non-Debye Relaxation Research Articles

Synergistic insights to ion-doped hydroxyapatite: bridging XRD, electrical impedance, dielectric characteristics, and antibacterial properties

ABSTRACT In this work, ion-doped hydroxyapatite materials were synthesized using the sol-gel technique. XRD analysis confirmed the purity of the products, with no secondary peaks observed. Doping with manganese, lithium, potassium, and zinc ions resulted in a crystalline size of 47–48 nm. Fourier transform infrared spectroscopy validated the structural bands, while scanning electron microscopy and energy-dispersive X-ray spectroscopy revealed nano-rod-like particles with sizes ranging from 30 to 80 nm in length and 13 to 40 nm in width. Impedance spectroscopy and dielectric relaxation studies showed electrical behaviour following the Maxwell-Wagner mechanism and non-Debye type relaxation. The materials exhibited strong antibacterial properties, making them promising for medical implant applications.

Analysis of the Sr2GdTi2Nb3O15 ceramic: Investigation into its structural properties and complex impedance spectroscopy

In this study, we successfully synthesized tetragonal tungsten bronze with the nominal formula Sr2GdTi2Nb3O15 and systematically examined of its structure, dielectric, and electrical properties. The material was synthesized through the solid-state reaction technique at a temperature of 1350 °C. The formation of the tetragonal tungsten bronze in the P4/mbm space group was verified via Rietveld refinement using X-ray diffraction data. The electrical characteristics of the ceramic were examined using non-destructive complex impedance spectroscopy (CIS) across a range of frequencies (10–106 Hz) at various temperatures. The real component of impedance (Z') displayed a decrease with rising frequency, suggesting a negative temperature coefficient of resistance (NTCR) for this sample. The Cole-Cole plot of the compound exhibits two semicircles, with the compound's resistance gradually decreasing as the temperature increased. Moreover, the activation energy (Ea) was found to be approximately 0.9 eV, which confirms that oxygen vacancies are responsible for the observed relaxation behavior. Complex modulus analysis confirmed the presence of non-Debye relaxations. These results contribute to a thorough comprehension of the structural and electrical characteristics of Sr2GdTi2Nb3O15, opening avenues for potential applications in diverse electronic devices.

Correlated barrier hopping transport and non-Debye type dielectric relaxation in Zn2V2O7 pyrovanadate

Herein, the Zn2V2O7 electro-ceramic pyrovanadate was synthesized via a conventional solid-state reaction technique and calcined at 700 °C. The single phase formation of Zn2V2O7 pyrovanadate crystallized in the monoclinic structure with C12/c1 space group was confirmed by X-ray diffraction (XRD). The XRD powder diffraction profile was analyzed by Rietveld refinement to investigate the structural details of the compound. The complex impedance analysis was carried out in the frequency domain of 83−2×106 Hz over a temperature range of 453–613 K to study the electrical charge conduction and dielectric relaxation mechanism in the material which revealed the presence of the distribution of relaxation times with thermal charge activation. Depressed semicircles in the Nyquist plots were modeled by an equivalent circuit with configuration (RGCG)(RGBQGB) which resolved the contributions of grains and grain boundaries towards the transport properties of the material. The electrical conductivity spectra followed Jonscher's power law behavior and the temperature variation of frequency exponent suggested correlated barrier hopping (CBH) as the governing transport mechanism in the Zn2V2O7 pyrovanadate system. The comparison between scaling behaviors of imaginary parts of impedance and modulus advocated the temperature-independent nature of relaxation time distribution. The imaginary electrical modulus spectra were reproduced by the Kohlrausch, Williams, and Watt formulism, and the fitted parameters confirmed the non-Debye type nature of the dielectric relaxation. Further, the Haveriliak-Negami function was employed to investigate the dielectric response of the material which was found to be consistent with impedance, conductivity, and modulus analyses. The frequency dispersion of the tangent loss verified that the hopping mechanism was thermally activated.

