Ac Conductivity Data Research Articles

Electrical characterization of lead-modified bismuth borovanadate glasses

Specifically, the study looks into dielectric characteristics (ε′andε″) and complex modulus formulation and AC conductivity of lead-modified bismuth borovanadate glasses (50-x) V2O5-40 B2O3-10 Bi2O3-xPbO, where x = 5,10, 15, 20 and 25 mol% with sample ID's VPb1, VPb2, VPb3, VPb4 & VPb5 according to different compositions of lead and vanadate. When the PbO content rises, there is a decreasing tendency in both the alternating current conductivity and dielectric constants. In order to fit AC conductivity data, Almond West equation is used to extract parameters, including crossover frequency (ωH), frequency exponent (s), and direct current conductivity (σdc). Direct current conduction mechanism in all glass samples except VPb5 [Correlated Barriers Hopping (CBH) conduction at all frequencies] at lower frequencies might potentially be attributed to large-polaron quantum mechanical tunneling (LQMT). Similar to this, at high frequencies, small polaron quantum mechanical tunnelling is followed by VPb2 & VPb3 while LQMT is followed by VPb1 & VPb4. Activation energy of dc conduction (Edc) at higher frequencies (0.373–0.476 eV) for samples having sample ID VPb1 to VPb4 and sample VPb5 at all frequencies with Edc 0.686 eV and modulus activation energy (ER) (0.382–0.534 eV) are found in good agreement. Dielectric studies reveal non-Debye-type behaviour.

Electrical properties and evaluation of band tail states in Mg doped p-type multilayer hBN

A series of Mg doped p-type multi-layered hBN films were prepared by atmospheric pressure chemical vapor deposition. Temperature dependent conductivity measurements were performed from 0.1 Hz to 10 MHz to analyze the characteristics of tail states close to the valence band edge. Jonscher's power law (Aωs) is successfully applied to understand charge carrier transport through these states. In this work, exponent S increases from 0.6 → 0.8, 0.8 → 0.995, and 1.4 → 1.6 for samples B (precursor temperature, 750 °C), D (850 °C), and E (900 °C), indicating that non-overlapping small polaron tunneling dominates to 548 K. Polaron binding energies of 0.2–0.40 eV and tunneling distances <4.9 Å are calculated, confirming transport through localized states. The density of states near the Fermi level N(EF) was extracted from a fit to the AC conductivity data, yielding values of 1015 and 1017eV−1cm−3 as the precursor temperature increases. Singular Mg acceptor levels of 74, 30, and 17 meV are identified for each sample. A hole concentration from 6.5 × 1017 to 1 × 1018 cm−3 and carrier mobility from 18 to 25 cm2/V s is measured at 300 K. From RC fitting, carrier recombination lifetimes of 1.2, 0.4, and 0.35 μs are determined. Fermi's golden rule is used to determine an optical joint density of states of 1.1 × 1021 eV−1 cm−3 at a band edge. Overall, we show that AC conductivity is an effective method to evaluate midgap states in 2D (two-dimensional) materials at EF and p-type hBN possesses sufficient electrical properties to be integrated into a wide range of semiconductor applications.

Probing variation of the structure and electrical conductivity of functionalized PVA based composite films doped with silver nanoparticles and irradiated by gamma rays

