Study of NiCuZn ferrite powders and films prepared by sol gel method

This paper reports that a series of NiCuZn ferrite powders and films are prepared by using sol-gel method. The effects of raw material composition and the calcinate temperature on magnetic properties of them are investigated. The NiCuZn ferrite powders are prepared by the self-propagating high-temperature synthesis method and subsequently heated at 700 ℃-1000 ℃. The results show that NiCuZn ferrite powders with single spinel phase can be formed after heat-treating at 750 ℃. Powders obtained from Ni0.4Cu0.2Zn0.4Fel.904 gel have better magnetic properties than those from gels with other composition. After heat-treating at 900 ℃for 3 h, coercivity Hc and saturation magnetization Ms are 9.70e （i Oe = 80 A/m） and 72.4 emu/g, respectively. Different from the powders, NiCuZn films produced on Si （100） from the Ni0.4Cuo.2Zno.4Fe204 gel formed at room temperature possess high properties. When heat-treating condition is around 600 ℃for 6 rain, samples with low Hc and high Ms will be obtained. The minimal Hc is 16.70e and Ms is about 300 emu/cm3. In comparison with the films prepared through long-time heat treating, the films prepared through short heat-treating time exhibits better soft magnetic properties.

Enhancement of magnetic and dielectric properties of low temperature sintered NiCuZn ferrite by Bi_(2)O_(3)-CuO additives

With a series of 1.0 wt%Bi_(2)O_(3)-x wt%CuO(x=0.0,0.2,0.4,0.6,and 0.8)serving as sintering additives,Ni_(0.23)Cu_(0.32)Zn_(0.45)Ee_(2)O_(4)ferrites are successfully synthesized at a low temperature(900℃)by using the solid state reaction method.The effects of the additives on the phase formation,magnetic and dielectric properties as well as the structural and gyromagnetic properties are investigated.The x-ray diffraction(XRD)results indicate that the added Bi_(2)O_(3)-CuO can lower the synthesis temperature significantly without the appearing of the second phase.The scanning electron microscope(SEM)images confirm that Bi_(2)O_(3)is an important factor that determines the sintering behaviors,while CuO affects the grain size and densification.With CuO content x=0.4 or 0.6,the sample shows high saturation magnetization,low coercivity,high real part of magnetic permeability,dielectric permittivity,and small ferromagnetic resonance linewidth(ΔH).The NiCuZn ferrites are a promising new generation of high-performance microwave devices,such as phase shifters and isolators.

Synergistic effect of V_(2)O_(5)and Bi_(2)O_(3) on the grain boundary structure of high-frequency NiCuZn ferrite ceramics

High-frequency soft magnetic ferrite ceramics are desired in miniaturized and efficient power electronics but remain extremely challenging to deploy on account of the power loss(Pcv)at megahertz frequencies.Here,we prepared NiCuZn ferrite with superior high-frequency properties by V_(2)O_(5)and Bi_(2)O_(3)synergistic doping,which proves to be a potent pathway to reduce Pcv of the ferrite at megahertz frequencies.The sample doped with 800 ppm V_(2)O_(5)and 800 ppm Bi_(2)O_(3)yielded the most optimized magnetic properties with a Pcv of 113 kW/m^(3)(10 MHz,5 mT,25℃),an initial permeability(μi)of 89,and a saturation induction(Bs)of 340 mT,which is at the forefront of the reported results.These outstanding properties are closely related to the notable grain boundary structure,which features a new type of nano-Bi_(2)Fe_(4)O_(9)phase around ferrite grains and a Ca/Si/V/O amorphous layer.Our results indicate great strides in correlating the grain boundary structure with multiple-ion doping and set the scene for the developing high-frequency soft magnet ferrites.

Structure and magnetic properties of NiCuZn ferrite materials with La doping

Ni0.3Cu0.07Zn0.63Fe2-xLaxO4 ferrites were prepared by solid phase method and sintered at 1,150 ℃ for 6 h.The phase formation,microstructure,and magnetic properties of samples were investigated.With doping of La3＋,the samples contain two phases：LaFeO3 and NiCuZn ferrites.Scanning electron microscope （SEM） image shows that La doping constrains the growth of NiCuZn ferrite,which is more uniform.La doping improves magnetic properties of NiCuZn ferrite when x ≤ 0.03.The saturation magnetization （Ms） increases first;when x =0.03,the highest value is 75.35 A.m2.kg-1.The permeability increases to the maximum value with frequency and then decreases with the concentration of La3＋ increasing.When x =0.03,the maximum value of real permeability at 1 MHz is 333.5,and the loss angle tangent （tanδ） is not more than 0.02.La doping improves the properties of NiCuZn ferrite,which can be applied to low-frequency filters.

Influence of Ni substitution on structural,morphological,dielectric,magnetic and optical properties of Cu-Zn ferrite by double sintering sol–gel technique

Polycrystalline NiCuZn ferrite(Ni_(x)Cu_(0.3)Zn(0.7-x)Fe_(2)O_(4);x=0.2,0.3,0.4 and 0.5)were prepared through solgel auto combustion method applying double sintering technique.Structural,morphological,elemental analyses(EDS),Fourier-transform infrared spectroscopy(FTIR),Direct Current(DC)electrical resistivity,dielectric,magnetic and optical properties of prepared samples were analyzed.XRD profiles reveal the formation of simple cubic spinel structure without any traceable impurity.The average crystallite size lies within the range of 22–29 nm.Lattice parameter decreases with increasing Ni concentration.Room temperature DC resistivity was recorded from 6:39×10^(5)to 3:79×10^(5)Ωcm.Both dielectric constant(ε)and loss factor(tanδ)were decreased with increase of frequency while AC conductivity increases.FTIR absorption peak occurred at three different frequency ranges at 570-577 cm^(-1),1635-1662 cm^(-1)and 3439–3448 cm^(-1).Magnetic properties were investigated by using vibrating sample magnetometer(VSM).Decreasing trends were observed for saturation magnetization(Ms),magnetic coercivity(Hc)and remanant magnetization(Mr)with the increase of Ni content.Optical band gap(-2.70-2.79 eV)were calculated from diffuse reflectance data by using Kubelka–Munk function.