A new organic–inorganic chloride (H3N–(CH2)6–NH3)[SnCl6]: Crystal structure, thermal analysis, vibrational study, and electrical properties

In this work, a new Organic-Inorganic chloride (H3N–(CH2)6-NH3)[SnCl6] (1) has been synthesized and characterized by single crystal X-ray diffraction (XRD), IR, Raman and impedance spectroscopies. The crystallographic study displays that the title compound crystallizes in the triclinic system with the P−1 space group. The vibrational study (IR, Raman) at room temperature confirmed the existence of the organic and inorganic functional groups. Differential scanning calorimetry (DSC) analysis reveals the existence of three reversible phase transitions at T1 = 345/325 K, T2 = 483/443 K, and T3 = 496/465 K (Heating/Cooling). Furthermore, the conductivity analysis and the dielectric properties confirm the presence of these phase transitions. AC-conductivity measurement of (1) has been investigated using complex impedance spectroscopy in frequency and temperature range 10 Hz–5 MHz and 313–523 K, respectively. The study of Nyquist plots showed the contribution of grains and grain boundaries in the electrical study, confirming the existence of a non-Debye type relaxation. The AC conductivity shows that the material has the potential of impedance sensors.

Relaxation behaviour, conductive grains and resistive boundaries of bismuth-based double perovskite Bi2-xLaₓFeGaO₆

The successful synthesis of the ceramic Bi2-xLaxFeGaO6 powder ceramic sample with varying La content (x = 0.01, 0.03, 0.07, 0.10) were synthesized via the solid-state method. Analysis using X-ray diffraction at room temperature was carried out to examine its structure, revealing a crystallite size of approximately 22.07–50.84 nm. This size indicates the potential applications in microwave technology due to its small grain size, which has the capability to enhance microwave absorption properties. The dielectric constant of the material shows an increase with the frequency applied, in accordance with the behaviour anticipated by the dielectric HN model and Debye model. This model proposes that the material's dielectric response can be manipulated by modifying the applied frequency, making it a valuable tool in the material design for specific purposes. The full width at half maximum (FWHM) curve of the electrical modulus displayed variability, suggesting the existence of a non-Debye relaxation mechanism in the material. This indicates that the material could possess distinct electrical properties that might be beneficial for certain applications. The outcomes demonstrated a negative temperature coefficient resistance (NTCR), indicating a decrease in the material's resistance with increasing temperature. Such behaviour can be advantageous in situations where temperature variations require monitoring or regulation. The Cole-Cole plot illustrated that the grains exhibit conductive behaviour at lower frequencies, a crucial insight for comprehending the material's electrical properties. In conclusion, these results indicate that the ceramic Bi2-xLaxFeGaO6 for x = 0.01, 0.03, 0.07, 0.1) showcases promising attributes for various applications, particularly in microwave technology and electrical conductivity.

Anomalous Diffusion and Non-Markovian Reaction of Particles near an Adsorbing Colloidal Particle

We investigate the diffusion phenomenon of particles in the vicinity of a spherical colloidal particle where particles may be adsorbed/desorbed and react on the surface of the colloidal particle. The mathematical model comprises a generalized diffusion equation to govern bulk dynamics and kinetic equations which can describe non-Debye relaxations and is used for the colloid’s surface. For the reaction processes, we also consider the presence of convolution kernels, which offer the flexibility of describing a single process or process with intermediate reactions before forming the final species. Our analysis focuses on analytical and numerical calculations to obtain the particles’ behavior on the colloidal particle’s surface and to determine how it affects the diffusion of particles around it. The solutions obtained show various behaviors that can be connected to anomalous diffusion phenomena and may be used to describe the ever-richer science of colloidal particles better.

Uncovering the Possibilities of Ceramic Ba(1−x)CoxTiO3 Nanocrystals: Heightened Electrical and Dielectric Attributes

