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In this communication, preliminary structural and detailed electrical (dielectric, polarization, impedence, and conductivity) characteristics of BaSnO 3 and BaSeO 3 modified complex Bi 0.5 Na 0.5 TiO 3 ceramics with a general chemical formula and composition, (1–2x)[(Bi 0.5 Na 0.5) TiO 3 ]+x(BaSnO 3)+x(BaSeO 3) (with x = 0, 0.05, 0.1, 0.15) (BNT–BSn–BSe) ceramics, synthesized by a high-temperature mixed-oxide technique (calcinations temperature = 925 °C and sintering temperature = 950 °C, for time = 4 h each) have been reported. Analysis of room temperature X-ray diffraction data has confirmed the formation of single phase perovskite of BNT–BSn–BSe in rhombohedral phase and provided crystal data. Studies of impedance spectroscopy and electrical conductivity of the materials in a frequency range of (1 kHz-1MHz) at different temperatures (25–500 °C) have shown the composition (x) effect on electrical characteristics of BSn and BSe modified BNT.The electric field dependent polarization study at room temperature exhibits the existence of ferroelectricity in the materials. Study of the impedance spectroscopy through Nyquist plots shows the contributions of the grains and grain boundary in the resistive and capacitive properties of the materials. This study also determines the existence of NTCR (negative temperature coefficient of resistance) behavior the prepared materials. The J–E characteristics demonstrate the Ohomic behavior with slope closer to 1. [ABSTRACT FROM AUTHOR]

The double perovskite material, Nd 2 CoMnO 6 , was prepared by a standard mixed oxide route. We found the monoclinic structure of the studied material from X-ray diffraction data analysis. The microstructure study shows that the presence of almost uniform distribution of grains with small voids. The analysis of both temperature and frequency variation of electrical and dielectric characteristics have been discussed. The frequency dependence of dielectric parameter was explained as per the Maxwell-Wagner model. An anomaly behaviour was observed in the temperature dependence dielectric curve corresponds to the ferroelectric-paraelectric phase transition. We found the presence of both grain and grain boundary effects in the complex impedance analysis. The occurrence of the negative temperature coefficient of resistance (NTCR) behaviour indicates this material is a semiconducting type of material. From the analysis of J-E characteristics curve, we found the low low-leakage current density. The scaling nature of Z″ and M″ specifies that the relaxation phenomena are almost independent of temperature. The existing property makes more appropriate for modern electronic device. • The material was synthesized in solid state reaction method and crystallizes in monoclinic structure. • The dielectric property was explained on the basis of Maxwell-Wagner mechanism. • The NTCR property in the material represents semiconducting type of behaviour. • The frequency dependence of conductivity was explained on the basis of Jonscher's Power law. • The obtained low leakage current density may be applicable for high temperature application. [ABSTRACT FROM AUTHOR]

The lead-free dielectric compound Bi(Mg 2/3 Ta 1/3)O 3 (BMT) has been synthesized at high temperature by a low-cost solid-state method. The X-ray diffraction (XRD) technique reveals that the fabricated sample has an orthorhombic crystal system. The scanning electron microscope (SEM) image displays the uniform distribution of grains on the surface of the specimen. The dielectric parameters (permittivity (ε r), and loss tangent (tan δ) are studied over a wide range of temperature (150–500 °C) and frequency (1 kHz–1 MHz). The temperature dependent conductivity plot follows Universal Johnson's power law. The complex impedance and modulus spectrum illustrate the electrical behavior of the compound at various frequency and temperature. The Nyquist spectra show the presence of the effect of grain and grain boundary in the synthesized compound. The grain resistance value declines with the rise in temperature that shows the presence of a negative temperature coefficient (NTCR) behavior in the compound. The complex modulus spectra display the occurrence of the conduction mechanism in the specimen. The reported compound has a relative dielectric constant and loss of 22 × 103 and 1.8 respectively at 1 kHz frequency and 500 °C, thus becoming an efficient applicant for dielectric applications that can operate at higher temperatures. [ABSTRACT FROM AUTHOR]

