Electric Modulus Spectroscopy Research Articles

Investigation of structural, dielectric and optical properties of the (Bi0.5La0.5Fe)0.5(Bi0.5Na0.5Ti)0.5O3perovskite for some electronic devices

This paper outlines the investigation of structural, dielectric, complex impedance and optical properties of lanthanum-modified (Bi[Formula: see text]La[Formula: see text]Fe)[Formula: see text](Bi[Formula: see text]Na[Formula: see text]Ti)[Formula: see text]O3 (BLF–BNT) single perovskite oxide synthesized by conventional solid-state reaction method. From Rietveld refinement, the crystal structure of the BLF–BNT ceramic has confirmed a tetragonal and the estimated average crystallite size is found to be 43.6[Formula: see text]nm. The dielectric properties of the La-doped BLF–BNT ceramic reveal the presence of Maxwell–Wagner-type dielectric dispersion. This suggests the occurrence of charge accumulation at grain boundaries and interfaces within the material. The complex impedance and complex electric modulus studies were employed to gain insight into the microscopic dielectric relaxations and conduction processes of the material. The electric modulus spectroscopy reveals the existence of nonDebye-type relaxation processes, including localized and long-range relaxation processes. The Nyquist and Cole–Cole plots show the semiconducting nature of the BLF–BNT ceramic. With the help of the Arrhenius method based on the imaginary portion of the electrical impedance and modulus, activation energies and relaxation times have been estimated. These parameters contribute to a deeper understanding of the electrical properties and conduction mechanisms within the material. Further, Raman spectroscopy, a nondestructive chemical analysis technique, was conducted to confirm the composition and structural integrity of the proposed system through its atomic vibrations. Also, the bandgap energy of the material has been estimated using Tauc’s relation and is found to be 1.69[Formula: see text]eV. This signifies that the BLF–BNT ceramic possesses a suitable bandgap for certain device applications, making it a promising candidate in various technological fields. Moreover, the overall comprehensive study of the proposed ceramic provides valuable insight and opens new possibilities for its potential applications in various electronic devices.

Dielectric relaxation studies in Sm2O3 doped boro-zinc-vanadate glasses

In this work, the conventional melting procedure was adopted to synthesize glasses with a composition of (ZnO)0.3 – (V2O5)0.3 – (B2O3)0.4-x – (Sm2O3)x, x = 0.002, 0.005, 0.007, 0.01 and 0.02 mol%. The dielectric properties of these glasses were measured. The dielectric constant (εʹ) and dielectric loss (εʹʹ) of glasses are found to vary in the range from 1.9177x102 to 3.9456x103 and from 1.5751 to 6.9095x105 respectively for the temperature range 343 K – 573 K and frequency range 50 Hz to 10 MHz. With increase of frequency, both dielectric constant and loss decreased and increased with increase of temperature. The analysis of dielectric constant and dielectric loss confirmed that the phenomenon of dielectric relaxation is mainly due to the frequency-dependent polarization mechanism. Electric modulus and impedence spectroscopy revealed non-Debye type and a single phase relaxation process. Activation energy for dc conductivity and dielectric relaxation are found to be of same size indicating that the potential barrier encountered by the charge carriers is same in both the processes. The master curves suggested that temperature-independent relaxation is occurring in the present glasses. The high values of measured dielectric parameters suggest that the present glasses are suitable in semiconducting and energy storage applications.

SnS/MnSe heterostructures for enhanced optoelectronics and dielectric applications.

In this work, we synthesized SnS and MnSe compositions using a hydrothermal method and then prepared the SnS/MnSe heterostructure. By using X-ray diffraction, the structural characteristics of these compounds were examined. It was discovered that both the pure phases MnSe and SnS appeared in the SnS/MnSe sample, confirming the heterostructure formation. The Raman analysis also confirmed the formation of a heterostructure of the SnS/MnSe sample containing two phases, MnSe and SnS. The individual MnSe and SnS compositions show good optical properties, having bandgap values around 1.3 and 1 eV, respectively, whereas the prepared heterostructure shows a very low bandgap value of around 0.4 eV. The SnS sample shows nano sheet-like morphology, and MnSe shows rectangular-like shapes, whereas the SnS/MnSe heterostructure shows the presence of both shapes. The EDX study shows all the constituent elements in the SnS/MnSe heterostructure sample. The electrical study also shows that the properties of the prepared heterostructure are different from those of pure compositions. Investigating the dielectric characteristics with respect to temperature and frequency allowed for a thorough analysis of several parameters, including the electric modulus, dielectric constant, AC conductivity, and impedance spectroscopy. Applications for electronic and energy storage devices may benefit from the aforementioned optical, electrical, and dielectric characteristics of the SnS/MnSe heterostructure.