The hydrothermal synthesis of Ba1−xCoxTiO3 (BCT) ceramic nanocrystals across varied substitution fractions (x = 0, …, 1) is the subject of this study. Hydrothermal synthesis is well known for producing high-purity and well-crystallized nanocrystals. A thorough examination is conducted to examine the effects on the structural and electrical properties of the resultant BCT nanocrystals by altering the cobalt substitution fraction. X-ray diffraction (XRD) is used to analyze the structure, while complex impedance spectroscopy (CIS) is used to analyze the electrical properties. As the cobalt content rises, XRD examination reveals a smooth transition from the ferroelectric BaTiO3 phase to the ferromagnetic CoTiO3 phase, offering extensive insights into the phase composition and crystallographic alterations. This phase shift is important because it creates new opportunities to adjust the properties of the material for particular uses. The electrical activity of BCT nanocrystals is clarified further by CIS measurements. A distribution of relaxation times, frequently linked to complex microstructures or heterogeneous materials, is suggested by the detected non-Debye relaxation. A thermally activated conduction process, in which higher temperatures promote the passage of charge carriers, is suggested by the temperature-dependent increase in conductivity. This behavior is strongly dependent on the cobalt content, suggesting that cobalt enhances electrical conductivity and crystallinity through a catalytic effect. A frequency-dependent dielectric constant that rises with temperature and cobalt content is shown by investigating the dielectric characteristics of BCT nanocrystals. Improved polarization mechanisms inside the material are suggested by this increase in dielectric constant, which may be the result of cobalt ion presence. With a thorough grasp of the dielectric behavior, the examination of the loss angle further validates the non-Debye relaxation process.

Polaron assisted hopping mechanism in microwave processed Nd doped second layered aurivillius SrBi2Nb2O9 ceramics

The polycrystalline Sr0.8Sn0.2Bi1.75Nd0.25Nb2O9 (NdSBN) was synthesized using the green synthesis microwave sintering method, which significantly reduced the processing parameters of the NdSBN ceramics. Orthorhombic crystal structure with A21am symmetry was revealed by Rietveld refinement study, whereas the doping-induced strain and crystallite size was studied using the Williamson Hall method. Crossectional SEM micrographs confirm the plate-like structure, with an average grain size of 273.7 nm. A diffuse type of phase transition was observed at 345 °C, which usually arises due to compositional fluctuations and mobile oxygen vacancies; further, the diffusiveness of the NdSBN was studied using Uchino and Nomura function, a modified version of Curie-Weiss law (CW). The frequency and temperature-dependent dielectric study of NdSBN ceramics display a Maxwell-Wagner relaxation with a high loss in a low frequency regime, possibly due to the presence of leakage current in the solid solution. Frequency dependent AC conductivity obeys Jonscher's power law, whereas DC conductivity supports polaron assisted hopping in NdSBN composition with dual activation energies of 0.55 eV and 0.75 eV, which correspond to electrons and ions, respectively. The non-Debye type relaxation mechanism in conjunction with negative temperature coefficient of resistance (NTCR) behavior was demonstrated by temperature dependent impedance spectroscopy, while modulus spectroscopy confirmed the multiple relaxation processes in NdSBN ceramics.

Photocatalytic activity (dye degradation) of pristine and doped LaFeO3 (dopant Y at a site and Ni at B site) by impedance spectroscopy

Lanthanum iron oxide (LaFeO3) nanoparticles, doped with yttrium (Y) at the A-site and nickel (Ni) at the B-site, were synthesized using a sol-gel method at 600 °C. This study focuses on the synthesis of nanocrystalline La1−xYxFeO3 (Y doped LaFeO3), LaFe1−xNixO3 (Ni doped LaFeO3) and La1−xYxFe1−xNixO3 (Y/Ni doped LaFeO3) materials, where x = 0.01. The Synchrotron-based XRD analysis confirmed the single-phase formation of orthorhombic LaFeO3 (Pbnm space group) in each sample. The characterization through scanning electron microscopy and EDX revealed grains of irregular shape with an average particle size of around 200 nm. Optical properties were explored using UV–Visible spectroscopy, indicating a band gap of 1.7 eV for the pure sample. Additionally, the photocatalytic properties of the synthesized nanoparticles were evaluated for dye degradation. Electrical properties were systematically examined using impedance spectroscopy across a frequency range of 1 Hz–10 MHz at room temperature. The effect of doping on crystal structure and possible implications on dielectric and photocatalytic properties were studied. The complex impedance diagram displayed a depressed semicircle, suggesting non-Debye relaxation processes. A correlation was established between impedance and UV–Vis spectroscopy. However, the current literature lacks a comprehensive investigation for isovalent i.e. +3 substitution at A and B site simultaneously for dye degradation properties of LaFeO3-based materials. This study addresses this research gap by systematically exploring the influence of separate as well as simultaneous Y+3 and Ni+3 doping on the structural, optical, electrical, and photocatalytic characteristics of LaFeO3 nanoparticles, thereby providing valuable insights for the development of advanced functional materials for environmental applications. It was found that Y+3 dopants had a notable impact on the dye degradation properties for Mythlene blue dye at room temperature.