Polyvinyl alcohol/sulfuric acid/ethanol films doped with nano-silver particles are prepared using in-situ chemical reduction method. The as-prepared films are irradiated with gamma rays at dose range 0–50 kGy. The elemental analysis of as-prepared samples using energy dispersive x-ray spectroscopy (EDXS) showed presence of oxygen and silver peaks which refers to the probable formation of silver oxide nano-particle (Ag2O NPs) phase. Moreover, scanning electron microscope (SEM) analysis confirmed that the inserted Ag nanoparticles have regular and uniformly distributed pores within the PVA network. X-ray diffraction (XRD) measurements indicated that of Ag2O and Ag nanoparticles are embedded in the PVA matrix in cubic face-centered structure. Structural variations due to gamma irradiation are also probed by high-resolution transmission electron microscopy (HR-TEM) which displayed that the diameter of encapsulated Ag nanoparticles increases from ∼15 nm up to 34 nm against irradiation dose. The measured dc electrical conductivity results indicated that the thermal activation energy decreased from 0.95 eV to 0.56 eV as a sequence of irradiation dose in the range 0–50 kGy The evaluation of the frequency exponent factor, s, derived from the measured ac conductivity data indicated that correlated barrier hopping (CBH) is the most probable conduction mechanism for the present films. The measured dielectric constants and Cole-Cole diagrams are employed in the analysis of the dependence of the dielectric constant on the irradiation dose.

Structural properties, dielectric relaxation, and impedance spectroscopy of NASICON type Na3+xZr2−xPrxSi2PO12${\rm Na}_{3+x} {\rm Zr}_{2-x} {\rm Pr}_{x} {\rm Si}_2 {\rm PO}_{12}$ ceramics

AbstractWe investigate the dielectric and impedance spectroscopic investigation of Pr‐doped NASICON type () samples as a function of temperature and frequency. The Rietveld refinement of X‐ray diffraction patterns confirms the monoclinic phase having C2/c space groups for all the samples. The scanning electron microscopy shows the granular‐like structure and energy dispersive X‐ray analysis confirms the desired compositions. The temperature (90–400 K) and frequency (20 Hz–2 MHz) dependence of electric permittivity are explained using Maxwell–Wagner–Sillars (MWS) polarization and space charge polarization mechanisms. The dielectric relaxation shows nearly equal activation energy for all the samples with a non‐Debye type of relaxation in the measured temperature range. The complex impedance analysis shows the presence of broad grain and grain boundary relaxation peaks. The stretched exponent analysis of electric modulus using the Kohlrausch–Williams–Watts (KWW) function further confirms the non‐Debye type of relaxation. Moreover, scaling analysis of the electric modulus shows a similar type of relaxation for all the samples. The ac conductivity data are fitted using modified power law, where the temperature dependence of exponent () confirms the correlated barrier hopping (CBH) type conduction for all the samples. Our results indicate that the Pr‐doped NASICON samples are potential candidates for charge storage devices due to their large electric permittivity.

Exploring the structural, magnetic, and dielectric properties of Fe and Y substituted NiCr2O4

This paper presents the successful single phase synthesis of NiCr2O4 and NiFe0.50Cr1.50-xYxO4 (x = 0 – 0.08) compounds followed by an investigation into their structural, magnetic and dielectric properties. The structural analysis confirms tetragonal structure for NiCr2O4 while a partially inverse cubic spinel structure for Fe and Y substituted samples (x = 0 – 0.08). Fe substitution (x = 0) induces a shift in room temperature hysteresis loop behaviour from paramagnetic to ferrimagnetic, suggesting enhanced superexchange interactions and a significant rise in magnetic transition temperature beyond room temperature. However, it is found that further inclusion of Y (x = 0.04 – 0.08) leads to a slight weakening of superexchange interactions. The saturation magnetization increases with Y substitution, while coercivity and magnetocrystalline anisotropy follows a decreasing trend. The complex impedance studies unveil a relaxation phenomenon and the dielectric constant is found to increase with the substitution of Fe and Y. Analysis of temperature dependent ac conductivity data and the frequency exponent profile suggests small polaron hopping as the predominant transport mechanism up to 380 K in NiCr2O4 and x = 0 samples, shifting to large polaron hopping beyond this temperature. In samples with x =0.04 and 0.06 the transport mechanism is found to follow the small polaron tunneling model. However, in the x = 0.08 sample, large polaron tunneling becomes predominant beyond 365 K.

