Jonscher's Power Law Research Articles

Tuning electrical properties of BaTiO3 with iron modification

BaTiO3 plays an important role in advanced functional devices owing to its fascinating properties. Though it is an excellent ferroelectric material, its magnetism can be switchable via suitable modification. In this report, we have studied iron-modified BaTiO3, which has been prepared using cost-effective high-temperature solid-state reaction techniques. The Fe-modified BaTiO3 maintains its crystallinity in the tetragonal phase with P4mm space group with a slight variation of tetragonality ratio to 1.002 from 1.008 of BaTiO3 of the identical synthesis method. This is confirmed by Rietveld refinement. Field emission scanning electron microscopy (FESEM) and EDX (energy dispersive X-rays) spectrum along with an elemental mapping analysis has provided the feature of the Fe-modifed BaTiO3. Atomic force microscope (AFM) has been employed to get the detailed surface topology (2D and 3D) and surface roughness of the developed systems. This deformation caused by the incorporation of Fe significantly modifies the electrical properties of barium titanate. The ferroelectric-paraelectric phase transition temperature (Tc) of Fe-modified BaTiO3 has been diffused and shifted to 300 °C from 120 °C of pure BaTiO3, suggesting the materials for the high-temperature capacitive application. The room temperature M-H hysteresis of Fe-modified BaTiO3 indicates the ferromagnetism developed in the BaTiO3 with the introduction of Fe. The ac conductivity is in the order of 10−4 Ω−1cm−1, and its frequency response obeys Jonscher's power law. Different charge carriers are responsible for diverse conduction processes in different temperature ranges confirmed by the Arrhenius plot. Impedance spectroscopy studies reveal the existence of NTCR characteristics of the developed system. Well defined ferroelectric hysteresis loop indicates the existence of ferroelectricity in the developed system. The analysis of various electrical parameters has provided information on the material's dielectric relaxation and conduction mechanisms for possible application in functional devices.

Studies of structural, dielectric, and electrical properties of polycrystalline barium bismuth tungstate for thermistor application

In this communication, preliminary investigation of structural and detailed analysis of electrical proprties of a new barium bismuth tungstate of a chemical composition Ba3Bi2WO9, produced via a standard high-temperature solid-state reaction method, is presented. The basic crystal structure of the compound is monoclinic (a = 8.4621 Å, b = 6.7358 Å, c = 6.9064 Å and β = 109.94°). The homogeneous distribution of grains (average grain size = 1.717 μm) is studied via surface morphology demonstrating the feasibility of fabricating a high-density sample under experimental conditions. This compound shows ferroelectric and related properties, which have been experimentally verified by examination of the frequency-temperature dependence of capacitance, impedance, and other related behaviors. The variation of ac conductivity of the material under alternating current varies according to Jonscher's universal power law. The ferroelectric property of the material (Pr = 0.331C/cm2, Ec = 0.207 kV/cm) is demonstrated by the electric field-dependent polarisation (P-E loop) study. The temperature dependence of resistance yields a thermistor constant (β) and temperature coefficient of resistance (TCR), which may be useful for fabricating thermistor-based device applications.

Distinct dominant dielectric relaxation mechanisms in CaCu3Ti4O12 – LaMO3 (M = Mn and Fe) perovskite oxide solid solution

Two synthesized perovskite oxide solid solutions, CaCu3Ti4O12 – LaMnO3 and CaCu3Ti4O12 – LaFeO3, possess a crystalline structure embracing an amalgamation of two distinct phases, namely, hexagonal and orthorhombic phases in CaCu3Ti4O12 – LaMnO3 and cubic and orthorhombic phases in CaCu3Ti4O12 – LaFeO3. Examination of dielectric properties reveals colossal dielectric constant (εr), the peak magnitude of εr at 1 kHz being approximately 6×103 and 2.5×104 for Mn and Fe based compound, respectively. Further, complex impedance investigation (CII) establishes the activation energy (Ea) of grains (0.21 eV and 0.07 eV for Mn and Fe based solid solution, respectively) and grain boundaries (0.19 eV and 0.19 eV for Mn and Fe based solid solution, respectively). The deviation in Ea of grains and grain boundaries, as established through CII, in both, Mn and Fe based samples validates the existence of Maxwell-Wagner (M − W) relaxation. The AC conductivity spectrum for both the samples obeying the Jonscher's universal power law (JUPL): σ(ω,T)=σdc+Aωn. The Ea of bulk samples (0.37 eV and 0.19 eV for Mn and Fe based solid solution, respectively) authenticates predominant M − W relaxation (interfacial polarization) with polaron hopping playing the secondary role in Mn based sample, while both, polaron hopping and M − W relaxation being identical contributors towards dielectric nature of Fe based sample.

