A dramatic improvement in the dielectric and electrical properties has been observed in ceramics of 0.8BaTiO3–0.2Bi(Zn1/2Ti1/2)O3 through the introduction of Ba vacancies. It possesses a high relative permittivity (er > 1150) along with a low dielectric loss (tan δ   255°C), a complex plane analysis of Z″ versus Z′ and the frequency dependence of Z″ suggests an electrically inhomogeneous microstructure for the stoichiometric composition. The stoichiometric composition exhibited activation energies of ~1 eV which suggests an extrinsic conduction mechanism. However, the introduction of Ba vacancies resulted in electrically homogeneous microstructure. An overlap of the Z″ and M″ peaks in the frequency domain and much larger activation energies were observed, on the order of half of the band gap, suggesting an intrinsic conduction mechanism. A more detailed analysis of the data reveals insights into the physical mechanisms underpinning the dielectric and ac conductivity.

Dielectric Relaxation in BaTiO3–Bi(Zn1/2Ti1/2)O3 Ceramics

Dielectric spectroscopy characterization of relaxation process in Ni/epoxy composites

Study of structural, magnetic and electrical properties on Ho-substituted BiFeO3

The polycrystalline sample of Ba(Pr 1/2 Ta 1/2 )O 3 was prepared by a high-temperature solid-state reaction technique. The crystal symmetry, space group and unit cell dimensions were derived from the experimental results using FullProf software. XRD analysis of the compound indicated the formation of a single-phase tetragonal structure with the space group P4/mmm (1 2 3). Impedance and electric modulus analysis were used as tools to analyze the electrical behavior of the sample as a function of frequency at different temperatures. The impedance analysis of the compound indicated a typical negative temperature coefficient of resistance behavior, and dielectric relaxation was found to be of non-Debye type. The frequency dependent maximum of the imaginary part of the electric modulus follows the Arrhenius law with activation energy of 0.15 eV. The ac conductivity data obeys double power law.

Complex impedance spectroscopic studies of Ba(Pr1/2Ta1/2)O3 ceramic

Structural, dielectric, electrical properties of Nd doped double perovskite ceramics and variation of density of states upon doping

Lead-free perovskite BaY 0.5 Nb 0.5 O 3 was prepared by conventional ceramic technique at 1375 °C/7 h in air atmosphere. The crystal symmetry, space group and unit cell dimensions were derived from the experimental results using FullProf software. XRD analysis of the compound indicated the formation of a single-phase cubic structure with the space group Pm3m. EDAX, X-ray mapping and SEM studies were carried to study the quality and purity of the compound. Complex impedance analyses suggested the dielectric relaxation to be of non-Debye type. To find a correlation between the response of the real system and idealized model circuit composed of discrete electrical components, the model fittings were presented using the impedance data. Electric modulus studies supported the hopping type of conduction in BaY 0.5 Nb 0.5 O 3 . The correlated barrier hopping model was employed to successfully explain the mechanism of charge transport in BaY 0.5 Nb 0.5 O 3 . The ac conductivity data were used to evaluate the density of states at Fermi level, minimum hopping length and apparent activation energy of the compound.

Electrical properties of BaY0.5Nb0.5O3 ceramic: Impedance spectroscopy analysis

Lead-free (1 − x)Ba(Y1/2Nb1/2)O3–xBaTiO3; (0 ≤ x ≤ 1) ceramics have been synthesized using solid-state reaction method and characterized by X-ray diffraction, scanning electron microscopy, dielectric and impedance studies. The crystal-structure of the compounds is found to be cubic with the space group Pm3m(221) except for BaTiO3 for which it is tetragonal (P4/mmm). Complex impedance spectroscopy analysis indicated the presence of non-Debye type dielectric relaxation in Ba(Y1/2Nb1/2)O3–BaTiO3 system. Compound 0.25Ba(Y1/2Nb1/2)O3–0.75BaTiO3 exhibited a low value of temperature coefficient of capacitance (<±8 %) in the working temperature range (up to +100 °C), room temperature dielectric constant equal to 295 and low loss tangent (0.039) which meets the specifications for “Z5F” of Class I dielectrics of Electronic Industries Association. Hence, this composition might be a suitable candidate for capacitor applications. Ac conductivity and electric modulus studies supported the hopping type of conduction in the system and frequency dependent ac conductivity data obeyed Jonscher’s power law.

Dielectric relaxation in Ba(Y 1/2 Nb 1/2 )O 3 -BaTiO 3 ceramics

Lead-free perovskite Ba(In 1/2 Nb 1/2 )O 3 was prepared by conventional ceramic fabrication technique at 1350 °C/5 h in air atmosphere. The crystal symmetry, space group and unit cell dimensions were determined from Rietveld analysis using FullProf software whereas crystallite size and lattice strain were estimated from Williamson-Hall approach. XRD analysis of the compound indicated the formation of a single-phase cubic structure with the space group Pm 3 m . EDAX and SEM studies were carried out in order to evaluate the quality and purity of the compound. Complex impedance as well as electric modulus analyses suggested the dielectric relaxation to be of non-Debye type. The correlated barrier hopping (CBH) model was employed to successfully explain the mechanism of charge transport in Ba(In 1/2 Nb 1/2 )O 3 .

Structural and electrical properties of lead-free perovskite ceramic: Ba(In1/2Nb1/2)O3

Lead-free perovskite Ba(Sb1/2Nb1/2)O3 was prepared by conventional ceramic fabrication technique at 1200 °C/5 h in air atmosphere. The crystal symmetry, space group and unit cell dimensions were determined from the experimental results using FullProf software whereas crystallite size and lattice strain were estimated from Williamson–Hall approach. XRD analysis of the compound indicated the formation of a single-phase monoclinic structure with the space group P2/m. EDAX and SEM studies were carried out to evaluate the quality and purity of the compound. Dielectric study revealed the frequency-dependent dielectric anomaly. To find a correlation between the response of the real system and idealized model circuit composed of discrete electrical components, the model fittings were presented using the impedance data. Complex impedance analyses suggested the dielectric relaxation to be of non-Debye type. The correlated barrier hopping model was employed to successfully explain the mechanism of charge transport in Ba(Sb1/2Nb1/2)O3. The ac conductivity data were used to evaluate the density of states at Fermi level, minimum hopping length and apparent activation energy of the compound.

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Papers

Electrical properties of BaY0.5Nb0.5O3 ceramic: Impedance spectroscopy analysis

Dielectric relaxation in Ba(Y 1/2 Nb 1/2 )O 3 -BaTiO 3 ceramics

Structural and electrical properties of lead-free perovskite ceramic: Ba(In1/2Nb1/2)O3

Structural and electrical properties of Ba(Sb1/2Nb1/2)O3 ceramic