Sol–gel synthesized (Bi0.5Ba0.5Ag)0.5 (NiMn)0.5O3 perovskite ceramic: An exploration of its structural characteristics, dielectric properties and electrical conductivity

This manuscript delves into the multifaceted exploration of the perovskite ceramic (Bi0.5Ba0.5Ag)0.5(NiMn)0.5O3, synthesized via the sol-gel technique. Unveiling the structural, morphological, dielectric, and electrical facets, the material's orthorhombic structure, affirmed through Rietveld-refined XRD data, showcases an average crystallite size of approximately 33 nm. Dielectric investigations illuminate the presence of Maxwell-Wagner-type dispersion, hinting at charge accumulation along grain boundaries and interfaces. Employing complex impedance and electric modulus analyses reveals microscopic dielectric relaxation intricacies and the material's conduction mechanisms. Electric modulus spectroscopy uncovers non-Debye-type relaxation, encompassing both localized and long-range processes. Nyquist plots attest to the ceramic's semiconducting nature. Applying the Arrhenius law to the imaginary part of electrical impedance and conductivity yields activation energies and relaxation times, significantly enriching our understanding of the material's electrical properties. This comprehensive scrutiny unravels the ceramic's potential applications, offering fresh insights for diverse device implementations.

Fast Na+ ion dynamics in the Nb5+ bearing NaSICON Na3+x−zNbzZr2−zSi2+xP1−xO12 as probed by 23Na NMR and conductivity spectroscopy

NaSICON-type (Na superionic conductor, Na1+yZr2SiyP3−yO12, 0 < y < 3) represent a class of fast Na+ ion conductors with bulk ion conductivities in the mS range near room temperature. Starting from Na3Zr2(SiO4)2(PO4), i.e., from y = 2, we investigated the change in ion transport parameter when x in Na3+xZr2Si2+xP1−xO12 is increased from 0 to 0.4 and Nb5+ is substituted for Zr4+ according to Na3+x−zNbzZr2−zSi2+xP1−xO12 (z = 0.04). The later might be beneficial also to change the transport properties in or near the grain boundary regions of our polycrystalline samples. To detect such changes, we used low-temperature conductivity and electric modulus spectroscopy to differentiate between the total and the bulk (intragrain) electrical responses. However, the main purpose of the present study is to corroborate the extraordinarily high bulk ionic conductivity of approximately 7.3 mS cm−1 (x = 0.4 and z = 0.04, room temperature) by diffusion-controlled 23Na NMR spin-lattice relaxation measurements. Indeed, such experiments directly sense the 23Na spin-fluctuations at the nuclear sites as a result of the fast intragrain motional processes. Both methods, nuclear and non-nuclear, point to a mean activation energy of 0.3 eV for Na+ exchange among the multiple sites in the NaSICON framework. In addition, NMR reveals local barriers characterized by activation energies as low as 0.1 eV. Altogether, from a dynamic point of view, Na3.36Nb0.04Zr1.96Si2.4P0.6O12 turned out to be indeed a very promising candidate for the breakneck development of Na-based all-solid-state battery applications.

Fluoride ion dynamics in nanocrystalline α-PbF2: On the tremendous impact of structural disorder on F− anion hopping in poor ion conductors

