Modulus Spectroscopy Research Articles

Impedance spectroscopy and transport properties of polymer-based flexible nanocomposites

The flexible nanocomposites of bismuth ferrite and polyvinylidene fluoride were prepared by the solution casting method. The X-ray diffraction technique confirms the presence of both the inorganic filler (bismuth ferrite) and polymer phases. Atomic force microscopy study shows the increasing values of root mean square (RMS) roughness in the nanocomposites. The modulus and impedance spectroscopy were performed to get insight contribution of grains, grain boundaries, and interfaces on the electrical properties. From the Nyquist plot analysis, grains effect is dominant over the grain boundaries and non-Debye type relaxation behavior is observed for the nanocomposites. Correlated barrier hopping (CBH) model is the most suitable model to explain the transport properties of the charge carriers. The hopping distance increases from 8.11 Å to 27.25 Å with increasing the content of inorganic fillers in the nanocomposites. The presence of the different conduction processes at various temperature regions is explained by the Arrhenius plot analysis.

Development of chemically synthesized lead-free double perovskite compound: BiBaFeCeO6

In this communication, preliminary structural and detailed electrical (impedance, and conductivity) along with multiferroic (ferroelectric and ferromagnetisc) characteristics of a cost effective chemically processed double perovskite compound, BiBaFeCeO6, have been reported. By analyzing the X-ray diffraction data, the orthorhombic crystal structure of the compound with a single-phase characteristic is obtained. Combining the two simple perovskite materials, BiFeO3 with BaCeO3, in equal ratio produces a new double perovskite compound BibaFeCeO6 with the enhanced dielectric constant (as compared to that of individual perovskite). The shift in the dielectric peak and increase of peak broadening with increase in frequency suggest the existence of relaxation process and relaxor characterizes in the studied compound. The variation of the characteristic of dc conductivity with temperature displays the presence of semiconductor (negative temperature coefficient of resistance) behavior in the compound. Analysis of frequency dependence of ac conductivity data shows that the studied compound obeys the Jonscher’s universal power law. The analysis of complex impedance and modulus spectroscopy data exhibits the non-Debye type of relaxation mechanisms in the compound. The multiferroicity in the compound has been confirmed from the P–E, M–H hysteresis loop and M–E coupling characteristics.

Effect of annealing temperature on the structural, dielectric and electric properties of $$\hbox {Ni}_{{0.7}} \hbox {Cd}_{0.3}\hbox {Fe}_{2}\hbox {O}_{4}$$ ferrites

A composition of Ni $$_{{0.7}}\hbox {Cd}_{{0.3}}\hbox {Fe}_{{2}}\hbox {O}_{{4}}$$ (NCF) ferrite nanoparticles was synthesized by a sol–gel auto-combustion technique. The particles in powder form were annealed at 550 and 700 $$^{\circ }\hbox {C}$$ to study the structural, dielectric and electric properties of NCF by using X-ray diffraction (XRD), field emission scanning electron microscopy, impedance and modulus spectroscopy. XRD patterns confirmed the single phase cubic spinel structure of the sample. The average crystallite size of NCF was found to be 17 nm at 550 $$^{\circ }\hbox {C}$$ and 31 nm at 700 $$^{\circ }\hbox {C}$$ , respectively. The variation in complex dielectric constant, loss tangent and impedance along with the modulus properties of NCF with frequencies was observed at room temperature because of their size and annealing temperature. Notably, dielectric dispersion of the materials was observed at low frequencies because of Maxwell–Wagner interfacial polarization. The impedance and modulus spectroscopy were used to investigate the electric properties of the materials, which revealed the increase in grain and grain boundary resistance with annealing temperature. A non-Debye type of relaxation in the materials was evidenced through the Cole–Cole study of impedance and modulus spectra.

Frequency- and temperature-dependent dielectric features of multi-component electronic material: (Pb0.8Dy0.1Bi0.1)(Fe0.2Ti0.8)O3

A multiple cation containing sample as [(Pb0.8Dy0.1Bi0.1)(Fe0.2Ti0.8)O3] is fabricated by adopting the solid-state reaction process. The crystallographic structure, crystallite size, morphology, dielectric behavior, conductivity, polarization, impedance as well as electric modulus spectroscopy are experimentally observed for this fabricated composition. The crystal structure of the specimen is observed to be tetragonal from X-ray diffraction. The micrograph shows the presence of polycrystalline microstructure with uniform distributed grains. The impedance spectroscopy analysis as a function of temperature (100–450 °C) and frequency (1–1000 kHz) helps to signify the resistive and capacitive behavior of the compound. The nature of the prepared specimen and conduction mechanism is illustrated through AC conductivity study. The modulus analysis elucidates the existence of non-Debye dielectric relaxation nature in the synthesized compound. The compound possesses appreciable value of loss tangent and remnant polarization, i.e., 0.02 and 0.014 µC/cm2, with high value of dielectric constant at room temperature. The dysprosium doping entails stability with interesting electrical and dielectric properties. The preliminary capacitive characteristic has been elucidated, thus making it a stronger contender for functional device applications.