Electrical transport characteristics of rare earth ions (Er³⁺, Sm³⁺) exchanged cobalt-manganese ferrite using impedance spectroscopy

This study presents findings on the AC impedance characteristics of rare earth-doped Co0.5Mn0.5RExFe2-xO4 ferrites (where RE = Er and Sm, and 0.0 ≤ x ≤ 0.1), synthesized utilizing the citrate auto-combustion process. Employing impedance spectroscopy at frequencies ranging from (100 −1 MHz) and temperatures between 30°C and 120°C, we distinguished the impact of grains (Gs) and grain boundaries (GBs) in these compositions. The Jonscher power law was applied to characterize the AC conductivity results. The dielectric constant έ and dielectric loss ε” decline as the frequency rises and reach a stable state at higher frequencies, indicating the characteristic dielectric dispersion. This phenomenon manifests the Maxwell-Wagner polarization, as described by Koop's hypothesis. The modified Debye formula provides a good match for the frequency-dependent dielectric permittivity fluctuation. The Cole-Cole plots revealed a single semicircle for the unaltered sample and lower Er³⁺ concentrations (up to x=0.02), but two semicircles appeared at higher Er³⁺ concentrations and in the Sm³⁺ doped samples. The G and GB resistances increased with higher concentrations of Er³⁺/ Sm³⁺ but showed a decrease at x=0.1 in Sm³⁺-doped samples. The data examination designates that the resistive and capacitive possessions are predominantly affected by G and GB processes. A relaxation phenomenon in the existing samples is shown by the frequency-dependent of the imaginary portion of impedance (Z"). Remarkably, the relaxation time (τz) showed linear temperature dependence. Additionally, studies of the electrical modulus (M’ and M”) highlighted non-Debye sort dielectric relaxation in all compositions, with peaks in the imaginary modulus indicating a shift in charge carrier mobility from long-range toward short-range. The investigation focused on the non-Debye relaxation, which was analyzed by determining the stretching exponential parameter (β). This factor was obtained by fitting the modified Kohlrausch-Williams-Watts (KWW) formula to the graph of the imaginary electric modulus. The substitution of Fe3+ by Er3+ and Sm3+ ions substantially enhanced the dielectric properties, particularly Co-Mn-Sm ferrite series, suggesting their potential use in high-frequency devices.

Modulating electrical response and impedance in Co–Cr substituted M-phase barium hexaferrites: Examining microstructure, grain boundaries, charge transport, and computational modeling

This study explores the influence of Co2+ and Cr3+ doping on the microstructure and electrical properties of Ba-hexagonal ferrite synthesized using the sol-gel method. X-ray diffraction (XRD) confirmed the formation of the anticipated hexagonal M-type crystal structure. Field emission scanning electron microscopy (FESEM) revealed the evolution of grain morphology with increasing doping levels, showcasing the formation of needle-like grains. Electrical characterization using an impedance analyzer investigated dielectric, impedance, electric modulus, and conductivity properties at room temperature. The analysis of the dielectric spectra indicated a decrease in dielectric constant and an increase in loss tangent with increasing dopant concentration. The electric modulus spectra provided evidence for non-Debye relaxation behavior, further supported by observations of relaxation processes at varying frequencies in the conductivity spectra. Additionally, an increase in doping led to a decrease in both relaxation time and AC conductivity. Electrochemical impedance spectroscopy (EIS) measurements yielded complex impedance curves. These curves exhibited good agreement with the values obtained through software-based simulations of grain and grain boundary characteristics. Furthermore, the distribution of grains and grain boundaries observed in FESEM micrographs aligned with the patterns predicted by the EIS software.