• The peak in ε r v/s temperature plot shows the antiferroelectricity in the sample. • As Bi(Sr 0.5 Ti 0.5)O 3 has low loss, the Q factor of the compound is very high. • The Nyquist plot study shows electrical process is for grains and grain boundaries. • From the Nyquist plot study, the compound shows non Debye type relaxation. Bismuth strontium titanate (Bi(Sr 0.5 Ti 0.5)O 3) compound is prepared by a solid state reaction technique. It has been characterized by means of different experimental procedures. Investigation regarding crystal structure via X-ray diffraction records has revealed the orthorhombic crystal structure of the material. The quality of the sample was asserted by studying its microstructure and morphology. Detailed investigations of dielectric and electrical properties of Bi(Sr 0.5 Ti 0.5)O 3 in a broad frequency (100 Hz–1 MHz) and temperature (25–500 °C) ranges have offered various exciting results of anti-ferroelectric behavior, conduction mechanism etc. The existence of Maxwell–Wagner dielectric relaxation and space charge polarization at lower frequencies and higher temperatures in the material has been observed. The analysis of Nyquist graphs confirmed the temperature-dependent grain and grain boundary effects. The transport properties and ac conductivity of the material, which are strongly affected by the temperature and frequency of the applied electric field, have been studied. [ABSTRACT FROM AUTHOR]

Some composites fabricated with PVDF (Poly-Vinyl-difluoride) and BFO (BiFeO 3 ) in 0–3 connectivity have been fabricated by a solution-casting method. The existence of all three polymorphic phases (α-, β- and γ-) of PVDF in the composites is confirmed by analysing x-ray diffraction (XRD) and Fourier Transform Infrared (FTIR) spectra. The intensity of the XRD peaks of the crystalline phase of the BFO ceramics increases with the increase of BFO filler concentration in the composites. Studies of micrographs recorded by scanning electron microscopy (SEM) technique reveal that the filler-particles have homogeneously been dispersed in the polymer matrix. The dielectric properties of the composites are very much dependent on both volume fraction of the filler and frequency of the applied field. The percolation threshold of electric field is observed in the composite at 50 vol percentage of BFO filler. A large enhancement in the dielectric constant and ferroelectric polarization in the composites is observed as compared to those of pure PVDF. With increase in BFO content in the composites, the leakage current density improves. Some IR inactive vibrational mode frequencies is found to be disappeared in the range of 400–800 cm −1 in FTIR spectra indicating a possible interaction between some molecules of PVDF and BFO. Incorporation of BFO filler in the polymer matrix has resulted in increase of optical band gap. [ABSTRACT FROM AUTHOR]

La 0.5 Na 0.5 Ga 0.5 V 0.5 O 3 (LNGVO) ceramic was prepared using a high-temperature solid-state reaction method. The structural phase, microstructure, dielectric, ferroelectric and optical properties of the material were systematically investigated. The preliminary structural analysis using x-ray diffraction (XRD) data shows the formation of the material in an orthorhombic crystal structure at room temperature. Detailed studies of dielectric and electrical properties have been carried out over a wide range of frequency (1 kHz–1 MHz) and temperature (25–450 °C) in order to elucidate the basic mechanism of the conduction and relaxation process. The dielectric characteristics show that the ceramic is a relaxor with strong diffuse phase transition and frequency dispersion. The nature of the variation of ac conductivity as a function of frequency obeys the universal power law, and confirms the existence of a hopping conduction mechanism in the material. The material also exhibits ferroelectricity at room temperature with a very low value of remnant polarization. The ionic conductivity and transport number of the ferroelectric ionic conductor were obtained with the standard experiment and calculation respectively. The material shows NTCR behavior similar to that of a semi-conductor. Similar behavior has also been observed in the study of I–V characteristics of the material. [ABSTRACT FROM AUTHOR]