Grain growth correlated complex impedance spectroscopy, modulus spectroscopy and carrier hopping mechanism in MnCo2O4: Influence of sintering temperature

This work primarily focuses on grain growth dependent electrical properties of spinel nano-cobaltite MnCo2O4 prepared by co-precipitation method and sintered at different temperatures between 400 and 1000 °C. XRD confirms formation of cubic manganese cobaltite. Rietveld method was used to estimate different microstructural parameters. Crystallite size increases with increasing sintering temperature from ~12.18 nm to ~97.95 nm which is comparable with grain growth noticed from FESEM micrographs. TGA-DSC curve shows long range phase stability of the materials. Cole-Cole plot obtained from complex impedance spectroscopy analysis shows non-Debye type depressed semi-circular nature. Activation energies evaluated from ac conductivity, migration energy and relaxation time approaches are consistent with each other indicating that the charge carriers have same barrier potential for conducting, migrating and relaxing. Hopping mechanism of charge carriers was confirmed from ac conductivity analysis. Conductivity is higher for sample sintered at higher temperature which might be associated with lowering of inter granular hopping distance. Master curves show good scaling behaviour of different spectra. It depicts that time-temperature superposition principle (TTSP) is valid for the samples and conduction mechanism is same at all temperatures.

The complex impedance, dielectric relaxation, complex modulus and photoluminescence studies of pure and L-Methionine doped ammonium dihydrogen phosphate

The ammonium dihydrogen phosphate (ADP) is one of the pioneer nonlinear optical materials utilized for frequency doubling experiment of Nd:YAG laser. The amino acids are bifunctional material that contains the weak hydrogen bonded side chain. In the present study the authors have studied influence of L-Methionine on structural, photoluminescence and a.c.electrical properties of ADP. The powder XRD study suggested tetragonal structure symmetry and single phasic nature of all the samples. The photoluminescence is confirmed existence of the Self Trapped Excitons. The Correlation Barrier Hopping and Nonoverllaping Small Polaron Tunnelling kind of conduction mechanism is observed in present system. The Complex Impedance and Complex Modulus spectroscopy have suggested presence of grain and grain boundary within the samples.

Lithium-Ion Transport in Nanocrystalline Spinel-Type Li[InxLiy]Br4 as Seen by Conductivity Spectroscopy and NMR.

Currently, a variety of solid Li+ conductors are being discussed that could potentially serve as electrolytes in all-solid-state Li-ion batteries and batteries using metallic Li as the anode. Besides oxides, sulfides and thioposphates, and also halogenides, such as Li3YBr6, belong to the group of such promising materials. Here, we report on the mechanosynthesis of ternary, nanocrystalline (defect-rich) Li[InxLiy]Br4, which crystallizes with a spinel structure. We took advantage of a soft mechanochemical synthesis route that overcomes the limitations of classical solid-state routes, which usually require high temperatures to prepare the product. X-ray powder diffraction, combined with Rietveld analysis, was used to collect initial information about the crystal structure; it turned out that the lithium indium bromide prepared adopts cubic symmetry (). The overall and electronic conductivity were examined via broadband conductivity spectroscopy and electrical polarization measurements. While electric modulus spectroscopy yielded information on long-range ion transport, 7Li nuclear magnetic resonance (NMR) spin-lattice relaxation measurements revealed rapid, localized ionic hopping processes in the ternary bromide. Finally, we studied the influence of thermal treatment on overall conductivity, as the indium bromide might find applications in cells that are operated at high temperatures (330 K and above).

Optical Responses of the Heterojunctions in Cu2ZnSn(S,Se)4 Solar Cells Studied by Electric Modulus Spectroscopy

The electrical properties of heterojunctions are essential to the charge transport and power conversion in Cu2ZnSn(S,Se)4 (CZTSSe) thin-film solar cells. In the present study, the impedances of the...