Rietveld refined structural, optical and temperature dependent impedance spectroscopy of NiO–ZnO heterostructure composite: Synthesized through solid state method for high-frequency devices

Multifunctional NiO–ZnO heterostructure composite powder is economically synthesized through a solid-state route having a crystallite size of 23 (±2) nm. Chemical composition is identified through FTIR, the peak associated with Zn–O is detected at 1049 cm−1. However, the peaks detected at 870 cm−1 and 590 cm−1 show Ni–O stretching vibrations. UV-DRS technique is employed to estimate the energy band gap (Eg) around 3.18 eV. The impedance studies confirmed the presence of a non-Debye-type relaxation mechanism, electrical parameters confirm the contribution of electroactive regions i.e. grains and interfaces. An equivalent circuit model (R-CPE) is employed to measure various electrical parameters. Adiabatic small polaron hopping model is applied to estimate activation energies for Ni+2 (0.30 eV), Zn+2 (0.35 eV), and bulk (0.32 eV) respectively. The hopping length at the interface is estimated at around 0.8 Å by employing Mott's variable range hopping model. Jonscher's power law (JPL) is used to fit ac conductivity data, and conclude activation energy around 0.3 eV. The conduction mechanism through the whole frequency range (1–107 Hz) is governed by correlated barrier hopping. Various physical parameters i.e. binding energy (Wm), hopping length, and barrier height compared throughout the whole temperature range (313–393 K). The rate of increase in real permittivity at low frequency is related to the disorder of the cation at sublattices. These results deduced potential for NiO–ZnO heterostructure composite for high dielectric permittivity with low tangent loss for high energy storage applications.

Solid state synthesis of lead-free Sm-doped Na0.5Bi4.5Ti4O15 ceramics for enhanced dielectric and electrical properties

Here we report the synthesis of Sm-doped Na0.5Bi4.5Ti4O15 (Na0.5Sm0.5Bi4Ti4O15) lead-free ceramics via a conventional solid-state technique. Investigations of Na0.5Bi4.5Ti4O15 (NBT) and Na0.5Sm0.5Bi4.5Ti4O15 (NSBT) ceramics were demonstrated in detail to understand the composition-based structure-property of Aurivillius compounds and related functional material. Dielectric properties for frequency and temperature in a wide range were analyzed. The conduction activation energy values of NSBT ceramics are obtained to be 1.40 eV, whereas, the NBT ceramics get the value to be 1.31 eV. At higher temperatures, the conduction activation energy value of NSBT ceramics is 1.32 eV for both frequencies of 100 Hz and 1 kHz, whereas, for NBT compounds, the calculated value is 1.27 eV for both frequencies. The simulation performed on the impedance data for capacitive and resistance elements shows well-fitting curves which indicates a single relaxation behavior in the material. Similarly, the AC-conductivity data were analyzed which gives different conduction processes and relaxation activation energies in the NSBT ceramics.

Strong magnetodielectric effect in Bi(La)Fe(Cr)O3 multiferroic nanomaterials

The Bi1-xLaxFe1-yCryO3 (x = 0.00, 0.06; y = 0.00, 0.03, 0.06, 0.09, 0.12) nanomaterials have been synthesized using the simple solvo-thermal technique. The Rietveld refinement of XRD analysis using FullProf Software confirms that all synthesized materials follow rhombohedral perovskite crystal structure of R3C space group. The dielectric and ac conductivity data are analyzed to understand the role of grain and grain boundary contributions. The enhancement of magnetic properties has been observed from SQUID measurement for the co-doped samples at room temperature. Also, a significant improvement in polarization has been observed for the doped nanocompounds from the ferroelectric hysteresis loop. The magneto-dielectric study reveals a large improvement in our co-doped BFO nanomaterials and the value is nearly three times of those reported earlier. The calculated energy storage efficiency for the co-doped samples are found to have as high as 51 %. The sample with x = 0.06 and y = 0.09 with a magneto dielectric coefficient of around 30 % and energy storage efficiency of 35 % is the most suitable for both spintronic and energy storage devices.

