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The complex perovskite oxide barium iron antimonate, BaFe_1/2Sb_1/2O₃ (BFS) is synthesized by a solid-state reaction technique for the first time. The X-ray diffraction of the sample at room temperature shows a monoclinic phase. The field dependences of dielectric response and the loss tangent of the sample are measured in a frequency range from 50 Hz to 1 MHz and in a temperature range from 143 to 463 K. An analysis of the loss factor with frequency is performed by the scaling behavior of the dielectric loss spectra. The frequency dependence of the loss peaks are found to obey the Arrhenius law with an activation energy ≃0.81 eV. The scaling behavior of the dielectric loss spectra suggests that the distribution of relaxation times is temperature-independent. The frequency-dependent electrical data are also analyzed in the framework of conductivity and electric modulus formalisms. The scaling behavior of the imaginary electric modulus shows the temperature-independent nature of the distribution of relaxation times. All these formalisms resulted in the qualitative similarities in the relaxation time. The relationship between relaxation parameters and electrical conduction indicates the hopping motion of electrons from Fe(II) to Fe(III) ions in BFS.

The electrical properties of alizarin doped anthraquinone were investigated using a complex impedance spectroscopy technique. Dielectric study revealed a phase transition from the semiconducting to the conducting state at 53°C. The dielectric relaxation was found to be of non-Debye type. Evidence of temperature-dependent electrical relaxation phenomena as well as a positive temperature coefficient of conductivity character were observed in the sample. The frequency dependence of AC conductivity data followed a power law. Electric modulus as well as AC conductivity analyses indicated the possibility of a hopping mechanism for electrical conduction in the system. The activation energy and minimum hopping distance were estimated from the AC conductivity data.

The dielectric properties, electric modulus and ac electrical conductivity (σ_ac) of Al/Co-doped (PVC+TCNQ)/p-Si structures have been investigated in the wide frequency and voltage range of 0.5 kHz–3 MHz and (-4 V)–(9 V), respectively, using the capacitance-voltage (C–V) and conductance-voltage (G/ω–V) measurements at room temperature. The real and imaginary parts of dielectric constant (ε′, ε″), loss tangent (tan δ), σ_ac and the real and imaginary parts of electric modulus (M′, M″) were found strongly function of frequency and applied voltage especially at low frequencies. The ε′–V plot shows an anomalous peak in the forward bias region due to the series resistance (R_s), surface states (N_ss) and interfacial layer (PVC+TCNQ) effects for each frequency and then it goes to negative values known as negative dielectric constant (NDC) at low frequencies (f ≤ 70 kHz). Such observation of NDC is important result because it implies that an increment of bias voltage produces a decrease in the charge on the electrodes. The amount of negativity ε′ value increases with decreasing frequency and this decrement in the NDC corresponds to the increment in the ε″.

Au/n-Si metal-semiconductor (MS) and Au/Bi₄Ti₃O₁₂/n-Si metal-ferroelectric-semiconductor (MFS) structures were fabricated and admittance measurements were held between 5 kHz and 1 MHz at room temperature so that dielectric properties of these structures could be investigated. The ferroelectric interfacial layer Bi₄Ti₃O₁₂ decreased the polarization voltage by providing permanent dipoles at metal/semiconductor interface. Depending on different mechanisms, dispersion behavior was observed in dielectric constant, dielectric loss and loss tangent versus bias voltage plots of both MS and MFS structures. The real and imaginary parts of complex modulus of MFS structure take smaller values than those of MS structure, because permanent dipoles in ferroelectric layer cause a large spontaneous polarization mechanism. While the dispersion in AC conductivity versus frequency plots of MS structure was observed at high frequencies, for MFS structure it was observed at lower frequencies.

A system of (100-x)B₂O₃ ⋅xCdSO₄ glasses (0 $\le$x$\le$ 40) is set by the ordinary quenching method. Density ($\rho$), molar volume (V${}_m$) and oxygen ion density (N${}_{\mathrm{\text{O-ion}}}$) are found to increase with the increase of CdSO₄ in the samples. The dc conductivity (${\sigma }_{\mathrm{\text{dc}}}$) and the ac conductivity (${\sigma }_{\mathrm{\text{ac}}}$) are measured in the temperature range from 308 to 735 K. ${\sigma }_{\mathrm{\text{dc}}}$ is found to follow the thermal activation Arrhenius relation with activation energies between 0.36 and 0.76 eV. Ac conductivity and the exponent factor (s) confirm that the CBH model is the origin of the conduction. The dielectric constant (${𝜀}^{\prime }$) and loss (${𝜀}^{″}$) are studied as a function of the temperature and frequency. The dielectric data are fitted according to the Cole–Cole equations. The values of $\alpha$ parameter are found to vary between 0.2 and 0.58 which means that these glasses exhibit a wide distribution of relaxation times.

Polycrystalline Dy-modified Pb_1-xK_2xNb₂O₆ (PKN) ferroelectric ceramic with a general formula Pb_1-xK_2x-3yM_yNb₂O₆ for x=0.20, y=0.10 and M=Dy, have been prepared by the solid-state reaction route. The X-ray diffraction (XRD) studies of the material at room temperature revealed orthorhombic structure with lattice parameters a=17.701 Å, b=17.958 Å and c=3.883 Å. The dielectric anomaly with a sharp peak is observed at 430°C. The impedance plots are used as a tool to analyze the sample behavior as a function of frequency. The grain and grain boundary contributions are estimated. The modulus mechanism indicates the non-Debye type relaxation. The activation energy value near the phase transition temperature has been found to be different in the above T_C from AC conductivity measurements.

0.5Ba(${\text{Zr}}_{0.2}$${\text{Ti}}_{0.8})$O₃-0.5(${\text{Ba}}_{0.7}$${\text{Sr}}_{0.3})$TiO₃ (BZT–BST) has been explored in recent times for potential applications in energy harvesting, electrocaloric and energy storage. To this end, energy harvesting/conversion and storage applications require an understanding of the conduction and loss mechanisms. The conduction mechanism in BZT–BST ceramics is studied using impedance spectroscopy (IS) at 0.1 Hz−3 MHz and 100−600${}^{\circ }$C. Impedance study reveals the presence of two types of relaxation processes due to grain and grain boundary contributions. The relaxation time and dc conductivity activation energies are obtained as 1.12/1.3 eV and 1.05/1.2eV for bulk/grain boundary, respectively, and found that oxygen vacancies dominated electrical behavior. The relaxation mechanism follows non-Debye-type behavior. The high resistance of the grain (bulk) in the ferroelectric region does not contribute to the high losses; the losses probably result from the phase transition. Also, BZT–BST ceramics exhibit a negative temperature coefficient of resistance (NTCR) behaviour. From a practical application point of view in the temperature regime of 25–65${}^{\circ }$C, the loss’s contribution is low. The significant contributions of loss result from the response of phase-transition in this temperature range (25–65${}^{\circ }$C).