PbF2 has already been the subject of one of Michael Faraday's experiments that played the crucial part in the discovery of fast F− anion transport in solids. In contrast to the cubic form of PbF2, ion dynamics in orthorhombic modification, that is, α-PbF2, is rather poor at ambient conditions. Its complex crystal structure hosts two magnetically inequivalent F sites (F1 and F2), which makes it, however, a rather interesting model substance to study fundamental aspects of ion transport. Here, to contribute to a general understanding of ion dynamics in compounds crystallizing with PbCl2 (cotunnite) structure, we studied the influence of structural disorder on ion dynamics in nominally pure α-PbF2. We expect that this approach will help us to understand also the hopping mechanisms in ordered PbF2. Broadband conductivity spectroscopy and electric modulus spectroscopy showed that disorder causes the F− anion conductivity of α-PbF2 to increase by a factor of 100. In excellent agreement with this result, atomic-scale 19F high-resolution NMR spectroscopy reveals a clear increase in F1-F2 exchange shedding, at the same time, light on a controversial discussion how to interpret the 19F MAS NMR spectra of α-PbF2 in detail. In addition, a quantitative analysis of long-range ion transport is provided by broadband conductivity measurements. We show that F− anion dynamics in nanocrystalline PbF2 has to be described by an activation energy of 0.48 eV, which is significantly lower than that found for the mechanically untreated sample (0.6 eV at T > 300 K). This change in ion dynamics is reflected also by time-domain 19F NMR spectroscopy pointing to local activation barriers with values ranging from 0.17 eV to 0.31 eV in nanocrystalline α-PbF2. NMR line shape measurements indicate that the F1 site, in particular, plays an important role in overall anion exchange in the nanostructured form.

Onset of vacancy-mediated high activation energy leads to large ionic conductivity in two-dimensional layered Cs2PbI2Cl2 Ruddlesden-Popper halide perovskite

We report the dielectric properties of a two-dimensional layered Ruddlesden-Popper halide perovskite ${\mathrm{Cs}}_{2}{\mathrm{PbI}}_{2}{\mathrm{Cl}}_{2}$ synthesized via a simple mechanochemical process to explore fundamental aspects of ionic conduction and relaxation mechanism over a wide temperature and frequency range. Several experimental techniques, such as complex impedance spectroscopy, alternating current (AC) conductivity spectroscopy, and complex electric modulus spectroscopy, have been employed to investigate the nuances of ionic conduction and relaxation mechanisms, and the results have been corroborated using different theoretical models, such as the Maxwell-Wagner equivalent circuit model, the modified Jonscher power law, the Havrilliak-Negami (HN), and the Kohlrausch-Williams-Watts (KWW) model. The contribution of the grains and grain boundaries to the total impedance in the system is estimated by the analysis of the Nyquist plots. In temperature-dependent AC conductivity spectra, a critical temperature (413 K) is observed, beyond which the conductivity increases abruptly. This critical temperature also defines two distinct temperature ranges: the low-temperature (303--413 K) and the high-temperature (423--463 K) regimes, where the ionic transport mechanism switches from the normal ionic transport to a vacancy-mediated ionic transport mechanism. A substantially high activation energy $\ensuremath{\sim}1.82\phantom{\rule{0.16em}{0ex}}(\ifmmode\pm\else\textpm\fi{}0.02)\phantom{\rule{0.28em}{0ex}}\mathrm{eV}$ is calculated from the Arrhenius plot of the ionic conductivity in the high-temperature region, while at the low-temperature region, the activation energy is found to be $\ensuremath{\sim}0.48\phantom{\rule{0.28em}{0ex}}(\ifmmode\pm\else\textpm\fi{}0.02)\phantom{\rule{0.28em}{0ex}}\mathrm{eV}$. The abrupt jump in the ionic conductivity beyond the critical temperature is attributed to the onset of the anionic vacancy-mediated enhanced ionic conductivity. Polaronic models have been used to interpret the AC conductivity and its power-law exponent. The activation energy obtained from ionic conductivity measurements is consistent with those calculated from relaxation time using the HN and KWW models. The presence of two master curves in time-temperature superposition scaling of AC conductivity and modulus loss spectra specifies the validity of two different conduction mechanisms.