Magnetoelectric Properties of Aurivillius-Layered Perovskites

In the present work, we have synthesized rare-earth ion modified Bi4−xRExTi2Fe0.7Co0.3O12−δ (RE = Dy, Sm, La) multiferroic compounds by the conventional solid-state route. Analysis of X-ray diffraction by Rietveld refinement confirmed the formation of a polycrystalline orthorhombic phase. The morphological features revealed a non-uniform, randomly oriented, plate-like grain structure. The peaks evident in the Raman spectra closely corresponded to those of orthorhombic Aurivillius phases. Dielectric studies and impedance measurements were carried out. Asymmetric complex impedance spectra suggested the relaxation of charge carriers belonging to the non-Debye type and controlled by a thermally activated process. Temperature-dependent AC conductivity data showed a change of slope in the vicinity of the phase transition temperature of both magnetic and electrical coupling natures. Based on the universal law and its exponent nature, one can suppose that the conduction process is governed by a small polaron hopping mechanism but significant distortion of TiO6 octahedral. The doping of the A-sites with rare-earth element ions and changes in the concentrations of Fe and Co ions located on the B-sites manifested themselves in saturated magnetic hysteresis loops, indicating competitive interactions between ferroelectric and canted antiferromagnetic spins. The magnetic order in the samples is attributed to pair-wise interactions between adjacent Fe3+–O–Fe3+, Co2+/3+–O–Co3+/2+, and Co2+/3+–O–Fe3+ ions or Dzyaloshinskii–Moriya interactions among magnetic ions in the adjacent sub-lattices. As a result, enhanced magnetoelectric coefficients of 42.4 mV/cm-Oe, 30.3 mV/cm-Oe, and 21.6 mV/cm-Oe for Bi4−xDyxTi2Fe0.7Co0.3O12−δ (DBTFC), Bi4−xLaxTi2Fe0.7Co0.3O12−δ (LBTFC), and Bi4−xSmxTi2Fe0.7Co0.3O12−δ (SBTFC), respectively, have been obtained at lower magnetic fields (<3 kOe). The strong coupling of the Aurivillius compounds observed in this study is beneficial to future multiferroic applications.

Formulation of conductivity, electric modulus and dielectric behaviour of calcium bismuth borovanadate glasses with varying temperature and frequency

This study explores various glass compositions within calcium bismuth borovanadate glass system, produced through melt quenching. The investigation focuses on AC conductivity, electric modulus formulation, and dielectric properties (ε′ and ε″). The AC conductivity and dielectric constants exhibit an increasing trend with rising CaO content until 10 mol%, followed by a decline for x = 15 and x = 20 mol%. Temperature and frequency-dependent conductivity reveal a dual plateau between 423 K and 523 K. The Almond west model is applied to fit AC conductivity data, extracting parameters such as direct current conductivity, crossover frequency, and frequency exponent. The glass samples demonstrate diverse conduction mechanisms, including small polaron quantum mechanical tunnelling and CBH conduction. The activation energy values for direct current conduction (Edc) ranging from 0.539 to 0.716 eV (at lower freq.) and electric modulus (ER) (0.531 to 0.707 eV) is nearly identical. Non-Debye type behaviour is reflected by dielectric studies.

Thermal, structural, and conductivity properties of As14Sb26S(60−x)–(AgI)x chalcogenide glasses

The present work describes the preparation of a new series of chalcogenide glasses in an As14Sb26S(60−x) (AgI)x system intending to explore its thermal, structural, optical, mechanical, and electrical properties. The differential scanning calorimetry results of the studied glasses show the sharp decrease in glass transition temperature (Tg) with the successive incremental inclusion of AgI in the composition, implying the structural changes in the glass network. A thorough Raman analysis corroborates the occurrence of changes in the glass network due to the formation of AsI3 units and Ag–S–As bonds with increasing AgI content. Also, structural changes can be reflected with the change in the optical bandgap (Eg) that was calculated using Tauc equations where it was found that Eg is in harmony with the observed structural variations of glasses. The studied glasses possess a transmittance window (∼0.68–12 μm) with transmittance above 60% in the mid-infrared region. These structural changes are closely related to the significant enhancement of conductivity of the present glasses from 10−8 to 10−6 S/cm at 373 K with a decrease in activation energies. Impedance spectra for the glass with highest AgI revealed the presence of two different relaxation processes. AC conductivity data followed an Arrhenius behavior as well as Jonscher’s power law. The present work provides insights into glass network modifications due to silver iodide inclusion and its role in the enhancement of conductivity.

