Papers by Keyword: SQUID

Abstract: LiFe(P,Si)O₄ is a material that belong to parent compound of LiFePO₄ widely known as cathode material for lithium-ion battery (LIB). Previous study reports that electrochemical performance of LiFePO₄ can be improved by silicon (Si) substitution to the phosphorus (P) site. The sample was obtained via a solid-state synthesis route with the amount of Si doping to the P site is ∼3%. The electrochemical performance of silicon substituted LiFePO₄ has been widely studied in other report whilst the magnetic properties is still less explored. Here we investigate the magnetic properties of LiFe(P,Si)O₄ using superconducting quantum interference device (SQUID) and muon spin relaxation (µSR). The two measurements display a good agreement result showing two anomalies at the temperature of ∼27 K and ∼52 K that represent the Neel Temperature (Τ_N) of Li₂FeSiO₄ and LiFePO₄, respectively. The presence of Li₂FeSiO₄ that is also a candidate of cathode of LIB has been confirmed by X-ray Diffraction (XRD). Based on the current study, there is no alteration of Τ_N on LiFePO₄ phase due to Si doping.

Abstract: Graphene oxide (GO) is 2D material made of honey comb carbon structure as backbone and decorated by oxygen functional groups in both sides. These functional groups have role to the GO properties, such as magnetic susceptibility, band gap, conductivity. There are several processes to reduce its oxygen content, such as chemical, photo and thermal reduction, resulted reduced graphene oxide (rGO). Several studies reported the magnetic properties of GO and rGO correlating with the process of synthesis and reducing oxygen contents. We report the magnetic characteristic of a commercial GO 0.5 mg/ml dispersed in H₂O from Graphenia and RGO that were synthesized through thermal reduction process of GO precursor. In this process, we use oven vacuum system at 200 °C for 1 hour. All samples were prepared as GO and rGO thick films. The GO and rGO samples structure were indentified from XRD data and SQUID data for magnetic characteristics. We explored the temperature dependence of magnetic susceptibility by applying magnetic field of 500 Oe in Zero Field Cooling (ZFC) and Field Cooling (FC). The result shows different susceptibility behavior of GO and rGO samples in all wide range of temperature between 0 to 300 Kelvin. The value of magnetic susceptibility rGO is higher than that of GO and has splitting curve of ZFC and FC at low temperatures below 200 Kelvin. However, GO has the splitting curve of ZFC and FC occurred at high temperatures above 200 Kelvin.

Abstract: Mechanical alloying of a mixture of Fe₂O₃ and CoO powders has been applied for the preparation of nanocrystalline. Utilizing a ball-to-powder mass ratio of 20, milling time of 20 hours followed by annealing at 900°C, we could obtain a nanocrystalline of high crystallinity and composed of mainly CoFe₂O₄ phase with presence of Fe₂O₃ as revealed by X-ray diffraction (XRD) measurements. Magnetic measurements using vibrating sample magnetometer (VSM) reveal high saturation magnetization for the annealed sample close to CoFe₂O₄ phase value. The heating efficiency of the obtained nanocrystalline is studied under an alternating magnetic field and as a function of the concentration. It was found that the nanocrystalline generate a substantial amount of heat when exposed to an alternating magnetic field. In vitro hyperthermia experiment was carried out and our result clearly demonstrates the ability of the obtained nanocrystalline to kill cancer cell through magnetic hyperthermia.

Abstract: Abstract. The powders of Bi_2-xPb_xSr₂CaCu₂O_8+δ (x=0; 0.4) superconductor have been prepared by using dissolved method followed by short period of sintering and calcination process . The purpose of this research is to study about the Pb doped effect to the properties of BSCCO nanopowders especially in the electric and superconducting properties. Based on the previous result, BSCCO nanopowders have ferromagnetic properties at the room temperature. This characteristic is not appeared in bulk superconductor. The 2212 phase of Bi-based system has been formed and observed by using X-ray diffraction (XRD) measurement. The superconducting quantum interference device (SQUID) observation showed that the Bi_2-xPb_xSr₂CaCu₂O_8+δ (x=0; 0.4) samples exhibited diamagnetic behaviour at the critical temperature, T_c=76 K and 78 K. The sample with partial Pb substitution exhibited stronger permanency to the external magnetic field indicating presence of flux pinning. The four point probe (FPP) measurement showed that the sample partially doped with Pb has lower resistivity (more metallic) than the Pb-free sample in the normal state.