Dynamics of charge carriers in La2CuO4 cuprates: Conductivity variation, scaling formalisms, and electric modulus study

In this work, we conducted a detailed investigation of the structural properties and the dynamics of the charges in the La2CuO4 Ruddlesden–Popper system that is prepared via the conventional solid-state process. Via the X-ray diffraction data and using the Rietveld refinement, we found that the compound exhibits a single crystallographic phase with a Bmab space group. The DC-conductivity investigation shows that the studied ceramic exhibits two electrical behaviors. Below 460 °C, the occurrence of a semiconductor behavior is attributed to the effect of the Variable range hopping conduction process. At high temperatures, the electrical nature of the material is linked to the thermally activated small polaron hopping conduction process via an activation energy Ea = 1.40 eV. Over the explored temperature range, conductivity spectra of the Ruddlesden–Popper are analyzed using the universal Double Jonscher power law. The dispersion region can be attributed to the coexistence of both hopping and tunneling processes. The conductivity spectra of the La2CuO4 Ruddlesden–Popper nicely follow the time-temperature superposition (TTSP) principle. This confirms that similar sources are responsible for relaxation and conduction processes. Using the Summerfield scaling approach, the superposition of the conductivity spectra into a single master curve confirms that the relaxation process is the microstructure's response independent. From the electrical modulus investigation, we found that the studied compound exhibits a non-Debye relaxation nature, over the explored temperature interval. Contribution of grain and grain boundary were resolved by complex modulus spectroscopy analysis. In addition, we found the absence of the electrode contribution at low frequencies. The correlation between both Z″ and the M″ peaks indicates that the conduction and relaxation processes are not related to the same origins.

Investigation of the role of sintering temperature on microstructure, ac conductivity, and dielectric constant of single phase NiSnO3 nanopowder

This study investigates the effect of sintering temperature on the structural and electrical properties of co-precipitated nickel stannate (NiSnO3) nanopowder. Sintering temperatures, determined using Thermo Gravimetric Analysis (TGA), reveal a pure hexagonal perovskite structure through X-ray diffraction (XRD) analysis. Crystallite size increased from 10.56 nm to 26.04 nm and lattice strain decreased from 23.05×10−3 to 2.35×10−3 with higher sintering temperatures, analyzed via the Scherrer formula. d-spacing values from SAED patterns align with XRD results, and TEM analysis shows particle size growth from ∼11.43 nm to ∼28.16 nm as sintering temperature rises from 600°C to 900°C. Elemental composition has been confirmed through EDX, and elemental mapping analysis. Impedance spectroscopy via Cole-Cole plots indicated non-Debye-type or multiple relaxations with depressed semicircles due to grain and grain boundary effects. The sample sintered at 900°C exhibits the highest conductivity (8.35×10−5 Ω−1cm−1) with lowest activation energy of 0.31 eV and maximum dielectric constant values, with a minimum relaxation time of 0.00029 sec. Also the frequency variation of Z′′ and M′′ confirm the presence of non-Debye type relaxation. Scaling behavior of the imaginary part of complex impedance and conductivity spectra confirms temperature-independent conduction and relaxation mechanisms. These materials are used in energy storage applications.

New graphene oxide doped polymer dispersed liquid crystal nanocomposites targeted to eco-friendly and energy-efficient smart windows

Graphene oxide-polymer dispersed liquid crystal (GO-PDLC) composites are proposed as a solution for energy-efficient switchable windows. These composites were prepared by incorporating varying concentrations of graphene oxide (GO) into a mixture of nematic liquid crystal (E7) and a UV–Vis curable resin using the polymerization-induced phase separation technique. The results indicate that the dispersion of GO at an optimum concentration of 0.005 wt% significantly affects the morphology, phase transition temperatures, and electro-optic properties of polymer dispersed liquid crystal (PDLC). In particular, the GO-PDLC composites exhibit a transition from an opaque to a transparent state at a remarkably low voltage (∼11.5 V) compared to pure PDLC cell. Dielectric analysis reveals that adding GO increases the permittivity, conductivity, and dielectric strength of PDLC composites. Moreover, the Cole-Cole plot indicates a non-Debye type relaxation in a higher frequency region. Furthermore, a blue shift in emission wavelength and enhanced photoluminescence intensity suggest alterations in electronic transitions within the composites. This comprehensive study provides valuable insights into optimizing the properties of PDLCs through the dispersion of GO, thereby offering promising prospects for their utilization in various optoelectronic applications.