Structure, dielectric, vibrational, and optical properties of lead-free double perovskite Bi2FeMnO6

The solid-state reaction technique was executed to form a hexagonal double perovskite Bi2FeMnO6 nanopowder. X-ray diffraction (XRD) analysis gives information regarding the product’s average crystallite size of 27.9 nm and lattice strain of 0.00125, respectively. The Ultra-Violet (UV) visible spectroscopy data provides a band gap energy of 2.49 eV, which may be a suitable range for photovoltaic applications. Fourier Transform Infrared (FTIR) spectroscopy data analysis reveals the presence of all constituent atomic vibration bands. The dielectric measurements confirmed the presence of the Maxwell-Wanger type of dispersion. The negative temperature coefficient of resistance (NTCR) character is well understood from impedance spectroscopy. The electrical modulus results indicate the presence of a non-Debye-type of relaxation mechanism in the sample. Analyzing ac conductivity data reveals the thermally activated conduction process. The sample’s semi-conducting character was confirmed by both Nyquist and Cole-Cole plots.

Effect of sodium substitution by yttrium on the structural, dielectric and electrical properties of Ba2Na(1-3x)YxNb5O15 ceramics

The effects of Na+ substitution by Y3+ on the structural, microstructural, dielectric and electrical properties of Ba2Na(1-3x)YxNb5O15 compositions with (x = 0, 0.02 and 0.04) have been studied in detail. The solid solutions of different compositions were prepared by the solid state reaction route method and characterized by X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and Complex Impedance Spectroscopy (CIS) techniques. The XRD study confirmed that all prepared compositions have a single-phase orthorhombic tungsten bronze structure with space group Cmm2 at room temperature. The microstructural studies revealed a grain shape and size change in response to increasing Y3+ concentration. The dielectric properties of the obtained compositions are evaluated over a temperature range of 40–600 °C. The dielectric properties were improved for the Y2O3-substituted Ba2NaNb5O15 compound compared to the undoped Ba2NaNb5O15 compound. The non-Debye type relaxation mechanism is confirmed by the -Z″ versus Z′ traces. The grain contribution was studied using an equivalent electrical circuit with a Resistor R, a Capacitor C, and a Constant-Phase Element CPE in parallel, in the absence of the grain boundary response and the electrode effect in the frequency range 10 Hz-1MHz. The experimental AC conductivity data were evaluated by using Jonscher's power law. The activation energies obtained from the relaxation and conduction processes, present two different regions as a function of temperature related to the two electrical processes for the prepared ceramics.

Effect of Sr doping on electronic transport properties of SnS2 hexagonal nanoplates

In this work, the electronic transport properties of SrxSn1-xS2 (x = 0, 0.02, 0.04, 0.06 and 0.08) nanoplates synthesized by hydrothermal method have been reported. AC conductivity, electric modulus and impedance spectra nanoplates have been studied in frequency and temperature ranging from 1Hz to 1 MHz and 313K–453K, respectively. AC conductivity data of the SrxSn1-xS2 nanoplates obeys the Almond-West relationship. In SrxSn1-xS2 nanoplates conduction governs by overlapping large-polaron tunnelling (OLPT), quantum mechanical tunnelling (QMT) and small polaron quantum mechanical tunnelling (SPQMT) mechanisms for x = 0, x = 0.02 and x = 0.04, 0.06 and 0.08, respectively. A modified KWW model has been used to understand the electric modulus behaviour of SrxSn1-xS2 nanoplates. The observed scaling behaviour of the imaginary component of the electric modulus supports the assertion of frequency exponent (s) with temperature about the conduction mechanism. The Nyquist plots are well-fitted with a double R-CPE model. The activation energy values estimated from conductivity (0.68–0.73 eV) and electric modulus (0.69–0.72 eV) analysis are in coherence.