The present work reports the synthesis and characterization of the ilmenite-type rhombohedral structured CoTiO 3 ceramic. The polycrystalline powder of CoTiO 3 was prepared by the mixed-oxide technique. X-ray structural analysis of the compound confirmed the formation of a single-phase compound. The study of microstructure by scanning electron microscopy shows that the compound has well defined grains which are distributed uniformly throughout the surface. It shows that the grain size lies in the range of 8–10 μm. The Fourier transform infrared spectroscopy (FTIR) studies confirm the presence of Ti O, Ti O Ti, Ti O O, Co O bond in the studied compound. The frequency dependence of dielectric constant was explained on the basis of Maxwell–Wagner mechanism and Koop's phenomenological theory. The frequency-temperature dependence of impedance analysis shows that the bulk effect dominates up to 250 °C, and the appearance of second semicircular arc above 280 °C indicates the presence of grain boundary effect in the sample. The depressed semicircles in Nyquist plot with depression angles clearly indicate the distribution of relaxation times in the ceramic samples. It also shows that the material has negative temperature co-efficient of resistance similar to that of semiconductors. Similar behavior has also been observed in the study of I V characteristics of the material. Through the study of dc conductivity of CoTiO 3 and using the relation; ln σ dc α E a /K B T, activation energy of the compound was calculated. The frequency dependence of ac conductivity is explained on the basis of Correlated barrier Hopping Model. [ABSTRACT FROM AUTHOR]

[Display omitted] • The synthesis of a stable BaKFeWO 6 double perovskite from BaWO 4 & KFeO 2 two non-perovskites materials. • Semiconducting property and NTC thermistor applications. • The study of I-V characteristics confirms the Ohmic nature with a low leakage current. • The study of UV visible spectrum provides the energy bandgap of 3.16 eV; which was found suitable for some optoelectronic devices. In this paper, the synthesis (solid-state reaction) and characterization (structural, electrical, and optical) of K+/Fe+3 co-doped inorganic BaWO 4 (i.e., BaKFeWO 6) double perovskite are reported. The x-ray diffraction (XRD) profile suggests an orthorhombic crystal symmetry with an average crystallite size of 95 nm and a lattice strain of 0.145 %. The incorporation of the potassium/iron ions on both sides of the barium tungstate is confirmed from RAMAN while microstructure (grain/grain boundary) analysis by scanning electron microscopy (SEM). The study of energy-dispersive X-ray spectroscopy (EDX) confirms the presence of all constituent elements with both weight and atomic percentage. The study of dielectric as a function of both frequency (1 kHz −1 MHz) and temperature (25 °C – 500 °C) insights into the structure, grain, grain boundary, transport properties and charge storage capacities. Modulus study suggests a non-Debye relaxation mechanism while impedance analysis suggests a negative temperature of coefficient of resistance (NTCR) behavior. The temperature-dependent dc conductivity follows Arrhenius's relation while frequency-dependent ac conductivity obeys Jonscher's power law and confirms the presence of the thermally activated conduction mechanism. The variation of the resistance with temperature confirms the character of the NTC thermistor. The I-V study supports the low leakage current and Ohmic character of the sample. The study of UV visible spectrum provides band-gap energy of 3.16 eV for some device applications. [ABSTRACT FROM AUTHOR]

A polycrystalline sample of (Bi0.5K0.5)(Fe0.5Nb0.5)O3 was prepared using a mixed oxide at 1000 °C. The preliminary structural analysis using X-ray diffraction data of the compound indicates the formation of a single-phase rhombohedral structure similar to that of parent BiFeO3. Microstructural and elemental analysis using a scanning electron micrograph and energy-dispersive X-ray spectroscopy, respectively, were carried out at room temperature with higher magnification exhibiting a uniform distribution of grains and stoichiometry. The appearance of hysteresis loops ( P- E) confirms the existence of ferroelectricity of the sample with a high remnant polarization of (2 Pr) 17.76 μCcm−2. Using impedance spectroscopy, the electrical properties of the material were investigated at a wide range of temperature (25-500 °C) and frequencies (1 kHz - 1 MHz) suggesting dielectric non-Debye-type relaxation in the material. The nature of the Nyquist plot ( ∼ ) shows the dominance of the grain contribution in the impedance. The bulk resistance of the compound decreases with increasing temperature, like that of a semiconductor, which shows a negative temperature coefficient of resistance (NTCR) behavior. The frequency dependence of AC conductivity suggests that that the material obeys Jonscher's power law. Magnetic hysteresis ( M- H) loop shows very weak ferromagnetic behavior at room temperature. [ABSTRACT FROM AUTHOR]

