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This work investigates the AC conductivity, impedance spectroscopy, and modulus formulation of varied compositions of glass samples within the modified borovanadate glassy system, synthesized using the melt-quenching technique. Up to 10 mol% of BaO, the AC conductivity shows a rising trend as BaO content rises; however, for x = 15&20 mol%, there is a drop. The Almond West model fits the experimental data of ac conductivity and parameters such as crossover frequency, frequency exponent (s), and direct current conductivity are retrieved. All samples feature a CBH conduction mechanism at varying frequencies, except for VBa1, which has a small polaron quantum mechanical mechanism. There is good agreement in the activation energy derived from conductivity (0.565–0.742 eV), electric modulus (0.526–0.616 eV), and impedance research (0.530–0.743 eV). Dielectric studies reveal non-Debye-type behavior. According to impedance formalism, electric conduction occurs through Ba2+ ions and electron/polarons. This characteristic renders the glasses well-suited for energy storage devices. [ABSTRACT FROM AUTHOR]

The complex lead-free perovskite ceramics, (1-x) BiFeO3-X(B/K) Ti/MnO3, where X = 0.05, 0.10 were fabricated by using a solid-state chemical reactions technology. The X-ray diffraction analysis exhibits the formation of the sample in rhombohedral crystal symmetry (#R3c). The average crystallite size for BKTM with 5% content and BKTM with 10% content was determined utilizing the Scherrer formula, resulting in sizes of 21.83 nm and 27.81 nm, respectively. Fourier-transformed infrared spectroscopy spectrum analysis also supports the formation of compounds based on the characteristics peak corresponding to Bi-O and Ti-O bonds. Scanning electron microscope (SEM) shows the distribution of grain and surface morphology. The surface morphology indicates dense grain development with no fractures. The mean grain size for BKTM with 5% content is approximately 2.73 μm, whereas for BKTM with 10% content, it is about 0.49 μm. This discovery could help with grain and grain border resistive and capacitive properties. The impedance study reveals the electrical behavior of the sample. The semicircular arc of the complex impedance and electrical modulus spectrum plots reveal the substance’s semiconducting properties. [ABSTRACT FROM AUTHOR]

In this work, perovskite oxide SrCeO3 was synthesized using the solution combustion method (SCM). Synthesized samples have been characterized using X‐ray diffraction (XRD), Raman, ultra violet (UV)–visible spectroscopy, and scanning electron microscopy (SEM) techniques. The XRD and Rietveld refinement has confirmed the orthorhombic structure with space group Pnma. The average grain size of this ceramic sample is 1.2 µm. The dielectric constant, dissipation factor, modulus, impedance, and alternating current (AC) and direct current (DC) conductivities were analyzed in the temperature range RT to 600°C and frequency range 20 Hz–2 MHz. Further, it was observed that the role of grain boundaries in dielectric and electrical properties is significant, at low temperatures. The origin of the dielectric relaxation and conduction process is the same. The activation energy for DC conduction (Edc) was found to be.79 eV. Electrical conduction/relaxation is assigned to the diffusion of doubly ionized oxygen (Vo··). The value of DC conductivity (1.2 × 10−3 Ω−1 cm−1 at 600°C) and activation energy of.79 eV is very close to the values reported for doped CeO2‐based oxide ion conductors for SOFCs. This study has demonstrated that SrCeO3 can be an alternative candidate for the oxide ion conductor electrolyte application and the potential to be used as a thermally stable capacitor application for microwave dielectric applications. [ABSTRACT FROM AUTHOR]

BaBiLaNbVO9 is a lead-free compound and has been synthesized by solid-state technique. The formation of the compound was confirmed by X-ray diffraction and is found to be crystallized in the monoclinic (space group P 21) crystal system (a = 13.7464± 0.0015 Å, b = 4.0156± 0.0012 Å, c = 12.4946 ± 0.0018 Å, β = 93.48 ± 0.01o). The crystallite size was found to be 52.91 nm. SEM and EDX studies analyzed the morphology, composition, and elemental distribution in the specimen. The average grain size is about 1.0651 μm. Several properties, such as frequency and temperature response resistivity, conductivity, and dielectric behaviours of the compound, have been analyzed. The overlapping large polaron tunnelling (OLPT) and correlated barrier hopping (CBH) models are appropriate for electrical conduction in the compound. The energy band gap (Eg) of the material was 2.40 eV, suitable for optoelectronic devices. Ferroelectric behaviour may be deduced from symmetric and well-shaped P-E hysteresis loops. The impedance study satisfies the negative temperature coefficient of resistance (NTCR) behaviour, which is suitable for thermistor devices and its correlated application. [ABSTRACT FROM AUTHOR]

Organic‐inorganic metal halide single crystals have attracted a lot of attention due to their flexible structural design and excellent optoelectronic applications. This study details the synthesis of copper‐based [(CH3)4N]2CuBr4 hybrid metal halide single crystals via a slow evaporation method. The crystal structure, crystal habit, chemical groups, intermolecular interactions, electrical properties of the sample were studied via single crystal x‐ray diffraction, scanning electron microscopy, Raman and Fourier transform infrared spectrometer, Hirshfeld surface analysis, impedance spectroscopy, and modulus spectroscopy, respectively. An orthorhombic crystal system with the non‐centrosymmetric space group Pna21 was identified at room temperature. The deformation in the tetrahedra was calculated by the bond angle and bond length deformation index. The Cole‐Cole plot displayed the existence of depressed semicircles, which indicated the predominant distribution of grains, further confirmed by the SEM image. The deformed semi‐circular arcs on the electric modulus curve undeniably prove that the bulk effect dominates the material's electrical properties. Significantly, the compound presents a phase transition at ~240 K and excellent thermal stability up to a temperature of 400 K. Therefore, our research sheds light on the temperature dependence of electrical responses in these hybrid crystals and gives inspiration for the development of single crystal‐based efficient energy devices. [ABSTRACT FROM AUTHOR]

