CoCr_(2)O_(4)nanoceramics are prepared by sol-gel auto combustion method.Synchrotron X-ray diffraction analysis affirms the singlephasepristine cubic structure with space group Fd3m.Debye-Scherrer method estimates the...CoCr_(2)O_(4)nanoceramics are prepared by sol-gel auto combustion method.Synchrotron X-ray diffraction analysis affirms the singlephasepristine cubic structure with space group Fd3m.Debye-Scherrer method estimates the crystallite size of main intense peak tobe~27:15 nm.Prominent bands obtained in infrared spectra at 448 and 599 cm^(-1)are due to metal-oxygen stretching bond presentat tetrahedral and octahedral sites.Dielectric parameters decrease as frequency increases from 103 to 106 Hz that can be interpretedby Maxwell-Wagner-type interfacial polarization.Complex impedance spectra(Nyquist plot)reveal arc like behavior,which ismainly due to intergrain(grain boundary)resistance that also exhibits conducting nature of the nanoceramics.Weak ferroelectricityis mainly associated with the partial reversal of the polarization.Leakage current behavior follows the Ohmic and Child square law.Electron conduction process was interpreted by space-charge limited current(SCLC)mechanism.Leakage current behaviorobserved in cobalt chromite nanoceramics is mainly attributed to the oxygen vacancies.展开更多
In the present work,series of Zn ion-doped Ni_(1-x)Zn_(x)Fe_(2)O_(4)(0:0≤x≤0.5)ceramics were prepared by the double sintered solidstate reaction route to find out the influence of Zn2t ions on the crystal structure,...In the present work,series of Zn ion-doped Ni_(1-x)Zn_(x)Fe_(2)O_(4)(0:0≤x≤0.5)ceramics were prepared by the double sintered solidstate reaction route to find out the influence of Zn2t ions on the crystal structure,lattice structure and dielectric behavior of parent NiFe_(2)O_(4).X-ray diffraction(XRD)study favors that all the prepared compounds belong to the cubic spinel structure.Lattice parameters found to have increasing value with increased Zn^(2+)ion substitution.The Raman scattering measurement discerns optical-active modes with blue shift as the doping increases.The dielectric constant(ε′)and dielectric tangent loss(tanδ)decrease with an increase in frequency and at higher frequency,both become constant.Dielectric parameters observe nonlinear behavior with increasing Zn^(2+)ion substitution.Room temperature dielectric constant of 10%Zn ion-doped NiFe_(2)O_(4)[Ni_(0.9)Zn_(0.1)Fe_(2)O_(4)]is much higher as compared to other prepared ceramics.The room temperature ac conductivity is found to increase with increase in frequency and temperature-dependent ac conductivity increases with increase in temperature.展开更多
基金UGC-DAE CSR,as an institute,is acknowledged for extending its facilities and financial assistance(Grant No.:CSRIC/BL-22/CRS-119-2014/269).
文摘CoCr_(2)O_(4)nanoceramics are prepared by sol-gel auto combustion method.Synchrotron X-ray diffraction analysis affirms the singlephasepristine cubic structure with space group Fd3m.Debye-Scherrer method estimates the crystallite size of main intense peak tobe~27:15 nm.Prominent bands obtained in infrared spectra at 448 and 599 cm^(-1)are due to metal-oxygen stretching bond presentat tetrahedral and octahedral sites.Dielectric parameters decrease as frequency increases from 103 to 106 Hz that can be interpretedby Maxwell-Wagner-type interfacial polarization.Complex impedance spectra(Nyquist plot)reveal arc like behavior,which ismainly due to intergrain(grain boundary)resistance that also exhibits conducting nature of the nanoceramics.Weak ferroelectricityis mainly associated with the partial reversal of the polarization.Leakage current behavior follows the Ohmic and Child square law.Electron conduction process was interpreted by space-charge limited current(SCLC)mechanism.Leakage current behaviorobserved in cobalt chromite nanoceramics is mainly attributed to the oxygen vacancies.
基金UGC-DAE-CSR,an institute,is acknowledged for extending its facilities and financial assistance(Grant No.CSRIC/BL-22/CRS-119-2014/269).
文摘In the present work,series of Zn ion-doped Ni_(1-x)Zn_(x)Fe_(2)O_(4)(0:0≤x≤0.5)ceramics were prepared by the double sintered solidstate reaction route to find out the influence of Zn2t ions on the crystal structure,lattice structure and dielectric behavior of parent NiFe_(2)O_(4).X-ray diffraction(XRD)study favors that all the prepared compounds belong to the cubic spinel structure.Lattice parameters found to have increasing value with increased Zn^(2+)ion substitution.The Raman scattering measurement discerns optical-active modes with blue shift as the doping increases.The dielectric constant(ε′)and dielectric tangent loss(tanδ)decrease with an increase in frequency and at higher frequency,both become constant.Dielectric parameters observe nonlinear behavior with increasing Zn^(2+)ion substitution.Room temperature dielectric constant of 10%Zn ion-doped NiFe_(2)O_(4)[Ni_(0.9)Zn_(0.1)Fe_(2)O_(4)]is much higher as compared to other prepared ceramics.The room temperature ac conductivity is found to increase with increase in frequency and temperature-dependent ac conductivity increases with increase in temperature.