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Highlights: [•] Barium orthoniobate (lead-free perovskite) crystallizes as palmierite with structural stability. [•] The material exhibits ferroelectric phase transition of diffuse-type suitable for devices. [•] The low values of εr and tan δ at high frequencies makes it a potential candidate for microwave applications. [•] The material has very good pyroelectric properties for detector application. [•] The material exhibits smaller value of dc activation energy. [ABSTRACT FROM AUTHOR]

Highlights: [•] The nanoceramics of La/Mn modified PbTiO3 are synthesized by mechano-thermal route. [•] Materials have been characterized using various experimental methods. [•] Drastic change in dielectric and electrical properties of PbTiO3 has been observed. [•] The high dielectric constant makes the material very promising candidate for DRAM. [•] The Mn substitution also makes the material useful for piezoelectric devices. [Copyright &y& Elsevier]

Abstract: The polycrystalline samples of Sr(Fe2/3W1/3)O3 (SFW) were prepared by a high-energy ball-milling followed by solid-state reaction technique. The X-ray structural analysis showed the formation of single-phase compound in the tetragonal system, which is a distorted structure of an ideal cubic perovskite. The temperature–frequency dependence of dielectric constant and loss tangent exhibited relaxation behavior of the compound. The studies of impedance parameters (Z′, Z″) as a function of temperature and frequency have confirmed the contribution of bulk resistance of SFW. The small value of activation energy of the compound (∼0.35eV) can be explained by mixed ionic–polaronic conductivity mechanism. [Copyright &y& Elsevier]

Abstract: A high-temperature solid-state reaction technique was used to prepare polycrystalline samples of Pb(Zr0.65− x Ce x Ti0.35)O3 (x=0, 0.05, 0.10, 0.15) (PZCT). X-ray diffraction (XRD) technique and scanning electron microscopy (SEM) were used to study the structural and microstructural properties of the compounds, respectively. The XRD study confirmed the formation of compounds at room temperature. Microstructural analysis of the surface of the compounds exhibits that there is a change in grain size, shape and density on introduction of cerium (Ce) in PZCT. Detailed studies of the dielectric properties reveal that PZCT show: (i) increase in Tc on increasing Ce concentration and (ii) improvement in dielectric constant and ac conductivity. [Copyright &y& Elsevier]

Abstract: The effect of plasticizer (polyethylene glycol, PEG200) on dielectric and electrical properties of an ionically conducting polymer nanocomposites PEO25-NaI+5wt.% DMMT (dodecyl amine modified Na+-montmorillonite)+ x wt.% PEG200 with different value of x has been investigated. At low frequency, the variation of relative dielectric constant with frequency shows the presence of material electrode interface polarization processes. The tangent loss peaks appearing at a characteristic frequency suggest the presence of relaxing dipoles in all the samples. On addition of plasticizer, the peak shifts towards higher frequency side suggesting the speed up the relaxation time. The electrical modulus formalism is used to study the ionic relaxation processes in these composites in terms of conductivity relaxation time. Analysis of electrical modulus and dielectric permittivity functions suggest that ionic and polymer segmental motions are strongly coupled. The frequency dependence of ac conductivity follows the universal power law with a small deviation in the low frequency region due to the electrode polarization effect. [Copyright &y& Elsevier]