Electrical conductivity and relaxation phenomena in Li2O·B2O3 based glass and glass-ceramic: A comprehensive and comparative analysis

This work reports a detailed investigation on the electrical conductivity and dielectric relaxation phenomena in Li2O·B2O3 based glass and glass-ceramic materials. Measurements reveal that the electrical conductivity of glass-ceramic is lower than glass. This owes to occurrence of grain boundaries which impede the mobility of charge carriers in glass-ceramic as confirmed by FESEM micrographs. The frequency-dependent behavior of electrical conductivity, within the measured temperature range, is analysed using Jonscher's power law. It is found that the conductivity rises with an increase in temperature and the range of conductivity reveals the semiconducting behavior of the material. The ac conductivity mechanism of system is observed to follow the overlapping large polaron tunneling model. The conduction and relaxation mechanism studies are performed using electric modulus and impedance spectroscopy within the frequency and temperature ranges varied from 103 Hz to 107 Hz and 593 K–773 K, respectively. Analysis of the relaxation mechanism in both samples is performed employing Kohlrausch-William-Watts (KWW) model, which reveals that the charge carriers are following non-Debye type relaxation. To distinguish between the contribution of grain boundaries and grains in the relaxation mechanism, a combined analysis of complex electric module and impedance spectroscopy has been discussed.

Crystal structure and dielectric properties of the Ca/Y co-substituted BaTiO3

Ba0.95Ca0.05Ti0.97Y0.04O3 solid solution has been fabricated by solid state method to investigate physical properties. The X-ray diffraction characterization at room temperature (RT) indicated that single-phase perovskite was obtained and no appreciable secondary phase was found. XRD analysis revealed that the desired main phase of our sample crystallizes in a cubic phase with (Pm 3¯ m) space group. The SEM image proves that the material is dense with high crystallinity and the particle size of the grains is 710 nm. The DC-conductivity enhances significantly with temperature confirmed that our sample has a semiconductor behavior. The electric modulus spectroscopy results discerned a thermally activated relaxation allocated to the phenomenon of space charge relaxation of the Maxwell-Wagner (M−W) type and the non Debye relaxation processes. The experimental results indicate that (ε) and the dissipation factor reduced along the rising in frequency. The demeanor observed can be clarified by extrinsic Maxwell-Wagner effects answerable for the electric conduction.

Bismuth pyrochlores with varying Fe/Co ratio for efficient Multi-functional Catalysis: Structure evolution versus Photo- and Electro-catalytic activities

Bismuth pyrochlores that the crystal structure tolerates lower site misplacements and higher vacancy concentrations exhibit unique stereo-chemical activity, therefore, the manipulation of the property by structural engineering has driven significant research activity, with the goal of realizing their transformative functional potential. Herein, an excellent platform to investigate the role of the strucutre in tuning catalytic activity is provided by varying Fe/Co ratio in a bismuth niobate pyrochlore oxide. Continuous Co-level from 0 to 100% was ingeniously designed on the basis of special phase diagrams and pryocholore-type pure samples were successfully fabricated by a modified sol–gel auto-combustion method. The effect of structural modulation on dielectric property and multi-functional catalytic activities were studied. Significantly, two opposing strucutral shifts were observed with increasing the Co-level, ascribled to the competition between displacive disorders on the Bi sites and strucutral distortions in the octahedral network. Tunable dielectric relaxation was exhibited by electrical modulus spectroscopy and one additional hidden relaxation process implies an outstanding thermal motion of electrons from variable oxidation states of Fe3+/ Co2+ ions when ionized oxygen vacancy becomes weak. For photocatalysis, the low-level Co showed a best visible-light-responsive photocatalytic activity by means of the RhB-dye decomposition, while the high-level Co exhibited a higher photoinduced current density. For electrocatalysis, the sample that maintains its structure with the coexistence of massive oxygen vacancies and low-spin-state Co2+ present a superior oxygen evolution reaction (OER) activity, with a lower OER overpotential (∼300 mV at 10 mA/cm2) and a smaller Tafel slope (∼70 mV/dec). Moreover, the underlying mechanism of the improved performances was analyzed in detail and the new insights were provied for constructing single-phase multi-functioning catalysts.