Investigating the temperature and frequency dependence of dielectric response using AC impedance spectroscopy on SnO2

In this investigation, we explored tin oxide's dielectric properties and impedance spectroscopy, focusing on its temperature dependence across a frequency range of 20 Hz to 2 MHz. We analyzed the x-ray diffraction pattern using Rietveld refinement and established that the sample has a tetragonal phase with P42/mnm space group. Afterward, the surface structure of the SnO2 was examined using (FESEM) and Raman spectroscopy. Through FESEM, we analyzed the morphology of the prepared sample, which were nanospheres in structure. In contrast, we discovered the non-degenerated A1g and B2g modes through Raman spectroscopy, which matches well with the literature and displays the contraction and expansion of Sn-O bonds. We performed dielectric studies at varying frequencies and temperatures to further analyze the properties. We discovered that the ac conductivity increased as temperature and frequency increased. The activation energy was calculated using dc electrical conductivity measurement. The DC conductivity exhibits a temperature dependence that can be described by the Arrhenius equation, which reveals that the tin oxide has to conduct behavior with an estimated activation energy of 0.025 eV, 0.035 eV, and 0.082 eV for three temperature ranges of 80–120 K, 120–175 K, and 175–270 K, respectively. Additionally, the AC conductivity data conforms to Jonscher's universal power law. The frequency-dependent parameter “s” increases as the temperature elevates. A transition from the QMT (Quantum mechanical tunneling) model to NSPT (non-overlapping small polaron tunneling) was employed to analyze the data.

Investigation of AC conductivity and dielectric relaxation of lithium modified zinc borate semiconducting glasses for energy storage applications

Conductivity spectra of (80-x)B2O3.20ZnO.xLi2O (x = 10, 20, 30 and 40) glass series were studied in frequencies ranging from 0.1 Hz to 106 Hz and temperature ranging from 313 K to 573 K. The experimental data of ac conductivity is fitted using the Almond West model, and the parameters such as direct current conductivity (σdc), frequency exponent (s) and crossover frequency (ωH) have been extracted. Overlapping Large Polaron Tunneling is found to be applicable in studied glasses. Activation energy estimated from conductivity (0.89–1.39 eV), electric modulus (0.88–1.32 eV), and impedance (0.89–1.27 eV) analysis are in good agreement. Activation energy corresponding to ionic conduction in x = 30 and 40 mol% is found to be 1.09 and 1.10 eV respectively. Highest conductivity ∼2.5 × 10−5 Scm−1 is obtained for 40B2O3.20ZnO.40Li2O glass composition at 573 K. Impedance formalism indicates that electric conduction occurs via Li+ and electrons/polarons. It makes the studied glasses suitable for energy storage devices.

Lead-free complex double perovskite SrLiFeWO6: Structural, microstructure, electrical and optical study

In this work, synthesis (solid-state reaction) and characterizations (structural, microstructure, dielectric, conductivity, Raman & UV–vis) of a newly prepared lead-free complex perovskite SrLiFeWO6 are reported. Preliminary X-ray diffraction (XRD) analysis suggests a tetragonal phase. The scanning electron microscope (SEM) micrograph and energy dispersive x-ray analysis (EDX) spectrum show the well-grown grains and sample purity. The study of Raman active lines determines the vibrational modes of the constituent molecules in the reported compound. Dispersed dielectric plots were explained by the Maxwell-Wagner polarization effect. The modulus study reveals the presence of a non-Debye type of relaxation. Jonscher's Power Law is fitted in ac conductivity data which follows a correlated barrier hopping mechanism. The direct bandgap energy of the studied sample is found to be 1.68 eV, which may be a good range for photovoltaic applications. For NTC thermistor applications, the analyzed thermistor constant and sensitivity factor are found to be within the permissible range. The idea of ferroelectric nature is opened up by the study of polarization versus electric field. The examination of current density versus electric field reveals that the sample has an ohmic character in the low region and a space charge-limited conduction (SCLC) mechanism in the higher field region.

