Influence of divalent metal ion (Zn2+) on Magnetic properties, Curie temperature and DC Electrical properties in Ce3+ Substituted Ni-Zn Ferrites.

Nanoparticles of Ni1-xZnxCe0.1Fe1.9O4 ferrite substituted with Zn2+ ion concentrations (0.0, 0.2, 0.4, 0.6, 0.8 & 1.0) have been synthesised via aqueous citrate precursor auto combustion method. The obtained Powder X-ray diffraction data suggests a good crystalline phase; the crystallite size exists in the range of 14~38 nm. The lattice constant of samples increases with Zn2+ concentration. It validates Vegard's law and the decreasing trends in porosity of the samples are identified. The inhomogeneity in the grains was confirmed from FE-SEM. The EDS spectrogram attributes the good stoichiometry in the product. The Thermogravimetric analysis reveals that the crystallization occurred within the temperature 800˚C. The high-temperature DC conductivity of the samples shows that NTC behaviour. The Curie temperature and activation energy are estimated and the activation energy of carriers are found to be more at the paramagnetic region. The magnetic saturation ('Ms*') has maximum for Zn2+ = 0.2 (57.7 emu/g) and coercive field (Hc) related with a radius of occupancy of Zn2+ ion validates the relation Hc∝1/r and also, the value of the remanence ratio suggests that isotropic magnetization took place in the heterogeneous material.

Microstructure and Magnetic Properties of NdFeB Films through Nd Surface Diffusion Process

Ta/Nd/NdFeB/Nd/Ta films were deposited by magnetron sputtering on Si (100) substrates and subsequently annealed for 30 min at 923 K in vacuum. It was found that the microstructure and magnetic properties of Ta/Nd/NdFeB/Nd/Ta films strongly depend on the NdFeB layer thickness. With NdFeB layer thickness increasing, both the grain size and the strain firstly reduce and then increase. When NdFeB layer thickness is 750 nm, the strain reaches the minimum value. Meanwhile, both the in-plane and perpendicular coercivities firstly drastically increase and then slowly decrease with NdFeB layer thickness increasing. The highest in-plane and perpendicular coercivities can be obtained at NdFeB layer thickness of 750 nm, which are 21.2 kOe and 19.5 kOe, respectively. In addition, the high remanence ratio (remanent magnetization/saturation magnetization) of 0.87 can also be achieved in Ta/Nd/NdFeB (750 nm)/Nd/Ta film.

Perpendicular Giant Magnetoresistance and Magnetic Properties of Co/Cu Nanowire Arrays Affected by Period Number and Copper Layer Thickness

One-dimensional magnetic nanowires have attracted much attention in the last decades due to their unique physical properties and potential applications in magnetic recording and spintronics. In this work, ordered arrays of Co/Cu multilayered nanowires which can be exploited to develop magnetoresistive sensors were successfully prepared using porous anodic alumina (PAA) templates. The structure and morphology of the multilayered nanowire arrays were characterized by transmission electron microscopy and scanning electron microscopy. The nanowire arrays are highly ordered and the average diameter is about 50 nm, which is controlled by the pore diameter of the PAA templates. The influences of period number and Cu layer thickness on the magnetic and the giant magnetoresistance (GMR) properties were investigated. The coercivity and remanence ratio increase first and then gradually tend to be stable with the increase of period number and the Cu layer thickness, while the GMR ratio increases first and then decreases with the increase of the period number accompanied by an oscillatory behavior of GMR as the Cu layer thickness changes, which are ascribed to the spin dependence electron scattering in the multilayers. The optimum GMR of −13% appears at Co (50 nm)/Cu (5 nm) with 200 deposition cycles in our experimental conditions.

The Effect of Dy-Additive on Phase Transformation and Magnetic Properties of Fe-Pt Alloy Films

A series of Fe-Pt based alloy films were deposited on glass substrates by DC magnetron sputtering. It is found that the Fe3Pt and FePt3 phases appear in Dy-addition films at first and then a composition reaction Fe3Pt + FePt3 FePt occurs at 500°C as annealing time increase. It suggested that Dy element can restrain the fct phase forming but help to form Fe3Pt and FePt3 phases. Coercivity and remanence ratio of DyxFe50-xPt50 alloy films annealed at 500°C for 200 h achieve the maximum 11kOe and 0.89 as x =1.5, respectively.

Influence of Annealing on Magnetic Performance for 1K107 Amorphous-Nanocrystalline Soft Magnetic Alloy

The morphology, microstructure and magnetic properties in 1K107 alloy annealed by nitrogen and transversal magnetic (N2) are studied. The results show that coercivity (Hc), remanence ratio (Br/Bs), core loss (Pc), and effective permeability (μe) are efficiently optimized by transversal magnetic annealing (N2) according to the methods of digital electric bridge, rectifier bridge, X-ray diffraction (XRD), and field emission scanning electron microscopy (FESEM), etc.

MAGNETIC FIELD ALIGNMENT OF BARIUM FERRITE THICK FILMS FOR MICROWAVE CIRCULATOR APPLICATIONS

Barium ferrite films were prepared using screen printing method for their applications in self-biased microwave integrated circulators. The influences of alignment magnetic field on the microstructure and magnetic properties of the barium ferrite thick films were investigated. The results show that the (00l) peaks of the barium ferrite films are enhanced with the increase of alignment magnetic field. Hexagonal BaFe 12 O 19 platelets rotate and orient with c-axis perpendicular to the film plane after the magnetic field aligning. The remanence ratio of the barium ferrite films is improved from 0.52 to 0.78 with the increase of alignment magnetic field from 0 to 8 kOe. By magnetic field aligning, barium ferrite thick films with the remanence ratio of 0.8 have been prepared. A prototype of microwave integrated circulator is developed with the prepared barium ferrite films.