Enhancement of dielectric properties of Ni and Co doped ZnO due to the oxygen vacancies for UV photosensors application

Abstract In our study, Zn1-xMxO (M = Ni, Co) were elaborated by a facile route polyol process. We used the impedance spectroscopy to find the impacts of temperature, frequency and oxygen vacancies on both dielectric and transport properties of our samples. We concluded that both the electrical and dielectric performances were related to the oxygen vacancies. Then, a colossal dielectric constant up to 4100 and a low dielectric loss of 0.2 have been found in Co doped ZnO Nps and it is a very high permittivity values as compared to other material oxides. That is why, reflectance diffuse and electric modulus spectroscopy are used to study the origin of this high permittivity. Furthermore, the electrical performances were characterized by current-voltage (I–V) under dark and light illumination. These important electrical and dielectric results obtained for the Co doped ZnO Nps make them interesting material for use in UV photodetector that require high dielectric constant.

Structural, dielectric, impedance and modulus spectroscopy of BiLa2TiVO9 ceramic

A standard solid-state ceramic technology (i.e., high-temperature solid-state reaction method) was used to fabricate new bismuth layer Aurivillius compound, BiLa2TiVO9. The formation of a single phase with an orthorhombic structure was confirmed by the X-ray diffraction structural analysis. The tangent loss measured at 200 °C is found to be in between 0.03 and 0.05 in the frequency ranging from 1 kHz to 1 MHz. The dielectric constant is found to be around 300 at room temperature. The resistance and reactance parts of complex impedance have been determined by the complex impedance spectroscopy (CIS) techniques. The electric modulus spectroscopy study of the compound confirmed the presence of the short range displacement of charge carriers. Jonscher’s power law fitting has been used to verify our experimental data of conductivity spectra. The nature of variation of exponent (n) obtained from the fitting follows the correlated barrier hopping as the predominant conduction mechanism in the sample. Room-temperature polarization loop confirms the ferroelectric nature of the sample.

Synthesis and characterization of Ruddlesden-Popper system (Ba1−xSrx)2SnO4

The samples of (Ba1−xSrx)2SnO4 with x = 0, 0.10, 0.20, 0.40, 0.80, 1.00 were synthesized by a high-temperature solid state ceramic route. Lattice parameters obtained from the Rietveld profile analysis; decreased with increasing Sr. The decreasing nature of lattice parameters indicated the complete solubility of Sr at Ba-site. Further, incorporation of Sr at Ba-site has been studied by Fourier transform infrared (FTIR) spectroscopy. The dielectric constant and dissipation factor increases with increasing Sr. Contribution of grain and grain boundary were resolved by complex modulus spectroscopy analysis. AC conductivity spectra of the entire sample follow Universal Jonscher's power law. The similar value of activation energy obtained from relaxation frequency and dc conductivity implies that the origin of conduction and relaxation mechanisms remains the same throughout the samples. The modulus and conductivity spectra of solid solutions nicely follow the time-temperature superposition (TTSP) principle. Further, conductivity spectra of solid solutions were studied by Ghosh and Summerfield scaling.

Growth and characterization of pure and picric acid doped ADP single crystals

Ammonium dihydrogen phosphate (ADP) is a pioneer kind of nonlinear optical crystal. It can be used in various electro-optical, nonlinear optical applications. The pure and different weight percentage of Picric acid doped ADP single crystals are grown using the slow solvent evaporation technique at room temperature. The powder XRD study shows single phasic nature of all the grown crystals. The photoluminescence study suggests that the dopant causes defect in structure of ADP by virtue of vibration relaxation and self trapping exciton. The dielectric constant and the dielectric loss of all the grown crystals exhibited universal behaviour over frequency range considered. The Correlation Barrier Hopping and the Non Overlapping Small Polaron Tunnelling kind of conductivity mechanism are observed. The grain and grain boundary is indentified using the complex Impedance and the complex modulus spectroscopy. The third order nonlinear optical susceptibility is increased on doping the Picric acid in ADP crystals. The results are discussed here.

Multifunctional character of revived double perovskite for device applications

The materials having multifunctional behavior are in the form of single crystal or poly crystalline. The present reports belong to polycrystalline samples of lead reducing double perovskite vanadates of Pb2-xSrxBiVO6 (0.5 ≤ x ≤ 1.5) oxide ceramics. To synthesize the present samples cost effective solid solution casting technique has been adopted. Their formation, density, phase identification as well as purity were verified through X-ray diffraction (XRD), Scanning Electron Microscope (SEM), Fourier transmission Infra-red (FTIR) and RAMAN spectroscopy. The optical properties of the materials have been investigated by utilizing room temperature UV–Vis and photo luminescence (PL) spectroscopic analysis. It is observed the band gap of the materials were found to be in the range of 2.68–2.23eV from UV–Vis study which suggest materials can be useful for photo catalytic devices whereas PL emission spectra confirms they are may be useful as blue white LED devices. Presence of ferroelectricity in the materials was confirmed from dielectric as well as polarization study which allows their utility for multi-layer capacitor and memory devices. Transport and leakage characteristics of the materials were studied from loss tangent, impedance spectroscopy as well as modulus spectroscopy recorded at different conditions of frequency and temperature which may be useful for microelectronics.