Experimental Investigation on Electric and Dielectric Properties of Thallium Ions Doped Sodium Zinc Phosphate Glass

Sodium zinc phosphate glasses modified by Tl2O addition of composition Na2−xTlxZnP2O7 (x = 0, 0.005, 0.01, and 0.015) are synthesized following the melt quenching technique. The structure of the glass samples is analyzed by the Fourier transform infrared absorption spectroscopy. The results suggest that the phosphate network is polymerized by the addition of Tl+ ions. The electrical conductivity, electric modulus, and dielectric constant characteristics of the glasses are measured over a wide continuous frequency range of 10−2 Hz–1 MHz and in the temperature range 293–473 K by the impedance spectroscopic method. The ac conductivity data are analyzed following the power law exponent (S) and the proposed correlated barrier hopping mechanism (CBH) is the most suitable conduction mechanism in the studied compositions. The electrical modulus formalism is applied to analyze the electric data to study their dielectric relaxation. Non‐Debye type relaxation is obtained. From the obtained results, the present glass can be used as a high‐energy capacitor.

Conduction mechanism in hot-pressed Poly(vinylidene fluoride)/Graphene Oxide composites

Poly(vinylidene fluoride)/Graphene Oxide (PVDF/GO) composites were prepared by solvent casting and processed by hot pressing. Filler GO is synthesized by the improved Hummers method and purified by centrifuging. GO is characterized by XRD, FTIR, RAMAN, SEM, and TEM. XRD, FTIR, and DSC techniques were employed to characterize composites. AC conductivity data of PVDF and PVDF/GO composites with varying GO content were fitted with Jonscher’s power law at different temperatures, and the obtained DC conductivity was used to find the activation energy of the samples. The frequency exponent in power law is analyzed to identify the conduction mechanism in the composites. The frequency and temperature dependence of the exponent value and the nature of the frequency exponent with temperature confirm the overlapping large polaron tunneling as the responsible mechanism of conduction in PVDF/GO composites.

Structural study and temperature dependent relaxation and conduction mechanism of orthorhombic tungsten bronze Ba4La28/3(Zr0.05Ti0.95)18O54 ceramic

In this study, the Ba4La28/3(Zr0.05Ti0.95)18O54 ceramic was prepared using the solid-state technique. The X-ray diffraction technique was used in this study to investigate the Ba/La order in the solid solution Ba4La28/3(Zr0.05Ti0.95)18O54. We have developed a structural model, to represent the order within the structure. The formula of model [Ba4−a□a]A2[La8+2b3□2−2b3]A1,A1′(Zr0.05Ti0.95)18O54 is described as perovskite layers with a thickness of 3 octahedral parallel to the xOz plane. Scanning electron microscopy (SEM) showed that Ba4La28/3(Zr0.05Ti0.95)18O54 ceramic exhibits a typical columnar grain with a heterogeneous distribution over the entire surface. Complex impedance spectroscopy was used to analyze the dielectric and electrical properties of Ba4La28/3(Zr0.05Ti0.95)18O54 materials over a frequency range of 10 Hz to 1 MHz and a temperature range of 350°C to 400°C. An appropriate equivalent electrical circuit was also used to investigate the contributions of grains and grain boundaries. The AC-conductivity data was analyzed using Jonscher's universal power law. The thermal behavior of the exponent parameter "s" indicates that the dominant conduction mechanism in our compound is the non-overlapping small polaron tunneling (NSPT) model. The activation energies calculated from the conduction and relaxation mechanisms are nearly identical for the Ba4La28/3(Zr0.05Ti0.95)18O54 ceramic.