Exploring the structural characteristics and electrical conductivity of MnTiO3 across ferroelectric and paraelectric phases

In this study, we present the ceramic's structural, dielectric, and impedance characteristics obtained through the solid-state reaction method synthesis. Initial structural analysis was conducted utilizing X-ray diffraction at room temperature. The XRD results show that MnTiO3 exhibits rhombohedral symmetry. SEM images of MnTiO3 show the presence of both cubic and large agglomerated grains. This demonstrates the effectiveness of the dielectric HN model in controlling the mechanism. The alternating current (ac) conductivity, when examined in relation to frequency, displays a remarkable adherence to the Johnscher's power law. The change in electrical modulus and the width at half maximum (FWHM) of the curve indicate that the as-prepared sample exhibits a non-Debye relaxation mechanism. Both the temperature data and the frequency dependence of the impedance were used to analyze the electrical conductivity of the sample, which showed a negative temperature coefficient resistance (NTCR).

The dielectric and radiation shielding features of Zn0.9Ni0.1Co2-xFexO4 nanopowder

Nano Zn0.9Ni0.1Co2-xFexO4 (x = 0, 0.05, 0.1, 0.15) specimens were synthesized utilizing the hydrothermal method. An extensive assessment was conducted on the structure and dielectric characteristics of the fabricated specimens. The synchrotron x-ray diffraction and scanning electron microscopy techniques were employed to analyze the formed phases and the morphological characteristics of the specimens. Rietveld refinement was utilized for determining the structural and microstructural parameters of all specimens. The impact of temperature and frequency on the dielectric properties of the material is thoroughly investigated. Except for the specimen with x = 0.15, all samples exhibit ferroelectric characteristics. The electric modulus corroborated the existence of the non-Debye relaxation phenomenon and the presence of relaxation times distributed at a specific frequency. Each specimen demonstrates a singular relaxation time, which was modified by the introduction of Fe ions. Through the utilization of the Phy-X/PSD software, the radiation shielding parameters for the examined specimens were computed across a wide energy spectrum ranging from 15 KeV to 15 MeV. These parameters encompass the linear attenuation coefficients (LAC), mean free path (MFP), mass attenuation coefficient (MAC), half value length (HVL), effective nuclear number (Z eff), and fast neutron removal cross-section (FNRCS). The specimens of Zn0.9Ni0.1Co2-xFexO4 exhibit elevated FNRCS values compared to RS-253-G18, RS-360, and RS-520 commercial shielding glasses.

Investigating grain and grain boundary effects on charge transport and dielectrics in BaCoxAlxFe12-2xO19 nanoferrites

This investigation centres on the sol-gel preparation of M-type barium hexagonal ferrite (M-BaFe12O19) incorporating Co2+ and Al3+ as dopants. X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) were employed to assess the impact of dopants on the crystallographic structure and microstructure. The dielectric characteristics, electric modulus, impedance, and conductivity of the synthesized materials were evaluated at ambient temperature using an impedance analyzer. The structural analysis verified the presence of the hexagonal M-type crystal phase. Increasing dopant levels led to a reduction in lattice parameters, signifying unit cell shrinkage. FESEM imaging exposed the emergence of needle-shaped grains resulting from the doping process. Dielectric spectroscopy showed a decrease in both the dielectric constant (from 135.95 at x = 0.0 to 39.8) and the loss tangent (from 3.68 to 0.610) as dopant concentration increased. Conductivity exhibited relaxation at varying intervals, supported by the electric modulus spectra, which validated non-Debye relaxation behavior. Both relaxation time and AC conductivity diminished with higher dopant concentrations (from 0.000222 Ωm−1 to 0.000036 Ωm−1). The relaxation observed in conductivity and dielectric responses implies their contribution to the charge transport processes within BaCoxAlxFe12-2xO19. Electrochemical impedance spectroscopy (EIS) software was used to generate complex impedance plots, which aligned with the experimentally obtained impedance values for the synthesized compositions. Micrographs revealed a distribution of grains and grain boundaries that were consistent with calculated characteristics. This further substantiates the measured dielectric and electrical parameters.