The solid-state reaction route created the lead-free dielectric material CaBiLaNbVO9 at a high temperature. The polycrystalline compound belongs to a monoclinic crystal structure having dimensions a = 10.6738 Å, b = 10.4488 Å, c = 7.1793 Å, and V = 798.04 Å3. The grain size is calculated to be 1.1029 µm. The doping of La3+ at the Bi-site and divalent cation Ca2+ substituted at site-A and Nb5+, V5+ in the site-B of ABO3 has considerably modified the structural, dielectric, and electrical conduction mechanism. The study of ac conductivity (frequency-temperature characteristics) shows CBH (correlated barrier hopping) and NSPT (non-overlapping small polaron tunneling) conduction mechanisms. Non-Debye type relaxation has been observed using impedance analysis. The modulus and impedance study have been used to confirm the short-range order of charge carriers. The average transmittance of the compound is about 82–84%, and absorption is in the range of 0.1–1.0% in the visible area applicable for transparent conductive oxide. The energy band gap is 2.73 eV. The analysis of the resistive and capacitive properties indicates the material is an electronic component for the creation of devices. [ABSTRACT FROM AUTHOR]

As purchased, PVDF and MWCNT were used to synthesise PD by varying the volume fractions of MWCNT (fMWCNT) into the polymer matrix through the novel cold-pressing method. The structure, microstructure and the electrical properties of the samples were obtained through XRD, FESEM, and Impedance analyzer. The microstructures of the PD show the presence of two components, such as the spherulites of PVDF (retained due to the novel cold-pressing) and the distribution of MWCNT into the PVDF matrix. The extent of distribution of MWCNT in the PD increases and the clustering of MWCNT also increases with increase of fMWCNT. The PD undergo an insulator to metal transition (IMT), with a non-universal low percolation threshold (fc) value of fMWCNT = 0.006, attributed to the high aspect ratio of MWCNT and the adhesiveness/method of preparation of the PD. The scaling equations hold good in the critical region around IMT, and the non-universal critical exponents [s = 0.36 ± 0.03, s' = 1.26 ± 0.1] were obtained. Impedance, Nyquist and Modulus spectra for the PD have been implemented to understand the relaxation behaviour/microstructure of the samples. For fc, a broad relaxation, understood by a modified Kohlrausch, Williams and Watts (KWW) function, showing a non-Debye type relaxation associated with the universal stretched coefficient of β = 0.54 is obtained. The σeff with frequency obeys universal Jonscher's power law with exponent, k = 0.91 ± 0.01. [ABSTRACT FROM AUTHOR]

A detail analysis on the structural, morphological, dielectric, conductivity, ferroelectric, magnetic and electrical behaviour of Gd doped GaFeO3 prepared by mixed oxide method is presented. XRD analysis, by using Rietveld refinement method, validates that all the samples have single phase orthorhombic structure. Decrement in the grain size with rise in Gd content is found from FESEM analysis. The dispersive characteristic of dielectric constant is described by the Maxwell-Wagner model and Koop's theory. The value of εr is found to increase with Gd content. The modified Debye formula is used to fit εr with frequency data, which indicates the existence of more than one relaxation processes. The frequency dependant ac conductivity curve is found to obey Jonscher's power law and the conduction mechanism for all the samples is explained by of small polaron hopping (SPH) transport model. The modulus and impedance spectra confirms the presence of non- Debye type of relaxation. The presence of semicircular curves of complex impedance plot suggests the effect of grain boundary contribution to the conduction process for all the samples at low temperatures. The value of remanent polarization is found to fall with Gd content. From M-H loop, magnetisation at M (30kOe) is found to rise while non-saturation is found to decrease with Gd content and analysed on the basis of Law of Approach.

In this study, the impact of Nd doping on the structural, microstructural, dielectric, ferroelectric, and transport properties of Pb (1 - x) Nd x (Fe 0.5 Nb 0.5) 1 - x / 4 O 3 (PNFN) solid solutions ( x = 0 , 0.02 , 0.04 , 0.08 , and 0.1 ) is reported. For all the solid solutions, room temperature Rietveld refined X-ray diffraction (XRD) analysis reveals the monoclinic crystal structure with Cm space group. From Field emission scanning electron microscope (FESEM) studies, the polyhedral-shaped grains are found to be homogeneously distributed. Variation of dielectric properties with temperature displays the decrease of phase transition temperature (TC) with increasing Nd content. The temperature-dependent AC conductivity follows the Arrhenius behavior and the activation energies are calculated for high temperature regions. The frequency dependent AC conductivity behavior obeys the Johnscher's power law. Impedance spectroscopy results show the impact of conductivity from the bulk (grain) and displays non-Debye type of behaviour. Electric modulus demonstrates thermally activated relaxation phenomenon in the materials. Polarization vs. electric field (P-E) loops analysis confirms the ferroelectric nature of the materials. With increase in Nd concentrations, the value of remanent polarization (2Pr) increases, on the other hand, the coercive field (2Ec) value decreases. Both of these properties are suitable for enhancement of the physical properties of the multiferroic materials. [ABSTRACT FROM AUTHOR]