Structural and electrical features of lead-free ferroelectric: Li1/2Bi1/2TiO3

In this communication, the detailed analysis of structural (including microstructural) and electrical (dielectric, impedance, conductivity, and modulus) features of a perovskite Li1/2Bi1/2TiO3 are reported. The compound is prepared by a high-temperature solid-state reaction technique. From X-ray diffraction, the crystal structure is fully satisfied with the monoclinic system of the material. Both dielectric permittivity and loss tangent of the pellet sample is scanned and analyzed in extensive temperatures (30–500 °C) and frequencies (100 Hz–1 MHz). Dielectric anomaly is detected at a particular temperature of 109 °C that may be associated with the ferroelectric-paraelectric phase transition. Through the Nyquist diagram, the presence of grains and grain boundary effect in the compound is detected. The observed non-Debye type of relaxation feature is confirmed through the complex impedance spectroscopy. Impedance analysis suggests that the grain resistance reduces with the rise of operating temperature, showing the negative temperature coefficient of resistance (NTCR) nature. Also, the non-Debye type of relaxation phenomenon is established from the modulus spectroscopy analysis. The significant result infers that this compound may be utilized for different high-temperature applications.

Effect of Cu substitution on structural and electric transport properties of Ni-Cd nanoferrites

Nanocrystalline samples of Ni0.7−xCuxCd0.3Fe2O4 (x = 0.0–0.5, with step of 0.1) have been synthesized via auto-combusted sol-gel method. In this study, we present the structural and electric properties of Cu substituted Ni-Cd ferrite nanoparticles at room temperature with varying frequencies from 20 Hz to 15 MHz. X-ray diffraction (XRD) patterns of samples confirm the single-phase cubic spinel structure without impurity. The crystallite size of samples is found in the nano-scale range (17–27 nm) and the lattice parameter is found to increase linearly with Cu content. The surface morphology of samples is studied through a Field Emission Scanning Electron Microscopy (FESEM) and the presence of elements in the samples are confirmed by Energy Dispersive X-ray (EDX) techniques. The materials show dielectric dispersion up to 10 kHz frequencies and their loss tangent values remain very low at MHz frequencies. The impedance and modulus spectroscopy confirm the existence of non-Debye relaxation phenomena of the materials and resolve the contribution of grain and grain boundary. The ac conductivity shows normal behavior with frequency, which is explained on the basis of hopping mechanism.

Improved optical absorption, enhanced morphological and electrochemical properties of pulsed laser deposited binary zinc and vanadium oxide thin films

The investigations were carried out on binary metal oxide ZnO/V2O5 nanostructured thin films prepared by pulsed laser deposition for the MOSFET channel application. The thin films were prepared at 298 (as deposited), 623, 773, and 923 K at 10 Hz laser repetition rate (LRR) for 30 min. The films were characterized by SEM, EDAX, XRD, UV–Visible spectroscopy, and IV measurements. The amorphous nature of the film deposited below 773 K was revealed by XRD analysis. Few diffraction peaks were seen in the 923 K sample, revealing the formation of Zn2V2O7 and Zn3V3O8 in the binary ZVO thin films. All the samples are partially or completely amorphous in nature till 923 K. The optical energy bandgap was measured using Tauc plot and it was found to be 3.1–3.7 eV for the ZVO thin films. Then, the films were investigated by impedance and modulus spectroscopy over a frequency range of 1 Hz–1 MHz and temperatures lying in the 298–473 K domain. The frequency response of the imaginary impedance (Z″) shows a relaxation behavior for each measuring temperature in all the three samples. However, four samples were fabricated, namely, at 298 (as deposited), 623, 773, and 923 K. The three binary metal oxides pulsed laser deposited at high temperatures show a semiconducting behavior. The activation energy (Ea) was determined from the Arrhenius plot based on impedance and modulus relaxation. The activation energy is minimal for the high-temperature PLD thin films.