Abstract: The temperature dependence of electronic and magnetic properties of the organic charge-transfer salt (DOEO)₄[HgBr₄]·TCE was investigated using magnetometry. The magnetic susceptibility shows a maximum at 40 K followed by an onset of a pronounced increase at 70 K and a constant behavior above 120 K. Implications on the charge carrier density are discussed. Combining the magnetometry with resistivity and ESR measurements we propose a sequence of insulating, metallic and semiconducting behavior with increasing temperature. Our results indicate that (DOEO)₄[HgBr₄]·TCE is close to the boundary between an insulating and conducting ground state.

Abstract: ²⁰⁹Bi NQR experiments, including analysis of zero-field line shapes, Zeeman-perturbed patterns and zero-field spin-echo envelopes were made to examine magnetic splitting of resonances revealed in the spectra of Main group element compounds of general composition Ba_kBi_lA_mO_n (A=Al, В, Ge, Br, Cl). The results were explained assuming the existence in the compounds of ordered internal magnetic fields from 5 to 250 G which notably exceed those of nuclear magnetic moments. A dramatic (8−10-fold) increase in the resonance intensities, instead of broadening and fading, was observed for such compounds upon applying weak (below 500 Oe) external magnetic fields. The effect was shown to relate to the spin dynamics, namely, to the influence of external magnetic field on the nuclear spin-spin relaxation of the compounds with anomalous magnetic properties. In α-Bi₂O₃, paramagnetism depending on the thermal prehistory of a sample was found using SQUID-technique; magnetoelectric effect linear in magnetic field was also observed for this oxide.

Abstract: We investigated the relationship between the microstructure and magnetic properties of a Cu–10 at% Ni–5 at% Co alloy by using a transmission electron microscope (TEM), a SQUID magnetometer and a magnetic thermo–balance. TEM observations were performed to examine the microstructures of the Cu–Ni–Co specimens annealed at four temperatures between 873 K and 1073 K below and above the Curie point (983 K).Particles with cubic shapes were linearly arranged along the <100> direction of the copper matrix in specimens prepared by isothermal annealing at temperatures below the Curie point, while octahedral precipitates were sparsely formed by annealing above the Curie point. The TEM observations confirmed that the microstructural evolution in the Cu–Ni–Co specimens isothermally annealed at 1023 K. Although coherent cubic particles appeared at the initial stage of annealing, incoherent precipitates were finally formed with increased annealing time at 1023 K. The present SQUID measurements indicated that the curve of coercive force vs. annealing time had a peak at a short annealing period.

Abstract: Deriving inspiration from the propulsion methods of squids, a pulsatile jet propulsion system is adopted in a robotic model. A squid-like direction control mechanism, which can direct the jet along any direction on a hemispherical work volume, is also implemented. To obtain a suitable robot velocity (_v) and a propulsive efficiency (η_p) for testing this mechanism, the stroke ratio (L/D) and outlet diameter are varied and the _v and the η_p of various alternatives are estimated experimentally using vision analysis. A Stroke ratio of 3.78 and an outlet diameter of 25.4 mm were found suitable and employed for testing the mechanism. When the jet is deflected by 60° in the horizontal plane, the robot rotates about its centroid, signifying excellent maneuverability. Reverse motion was also demonstrated by removing inlet valves and blocking the outlet through the direction control mechanism. The performance of the direction control mechanism indicates that the robotic model was a feasible alternative to conventional screw-propelled aquatic robots.

Abstract: In order to detect optical fiber submarine cable effectively, based on magnetic anomaly detection, the article presents a method for calculating magnetic field of central tube and layer stranded submarine cable by modeling. SQUID proved can be applied in the passive magnetic detection of optical fiber submarine cable.

Abstract: Metallic particles with outer dimensions smaller than 100 microns in Li-ion battery cannot be detected using a conventional X-ray imaging system. We propose two systems using high Tc SQUIDs: One is a direct detection type and the other is an indirect type. In the direct detection system, an object with a contaminant is magnetized by a permanent magnet and then the remanent field of the contaminant is detected by SQUID. In the indirect detection system, the principle is based on Faradays law of electromagnetic induction. The diameter of the detection coil is 2 to 3 times larger than the SQUID; as a result, less number of SQUIDs, two or three is enough to inspect a specimen with a width of 65 mm. This method is applicable for an inspection of metallic contaminants in non-magnetic film such as a separator for Li-ion battery. We discuss the results of the evaluation of the new system as compared with a direct detection system.