Copper -doped Strontium Titanate (STO) with Copper filler percentages of 5% and 10% was prepared through a solid-state reaction method at high temperatures. The structural study of the materials was characterized by the X-ray diffraction technique and confirmed to be in the Cubic phase. Also, the surface morphology of the samples was studied by scanning electron microscopy. The impedance study of the samples was characterized by an LCR meter between the frequencies ranges 102-106 Hz. The exponential dependence of ac conductivity on frequency was confirmed where the value of ac conductivity increases with the rise in filler concentration from 5% to 10%. [ABSTRACT FROM AUTHOR]

Copper -doped Strontium Titanate (STO) with Copper filler percentages of 5% and 10% was prepared through a solid-state reaction method at high temperatures. The structural study of the materials was characterized by the X-ray diffraction technique and confirmed to be in the Cubic phase. Also, the surface morphology of the samples was studied by scanning electron microscopy. The impedance study of the samples was characterized by an LCR meter between the frequencies ranges 102-106 Hz. The exponential dependence of ac conductivity on frequency was confirmed where the value of ac conductivity increases with the rise in filler concentration from 5% to 10%. [ABSTRACT FROM AUTHOR]

[Display omitted] • Improved ε r and ac-conductivity of Sn-modified lead germanate. • Temperature-dependent dielectric and electrical properties. • Decreased E a and revealed conduction mechanism of PGSO at higher temperatures. • NTCR behavior of PGSO for high-sensitivity thermistors and sensors. • Thermistor constant (β) of 1662 K in 250 °C-300 °C. A solid-state reaction was used to synthesize the tin modified lead germanate: Pb 5 Ge 1.5 Sn 1.5 O 11 (PGSO). The composition was modified to enhance its dielectric and electrical properties. The PGSO sample was characterized by various analytical techniques, such as XRD for structural analysis and FTIR for additional structural information. The surface morphology and features of PGSO were examined by SEM, while its band gap was determined by UV–Visible-Diffuse Reflectance Spectroscopy absorbance spectra. The impedance, dielectric behaviour, AC conductivity, activation energy, and modulus of PGSO were also studied. The temperature dependence of the dielectric constant and AC conductivity showed an increase with increasing temperature. The electrical resistivity (R) decreased as the temperature increased from 100 °C to 300 °C, exhibiting a NTCR behaviour for PGSO sample, which could be applied as a high temperature thermistor and sensor, and could be used to fabricate a high sensitivity, low-cost thermistor. The circuit parameters such as bulk resistance (R b), frequency factor (n), and bulk capacitance (C b) were determined by fitting the Nyquist plot using an equivalent circuit (CQR)(CR). [ABSTRACT FROM AUTHOR]

A lead free polycrystalline double perovskite-based ceramic oxide Ca2BiNbO6(CBNO) was synthesized by the conventional solid state reaction route. Emergence of a new single-phase double perovskite structure exhibiting cubic phase with space group fm-3 m was confirmed through the room temperature XRD analysis. Particle size of 34.29 nm was obtained using Scherrer's formula. Different electrical parameters such as complex impedances, modulus, dielectric (εr and tanδ) and conductivity were recorded carefully by the LCR analyzer for a wide range of temperatures (25–500 ø°C) and frequencies (100 Hz–5 MHz), respectively. Large room temperature dielectric constant with a NTCR property was investigated. The ferroelectric nature with a transition temperature above 300 °C was analyzed from the study. The thermal dependent conductivity fitted curve satisfies the Arrhenius law and leads to a calculated activation energy of 0.0597 eV. The obtained result promotes this new material to be a favorable candidate to uses in smart and modern electronic device applications. [ABSTRACT FROM AUTHOR]

Among La1-xCaxFeO3-δ (0 ≤ x ≤ 0.5) compounds, the optimal value of the direct current conductivity was registered for a 20% substituted amount. We therefore attempted to study the impedance and dielectric properties of 20% calcium-substituted lanthanum ferrite. We investigated the electric properties in depth between 5 Hz and 13 MHz from 350 to 800°C. The results reveal interesting properties. Indeed, the perovskite shows a huge dielectric constant which promotes its utilization in high-performance dielectric material applications. At a given temperature, ε’ and tan(δ) decrease with increases in frequency. This trend was explained based on the Maxwell Wagner polarization model. The variations in dielectric loss (ε”) with frequency obey the Giuntini theory based on the hopping model. As the temperature increases from 350 to 800°C, the binding energy increases from 0.22 to 0.34 eV, while the minimum hopping distance decreases from 2.16 to 0.12 pm. Consideration of the electric modulus analyzes showed that the relaxation mechanism is dominated at below 400°C by a short-range movement of charge carriers, whereas at above that temperature, a long-range movement of charge carriers is dominant. This study presents a solid foundation for the polarization and dielectric properties of lanthanum ferrite, which is a lead-free, environmentally friendly material and a promising candidate for use in nonlinear optical applications and microwave devices.