Abstract: The polycrystalline samples of Pb(Zr0.65−x Mn x Ti0.35)O3 (x =0, 0.05, 0.10, 0.15) (PZMT) were prepared by a high-temperature solid-state reaction technique. Structural properties of the compounds were examined using an X-ray diffraction (XRD) technique to confirm the formation of single-phase compounds (with perovskite structure) at room temperature. Microstructural analysis of the surface of the compounds by scanning electron microscopy (SEM) exhibits that there is a significant change in grain size on introduction, at the Zr-site, of Mn. Detailed studies of the dielectric properties of PZMT show a measurable shift in T c, change in dielectric constant, and ac conductivity. [Copyright &y& Elsevier]

Abstract: Polycrystalline samples of Nd2(Ba0.5R0.5)2O7 (R=W, Mo) were synthesized using a high-temperature solid-state reaction technique. A preliminary structural (XRD) analysis of these compounds show the formation of a single-phase orthorhombic system at room temperature. The scanning electron microscopic (SEM) study with different magnifications provides information on quality of these samples and the uniform grain distribution over the entire surface of the samples. Detailed studies of dielectric constant (ε r and loss tangent (tan δ)) as a function of frequency (50–104 Hz) at different temperatures (300–623K) revealed that the compounds do not have any dielectric anomaly in the studied frequency and temperature range. The nature of variation of (dc) resistivity at three different temperatures, and its variation with temperature (∼300–623K) at a constant electric field (50V/cm) showed the semiconductor characteristics of the materials. [Copyright &y& Elsevier]

Abstract: The solid solutions of (1− x)BiFeO3 (BFO)− xBa(Zr0.4Ti0.6)O3 (BZT) with x =0, 0.15, 0.25, 0.40, and 0.50 were prepared by mechano-chemical and solid-state reaction techniques. The distortion in the parent structure (i.e., BFO and BZT) of (Bi1−x Ba x )(Fe1−x Zr0.6x Ti0.4x )O3 (BBFZT) system has been estimated by the tolerance factors (t), which are significantly different from the ideal perovskite (t =1). The dielectric constant and the loss tangent of BFO were found to be decreased on increasing BZT contents in the solid solutions. The values of loss tangent, leakage current and electrical conductivity of BBFZT were significantly improved on increasing BZT contents of BBFZT. [Copyright &y& Elsevier]

Polycrystalline samples of MgTeO 3 were prepared by a conventional solid-state reaction technique at 750°C. An X-ray powder diffraction (XRD) technique was used to check the formation of a single phase MgTeO 3 compound with cell parameters a = 4.421(1) Å, b = 14.916(1) Å and c = 12.289(1) Å in an orthorhombic crystal system. Detailed studies of dielectric and electrical properties show that the compound has a sharp ferroelectric phase transition of first order. [ABSTRACT FROM AUTHOR]

In this communication, the structural and electrical (dielectric, polarization, impedence, and conductivity) properties of the polycrystalline samples of Ca/Zr modified BiFeO 3 samples with chemical formula (Bi 1-x Ca x) (Fe 1-x Zr x)O 3 ; x = 0.05, 0.1, 0.15, 0.20 were prepared using a solid-state reaction method at 800 °C have been reported. The analysis of room temperature X-ray diffraction data of above-synthesized electro-ceramics confirms the formation of single phase perovskite in rhombohedral phase. The scanning electron microscope photographs provide the micro-structural study of the samples. The existence of ferroelectricity in the materials was studied by the variation of electric polarization with the applied electric field. Many important results have been obtained from the dielectric and impedance studies of the samples at a varying frequency (1 kHz–1000 kHz) and temperature (250C–300 °C). The contribution of both grains and grain boundaries towards the total resistance and capacitance of the four compounds is found from the Nyquist plots. From the conductivity study, the dielectric properties and conductivity of the materials were obtained. The J–E characteristics of the samples provide the Ohmic behavior with slope closer to 1. • Rietveld refinement confirms the compounds crystallize with rhombohedral (R 3 c) symmetry. • A small tangent loss with high dielectric constant and improved ferroelectric characteristics are achieved. • The P-E loops show the ferroelectric behavior. • The J-E characteristics confirms the Ohmic behavior. [ABSTRACT FROM AUTHOR]