Investigations of Structural, Magnetic, and Electrochemical Properties of NiFe2O4 Nanoparticles as Electrode Materials for Supercapacitor Applications.

Magnetic nanoparticles of NiFe2O4 were successfully prepared by utilizing the sol-gel techniques. The prepared samples were investigated through various techniques such as X-ray diffraction (XRD), transmission electron microscopy (TEM), dielectric spectroscopy, DC magnetization and electrochemical measurements. XRD data analysed using Rietveld refinement procedure inferred that NiFe2O4 nanoparticles displayed a single-phase nature with face-centred cubic crystallinity with space group Fd-3m. Average crystallite size estimated using the XRD patterns was observed to be ~10 nm. The ring pattern observed in the selected area electron diffraction pattern (SAED) also confirmed the single-phase formation in NiFe2O4 nanoparticles. TEM micrographs confirmed the uniformly distributed nanoparticles with spherical shape and an average particle size of 9.7 nm. Raman spectroscopy showed characteristic bands corresponding to NiFe2O4 with a shift of the A1g mode, which may be due to possible development of oxygen vacancies. Dielectric constant, measured at different temperatures, increased with temperature and decreased with increase in frequency at all temperatures. The Havrilliak-Negami model used to study the dielectric spectroscopy indicated that a NiFe2O4 nanoparticles display non-Debye type relaxation. Jonscher's power law was utilized for the calculation of the exponent and DC conductivity. The exponent values clearly demonstrated the non-ohmic behaviour of NiFe2O4 nanoparticles. The dielectric constant of the nanoparticles was found to be >300, showing a normal dispersive behaviour. AC conductivity showed an increase with the rise in temperature with the highest value of 3.4 × 10-9 S/cm at 323 K. The M-H curves revealed the ferromagnetic behaviour of a NiFe2O4 nanoparticle. The ZFC and FC studies suggested a blocking temperature of ~64 K. The saturation of magnetization determined using the law of approach to saturation was ~61.4 emu/g at 10 K, corresponding to the magnetic anisotropy ~2.9 × 104 erg/cm3. Electrochemical studies showed that a specific capacitance of ~600 F g-1 was observed from the cyclic voltammetry and galvanostatic charge-discharge, which suggested its utilization as a potential electrode for supercapacitor applications.

Development of a novel triple perovskite barium bismuth molybdate material for thermistor-based applications

In this communication, development (synthesis and characterization) of a novel triple perovskite sample Ba3Bi2MoO9 (BBMO) is reported. The material has monoclinic crystal symmetry. A detailed study of microstructure and compositional analysis of the sample by using scanning electron microscopy (SEM) and EDX (energy dispersive X-rays) spectrum has provided the quality of the BBMO ceramic. The topological and surface roughness of the novel material has been analyzed to clarify the surface texture and compactness of the sample surface. The variation of conductivity under the alternating current of the material varies according to the Jonscher's universal power law. The high dielectric constant and low tangent loss are applicable for fabrication of various electrical instruments. The resistance decreases with an increase in temperature supports the NTCR (negative temperature coefficient of resistance) behavior, which is clarified by using TCR and β (thermistor constant) for NTC thermistor application.