In this study, structural, morphological, dielectric and AC conductivity properties of CoMgLa ferrite samples (Co0.5Mg0.5LaxFe2-xO4) were investigated according to the change of x (x=0, 0.1, 0.2, 0.3, 0.4 and 0.5). Samples were synthesized by co-precipitation method. The structural properties were examined using XRD and results show that the prepared sample crystallizes in the cubic spinel structure. Crystallite sizes are changing between 24.92 to 9.80 nm. Morphological and elemental properties were analyzed by SEM and EDX. Dielectric properties were investigated by impedance spectroscopy. The samples showed normal dielectric properties consistent with the Maxwell-Wagner model due to interfacial polarization. When the impedance characteristics were examined, it was found that the relaxation process was compatible with the Cole-Cole model. The results of the modulus show that grains contribute to the relaxation process as well as grain boundaries. AC conductivity exhibited semiconductor behavior. The constant behavior of conductivity at low frequencies is a sign that the examined samples may be suitable for many applications [ABSTRACT FROM AUTHOR]

Among La1-xCaxFeO3-δ (0 ≤ x ≤ 0.5) compounds, the optimal value of the direct current conductivity was registered for a 20% substituted amount. We therefore attempted to study the impedance and dielectric properties of 20% calcium-substituted lanthanum ferrite. We investigated the electric properties in depth between 5 Hz and 13 MHz from 350 to 800°C. The results reveal interesting properties. Indeed, the perovskite shows a huge dielectric constant which promotes its utilization in high-performance dielectric material applications. At a given temperature, ε' and tan(δ) decrease with increases in frequency. This trend was explained based on the Maxwell Wagner polarization model. The variations in dielectric loss (ε") with frequency obey the Giuntini theory based on the hopping model. As the temperature increases from 350 to 800°C, the binding energy increases from 0.22 to 0.34 eV, while the minimum hopping distance decreases from 2.16 to 0.12 pm. Consideration of the electric modulus analyzes showed that the relaxation mechanism is dominated at below 400°C by a short-range movement of charge carriers, whereas at above that temperature, a long-range movement of charge carriers is dominant. This study presents a solid foundation for the polarization and dielectric properties of lanthanum ferrite, which is a lead-free, environmentally friendly material and a promising candidate for use in nonlinear optical applications and microwave devices. [ABSTRACT FROM AUTHOR]

Magnetoelectric composites combining ferromagnetic cobalt ferrite (CFO) and ferroelectric barium titanate (BT) are prepared using conventional solid-state reaction. Dielectric measurements reveal that CFO and CFO-BT composites exhibit Maxwell–Wagner polarization and temperature-dependent relaxation originating due to the presence of ions/defects vacancies. Prominently, CFO-30%BT composite showed an unexpected low dielectric loss ≈ 0.5 above 1 kHz and has potential for device application. Impedance spectroscopy confirms the thermally activated relaxation mechanism and high impedance behavior in the samples. Modulus analysis affirms the statistically distributed non-Debye-type behavior existing in CFO-BT composites. The electric conductivity takes place via correlated barrier hopping in CFO and CFO-10BT composite and overlapping large polaron tunneling in CFO-30BT composite. The addition of BT in CFO initiates the structural modification and results in conductivity cross-over with improved conductivity. These results are useful for exploring devices based on CFO-BT composites. [ABSTRACT FROM AUTHOR]

The influence of co-substitution of Co and W on structural and electrical properties of BaTiO 3 (i.e., Ba(Co 1/3 Ti 1/3 W 1/3)O 3) was investigated. This perovskite ceramic was synthesized using a conventional ceramic technology (i.e., high-temperature solid state reaction route, calcination temperature = 1100 °C and sintering temperature = 1200 °C). The compound crystallizes in the orthorhombic phase. The Nyquist plots exhibit the activation of grain boundary effect at 300 °C and the Non-Debye behavior in the sample. The relaxation distribution parameter for the sample at different temperatures is calculated from the depression angle of the semicircular arcs in the Nyquist plot. The activation energy of 0.69 eV estimated for the charge carriers in the grain is almost in good agreement with that of 0.66 eV calculated from the relaxation process of grains. The sample possesses a dielectric constant of 1140 and loss tangent of 0.27 at room temperature which can be exploited for some applications including memory devices, etc. The existence of room temperature hysteresis loop confirms the ferroelectric nature of the sample. On the basis of variation of the exponent in the Jonscher's power law with temperature, correlated barrier hopping is favored as the dominant conduction mechanism in the sample. [ABSTRACT FROM AUTHOR]

Ba(Fe 1/3 Ti 1/3 W 1/3)O 3 , was successfully prepared by the cost effective mixed oxide reaction method at 1000 °C. Analysis of X-ray diffraction (XRD) data indicates the crystallization of the compound in the orthorhombic crystal system. A dielectric anomaly observed at around 59 °C shifts to the higher temperature side with increase in frequency can be explained by Maxwell-Wagner polarization mechanism, whereas an another anomaly observed at 126 °C can be considered as the ferroelectric to paraelectric transition. The dielectric property was analyzed by modified Cole-Cole relation, and the impedance using Nyquist plot. The activation energy calculated from grain resistance and the relaxation parameters amounts to be 0.54 eV. Analysis of the conductivity curves using the Jonscher's power law suggests OLPT model and CBH model as the dominant conduction mechanism in the ferroelectric and paraelectric phase in the sample. The ferroelectricity of the sample was confirmed by the room temperature P ~ E loop. [ABSTRACT FROM AUTHOR]

Graphical abstract Dual positive temperature coefficient of resistance (PTCR) to negative temperature coefficient of resistance (NTCR) transitions of this system. Highlights • Positive temperature coefficient of resistance (PTCR). • Interface magnetoelectric (ME) effect in this system. • Small polaron hopping and over lapping large polaron tunneling at interface. Abstract Polycrystalline nano grain size Na 0.5 Bi 0.5 TiO 3 (NBT) system is synthesized by using modified sol–gel method. X-ray diffraction (XRD), Transmission electron microscopy (TEM) studies and Field emission scanning electron microscopy (FESEM) are employed for structural and morphological confirmation. Electrochemical transport properties of this nano system have been investigated systematically in the range of temperature (30 °C−450 °C) and frequency (100 Hz−1 MHz) with the help of complex impedance spectroscopic technique. From impedance and modulus results, two (one at low and another at high temperature regime) positive temperature coefficient of resistance (PTCR) to negative temperature coefficient of resistance (NTCR) transitions are observed which is useful for electrochemical temperature sensor application. From electric transport analysis it found that due to small polaron hopping of charge carriers at NBT-NBT interfaces system shown PTCR nature. However, the system has shown both −ve magnetoresistance [MR (%)] and magnetocapacitance [MC (%)] at RT due to overlapping of large polaron tunnelling (OLPT) at NBT-NBT interfaces (which is explored with the help of magnetic transport analysis). [ABSTRACT FROM AUTHOR]