Optical, dielectric and electrical properties of Gd3+ ions doped barium hexaferrite ceramic compounds for microwave device applications

The present work reports synthesis, optical, dielectric and electrical properties of M-type BaFe12−xGdxO19 (x = 0, 1, 1.25, 1.5, 1.75 and 2 mol%) ceramics. Auto combustion synthesis technique was applied for the preparation of the ceramics. Structural analysis was done using PXRD patterns which confirms the hexagonal structure of prepared ceramics. The average particle size of the prepared samples was found to be 25.29 nm and the lattices parameters 'a' and 'c' values ranges from 5.8864 Å to 5.9282 Å and 23.2135–23.3981 Å respectively. UV-Visible spectroscopy and Photoluminescence (PL) analysis were used to investigate the optical characteristics of the prepared samples. The PL emission spectra show that the emission peaks were observed at 689 nm due to the optical transition 6GJ to 6PJ emission. The direct band gap (Eg) of BaFe12O19 is 4.07 eV and Eg value decreases from 4.07 eV to 3.92 eV with substitution of Gd3+ ions. The indirect band gap value also decreases with Gd3+ substitution. The electrical properties were investigated through CIS (complex impedance spectroscopy), EMS (electrical modulus spectroscopy), ac-conductivity and dielectric studies. The dielectric behavior of the samples is explained by Maxwell- Wagner’s two-layer model. NTCR behavior of the prepared powder samples are confirmed from CIS studies. The ac-conductivity studies follow the universal power law. By the substitution of Gd3+ ions, the dielectric constant value increases up to four times and value of dielectric loss decreases by four times, so the BaFe12−xGdxO19 samples can be used in various microwave devices.

Phase structure refinement, electric modulus spectroscopy, Urbach energy analysis, and magnetic properties of Ce3+–Ni2+-substituted Y-type barium hexaferrites

In this work, the influence of Ce3+–Ni2+ substitution on the properties of sol-gel–synthesized Y-type hexaferrites with the following chemical composition is investigated: Ba2-xCexZn0.7Co0.7Cu0.6Fe12-yNiyO22 (x = 0.0, 0.4, and 0.6; y = 0.0, 0.5, and 0.7). X-ray diffraction analysis reveals the presence of a few NiFe2O4 and Fe3O4 secondary phases in the substituted samples (M2 and M3). The Fourier-transform infrared bands at 430, 543, and 582 cm−1 are characteristic bands of iron-oxides, which indicate the vibrations of the octahedral and tetrahedral sites in the S-block of the Y-type hexaferrite. The morphology analysis reveals agglomerated grains, which were generated by weak Van der Waals force and magnetic interaction. The optical analysis reveals the presence of an Urbach energy tail. The electrical properties were investigated based on the Maxwell–Wagner two-layer model and Koop’s phenomenological theory. Increase in the magnetization is observed by substituting Fe3+ with Ni2+ and was studied according to the ligand-field theory.

Efficient Charge Storage Capability of BiFeO3-Based Bi-Phase Nanocomposites

Here, we report a facile synthesis of bi-phase nanocomposites of the form (1−x)BiFeO3−xPbTiO3 for their efficient utilization in modern day energy storage gadgets. X-ray diffraction confirmed the distorted rhombohedral structure of pure BiFeO3 while PbTiO3 exhibited tetragonal structure and hence confirmed the formation of nanocomposites. Morphological analysis revealed the reduction in particle size, improvement in bulk density and decrease in porosity with the increase of PbTiO3 contents. A wide dispersion in dielectric response was explained on the basis of Maxwell-Wagner model. A significant improvement in dielectric behavior was observed when PbTiO3 was added in the composite. The contribution of grains and grain boundaries in the electrical response of these composites was witnessed through impedance analysis. The nature of charge transport mechanism was established using electric modulus spectroscopy. These kinds of nanocomposites are recommended for the improvement of data storage capacity of devices as compared with phase-pure compounds.

Structural, capacitive and resistive characteristics of (Pb0.6Bi0.2Sm0.2)(Fe0.4Ti0.6)O3

Samarium substituted BiFeO3–PbTiO3 ceramic compound of (Pb0.6 Sm0.2 Bi0.2)(Fe0.4Ti0.6)O3 has been fabricated by mixed oxide solid state reaction method. The crystallographic structure from XRD study, distribution of grains from SEM micrograph, dielectric behavior, conductivity spectrum, impedance along with electric modulus spectroscopy have been illustrated. The experimental results corroborate the impact of samarium substitution in BiFeO3–PbTiO3 entailing reduced grain size, higher dielectric response with reasonably dielectric loss and enrichment in capacitive behavior with negative temperature coefficient of resistance. The temperature dependent conductivity spectra exhibit Arrhenius behavior, whereas the frequency dependent conductivity spectra follow the Jonscher universal power law. The basic correlated barrier hopping (CBH) model governs the charge transport mechanism in the fabricated compound. The exploration reveals the enriched dielectric and electrical behavior that endorse the samarium substituted material as a potential ceramic entity for designing electronic devices such as capacitors and ferroelectric accessories.