Impedance spectroscopy and conduction mechanism analysis of bulk nanostructure Prussian blue pellets

The structure and morphology of the fabricated Prussian Blue (PB) pellets are examined using FTIR, XPS, XRD and FESEM techniques. The morphology of the crystalline Prussian blue (PB) revealed a nanostructure with an average crystallite size of 91 nm. The frequency (42 Hz–1 MHz) and temperature (303–393K) of the Prussian Blue (PB) in Bulk form are dependent. In the medium region (1 kHz–100 kHz), the electric dipoles relax and start to lag the applied ac electric field signal and the estimated activation energy of 0.247 eV. The investigated Nyquist plots (Z″ versus Z′) of the Prussian Blue (PB) samples at different temperatures (303–393 K) are interpreted by an equivalent parallel RgCg circuit. The bulk resistance of Prussian Blue samples was estimated at various temperatures, and its behaviour exhibited temperature dependence; generally, it follows the Nearest Neighbor Hopping (NNH) model. According to Meyer–Neldel rule, the calculated activation energy is 0.565 ± 0.001 eV. The evidence of localized states is investigated, and its density, N(EF) ∼ 5.47 × 1018 eV−1 cm−3. The ac conductivity, σac, merges into a plateau of two parts: the first is a frequency-independent dc conductivity, σdc, which is strongly temperature-dependent. The rest of the plateau at higher frequencies showed the temperature-insensitive ac conductivity obeying Jonscher's power law. The values of the exponent s were investigated to figure out the intimate conduction mechanism in Prussian Blue (PB) samples; it follows the correlated barrier hopping (CBH) theoretical model. The hopping distance and energy have values ∼ unity and ≥ kBT, respectively. The experimental results revealed a linear relationship between hopping distance and energy against temperature, with the first decreasing and the second increasing linearly.

Investigation on structural, optical and electrical properties of BiFeO3:ZnO nano–micro particles–matrix composite

A new class of materials called matrix-nano composites has the ability to meet the needs of modern advanced applications and technology. To prepare the BiFeO3:ZnO composite, BiFeO3 nanoparticles were prepared using a low–cost sol–gel method, to which ZnO in its micron-sized form was added in varying concentrations of 5%, 10%, and 15%. The structural, morphological, and optical properties of the pure and composite materials were characterized using XRD, FESEM, EDAX, PL spectra, and UV-Visible spectroscopy. The dielectric properties of the pristine and composites were investigated at room temperature. The a.c. conductivity fit with Jonscher's power law and CBH model described the charge conduction behaviour in all pure and composite materials. The temperature-dependent dielectric and loss measurements showed a temperature dependent relaxation process. UV–vis and PL characterization show that the composite materials exhibited improved charge separation efficiency and wider band gaps with increasing BFO content.

Effect of Cr3+ substitution on the magnetic and dielectric properties of cobalt ferrites

Co(Fe1-xCrx)2O4 (x = 0.02, 0.10, 0.15, 0.30, 0.50) samples are synthesized by the sol-gel method. The XRD patterns and subsequent Rietveld refinement provided structural analysis and confirmation of the samples' single-phase formation. XPS measurement reveals the existence of the elements Co, Cr and Fe in 2+ and 3+ oxidation states. The saturation magnetization (Ms), coercivity (Hc) and magnetocrystalline anisotropy (K1) are observed to decline to as low as 10 emu/g, 35 Oe and 0.50 (106 erg/cm3) following Cr substitution, which indicated that the samples transform to a soft magnetic material. Cr substitution also lowers the ferrimagnetic (FiM) to paramagnetic (PM) transition temperature, Tc, from 752 K for x = 0.02 to 307 K for x = 0.50. With Cr replacement, the dielectric constant and dielectric loss values decrease, indicating it to be a potential contender for high frequency applications. The dielectric constant for x = 0.30 and x = 0.50 samples rises sharply around 1 MHz owing to the LC resonance effect between the samples and the measurement leads. The ac conductivity plots are found to be in conformity with Jonscher's single power law, and the conduction process is revealed to be attributable to the small polaron hopping mechanism.