The polycrystalline 0.7Bi(Fe 0.98 Ga 0.02)O 3 -0.30BaTiO 3 (BFG-BTO) ceramic was processed by high temperature reaction route. The room temperature X-ray spectra suggest a tetragonal symmetry. The structural refinement was also carried out. The high densification of sample formation is depicted from a scanning of the natural surface of the sample. The electrical properties were measured using a complex impedance method over a wide range of frequencies and temperatures. The overlapping large-polaron tunnelling model type of conduction mechanism is obtained from the frequency dependent ac conductivity plots. The relaxation mechanism is studied with the help of various spectroscopic tools (modulus and dielectric). The Nyquist plot indicates the non-Debye characteristics and the combined contribution of both grain and grain boundary towards the resistive property of the sample. Image 1062858 • The BFG-BTO is synthesized by cheap cost ceramic processing. • Dielectric properties with respect to temperature is investigated. • The complex impedance plots shows grain and grain boundary effects in the BFG-BTO. • A well defined relaxation mechanism was identified by modulus analysis. [ABSTRACT FROM AUTHOR]

In the present study, NaYP2O7 compound was prepared by solid-state method and was characterized by powder X-ray diffraction and Raman spectroscopy. The X-ray diffraction of the sample at room temperature showed a monoclinic phase. Electrical conductivity and modulus studies over a wide range of frequencies (40 Hz to 7 MHz) and temperature (400–560 K) were studied using impedance spectroscopic technique. The impedance plane plot shows semicircle arcs at different temperatures and an electrical equivalent circuit has been proposed to explain the impedance results. The ac conductivity of the investigated compound obeys the power law: σac(ω) = σdc + Aωn where n < 1. The frequency-dependent maxima of the imaginary part of modulus are found to obey Arrhenius law with activation energy 0.64 eV. The activation energy responsible for dielectric relaxation extracted from the modulus spectra is found to be almost the same as the value obtained from the equivalent circuit. These results indicate that the transport is through ion hopping mechanism dominated by the motion of the Na+ ion in the structure of the investigated material. [ABSTRACT FROM AUTHOR]

Abstract The multiferroic ceramic (BiBa 0.5 Sr 0.5) 0.5 (Fe 0.5 Ti 0.5) O 3 (BFO-BST) is prepared in an economic way by conventional solid state reaction route and its different behaviours are studied and reported. The X-Ray diffraction (XRD) and Scanning Electron Microscope (SEM) investigations have confirmed single phase forming by the compound. Full proof reitveld analysis has been used for structural refinement. XRD pattern of the sample it is inferred that the observed peaks and calculated peaks are well matched with each other having minimum deviation. The density of the compound is quiet high as calculated by above analysis as well as from SEM image. Dielectric behaviour of the compound has been analyzed through the variation of dielectric constant with frequency while the electrical behaviour is studied through the complex impedance and modulus analysis. Additionally, verification of Jonscher's power law from ac conductivity study gives the detail findings about electrical behaviour of the material. Highlights • BFO-BST is a potential candidate for electronic devices. • BFO-BST is suitable for sensors, actuators or FeRAM. • BFO-BST can also be used for energy storage devices. • Low loss, high dielectric constant, high quality factors. [ABSTRACT FROM AUTHOR]

Graphical abstract Dual positive temperature coefficient of resistance (PTCR) behaviour of this composite system. Highlights • Nanocomposite of [90 wt% NBT-10 wt% BaM] synthesized by solid state reaction technique. • This nanocomposite has shown doubly PTCR behavior. • Significant magnetoresistance [MR (%)] is observed at RT. Abstract Polycrystalline [90 wt% Na 0.5 Bi 0.5 TiO 3 (NBT) – 10 wt% BaFe 12 O 19 (BaM)] nanocomposite system has been fabricated with the help of solid state reaction method. The Rietveld refinement of X-ray diffraction (XRD) pattern and Transmission electron microscopy (TEM) have been provided the information about the pure phase formation and grain size of desired composite system. Microstructural electric and magnetic transport properties have been carried by complex impedance spectroscopic technique. From electric transport properties it is interestingly observed that, the system has shown double positive temperature coefficient of resistance (PTCR) behaviour due to different transport mechanism of BaM-NBT and NBT-NBT interfaces in different temperature ranges. Magnetoimpedance study has been revealed the negative magnetoresistance [MR (%)] behaviour of both the interfaces. From magnetotransport properties of this nanocomposite system it is explored that BaM-NBT interfaces obey the small polaron tunnelling where NBT-NBT interfaces obey the over lapping large polaron tunneling mechanism for charge transportation. [ABSTRACT FROM AUTHOR]

