composite (with the metallic Fe particles >100 angstrom) when reduced at 1270 K. Samples calcined at 1220 K or higher give the Fe0-Al2O3 composite when reduced in the 870-12,70 K range, but a substantial proportion of Fe3+ remains unreduced in the form of Al2-xFexO3, showing thereby the extraordinary stability of substitutional Fe3+ to reduction even at high temperatures. Besides the ferromagnetic Fe0-Al2O3 composite, high-temperature reduction of Al2-xFexO3 yields a small proportion of superparamagnetic Fe0-Al2O3 wherein small metallic particles ( 3Fe2+.

Reduction behaviour of Fe3+/Al2O3 obtained from the mixed oxalate precursor and the formation of the Fe0–Al2O3 metal–ceramic composite

Reduction behaviour of Fe3+/Al2O3 obtained by the decomposition of the oxalate precursor has been investigated by employing X-ray diffraction (XRD), Mossbauer spectroscopy and electron paramagnetic resonance (EPR) spectroscopy. Calcination of Fe3+/Al2O3 at or below 1070 K yields mainly a poorly ordered, fine particulate form of η-Al2–xFexO3. Calcination at or above 1220 K yields α-Al2–xFexO3. Reduction of Fe3+/Al2O3 samples calcined at or below 1070 K gives the FeAl2O4 spinel on reduction at 870 K; samples calcined at or above 1220 K give Al2-xFexO3 with a very small proportion of metallic iron. Fe3+/Al2O3 samples calcined at 1220 K or above yield metallic iron and a very small proportion of the spinel on reduction below 1270 K. In the samples reduced at or above 1270 K, the main product is metallic iron in both ferromagnetic and superparamagnetic forms. The oxalate precursor route yields more metallic iron than the sol–gel route.

Investigations of iron-alumina metal-ceramic composites: Effect of ruthenium and nickel on the hydrogen reduction of trivalent iron during the formation of the composite

Effect of ruthenium and nickel on the reduction behavlor of

Structural and Photomagnetic Studies of Two Compounds in the System Cu2+/Mo(CN)84-: From Trinuclear Molecule to Infinite Network†

Fe^{3+}/AI_20_3

Synthesis and Characterization of CoO, Co3O4, and Mixed Co/CoO Nanoparticules

to give the

Long-range structuring of nanoparticles by mimicry of a cholesteric liquid crystal

Fe-AI_20_3

Metal-Insulator Transitions in Anion-Excess LaMnO3+δ Controlled by the Mn4+ Content

metal-ceramic composite has been studied by employing x-ray diffraction,

Synthesis, structure, and magnetic properties of tetranuclear cubane-like and chain-like iron(II) complexes based on the N4O pentadentate dinucleating ligand 1,5-bis[(2-pyridylmethyl)amino]pentan-3-ol

^{57}Fe

Structural studies and magnetic properties of polymeric ladder-type compounds {Ln2[Ni(opba)]3}.S (Ln = lanthanide element; opba = o-phenylenebis(oxamato), S = solvent molecules)

M