Formation of silver particles in [PVA:CS:PEG]-AgNO3 based biopolymer electrolyte membranes: Structural and electric transport properties study

[Chitosan (CS)-poly(vinyl) alcohol (PVA)-polyethylene glycol (PEG-200)]+xwt% silver nitrate (AgNO3) (x = 0, 10, 20, 30, 40) based biopolymer blend electrolytes (BPBEs) were prepared using solution casting method. FTIR results show the interaction of Ag+/NO3− with the constituents of polymers CS/PVA. XRD results reveal that the amorphousness increases with increasing AgNO3 concentration. Optical morphological (OM) images show that the silver, Ag(o) particles are agglomerated on the surface of the membrane. Temperature dependent dc conductivity (σdc) and dielectric relaxation frequency (fr) for BPBEs follow the Arrhenius type behavior and the sample containing 30 wt% salt has optimum dc conductivity, σdc∼1.7×10−4 S/cm at 30oC with lowest activation energy∼ 0.16 eV. The ac conductivity spectra follow the Jonscher's power law (JPL) with power law exponent, s > 1. The scaling of AC conductivity and loss tangent (tanδ) spectra were performed with respect to temperatures/concentrations of salt. The dielectric permittivity study reveals that the electrode polarization effect predominates at low frequencies. The Ionic Transference Number (ITN) measurement was used to determine the nature species of charge carrier, either ionic or electronic. The linear sweep voltammetry (LSV), result shows that 30% AgNO3containing sample has the electrochemical stability window (ESW) ∼+1.5 to -1.5 V.

Consistency between theoretical conduction models and experimental conductivity measurements of strontium-doped lanthanum manganite

La0.9Sr0.1MnO3 nanoparticles are elaborated using the citrate-gel route. The X-ray patterns show that the prepared sample crystallizes in the rhombohedral symmetry. Interesting results were obtained from the electrical conductivity measurements of the lanthanum manganite doped low strontium content. Indeed, numerous conduction models are used to analyze the electrical conductivity response. It is found that transport properties are governed by hopping processes at different temperature ranges. Such mechanisms explain the evolution of the DC-conductivity as well as the displacement of charge-carriers with temperature excitation. Then, thermal activation of the charge-carriers is confirmed. The temperature dependence of the frequency exponents reveals the contribution of Non-overlapping Small Polaron Tunneling (NSPT), Quantum Mechanical Tunneling (QMT), Over-lapping Large Polaron Tunneling (OLPT) and Correlated Barrier Hopping (CBH) to the transport properties. Conductivity spectrum shows a significant increase with frequency in the temperature range [80–500 K]. The frequency dependence of the AC-conductivity obeys to the "Double Jonscher Power Law" in the temperature range [80–300 K]. From 340 to 500 K, it is governed by the "Single Jonscher Power Law". Moreover, a high frequency plateau is observed presenting a percolation behavior in the conductivity spectrum. The deduced values of the disorder and hopping energies show the impact of hopping distance and polaron radius on the charge-carriers transport.

Modification and development in the microstructure of PVA/CMC-GO/Fe3O4 nanocomposites films as an application in energy storage devices and magnetic electronics industry

We used casting method to create nanocomposites films from carboxymethylcellulose (CMC)/polyvinyl alcohol (PVA) and GO/Fe3O4 as nanofiller. Various analyses such as structural, vibrational, optical, conductivity, dielectric and magnetic studies reveal promising properties of the prepared polymer nanocomposites (PNCs) films. The amorphous phase of the polymer blend increased with increasing GO/Fe3O4 concentration up to samples containing 0.05%GO/1%Fe3O4 nanofiller, according to X-ray diffraction. The complexation of the nanofiller with the polymer blend's –OH, –COO, CO, and –CH groups through a coordinate bond/hydrogen bond was confirmed by Fourier-transform infrared analysis. While the Urbach energy showed a trend in the opposite direction, the optical bandgap gradually turned red as the nanofiller concentration increased. The interaction of GO/Fe3O4 ions with the CMC/PVA matrix is attributed to the changes in optical properties of CMC/PVA. The Jonscher's power law (JPL) is observed in all samples' ac conductivity spectra. To comprehend the charge storage competences, research of dielectric permittivity was also conducted. A study of dielectric permittivity was also conducted to comprehend the charge storage competences. While AC conductivity increases with frequency, dielectric characteristics decrease with frequency. With the addition of nanofiller, AC conductivity and dielectric characteristics increase. For 0.05%GO/1%Fe3O4 nanofiller loaded sample, the highest AC conductivity and dielectric constant were attained. The results of vibrating sample magnetometer (VSM) revealed that synthesized nanocomposite films exhibit superparamagnetic features. The unique features of CMC/PVA-GO/Fe3O4 films enable their employment in a variety of industries, including magnetic electronics, energy storage devices, and optoelectronics.

