T. Skibiński

EPR and optical properties of KYb(WO4)2 and KTb0.2Yb0.8(WO4)2 single crystals

Well oriented KYb(WO4)2 and KTb0.2Yb0.8(WO4)2 single crystals have been investigated for their magnetic and optical properties using the Raman and EPR techniques. The registered EPR signal is dominated by three lines ascribed to ytterbium ions: one main and two satellites. Tb ions, although non-paramagnetic, distinctly modify magnetic properties of the KYb(WO4)2 single crystal. Basic parameters of the spin Hamiltonian, including Zeeman and hyperfine terms (g and A matrices) as well the spatial orientation between principal and crystallographic axes systems were determined for both crystals.

Growth and EPR properties of KSm(WO4)2 and KEr(WO4)2 single crystals

Growth conditions and electron paramagnetic resonance investigations of two well oriented KSm(WO4)2 and KEr(WO4)2 single crystals have been presented and discussed. Hyperfine structure of Sm3+ ion was detected and analyzed for angular and temperature dependences. EPR spectra of KEr(WO4)2 and its angular dependence showed the presence of 5 magnetically nonequivalent Er centers in the crystal. A change in the type of magnetic interactions was analyzed using mixed (Gaussian and Lorentzian) fits of the EPR spectra.

Growth and EPR properties of ErVO4 single crystals

Abstract Single crystals of ErVO4 were grown by the Czochralski method under ambient pressure in a nitrogen atmosphere. Obtained crystals were transparent with strong pink coloring. Electron paramagnetic resonance (EPR) spectra were recorded as a function of the applied magnetic field. Temperature and angular dependences of the EPR spectra of the samples in the 3–300 K temperature range were analyzed applying both Lorentzian––Gauss approximation for diluted medium and Dyson for dense magnetic medium. EPR-NMR program was done to find local symmetry and spin Hamiltonian parameters of erbium ions.

Synthesis and spectroscopic properties of LiIn(WO4)2 nanopowders and single crystals doped with chromium(III) ions

LiIn(WO4)2 single crystals and nanopowders doped with chromium(III) ions were synthesized and investigated, including their EPR spectra and magnetic properties. The EPR spectra have shown low and high field lines attributed to isolated chromium ions with an electron spin S=3/2 and complex chromium centers with higher spin value, respectively. Magnetic susceptibility measurements revealed an almost linear dependence on the magnetic field. The electron resonance and magnetic properties have been related to the structural and spectroscopic data of the studied material.

Nano-structured (Mo,Ti)C-C-Ni magnetic powder

Purpose: The paper presents the results of phase composition and magnetic properties of Mo-Ni-Ti-C nanostructured powders. The aim of this research is understanding the correlation between key magnetic properties and the parameters that influence them in the nanostructured powders from Mo-Ni-Ti-C system. Design/methodology/approach: The powder samples were synthesised using modified sol-gel method. Obtained powder were subjected for composition and magnetic properties in a wide temperature range by means of Electron Paramagnetic Resonance (EPR) and magnetic susceptibility measurements. To study the phase composition X-ray diffraction were performed. The morphology of the powders were investigated by scanning electron microscopy (SEM). Findings: Different kinds of structural and magnetic phases have been found in the investigated compounds, e.g. (Mo, Ti)C, C, Ni. It was found that such different phases create different kinds of magnetic interactions, from paramagnetic, antiferromagnetic up to superparamagnetic. Significant magnetic anisotropy has been revealed for low temperatures, which lowers with temperature increase. Moreover, non-usual increasing of the magnetization as a function of temperature was observed. It suggests, that overall longrange AFM interaction may be responsible for the magnetic properties. Research limitations/implications: For the future work explanation which phases in Mo-Ni-Ti-C system are responsible for different kinds of magnetic interactions are planned. Practical implications: The composition of different kinds of phases may be controlled to tune magnetic properties of the nanostructured Mo-Ni-Ti-C systems. Originality/value: In this study, for the first time Mo-Ni-Ti-C nanostructured samples were prepared with different kinds of structural and magnetic phases, creating different kinds of magnetic interactions, from paramagnetic, antiferromagnetic up to superparamagnetic-like. The latter seems to be formed due to the presence of magnetic nanoparticles and longrange antiferromagnetic interactions dominating in the whole temperature range.