Bismuth barium magnesium ferric titanate (Bi 0.5 Ba 0.5) (Mg 0.125 Ti 0.625 Fe 0.25)O 3 is fabricated through a standard ceramic technology route. By using various experimental techniques, the material has been characterized. Study of crystal structure using XRD (X-ray diffraction) data shows the rhombohedral system. Analysis of dielectric study reveals that the compound has low tangent loss and high dielectric constant at room temperature. At low frequencies and high temperatures, the existence of space charge polarization and the Maxwell–Wagner dielectric mechanism in the material has been realized. The existence of ferroelectricity in the material is confirmed by the PE loop. The impedance plots reveal that the compound shows semiconductor (based on negative temperature of coefficient of temperature) behavior at high temperature ≥ 300 °C. Analysis of Nyquist plots reveals the non-Debye type of dielectric relaxation and the contribution of grains and grain boundaries in the resistive and capacitive nature of the material. From the conductivity analysis, it can be seen that the sample obeys the Josher universal power law, and the Arrhenius type of conductivity. The low-leakage current of compound makes it suitable for the high temperature applications, and hence it shows probable Ohmic-type of conduction mechanism. • The high values of dielectric permittivity and low tangent loss make these materials suitable for devices applications. • The impedance analysis reveals that the dielectric relaxation in the material is a non -Debye type. • The grain and grain boundary effects in electrical conduction have been confirmed. • The material has a low leakage current value. [ABSTRACT FROM AUTHOR]

This article demonstrates that both ferroelectric and magneto-electric responses can be attained simultaneously in the ceramics of NiTiO 3 , Bi-modified NiTiO 3 , Bi- and PbTiO 3 -modified NiTiO 3 synthesized by the precursor solution method. The samples have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), ultraviolet–visible (UV–Vis) spectroscopy, electric field dependent polarisation (P-E hysteresis measurement), magneto-electric coefficient measurement, impedance spectroscopy, and electronic conductivity measurement techniques in different experimental conditions. The modifications of NiTiO 3 with bismuth and then with lead titanate (PbTiO 3) have provided a pure-phase perovskite structure with an excellent crystalline morphology, featuring a high relative permittivity and enhanced ferroelectricity and magneto-electric effect. It also exhibits that not only the magneto-electric effect is enhanced, but also the leakage current is reduced with the modifications. • The samples were synthesized by precursor solution method. • The dielectric constant, impedance and conductance were analyzed. • Enhancement in ferroelectricity and Magneto-electric coefficient value were observed in NiTiO 3 after modifications. • The modifications in NiTiO 3 result in the reduction of leakage current. [ABSTRACT FROM AUTHOR]

Ba(Fe 1/3 Ti 1/3 W 1/3)O 3 , was successfully prepared by the cost effective mixed oxide reaction method at 1000 °C. Analysis of X-ray diffraction (XRD) data indicates the crystallization of the compound in the orthorhombic crystal system. A dielectric anomaly observed at around 59 °C shifts to the higher temperature side with increase in frequency can be explained by Maxwell-Wagner polarization mechanism, whereas an another anomaly observed at 126 °C can be considered as the ferroelectric to paraelectric transition. The dielectric property was analyzed by modified Cole-Cole relation, and the impedance using Nyquist plot. The activation energy calculated from grain resistance and the relaxation parameters amounts to be 0.54 eV. Analysis of the conductivity curves using the Jonscher's power law suggests OLPT model and CBH model as the dominant conduction mechanism in the ferroelectric and paraelectric phase in the sample. The ferroelectricity of the sample was confirmed by the room temperature P ~ E loop. [ABSTRACT FROM AUTHOR]