Electrical properties of 0.884Bi 0.5 Na 0.5 TiO 3 -0.036BaTiO 3 -0.08Bi 0.5 K 0.5 TiO 3 ceramic samples were investigated in 100Hz to 1 MHz frequency range and in 200–450 °C temperature range using impedance spectroscopy technique. Real part of impedance versus frequency plots in lower frequency region revealed its PTCR behavior and NTCR behaviors in higher frequency region. Impedance study also suggested the presence of non-Debye type relaxation mechanism. Cole-Cole plots suggested two relaxation regions, in which grain and grain, grain boundary effects were prominent in lower and high temperature regions, respectively. DC conductivity followed Arrhenius law with an activation energy of ∼0.79 and 1.2 eV, which suggested that the charge carrier were cation vacancies in lower temperature region whereas cation vacancies and oxygen vacancies in higher temperature region. [ABSTRACT FROM AUTHOR]

Impedance spectra of 0.93BNT-0.07KNN revealed positive and negative temperature coefficient of resistance behaviour up to 400°Cand above 400°C. With the increase of temperature, decreased radii and displaced centres of semicircles from the real axis of impedance Cole-Cole plots suggested non-Debye type relaxation mechanism. Three dielectric relaxation regions: within (i) grain, (ii) grain- grain boundary and (iii) grain boundary were prominent in lower, middle and high temperature regions, respectively. The activation energy ranging from ∼0.79 to 1.2eV, suggested that the conduction carriers were cation and cation, oxygen vacancies in lower and higher temperature regions, respectively. [ABSTRACT FROM AUTHOR]

Polycrystalline (1-x) Na 0.5 Bi 0.5 TiO 3 (NBT) – (x) BaFe 12 O 19 (BaM) [x in wt%=40, 30, 20 and 10] novel particulate magnetoelectric (ME) composite systems have successfully fabricated by the solid-state reaction method. The Rietveld refinement of X-ray diffraction patterns provided the evidence about the pure phase formation of desired composite systems. Scanning Electron Microscopic (SEM) images provided the information about grain size and connectivity of both the phases in composite systems. The microstructural conduction mechanism of all the composite systems has been systematically investigated with the help of complex impedance spectroscopic technique. From both impedance and modulus spectroscopic study it is observed that different interfaces (BaM-BaM, BaM-NBT and NBT-NBT) are activated at different temperature ranges (in all the systems). It is also observed that, decreasing of BaM wt%, has significant effect on conduction mechanism of different interfaces. When BaM wt% is decreased, it has been perceived that BaM-NBT interfaces conduction gradually dominating over BaM-BaM interfaces conduction at room temperature (RT) as the result of which S1(NBT90) composite system has shown positive temperature coefficient of resistance (PTCR) behavior. [ABSTRACT FROM AUTHOR]

Polycrystalline [50 wt% BaFe 12 O 19 (BaM)–50 wt% Na 0.5 Bi 0.5 TiO 3 (NBT)] particulate novel magnetoelectric nanocomposite system was successfully fabricated by solid state reaction technique. The Rietveld refinement of X-ray diffraction pattern was provided the evidence about the pure phase formation of desired nanocomposite system as well as the presence of both ferrimagnetic (FM) BaM & ferroelectric (FE) NBT phases separately. The Field Scanning Electron Micrograph (FESEM) and Scanning Tunneling Electron Micrograph (STEM) explored the information about grain size and connectivity of the composite system. The XPS study was helped to examine the presence of oxygen vacancy (O v ) as well as multi oxidation states of transition metal ions for nanocomposite system. In this report we have systematically examined the conduction mechanism of different interfaces (BaM-BaM, BaM-NBT and NBT-NBT) by the help of complex impedance spectroscopy technique. From our investigation it was observed that, different interfaces activates at different temperature ranges. Due to absence of O V , BaM-NBT interfaces conduction dominants over BaM-BaM interfaces conduction even at room temperature (RT). The mechanism behind the appeared high dielectric loss ( tan δ ) at RT which was reduced when NBT-NBT interfaces were activates at higher temperature was explained by Maxwell-Wagner type interfacial polarization concept. [ABSTRACT FROM AUTHOR]

ZnO/TiO2 composite ceramics have been prepared by solid-state reaction technique at 900°C. The X-ray diffraction results revealed the formation of secondary phases referred to as spinel Zn2TiO4 and hexagonal ZnTiO3. The structural analysis showed that all the composites that have been prepared have a polycrystalline nature and a hexagonal wurtzite structure. The complex modulus ( M) and electric impedance of the samples have been investigated by broadband dielectric spectroscopy in a wide range of temperature (40°C-110°C) and frequency (0.1 Hz to 10 MHz). The modulus plots (M′′, M′) illustrate the presence of non-Debye type of relaxations attributed to the effects of interfacial and dipolar polarizations. The real and the imaginary parts of the impedance are well fitted to equivalent circuit models. At high temperatures, Z″max varies from 0.03 × 106 to 4.9 × 106 Ω when the TiO2 doping concentration increases from 1 to 7 wt%. From the obtained results, the secondary phase ZnTiO3 plays an important role in the electrical properties. [ABSTRACT FROM AUTHOR]

The Bi2Fe2WO9 ceramic was prepared using a standard solid-state reaction technique. Preliminary analysis of X-ray diffraction pattern revealed the formation of single-phase compound with orthorhombic crystal symmetry. The surface morphology of the material captured using scanning electron microscope (SEM) exhibits formation of a densely packed microstructure. Comprehensive study of dielectric properties showed two anomalies at 200∘C and 450∘C: first one may be related to magnetic whereas second one may be related to ferroelectric phase transition. The field dependent magnetic study of the material shows the existence of small remnant magnetization (Mr) of 0.052emμ/g at room temperature. The existence of magneto-electric (ME) coupling coefficient along with above properties confirms multi-ferroic characteristics of the compound. Selected range temperature and frequency dependent electrical parameters (impedance, modulus, conductivity) of the compound shows that electric properties are correlated to its microstructure. Detailed studies of frequency dependence of ac conductivity suggest that the material obeys Jonscher’s universal power law.

