FMR Study of the Porous Silicate Glasses with Fe 3

The results of research on new magnetic materials for biomedical applications are discussed. These materials are porous silicate glasses with magnetic fillers. To ensure the smallest number of components for subsequent removal from the body, the magnetic fillers are bare magnetite nanoparticles (Fe3O4). The magnetic properties of these materials have been investigated using the ferromagnetic resonance method (FMR). The FMR analysis has been complemented by scanning electron microscope (SEM) measurements. In order to examine the effect of time degradation on filling the porous glass with bare magnetite nanoparticles the FMR measurement was repeated five months later. For the samples with high degree of pore filling, in contrast to the samples with low degree of pore filling, the FMR signal was still strong. The influence of different pH values of magnetite nanoparticles aqueous suspension on the degree of filling the pores of glasses is also discussed. The experimental results are supported by computer simulations of FMR experiment for a cluster of N magnetic nanoparticles locked in a porous medium based on a stochastic version of the Landau-Lifshitz equation for nanoparticle magnetization

Photoacoustic study of a new neodymium(III) hydrazone complex

The neodymium(III) hydrazone complex [Nd(DBH) 2 (NO 3 ) 3 ] has been synthesized and characterized using microanalysis and IR spectroscopy. High-resolution photoacoustic spectrometry has been applied for studying the complex. The obtained photoacoustic spectrum has been analysed and compared to a similar [Nd(PicBH) 2 (NO 3 ) 2 ]NO 3 complex. The intensities of the f-f transitions in the photoacoustic spectrum of Nd(DBH) 2 (NO 3 ) 3 were two times greater than for the [Nd(PicBH) 2 (NO 3 ) 2 ]NO 3 complex

Ground State of the Gd3+ Ion in MF2 Single Crystals under the Influence of an External Static Electric Field

The quadratic electric field effect for cubic Gd3+ centers in MF2 single crystals is discussed in terms of the quasimolecular and superposition model. Very high electric fields (above 300 kV/cm) are required to observe this effect. Zero‐field splitting of Gd3+ ions in the crystal field is also discussed. It is shown that these models interpret the changes in the induced B 20 spin‐Hamiltonian parameter consistently. Copyright © 1989 WILEY‐VCH Verlag GmbH & Co. KGa

Extended free radical network from condensed cyanuric chloride with p-phenylenediamine: An EPR/FMR study

A covalent layered network was obtained by condensation of cyanuric chloride with bridging paraphenylenediamine. The local chemical environment of the layered solid can be changed by a redox reaction to obtain new reconstructed derivatives. A blue product was obtained by treating an alcoholic dispersion of the layered solid with ferric nitrate or potassium persulfate, indicating the possible formation of an extended free radical. When iron nitrate was used as oxidant, the temperature-dependent magnetic resonance spectra were measured in the 290-4 K region. The magnetic resonance measurements showed the coexistence at room temperature of two spectra arising from two different magnetic centers: a narrow line centered at g = 2.0038(1) with linewidth of ΔH = 7.42(2) G (free radical) and a broad line centered at g = 2.254(1) with linewidth of ΔH = 1300(5) G (magnetic iron-oxide cluster). A new sample was prepared so that the broader line was more intense. The temperature dependence of the magnetic resonance lines was subject to intense changes in both cases. The integrated intensities decreased with decreasing temperatures in both spectra in the high temperature region. This type of behavior is similar to that of magnetic nanoparticles in non-magnetic matrices. Upon reducing the temperature with the gradient of ΔHr/ΔT = 1.5(1) G/K, the resonance field of the broad line was shifted towards lower magnetic fields, while the narrow line was shifted towards higher magnetic fields with ΔHr/ΔT = 0.020(1) G/K. The linewidth of the broader line increased with decreasing temperature, while the narrow line remained almost constant. The magnetic iron-oxide clusters could produce an internal magnetic field acting on free radicals. This field could compel free radicals to form a magnetic ordered state at high temperatures

Magnetic and transport properties of nanocrystalline titanium carbide in carbon matrix

Samples of titanium carbide (TiCx) in a carbon matrix have been prepared by the nonhydrolytic sol-gel process. The nanocomposite powder samples containing one the TiCx of average size ca. 30 nm encapsulated in carbon cages of 3 wt.% and other the TiCx in carbon matrix (ca. 10 wt.%) have been obtained. The temperature dependence of the EPR spectra of titanium carbide has shown coexistence of two different paramagnetic centers, one arising from conducting electrons and the other from trivalent titanium ion complexes. Comparison with a similar titanium nitride (TiNx) is made, where no EPR spectra of trivalent titanium ions exist. The titanium nitride has shown only the EPR spectra arising from magnetic localized centers and not from trivalent titanium ion complexes. The magnetic ordering and superconducting states are observed in titanium carbide in the low temperature region, while in titanium nitride only the later state is recorded. The titanium nitride is a good conducting material while the titanium carbide shows an extraordinary behaviour, especially in the higher temperature region where a sharp jump in conductivity is recorded about 250 K. It is suggested that the disorder-order processes are more intense in the nonstoichiometric titanium carbide. © 2009 Springer Netherlands