Papers by Keyword: Magnetic Nanomaterial

Abstract: Nanocomposite Nd₂Fe₁₄B/α-Fe magnetic material had been prepared by ball milling Nd₈Fe₈₆B₆ as-cast alloy in Argon and subsequent crystallizing. Influence of ball milling on their magnetic properties had been investigated by means of X-Ray Diffraction (XRD), Transmission Electron Microscopy (TEM) and Vibrating Sample Magnetometer (VSM) etc. The results show that Nd₂Fe₁₄B grain are refined quickly and grain size of α-Fe decreases while extending milling time. After milling for 25h, grain size of α-Fe reaches about 7nm. Magnetic properties increase with milling time. Milled for 25h and crystallizing at 700°C for 30 minutes, samples have the best comprehensive magnetic properties (remanence, coercivity and magnetic energy product). To obtain nanocomposite permanent materials with high magnetic properties, it is necessary to combine ball milling with crystallizing.

Abstract: Nanocrystalline material of ferrites with composition Ni_0.5Zn_0.35Cu_0.15Fe₂O₄ was successfully synthesized by sol-gel method. This paper investigates nanostructure and magnetic properties of nanocrystaline material Ni_0.5Zn_0.35Cu_0.15Fe₂O_4. Crystallite size, intensity,d-spacing and lattice parameters of material were investigated by using X-Ray diffractometer (XRD). While nanostructure, size, shape, surface morphology and topography of Ni_0.5Zn_0.35Cu_0.15Fe₂O₄ were examined by variable pressure field emission scanning electron microscope (VP-FESEM) SUPRA 55VP. Magnetic properties was investigated using vibrating sample magnetometer (VSM). According to thermo gravimetric analysis (TGA) result, it was found that after temperature 600^oC there is no more weight loss detected and it was considered as minimum calcination temperature. XRD result shows that the samples is in single-phase cubic spinel structure. Crystallite size of the material is in range of 42.3-163.7nm. Highest intensity was 88.89 arb.units at highest calcination temperature 900^oC. The value of d-spacing and FWHM decrease with increasing calcination temperature. Lattice paramenters decrease in the range of 8.4040-8.2458^oA. VP-FESEM analysis shows that grain size increase by increasing calcination temperature. Grain size of the material is in the range of 47.6-506.9nm with cubic structure of the Ni_0.5Zn_0.35Cu_0.15Fe₂O_4. VSM result shows that the highest value of magnetic saturation was at 152.8emu/g. The best value of coercive force (Hc) was in 31.8Oe and magnetic remanence (Mr) was in 2.6emu/g.

Abstract: We presented a fast, specific, and sensitive DNA sensing system, which composed of a CdTe/Fe3O4 magnetic core-shell quantum dots (energy donor), a commercial quencher (BHQ2; energy acceptor), and a designed single strand Toxoplasma gondii DNA. The designed single strand Toxoplasma gondii DNA was applied to link the energy donor and acceptor, and target DNA was detected based on mechanism of fluorescence resonance energy transfer. The CdTe quantum dots, Fe3O4 magnetic nanoparticles, CdTe/Fe3O4 magnetic core-shell quantum dots, and sensing probe were step-wisely prepared. Properties of synthesized quantum dots were investigated by transmission electron microscopy, fluorescence spectrum, nano zeta potential and submicron particle size analyzer, and X-ray diffraction, respectively. Specificity and sensitivity of sensing probe was determined by measuring the recovery of fluorescence intensity. The obtained sensing probe with magnetic properties can be simply separated or concentrated from the hybridized solution with a common magnet. The resulting data revealed the sensing system was successfully fabricated, and which has high sensitivity and specificity.