F anion transport in nanocrystalline SmF3 and in mechanosynthesized, vacancy-rich Sm1—x BaxF3—x

Abstract Nanostructured materials can show considerably different properties as compared to their coarse-grained counterparts. Especially prepared by high-energy ball milling they are to be characterized by a large fraction of point defects in the bulk and structurally disordered interfacial regions. Here, we explored how the overall conductivity of SmF3 can be enhanced by mechanical treatment and to which degree aliovalent substitution is able to further enhance anion transport. For this purpose nanocrystalline (hexagonal) SmF3 was prepared by high-energy ball milling; mechanosynthesis helped us to replace Sm3+ in SmF3 by Ba2+ and to create vacancies in the F anion sublattice. We observed a remarkable increase in total (direct current) conductivity when going from nano-SmF3 to Sm1−x Ba x F3−x for x = 0.1. Electrical modulus spectroscopy was used to further characterize the corresponding increase in electrical relaxation frequencies.

Impedance and Electric Modulus Spectroscopy of Polycrystalline La0.5Sr0.5Bi0.2Co0.4Fe0.4O3–d Cathode Ceramic for Intermediate Temperature SOFCs

In the present research work, La 0.5 Sr 0.5 Bi 0.2 Co 0 . 4 Fe 0.4 O 3– d cathode ceramic powder is synthesized through cost-effective flash pyrolysis process and further conventional heat treatment for sintering for IT-SOFCs. The crystal structure, unit cell parameters and bond length are determined by using the Rietveld refinement program. The XRD result indicates existence of a pure single phase with R C space group symmetry detected from the sample which has been sintered at 700 ℃. SEM images of fracture surface of sample sintered at 700 ℃ showed a high porosity and nano grain sizes (50-100 nm). Impedance and electric modulus spectroscopic methods are used to identify the relaxation phenomena in La 0.5 Sr 0.5 Bi 0.2 Co 0 . 4 Fe 0.4 O 3– d ceramic over a broad range of temperature and frequency. A single relaxation peak is observed in the imaginary part of impedance and electric modulus spectra, which could be due to the contribution of grain boundary of La 0.5 Sr 0.5 Bi 0.2 Co 0 . 4 Fe 0.4 O 3– d ceramic. The imaginary part of modulus ( ) spectra is analyzed with help of non-exponential decay function or Kohlrausch–Williams–Watts (KWW) parameter ( β ). In the combined plot of the imaginary part of impedance and electric modulus spectra at 210 ℃, only a single peak of and is observed at the same frequency which indicates that the conduction process is a long-range motion of the charge carriers. The frequency-dependent conductivity is followed by the Jonscher’s double power law in the temperature range 30-210 ℃.

Dielectric properties of A-site Mn-doped bismuth sodium titanate perovskite: (Bi0·5Na0.5)0.9Mn0·1TiO3

We synthesized A-site Mn-doped Bi0·5Na0·5TiO3 polycrystalline ceramic ((Bi0·5Na0.5)0.9Mn0·1TiO3 ceramic (BNMT10)) via solid-state reaction route and investigated the structural and temperature-dependent dielectric properties. The dielectric properties of the synthesized samples are explained using the brick-layer model. The relaxation time and corresponding activation energies were obtained through the Arrhenius mechanism by using the imaginary impedance and modulus results. Analysis of the activation energy and other dielectric results suggests that the electric conduction in our BNMT10 sample is due to single and doubly charged oxygen ion vacancy-defects at low and high temperatures, respectively. The grains and grain boundaries contribute to the inherent defect-based conduction mechanism and the dielectric behavior. The electric modulus spectroscopy results discerned the non-Debye type relaxation processes that these processes consist of the localized and long-range relaxation processes. Our results demonstrate that the dielectric behavior of Bi0·5Na0·5TiO3 ceramics can be enhanced through Mn-doping at the A-site.

