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.

Synthesis,structural investigation,dielectric and magnetic properties of Zn^(2+)-doped cobalt ferrite by the sol-gel technique

Zinc substituted cobalt ferrite nanoparticles with elemental composition Co_(1-x)Zn_(x)Fe_(2)O_(4)(x=0.0,0.2,0.4,0.6)were prepared by the sol-gel auto-combustion technique using Co,Fe,Zn nitrate as a precursor where nitrates to citrate was 1:3.The as prepared powder of cobalt zinc ferrite was sintered at 900○C for 3 h.Structural,morphological,dielectric and magnetic properties were studied by x-ray diffractometer(XRD),scanning electron microscope(SEM),high precision impedance analyzer and vibrating sample magnetometer(VSM),respectively.The peaks obtained from the XRD confirmed samples having crystallite(32–36 nm)single phase inverse spinel structure without any traceable impurity.Lattice parameters were calculated from XRD and it increases with Zn content.SEM revealed irregularly shaped grains(-0.5–0.7μm)morphology with heterogeneous distribution.The dielectric constant(ε′)and dielectric loss(tanδ),have been measured as a function of frequency at room temperature.The dependence of ε′ and tan δ with frequency showed the normal dielectric behavior in accordance with the Maxwell-Wagner type of interfacial polarization and electron hopping change between Co^(2+)and Co^(3+)as well as between Fe^(2+)and Fe^(3+)ions at octahedral sites.