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The second harmonic signal, which is generated by co-application of AC and DC fields to polycrystalline type-II superconductors, were analyzed in terms of the weak links and the critical current density. With this aim the YBaCuZnO ( x=0, 0.01, 0.02, 0.03, 0.05, and 0.1) samples were synthesized in order to adjust intergranular couplings and thus the strength of weak links. The mechanical and magnetic measurements are in good agreement on that Zn doping reduces strength of the links between grains; however, contrary to the common expectations, it has no direct contribution to the 2nd harmonic signal strength. [ABSTRACT FROM AUTHOR]

Abstract: In the present study, the effects of B2O3 addition on the remanence properties of barium ferrite magnets are examined. The relationship between isothermal magnetization remanence M R(H) and demagnetization remanence M D(H) for non-interacting single domain particles, M D(H)=M R(H max)−2M R(H), was used in order to investigate the interactions between particles. We have found that remanence magnetization M R increased by 40% in magnitude with B2O3 addition in addition to the weakened couplings between particles. The B2O3 addition seems to supply the required conditions for usage of these materials in the magnetic recording media. [Copyright &y& Elsevier]

Abstract: In the present study, we have investigated the influence of B2O3 addition on structural and magnetic properties of hard magnetic BaFe12O19 foams. In the presence of B2O3 open-celled foams were successfully fabricated at a calcination temperature of 1300°C. Magnetization values have been improved by 50% with B2O3-addition. Remanence magnetization (M R), specific magnetization at 1.5T (M S) and coercive field (H c) values were obtained to be 32.7emu/g, 63.0emu/g and 2100Oe, respectively for the 0.5wt% B2O3 containing foams having 30pores/in. Foams with these magnetic properties have the potential to be used in different areas of technology as permanently magnetic materials. [ABSTRACT FROM AUTHOR]

Abstract: In the present study, we investigate structural and magnetic properties of the Y8Ba5Zn4O21 structure, which was recently included in the catalog of the International Centre for Diffraction Data (ICDD) as a prototype structure. It was found that the Y8Ba5Zn4O21 bulk sample seems to be electrically insulating at temperatures of liquid nitrogen and the room temperature. On the other hand, it has quite interesting magnetic properties. Diamagnetic phase transition was observed at ~90K, which resembles that of the superconducting materials. The studied composition repels permanent magnets at the liquid nitrogen temperature. Ferromagnetism also co-exists with diamagnetism in the temperature range between 50K and 90K. Possible reasons for these behaviors are discussed. [Copyright &y& Elsevier]

Abstract: In the present study, we examine the energy dissipation mechanisms and grain boundary effects on the superconducting properties of high-T c SmBa2Cu3O7−x samples. Sm-123 was synthesized with the top-seeded-melt-growth technique. Grain sizes, as determined by optical microscopy, ranged between 0.5mm and 1.5mm. Thus, each specimen, on which the electrical and magnetic measurements were carried out, contained several grains. Some of our findings are as follows: (1) the intragrain T c is 93.5K and the intergrain T c is 87.5K. Superconducting transition width is narrow and is not affected much by the magnetic field. (2) The intragrain J c is 110,000Acm−2 while the intergrain J c is 210 Acm−2 at 10K. (3) The intergrain J c shows a secondary peak with the increase in temperature from 10K to 30K. The main reasons behind these observations are discussed in detail. [Copyright &y& Elsevier]

Abstract: This paper presents the phase formations and magnetic properties of Co-doped TiO2 synthesized by the colloidal and ammonium nitrate melt techniques (ANMT). The phase formations and ferromagnetic properties were studied with XRD and SQUID magnetometry. Crystallization of the TiO2 rutile lattice was completed at 1000°C and that was preserved during annealing up to 1300°C. For the samples annealed at 1200°C, elemental analysis has shown that the colloidal technique leads to a single-phase rutile with cobalt concentration of almost nothing even in the initially 0.5mol Co-added samples. Further increase of annealing temperature results in the appearance of other Ti-phases in addition to the rutile. On the other hand, it is quite interesting that these samples show ferromagnetic behavior. The samples synthesized by the ANMT method contain larger amounts of Co compared to the colloidal technique. [Copyright &y& Elsevier]

Abstract: In the present work, the magnetic properties and the phase composition of barium ferrite BaFe12O19 powders prepared by the ammonium nitrate melt technique with Fe/Ba ratios varying from 2 to 13 was investigated. We observed that BaFe2O4 phase is formed at low values of Fe/Ba ratios (2–6) and α-Fe2O3 phase is formed at high values of Fe/Ba ratio as secondary phases. BaFe2O4 phase could be easily eliminated from the structure by washing the annealed powders with diluted HCl. HCl-washing is not effective for the elimination of α-Fe2O3 phase. Consequently, we succeed to obtain high quality single phase BaFe12O19 powders at low Fe/Ba ratios. Highest specific saturation magnetization M s of the powders with Fe/Ba ratio of 2 was determined to be 66.7emu/g. [Copyright &y& Elsevier]

Abstract: We propose a new method of synthesis for the preparation of nanocrystalline BaFe12O19 powders using the ammonium nitrate melt. The X-ray diffraction patterns of the calcined samples show the formation of BaFe12O19 at temperatures as low as 850°C. The effects of calcination temperature and time on particle size and magnetic properties are mainly studied. The magnetic measurements and structural analysis show, in good correlation, that the particles have mostly single domains but there is a tendency towards multi-domain behavior with the increase of the calcination temperature. The powders obtained by this method have better magnetic properties than those obtained by the ceramic method with a coercivity value of 4.1kOe. [Copyright &y& Elsevier]