Investigation of electrical conduction in Ca6-xNa2Y2(SiO4)6F2:xEu3+ ceramic by complex impedance and electric modulus spectroscopy

The electrical conduction mechanism of Ca6-xNa2Y2(SiO4)6F2:xEu3+ fluorapatite ceramic with (x = 0–0.05 mol%) synthesized by solution combustion method has been investigated by dielectric, complex impedance and electric modulus spectroscopy. Microstructural analysis was carried out by scanning electron microscopy (SEM) which shows that the spheroidal and ellipsoidal grains were distributed uniformly in the prepared ceramic with average grain size of the order of 3 μm. The electrical and dielectric studies of the ceramic were done in the frequency range of 100 Hz–100 KHz and temperature range of 50 °C–500 °C. The temperature and frequency dependent dielectric loss and dielectric constant decreases with an increase in frequency due to the ceasing effect of polarization. Dielectric relaxation behaviour of the prepared ceramics were studied using Complex impedance spectroscopy (CIS). Nyquist plots show that with increase in Eu3+ ion concentration the resistance of grains and grain boundaries decreases for the prepared ceramics. The investigation of charge transport phenomena was done by electric modulus spectroscopy. The drastic increase in a. c conductivity with increase in temperature shows that the ceramic follow the Jonscher’s power law and appear Debye in nature.

Investigation of relaxation phenomenon in lanthanum orthoferrite extracted through complex impedance and electric modulus spectroscopy

Impedance and electric modulus spectroscopy is exploited over a broad frequency and temperature range to find the relaxation phenomenon in LaFeO3 (LFO), which otherwise was concealed by the dc conductivity in dielectric ɛ*(ω) representation. The impedance measurements and the ac resistivity determined from Z′(ω) indicate that LFO is an insulator at room temperature and divulges the negative temperature coefficient of resistance. At higher temperatures, capacitive behavior flips to inductive behavior. The ac resistivity is exploited to determine the activation energy using the Arrhenius model. The relaxation peaks appear in the imaginary parts of electric modulus [M*(ω)] and impedance [Z(ω)], which have been exploited to determine the activation energy. The single distorted semicircle in the Nyquist and complex plots of electric modulus is evidence of the contribution of grains in the conduction process. At higher temperatures, data corresponding to the grain interior transform from an arc to a line with an intercept on the Z′(ω) axis and is parallel to the imaginary axis Z″(ω). Relaxation times calculated from the imaginary parts of impedance and electric modulus fit well in accordance with the Arrhenius law. Electron hopping, hole hopping, and oxygen vacancies play an important role in the dielectric response of grains. The relaxation frequencies of Z″(ω) and M″(ω) follow the sequence of scaling of magnitude of relaxation frequencies, i.e., fz′′≤fM′′. The separation of relaxation peaks of M″(ω) and Z″(ω) are indicative of a localized conduction process. The Giuntini law is applied to determine the hopping energies of charge carriers.

Electrical, Dielectric Property and Electrochemical Performances of Plasticized Silver Ion-Conducting Chitosan-Based Polymer Nanocomposites.

In the present work, chitosan (CS) as a natural biopolymer was used to prepare nanocomposite polymer electrolytes (NCPEs) in order to reduce plastic waste pollution. The plasticized CS-based NCSPE has been prepared via the solution casting technique. The electrical properties of the films were investigated using AC conductivity, dielectric properties, electric modulus, and electrical impedance spectroscopy (EIS). The obtained results from the dielectric properties and electric modulus study confirm the non-Debye behavior of ion dynamics. The effect of glycerol plasticizer on ionic conductivity of the CS:AgNO3:Al2O3 system was investigated via AC conductivity and impedance studies. The conductivity of the samples was explained based on electrical equivalent circuits and Bode plots. The electrochemical properties such as transfer number measurement (TNM), linear sweep voltammetry (LSV), and cyclic voltammetry (CV) were carried out to inspect the sample suitability for electrochemical double-layer capacitor (EDLC) application. The highest conductivity was 3.7 × 10−4 S cm−1 with the electrochemical stability window up to 2.1 V at room temperature. Through the TNM study, the ionic conductivity of plasticized CS-based NCSPE was confirmed, and ion transport (tion) of the highest conducting sample was found to be 0.985. The activated carbon electrode with the highest conducting sample was employed in the EDLC device fabrication. Accordingly, it can be said that the highest conducting sample had capable performance to be applied in electrochemical device application.