Investigation of frequency dependent dielectric properties of La-doped BaSnO3-ZnSnO3 solid-solutions

In this study, we report the structural, optical, and dielectric properties for La-doped BaSnO3 and ZnSnO3 solid solutions, La0.03(Ba1−xZnx)0.97SnO3 (x = 0,0.1,0.5,1) prepared at 1100 °C by isovalent substitution of Zn+2 at the Ba+2 site using the conventional solid-state reaction route. Structural data shows the transformation from cubic perovskite to orthorhombic perovskite structure as the amount of Zn increases in La-doped BSO samples. A minor pyrochlore phases, La2Sn2O7 and Ba2SnO4 were found in the XRD. This paper mainly focuses on understanding the contribution of physical phenomena of ac conductivity in terms of dielectric properties. The dielectric properties of the composites follow non-Debye type behavior. There was a moderate increase in the dielectric constant from 10.07 to 334 at 20 Hz, and 2.99–133 at 1 kHz, respectively, as we increased the amount of Zn, which is high as compared with other reported dielectric materials. By using Jonscher's power law, ac conductivity was found to increase in LZSO samples. This conduction mechanism due to the hopping of ions between coordination sites present in the composite and can be understood by the classically correlated barrier hopping phenomenon. Furthermore, the trivial loss of electromagnetic waves over a given frequency range demonstrates the great potential of La-doped ZnSnO3 materials to be utilized in ground penetrating radar systems, communication systems, and energy storage devices.

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.

Temperature-driven complex dielectric and polaron-hopping mediated electrical conduction in aurivillius Gd2MoO6

In this work, aurivillius gadolinium molybdate (Gd2MoO6) was synthesized by the conventional solid-state route which was accompanied by cutting-edge characterization i.e., structural, and electrical, to give insight into the material characteristics required for possible high-temperature applications. The single-phase crystalline nature with monoclinic symmetry (C2/c, Space group-15) of Gd2MoO6 was confirmed by the X-ray diffraction (XRD) pattern. The average particle size was obtained to be ∼0.495 µm. The electrical conductivity and dielectric properties of a Gd2MoO6 plate capacitor were investigated in the frequency range between 10 Hz and 1 MHz and temperature from 473 to 773 K. A high dielectric constant (ε') of ∼3272 and low dielectric loss (δ) of ∼200 was observed at the low frequency and high-temperature regions, respectively. The Maxwell–Wagner interfacial polarization was found to be responsible for the decrease of the dielectric constant with increasing frequency. The behavior with the temperature of the frequency exponent (n) from the fitted conductivity spectra by Jonscher power law corresponds to the non-overlapping small polaron tunneling model between 473–673 K and correlated barrier hopping model at/over 673 K. The non-exponential Kohlrausch Williams-Watts function was introduced to fit the imaginary modulus (M′′) spectra and the activation energy was obtained to be 0.81 eV for grain and 0.94 eV for grain boundary conduction. The Nyquist plots(Z′vs.Z′′) differentiate the grain and grain boundary contribution and were fitted with the combinations of resistance (R), capacitance (C), and constant phase element (Q) in an equivalent circuit model(RC)(RCQ). Typical negative temperature coefficient of resistance behaviors of Gd2MoO6 suggest its possible application as thermistors in modern electronics circuits.

