Papers by Keyword: EPR

Abstract: Polymer films of poly(3,4-ethylenedithiothiophene) obtained by electrochemical oxidative polymerisation of the corresponding monomer have been investigated. p-Doping process of the polymer was characterized by in situ EPR spectroelectrochemisty. Compared to its close relative – PEDOT, the polymer features two distinct voltammetric peaks. The results of our studies indicate that both represent faradaic processes and that each manifests generation of charge carriers in the polymer.

Abstract: The paper presents the results of the EPR examination of free radical content in GUR1020 and GUR1050 polyethylenes which were irradiated with an electron beam. Changes in the amount of radicals in the period of 12 months in the UHMWPE cross-linked with a dose of 26-156 kGy were analysed. Spectra registered 90 days after irradiation show a hyperfine structure. An image consisting of 7 characteristic lines is the most similar pattern that can be used to analyse this spectrum. Subsequent measurements (255 and 372 days after irradiation) produce images consisting of one resonance line. Alkyl and allyl radicals generated during the irradiation are the source of the EPR signal. The influence of atmospheric oxygen causes further changes of the radicals mentioned above, which leads to the formation of peroxyl radicals. The content of radicals in the polymer and its changes over time were calculated. The amount of radicals increases as the absorbed dose grows, but decreases over time. Comparative measurements of the material subjected to thermal processing at the temperature of 423 K have shown that in this case, no resonance lines are present, which testifies to the effective elimination of free radicals by means of UHMWPE recrystallisation.

Abstract: Ni-doped titanate nanorods were synthesized from anatase TiO2 powder and Ni nitrate using a one-step hydrothermal reaction in alkaline solution. The nanorods are straight with lengths a few micrometer and diameters between 80 and 120 nm. The Ni-doped nanorods have the similar structure as hydrogen titanate nanorods of monoclinic structure. Magnetic measurement revealed that Ni-doped titanate nanorods are ferromagnetism at 300K. Electron paramagnetic resonance were studied and the spectra showed that a broad asymmetric signal and a signal in low field appeared due to the Ni ions incorporated into the titanate lattice. The results suggest that Ni-dopants play an important role in the ferromagnetism. The ferromagnetic response could be attributed to Ni intercalated into the titanate lattice.

Abstract: The paper presents the results of an examination of UHMW polyethylene type GUR1050 using the EPR, FTIR and SEM methods. The relationship between the number of radicals in the polymer and the absorbed dose of ionizing radiation has been shown. The radicals, being highly active macroparticles, disappear in time, so that after about a year their amount is reduced by approximately one order of magnitude. The disappearance of the radicals over time results in a change in EPR spectra, an increase in the degree of oxidation, and cross-linking. The most probable mechanisms are the formation of alkyl and allyl radicals and their gradual transitions, which lead to the absorption of atmospheric oxygen, and the recombination of radicals, which leads to the formation of cross linkages. Thermal treatment of the samples is an effective method of eliminating the radicals. Tribological tests and their analysis by means of SEM observation showed that the irradiated samples proved to have higher resistance to abrasion than the material that was not exposed to radiation.

Abstract: Now, the renewable resources recycling system do not include the traction battery recycling in China, and there are also some problems in the existed recycling system. In the field of resource recycling, especially for battery recycling, the management system, laws and regulations, and technical standards have been behind of the developed countries. This paper from producers self-establish the recycling system, producers alliance self-establish the recycling system and producers recycling business commission mode to discuss the recycling model for traction battery.

Abstract: EPR spectroscopy has been used to characterize neutron-irradiated cubic SiC samples after thermal annealing in the 200-1100^OC temperature range. Three new paramagnetic defects named Ky6, Ky7 and Ky8 have been revealed. Based on the present results, these defects have been tentatively attributed to the negatively charged carbon vacancy-carbon antisite pair, negatively charged divacancy and neutral carbon <100> split interstitial, respectively. Furthermore, the finding of practically isotropic hyperfine splitting for EPR lines of the T6 center confirms its assignment as a carbon vacancy-interstitial pair.

Abstract: Triplet center with spin state S = 1 is detected in the EPR spectrum of the self-assembled 6H SiC nanostructure obtained by non-equilibrium boron diffusion into the n-type 6H SiC epitaxial layer (EL) under conditions of the controlled injection of the silicon vacancies at the temperature of T = 900°C. From the analysis of the angular dependences of the EPR spectrum and the numerical diagonalization of the spin Hamiltonian, the value of the zero-field splitting constant D and g-factor are found to be D = 1140•10^-4см^-1 and g_par = 1.9700, g_per = 1.9964. Based on the hyperfine (hf) structure of the defect originating from the hf interaction with one ¹⁴N nuclei, the large value of the zero-field splitting constant D and technological conditions of the boron diffusion into the n-type 6H SiC EL, the triplet center is tentatively assigned to the defect center consisting of nitrogen atom and silicon vacancy.

Abstract: Room temperature ferro-magnetism in Fe-doped CdS nanoparticles (NPs) synthesized by a wet chemical precipitation method is reported. Magnetic studies revealed that pure CdS NPs exhibit diamagnetic behavior as like bulk material, where as 3% Fe doped CdS NPs shows the ferromagnetic behavior. At room temperature, ESR signal characteristic of Fe3+ was observed in doped NPs.

Abstract: The magnetic susceptibility of Pb1-xCexX (X = S, Se and Te) crystals with several Cerium concentrations ranging from x = 0.006 to 0.036 has been measured between 2 K and 300 K. The experimental susceptibility curves were found to be consistent with a 2F5/2 lowest manifold for Ce3+ ions; the cubic crystal-field splitting values of 2F5/2 were estimated to be about 340 K, 440 K and 540 K for Pb1-xCexTe, Pb1-xCexSe, and Pb1-xCexS, respectively. For all the studied samples, it was found that the 7 doublet lies below the 8 quadruplet. These results confirm that Ce3+ ions substitute Pb2+ in the host crystals. Furthermore, the effective Landé factors were determined by X-band (~9.5 GHz) Electron Paramagnetic Measurements (EPR) to be g = 1.333, 1.364, and 1.402 for Ce ions in PbX, X = S, Se, and Te, respectively.

Abstract: We utilize electrically detected magnetic resonance (EDMR) via spin dependent recombination (SDR) to provide a definitive identification of an interface/near interface defect present in a wide variety of 4H SiC/SiO2 metal oxide semiconducting field effect transistors (MOSFETs).