Synthesis, Structural characterization and complex impedance analysis of a novel organic-inorganic hybrid compound based on Mercury (II) chloride

The organic-inorganic hybrid compounds are promising materials due to their electro-optical and semiconducting properties. In this study, a single crystal of (C6H16N)2[HgCl4] has been synthesized and characterized using single-crystal X-ray diffraction at room temperature, SEM/EDS and complex impedance spectroscopy. The crystal structure is centrosymmetric with the monoclinic system (P21/c space group). It consists of isolated tetrahedral anions [HgCl4]2− and protonated amines (C6H16N) +. SEM/EDS analyses proved the composition of the title compound. The frequency-dependent electrical and dielectric properties were analyses using complex impedance spectroscopy in the frequency range of 10−1 Hz – 1 MHz. The Nyquist plots (-Z’’ vs Z’) was characterized by the appearance of a single semicircle arc, indicating a non-Debye type relaxation process in the (C6H16N)2[HgCl4] material. The AC conductivity followed Jonscher law, and the variation of frequency exponent s with temperature suggested that non-overlapping small polaron tunneling (NSPT) is the dominant electrical transport mechanism. So, this work will be very beneficial to the further development of the (C6H16N)2[HgCl4] compound and its potential electrical applications.

Enhancement the electrical and linear/nonlinear optical properties of ZnCo2O4 through Al3+doping

In this work, ZnCo2O4 samples doped with Al3+ were prepared by the hydrothermal method. Synchrotron x-ray diffraction, FTIR, SEM and EDX techniques were used to investigate the structure, microstructure, morphology, and composition of ZnCo2-xAlxO4 samples. Rietveld analysis revealed a nearly inverse structure for the undoped ZnCo2O4. The degree of inversion is increased upon increasing the Al3+ doping content. Al ions preferentially occupy the octahedral B-site. The optical band gaps of ZnCo2−xAlxO4 samples are 1.9, 1.8 and 1.91 eV for x = 0, 0.1 and 0.2, respectively. Different empirical models were used to obtain the refractive index of the different samples using their corresponding optical band gaps. The increase in non-linear optical values in the sample with x = 0.1 suggested that this sample could be used in a variety of photonic applications. The effects of frequency and temperature on the dielectric permittivity, impedance and electrical modulus of different samples were explored. All samples exhibited the non-Debye relaxation phenomenon. The relaxation time of each sample is affected with the frequency and temperature. The Cole-Cole curve is employed to reduce uncertainty regarding the electrical characteristics of these ZnCo2−xAlxO4 samples induced by grain boundaries or bulk grain. The substitution of Al3+ ions can regulate the conductivity of the ZnCo2O4 sample.

A double perovskite BaSrTiMnO6: Synthesis, microstructural, transport and optical properties for NTC thermistor applications

The provided communication reports the synthesis and comprehensive characterization of the BaSrTiMnO6 (BSTMO) ceramic. Rietveld analysis suggests the formation of monoclinic crystal symmetry with average crystallite size of 75.3 nm and micro-lattice strain of 0.00174. Scanning Electron Microscope (SEM) analysis reveals uniform grain distribution with well-defined grain boundaries. Well-grown grains and grain boundaries actively contribute to the transport mechanism. Energy Dispersive X-ray Analysis (EDX) is employed to check the purity and compositional analysis of the prepared sample. Raman spectrum analysis confirms the presence of all constituent atomic vibrations. UV-visible spectrum investigation yields a bandgap energy of 1.94 eV, suitable for photovoltaic applications. Maxwell-Wagner type of polarization effect is observed from frequency-dependent dielectric constant and loss study. Modulus study confirms non-Debye relaxation nature. Temperature-frequency-dependent electrical impedance analysis shows negative temperature coefficient, non-Debye type relaxation. The study of temperature dependence of resistance suggests NTC thermistor behavior.