Electron paramagnetic resonance spectra near the spin-glass transition in iron oxide nanoparticles. Koksharov Yu.A., Gubin S.P., Kosobudsky I.D., Yurkov G.Yu., Pankratov D.A., Ponomarenko L.A., Mikheev M.G., Beltran M., Khodorkovsky Y., Tishin A.M. //Physical Review B: Condensed Matter and Materials Physics. 2001. V. 63. № 1. P. 124071-124074
Electron paramagnetic resonance (EPR) in iron-oxide nanoparticles (∼ 2.5 nm) embedded in a polyethylene matrix reveals the sharp line broadening and the resonance field shift on sample cooling below TF ≈ 40 K. At the same temperature a distinct anomaly in the field-cooled magnetization is detected. The temperature dependences of EPR parameters below TF are definitely different than those found for various nanoparticles in the superparamagnetic regime. In contrast to canonical bulk spin glasses, a linear fall-off of the EPR linewidth is observed. Such behavior can be explained in terms of the random-field model of exchange anisotropy.
Potassium hexahydroperoxostannate: synthesis and structure. Ippolitov E.G., Tripol'skaya T.A., Prikhodchenko P.V., Pankratov D.A. //Russian Journal of Inorganic Chemistry. 2001. V.46. №6. P.851-857
Polycrystalline potassium hexahydroperoxostannate was prepared by replacement of hydroxo groups in potassium hexahydroxostannate upon its dissolution in hydrogen peroxide. A comparative study of the product and the starting hydroxostannate by powder X-ray diffraction analysis, thermogravimetry, and IR, 2H, 39K, and 119Sn NMR, and Mössbauer spectroscopy was carried out. The peroxo compound K2Sn(OOH)6 crystallizes in the hexagonal system with a = 7.264(7) Å, c = 10.168(4) Å. IR, NMR, and Mössbauer spectroscopy data show that the tin coordination polyhedron in the peroxo compound is an octahedron formed by the coordinated hydroperoxo groups.
Previously, sodium hexahydroperoxostannate was prepared and characterized by powder X-ray diffraction analysis, thermogravimetry, IR, 1H NMR, and Mossbauer spectroscopy, and by thermodynamic and kinetic method. The tin atom in this compound were found to occur in the octahedral environment of hydroperoxo group. It appeared pertinent to confirm the possibility of formation of this type of tin compound by preparing a new hydroperoxo complex. To this end, we performed the first synthesis of potassium hexahydroperoxostannate. Comparative study of potassium hexahydrosstannate (1) and hexahydroperoxosstannate (2) and their deuterated analogue (1a and 2a, respectively) was carried out by powder X-ray diffraction analysis, thermogravimetry, and IR, NMR (2H, 39K and 119Sn), and Mossbauer spectroscopy.