This report presents the fabrication, electrical properties along with the magnetic parameters of a composite system considering a strong ferrimagnetic (BaFe 12 O 19 ) and a ferroelectric (Na 0.5 Bi 0.5 TiO 3 ) material. Polycrystalline 50 wt% BaFe 12 O 19 (BaM)–50 wt% Na 0.5 Bi 0.5 TiO 3 (NBT) composite system was prepared by the solid state reaction method. Rietveld refinement of XRD pattern confirms the presence of BaM and NBT phases without any impurity phase. From scanning electron micrograph both the phases are also clearly identified. In this report, the electric relaxation and conductivity properties were systematically investigated and analyzed in the frequency range of 100 Hz to 1 MHz and temperature range of 30–200 °C. The presence of different type of grains and significant reduction in the resistance of the composite system were found to be responsible for the nature of electric relaxation behavior. A peculiar and interesting evolution of grain boundary conduction was detected which was argued due to the existence of three possible grain boundaries such as: (i) BaM–BaM interface, (ii) NBT–NBT interface and (iii) BaM–NBT interface. The magnetization study (M–H loop) paves that, the saturation magnetization and coercive field reduces for composite system. [ABSTRACT FROM AUTHOR]

Sn-substituted lead calcium iron niobate specimens with general formula (PbCa)(FeNb)SnO with 0.00 ≤ y ≤ 0.15 in steps of 0.03 have been synthesized using a two-stage method. The x-ray diffraction patterns for all the synthesized samples reveal a perovskite structure with pseudocubic symmetry. A small amount of pyrochlore phase was obtained along with the perovskite phase, decreasing with increasing Sn content up to y = 0.09. The temperature and frequency dependence of the dielectric and electrical properties of Sn-substituted lead calcium iron niobate were studied. Two dielectric anomalies were observed in ε- T plots for all the samples due to generation of oxygen vacancies. The temperature coefficient of relative permittivity, τ, decreased with increasing Sn content. The single, semicircular arc observed in Nyquist plots suggests a single relaxation process. The activation energies obtained from the temperature dependence of the relaxation time and grain resistance were found to be approximately comparable. [ABSTRACT FROM AUTHOR]

New alternating poly(propylene- alt -carbon monoxide/ethylene- alt -carbon monoxide) (PECO)/multiwalled carbon nanotubes (MWCNTs) composites have been prepared. Dielectric permittivity, electric modulus and ac conductivity of the isolated materials were investigated as a function of fiber aspect ratio, frequency and temperature. For aspect ratio of 30 and 200, a transition from insulator to semiconductor was observed at frequency 1×10 4 . However, for high aspect ratio sample (660), no transition was observed and the conductivity is frequency independent in the measured frequency range of 10–10 6 Hz. The conductivity increases from about 1×10 −4 for the sample that contain fibers of aspect ratio 30 and reaches 5×10 −2 (Ω m) −1 for aspect ratio was 660. This behavior can be modeled by a circuit that consists of a contact resistance in series with a parallel combination of resistance ( R ) and capacitance ( C ). The calculated activation energy for sample filled with fibers having aspect ratio 30 is about 0.26 eV and decreases to about 0.16 eV when the aspect ratio is 660. [ABSTRACT FROM AUTHOR]

The physicochemical properties of soft electrode materials for the abio–bio interface of advanced biosensors and next generation bionic devices in the form of electroconductive hydrogels (ECH) of interpenetrating networks of polypyrrole formed within poly(hydroxyethylmethacrylate)-based hydrogels were examined. The 1.5 mol% UV-crosslinked tetraethyleneglycol diacrylate (TEGDA) (step 1) poly(HEMA) and the electropolymerized (step 2) polypyrrole co-networks were covalently joined by the inclusion of a bifunctional monomer (1.5 mol%), 2-methacryloyloxyethyl-4(3-pyrrolyl)butanate (MPB) that served to covalently link the two networks. The optical absorbance, degree of hydration, the frequency dependent electrical impedance and the elastic modulus were examined as a function of electropolymerization charge density (step 2) (1–900 mC/cm2) used to prepare the linked, interpenetrating co-networks. The absorption at 430 nm showed a monotonic increase with electropolymerization charge density and correlated with the increase in elastic modulus [56 (±32)–499 (±293) kPa], the decrease in % hydration (68–0%) and the decrease in membrane electrical resistance. Polypyrrole (PPy) grows initially from the gel–electrode interface to fill voids within the hydrogel and ultimately onto the surface of the hydrogel. Growth of attachment dependent Rhabdomyosarcoma (RMS13) and pheochromocytoma (PC 12) cells reflects this evolution, showing an increase to a maximal value and then to decrease again at high electropolymerization charge density. [ABSTRACT FROM AUTHOR]

Abstract: Nanocrystalline powders of (Ba1− x Ce x )(Zr0.52Ti0.48)O3 [x =0.1 and 0.2] have been synthesized by conventional solid state reaction method. X-ray diffraction patterns confirm the formation of single phase cubic crystal symmetry. The increase in grain size reveals the influence of Ce ions on microstructure. The electrical behavior of sintered pellets investigated by impedance spectra showed frequency dependent behavior. The complex impedance plots display a single semicircle highlighting the influence of grain resistance on the electrical behavior. The modulus curve illustrates the possibility of non-exponential type conductivity. The values of activation energy calculated from both plots of Z″ and M″ confirms that the oxygen vacancies play an important role in the conduction. The temperature dependant dc-resistivity depicts a negative temperature coefficient of resistance behavior of synthesized ceramics. The ac conductivity of both ceramics increases as a function of frequency due to relaxation phenomenon arisen due to mobile charge carriers. [Copyright &y& Elsevier]