Features of immittance spectra as performance indicators for cement-based concretes

Design for durability and performance-based standards and specifications for reinforced concrete infrastructure is limited by the lack of rapid, science-based test methods for characterising the deterioration resistance of concrete. In this paper, this issue is addressed though the application of two-point electrical impedance measurements taken within the frequency range 100 Hz–10 MHz. Data are presented for a range of industry-standard cement-based concrete mixes with and without supplementary cementitious materials. Nyquist plots (−iZ″(ω) against Z′(ω)) and Bode plots (Z*(ω) and θ against frequency) clearly highlight the frequency dependence of the electrical response. However, when presented in the form of permittivity and conductivity, a region of dispersion was evident over the entire frequency range for all concretes. The features of this response, which could be gainfully exploited as durability indices for assessing the long-term performance of concrete, are identified and discussed. A range of formalisms is presented and it is shown that, within this frequency range, conductivity was found to obey Jonscher's universal power law. Two novel durability parameters are presented based on features of Jonscher's model; from a practical viewpoint, the power-law model can be evaluated using conductivity measurements obtained at three, easily measured, spot frequencies (10 kHz, 1 MHz and 10 MHz).

The Influence of NiO Nanoparticles on Structural, Optical and Dielectric Properties of CMC/PVA/PEDOT:PSS Nanocomposites

The solution casting process was used to fabricate nanocomposite samples composed of carboxymethylcellulose (CMC), polyvinyl alcohol (PVA), poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) and filled with varied concentrations of nickel oxide nanoparticles (NiO NPs). The effect of NiO nanoparticles on the structural, optical, and electrical properties of the pure CMC/PVA/PEDOT:PSS mixture was studied and discussed. X-ray diffraction (XRD) and transmission electron microscopy (TEM) analysis revealed that the NiO NPs are cubic in phase and range in size from 10 to 55 nm. The XRD analysis of the incorporated films indicated that the NiO NPs crystallinity increased at expense of the CMC/PVA/PEDOT:PSS composites. Fourier Transform Infrared (FTIR) examination revealed the main absorption vibrational peaks of CMC, PVA, PEDOT:PSS, and Ni-O, whose intensities changed randomly after filling, revealing the intermolecular interaction between the nanocomposite components. The UV and visible range absorption spectra showed a sharp peak around 228 for the pure blend, which can be assigned to the π→π* transition. After being filled with NiO NPs, the nanocomposites produced displayed new peaks at 292 and 422 nm that steadily increased with increasing NiO NPs concentration. The optical energy gap (Eg) was computed, and it was discovered that when the NiO NPs content increased, the Eg decreased (from 4.88 to 4.06 eV). At room temperature and over a wide frequency range, between 10− 1 and 107 Hz, the samples’ impedance, AC conductivity, and dielectric qualities were examined. Increased NiO NPs content was seen to gradually enhance dielectric loss (up to 2255), and dielectric constant (up to 311). The AC conductivity of the filled samples is also enhanced and corresponds to Jonscher power law. By analysing impedance components of the Z*, the equivalent electrical circuit for each sample was determined. Because of the considerable improvement in optical and electrical properties, these composite films could compete for usage in optoelectronic applications.

Origin of improved Na+ ionic conductivity in the NASICON-type solid state electrolyte with Sm modification

The NASICON-type (Na1+xZr2SixP3-xO12, 0≤x ≤ 3) sodium-ion solid state electrolyte (SSE) has emerged as an alternative for liquid electrolyte due to its good chemical/electrochemical stability, high thermal stability and high safety. However, the insufficient ionic conductivity and poor understanding of Na+ transport mechanism hinder the further development of sodium-ion SSE. Herein, we report Sm modified Na3+xZr2-xSmxSi2PO12 (0≤x ≤ 0.4) electrolytes with a highest ionic conductivity of 2.25 × 10−3 S cm−1 at 25 °C when x = 0.2. The introduction of Sm element adjusts the Si/P ratio in NASICON phase and densifies the electrolyte pellets by formation of Na3Sm(PO4)2. To get a deep insight into the enhanced mechanism of Na + transport in grains, low-temperature electrochemical impedance spectra (LT-EIS) and Jonscher's power law relationship are employed to analyze the electrical behavior of grains. The results demonstrate that the regulation of Si/P ratio can evoke lower migration energy, more charge carrier concentration and higher hopping frequency, which synergistically improve the ionic conductivity in grains.