Effect of LaNiO3 on the impedance and dielectric properties of CoFe2O4: a high temperature study

In this article, we report the impedance and dielectric properties of the nanocomposites comprising of CoFe2O4 (CFO) and LaNiO3 (LNO) with varying LNO content (0, 5, 10 and 15%) in the temperature range from 35 °C–400 °C. The impedance and modulus spectroscopy show the non-Debye type dielectric relaxation behaviour of the grain and grain boundary separately in pure CFO with an additional relaxation in the composite with 15% LNO, arising from the electrode polarization. Mostly the grain boundary of the composites is affected by the presence of LNO as its activation energy in the composite with 15% LNO is reduced by ~0.2 eV compared to pure CFO, whereas that of the grain remains similar. The dielectric constant increases consistently with increasing LNO content in the composites owing to the Maxwell–Wagner–Sillar type polarization effect between the interfaces of LNO and CFO. The dielectric constant manifests a negative value in both pure CFO and the composite with 15% LNO at all temperatures in the frequency of hundreds of MHz which is explained by the interband transition. The ac conductivity of pure CFO reveals short range and orientational hopping inside the grains and across the grain boundary, respectively. However, in the composite with 15% LNO, the reduced activation energy assists the charge carriers for short range hopping across the grain boundary while the conductivity inside the grain remains unaffected.

Evidence for dielectric suppression in non-magnetic modified multiferroic bismuth ferrite

Structural, magnetic, and electrical properties of polycrystalline Y-Sc codoped BiFeO3 (BFO) ceramics are investigated. Rietveld refinement and Raman spectroscopy analysis provide strong evidence of structural distortion without changing the structure of parent compound (rhombohedral: R3c) after codoping. Distortion due to nonmagnetic codoping marks an abrupt change in magnetic and electrical properties of BiFeO3. Ferromagnetic property is enhanced with a maximum remanent magnetization of 0.0045 emu/g at higher Sc-concentrations. Codoping improves the ferroelectric properties [Pr=13μC/cm2 at (Y,Sc)=(0.03,0.05)] due to the suppression of oxygen vacancies. The frequency-dependent dielectric properties at various temperatures are investigated. The relaxation peak shifts toward room temperature for Bi1−xYxFe1−yScyO3 ceramics, which eventually appeared above 100°C for parent BFO. The suppression of relaxation peak indicates the change in conduction mechanism for codoped ceramics. The conduction process and the relaxation mechanism in parent and Y-Sc codoped BiFeO3 are investigated with electrical modulus and impedance spectroscopy. Frequency-dependent ac conductivity at various temperatures indicates that the conduction mechanism follows the correlated barrier hopping model and is thermally activated. Temperature dependent conductivity studies at different frequencies reveal that the relaxation process in codoped ceramics is due to the long-range oxygen vacancy movement and the low loss values.

Frequency and temperature-dependent electric modulus spectroscopy of osmium-doped YbFeO3 structure

Orthoferrites have occupied important place in the material science and condensed matter physics investigations due to their unique features such as electrical, magnetic and optical. The present investigation illuminates light on the electrical properties of osmium (Os) doped YbFeO3 (YbFO) rare-earth orthoferrite. The undoped YbFO and YbFe1−xOsxO3 (YbFOO) (x = 0.01 and 0.05) powders were synthesized via solid-state. X-ray diffractometer (XRD) has been utilized to examine the crystal structure of the YbFO and YbFOO powders. The cross sectional morphology of the obtained pellets was inspected via scanning electron microscope (SEM). Moreover, x-ray photoelectron spectroscopy was exploited to determine the oxidation states of the constituted elements. The electrical features for instance electrical modulus, dielectric constant and conductivity of the synthesized pellets were detailed at different frequencies and temperatures by dielectric/impedance spectroscopy studies. The x = 0.01 Os doped sample exhibits higher dielectric constant and conductivity compared to other samples. Moreover, in order to explain conductivity mechanism of the studied samples, multiple conduction models are needed to employ.

Structural and impedance analysis of Bi0.5Na0.5Ti0.80Mn0.20O3 ceramics

The Bi0.5Na0.5Ti0.80Mn0.20O3 ceramic was synthesized by a conventional solid-state reaction technique. Rietveld refinement of X-ray diffraction data confirms the rhombohedral crystal structure of the compound with R3c space group. The optical band gap energy of the compound is found to be 1.93 eV. The substitution of 20% Mn ions at the Ti sites results in the improved dielectric characteristics and a shift in the ferroelectric to paraelectric electric phase transition peak from 330 °C to 370 °C in the material. The frequency dispersion of dielectric constant and its footprint in the Nyquist and Cole-Cole plots have been analyzed. The analysis of complex impedance and modulus spectroscopy confirms the non-Debye type of relaxation mechanisms in the material with contributions from both the grain and grain boundary to the electrical properties. The frequency dependence of AC conductivity data exhibits overlapping large polaron tunneling conduction mechanism in the compound.