BaTiO film was prepared on Pt/Ti/SiO/Si substrate by the laser chemical vapor deposition method. A single-phase BaTiO film with $$ (\overline{3} 22)/(\overline{2} 23) $$ preferred orientation and columnar cross-section was obtained at high deposition rate (154.8 μm h). The dielectric constant ( ε) of the BaTiO film was 21, measured at 300 K and 1 MHz. The electrical properties of the BaTiO film were investigated by ac impedance spectroscopy from 300 K to 1073 K at 10 Hz to 10 Hz. Plots of the real and imaginary parts of the impedance ( Z′ and Z″) and electrical modulus ( M′ and M″) in the above frequency and temperature range suggested the presence of two relaxation regimes, which were attributed to grain and grain boundary responses. The ac conductivity plots as a function of frequency showed three types of conduction process at elevated temperature. The frequency-independent plateau at low frequency was due to dc conductivity. The mid-frequency conductivity was due to grain boundaries, while the high-frequency conductivity was due to grains. [ABSTRACT FROM AUTHOR]

PEO containing AgCF3SO3 polymer films have been prepared by the hot press technique. The effect of salt concentration on the frequency-dependent conductivity properties of PEO: AgCF3SO3 complexes are investigated by impedance spectroscopy in the temperature range from 303 K to 328 K. The ac conductivity and dielectric properties of the prepared samples have been analyzed. The ac conductivity obeyes the universal power law and as the temperature increases, the feature of σ(ω) α ωn is more predominant. The dielectric permittivity is found to increase with temperature of the prepared samples. The imaginary part of electrical modulus, M' shows the formation of dispersion peak. Relaxation times for the ionic charges carriers were extracted from the peak maxima of imaginary part of modulus at various temperatures. The plot of relaxation times as a function of temperature shows Arrhenius type behavior. [ABSTRACT FROM AUTHOR]

Abstract: 0.65Pb(Mg1/3Nb2/3)O3–0.35PbTiO3 ceramic was prepared by citrate gel method. The electrical property of this compound was investigated using impedance spectroscopy. The appearance of grain and grain boundary is evident at higher temperature (≥425°C). The depression of semicircle in the impedance plot and the value of full width half maximum (FWHM) of the peaks in the modulus plot show that the compound exhibits non-Debye relaxation process. The impedance analysis further provided the value of relaxation frequency, which is a characteristic intrinsic property of the material. The temperature variation of the bulk conductivity indicated an Arrhenius type of thermally activated process, showing a linear variation upto 425°C and above which it is dominated by grain boundary conduction, which was evident from the slope change at 425°C. The temperature coefficients of the resistance (α) were derived being equal to −1.4×10−2 C−2 at 400°C. The low value of exponent (s) indicates the presence of asymmetric charge defects. [Copyright &y& Elsevier]

Abstract: In the present work, an evaluation of the transport properties of super ion conducting quaternary system 20CdI2–80[xAg2O–y(0.7V2O5–0.3B2O3)], where 1≤ x/y ≤3, in steps of 0.25, to study the effect of changing the modifier to former ratio on the conduction phenomena has been undertaken. Electrical conductivity measurements were made using complex impedance method. The electrical conductivity and conductivity relaxation of the system were studied in the temperature range from 303 K to 333 K and in the frequency range from 100 Hz to 10 MHz. The highest conductivity at room temperature is obtained for the system with modifier to former ratio 1.75. Impedance and modulus analyses had indicated the temperature independent distribution of relaxation times and the non-Debye behavior in these materials. The co-operative motion due to strong coupling between the mobile Ag+ ions is assumed to give rise to non-Debye type of relaxation. The silver ionic transport number (t Ag+) obtained by the emf technique suggested the occurrence of silver ion conduction in the CdI2-doped Ag2O–V2O5–B2O3 system. [Copyright &y& Elsevier]

Abstract: The electrical conductivity and the conductivity relaxation of the glass system xCdI2-(100− x)[2Ag2O–(0.7V2O5–0.3B2O3)] were studied in the temperature range from 303K to just below the glass transition temperature and in the frequency range from 100Hz to 10MHz. The ionic conductivity of the system is found to increase with increase in the dopant content and maximum value is obtained for 30mol% of CdI2 doped system. The impedance data is analyzed in the modulus formalism. The ionic conductivity and conductivity relaxation calculated from impedance and modulus spectra, respectively, were found to be thermally activated and the activation energy obtained from both measurements are comparable. The value of the β parameter has been found out and a comparative study of the impedance and modulus spectrum indicate the non-Debye type of frequency dispersion in the mixed system. [Copyright &y& Elsevier]

It has been observed that phosphorous incorporation (1 wt.% as P2O5) in Pb(Zr0.52Ti0.48)O3 [PZT] ceramics can lead to an appreciable densification (98%) at a temperature as low as 1050 °C. The impedance of the samples initially increases with the increase in phosphorous addition (up to 2 wt.% P2O5) followed by a decrease after further addition. The enhancement of dielectric constant and dielectric loss at low frequencies, especially for the sample containing 4 wt.% P2O5, suggests Maxwell–Wagner relaxation. Although the d33 and g33 values decrease with the phosphorous addition, PZT containing 1 wt.% P2O5 can be used as a cost-effective substitute of pure PZT for low-end applications. [Copyright &y& Elsevier]