A multifunctional transition metal based double perovskite Ba2(FeW)O6: Structural, microstructural, optical, electrical and ferroelectric properties

In this article, synthesis (solid-state reaction) and characterizations (XRD, SEM-EDX, RAMAN, UV–Vis, LCR & P-E measurements) of a polycrystalline double perovskite Ba2(FeW)O6 are reported. The prepared sample crystallizes in tetragonal symmetry with an average crystallite size of 60.7 nm and lattice strain of 0.00045 respectively. Vibrational modes of the molecules in the prepared sample are investigated using Raman spectroscopy. Analysis of scanning electron microscope (SEM) and energy dispersive analysis of x-ray (EDX) supports homogenous distribution of grains and compositional consistency. Optical investigation calibrates direct energy bandgap of 2.72 eV; which may be suitable for photocatalytic and photovoltaic devices. Dielectric, impedance, and modulus spectra have been studied over a wide range of frequencies (1 kHz–1 MHz) and temperatures (25 °C–500 °C). Wide dielectric dispersion at low-frequency encounters space charge polarization with the Maxwell-Wager effect. Study of impedance plots reveals negative temperature coefficient resistance (NTCR) character while existence of non-Debye relaxation mechanism is confirmed from modulus plots. Frequency dependence ac conductivity obeys Jonscher's Power Law (JPL) and confirms the presence of a non-overlapping small polaron and correlated barrier hopping process (CBH). The study of activation energy (Ea), sensitivity factor (α) and thermistor constant (β) values from resistance versus temperature supports NTC thermistor behaviour and explore the possible applications related to temperature-based sensors.

Anisotropic electrical properties of 200 MeV Ag+15 ion irradiated manganite films

In the present communication, the investigations on the structural, morphological, electrical and magnetodielectric (MD) properties of pulsed laser deposited La0.90Ca0.10MnO3 (LCMO) nanostructured thin films grown on SNTO substrate followed by irradiation using 200 MeV Ag+15 ions have been carried out. Structural properties were studied using X–ray diffraction (XRD) technique. The lattice mismatch was calculated from the XRD spectra in order to get insights on the interfacial strain in all the thin films. Morphological properties were determined using atomic force microscopy (AFM) to study the irradiation induced alterations in the LCMO nanostructured thin films. Dielectric spectroscopy as a function of frequency was carried out to study the electrical properties of pristine and irradiated samples. The anisotropic MD properties were measured by employing the external magnetic field of 1 T in two different geometries, i.e. magnetic field perpendicular and parallel to the samples' plane. Various theoretical models such as relaxation time and universal dielectric response model were employed to explain the mechanisms governing the electrical properties. The ac conductivity and impedance were also measured under the presence of external magnetic field and compared with the measurements carried out in the absence of the magnetic field. The measured ac conductivity was modeled using Jonscher's power law which signified the conduction mechanism in the presently studied samples.

Marigold flower shaped nanopetteled Co0.7Zn0.3Fe1.7Ni0.3O4 microspheres as efficient glucose sensor

The spinel-type porous Co0.7Zn0.3Fe1.7Ni0.3O4 mesoporous flower alike microspheres were fabricated using hydrothermal technique. Electron microscopic investigations reveal interconnected porous nano lamella which construct highly stable microspheres. XRD results demonstrate an increase in the values of lattice constants due to effective substitution of Zn and Fe. The electrochemical characterizations, cyclic voltammetry (CV), chronoamperometry techniques, and electrochemical impedance spectroscopy (EIS) are conducted in three electrode system. The EIS and CV results indicate frequency dependent conductivity of the compound obeyed the Jonscher's power law. A glucose concentration range from 0.1 mM/L to 11.1 mM/L is chosen to cover non-diabetic to diabetic person. The sensitivity response of the electrochemical sensor for glucose is 92% in contrast with urea (13%), folic acid (9.1%), ascorbic acid (9%), potassium chloride (1%) and NaCl (2.2%) interferers. Further, on the same electrode the repetitive responses display its reproducibility and excellent sensitivity towards glucose; point to its potential application as effective glucose sensor.