Bismuth calcium titanate (BiCa 0.5 Ti 0.5 O 3 ) ceramic, fabricated by a ceramic processing technique, has been characterized using a variety of experimental techniques. Analysis of basic crystal structure using X-ray diffraction data exhibits the orthorhombic system. Measurements and detailed analysis of some electrical parameters (i.e.,dielectric constant, loss tangent (energy loss), electrical impedance and modulus, conductivity, etc.) of Bi(Ca 0.5 Ti 0.5 )O 3 in a wide range of frequency (10 3 –10 6 Hz) and temperature (30–500 °C) have provided some interesting and useful data and results on structure–properties relationship, conduction mechanism, etc.The role of interface, space charge polarization and Maxwell–Wagner dielectric relaxation in getting high dielectric constant of the material at low frequencies and high temperatures has been discussed. Study of temperature dependence of Nyquist plots clearly shows the contributions of grains in resistive and capacitive properties of the material. The frequency of the applied electric field and temperature strongly affect the dielectric (permittivity and dissipation of energy) and electrical (impedance, electrical modulus and conductivity) characteristics of the material. [ABSTRACT FROM AUTHOR]

The structural transformation, ferro-paraelectric and magnetic ordering induced dielectric phase transitions, multiferroic properties, relaxation and conduction mechanisms of (Gd 1- x Ba x)(Fe 1- x Ti x)O 3 ceramics with different compositions (x = 0.0–0.4) have systematically been investigated. The chemical route is adopted for material synthesis. Rietveld refinement reveals the structural transformation from orthorhombic to mixed phase (coexistence of orthorhombic and tetragonal phase) for x > 0.2. The analysis of the FESEM micrographs suggests a decrease in average grain size with the increase in BT in the composition. Dielectric anomalies are explained based on ferroelectric-paraelectric phase transition of BaTiO 3 , polarization induced by a spin reorientation, and antiferromagnetic ordering of GdFeO 3. The multiferroic properties of all the samples are studied from P-E, M-H, and magneto-electric plots. The improved magnetic properties in compositions x = 0.1–0.3, make them suitable candidates for spintronic devices. The maximum magneto-electric coupling coefficient of 4.77 mV/cm‧Oe in the composition x = 0.3, makes it very much suitable for application in magnetoelectric coupling devices. [ABSTRACT FROM AUTHOR]

[Display omitted] • The material is new ceramic with no previous data. • The material exhibits a high dielectric constant with low loss, which is suitable for electronic devices. • The impedance analysis established the material's Negative Temperature Coefficient of Resistance (NTCR) behaviour. • The study of the UV spectroscopy indicated a band gap of 4.01 eV of the material. • The developed system could be a potential candidate for the thermistor application. This communication delves into the structural, microstructural, dielectric, impedance, modulus, and optical properties of the double-perovskite ceramic Na 2 MnWO 6. Our X-ray diffraction study revealed a multiphase crystal structure in this ceramic, a result of high-temperature mixed-oxide synthesis. Morphological studies indicated a nearly uniform grain scattering and distribution with minimal spaces. The Maxwell-Wagner model, by addressing alternative polarisation mechanisms, studied the frequency-dependent dielectric properties. Our study of temperature-dependent dielectric permittivity identified a ferroelectric to paraelectric phase transition dielectric aberration. The material's NTCR characteristic was determined using impedance analysis. Jonscher's power law showed that the conduction mechanism follows the overlapping of large polaron tunnelling and correlated barrier hopping models, establishing the link between conductivity and frequency. Relaxation and conduction activation energies support electron hopping. UV spectroscopy revealed a band gap of 4.01 eV, and temperature-dependent resistance studies suggest a potential use in thermistors with due parameters. These findings significantly enhance our understanding of NMWO, paving the way for its potential uses in electronics and optics, owing to its unique structural, electrical, and optical features. [ABSTRACT FROM AUTHOR]

Abstract: The polycrystalline complex tungsten–bronze (TB) type compounds LiBa2Nb5O15 (LBN) and LiBa2Ta5O15 (LBT) were prepared by a high-temperature solid-state reaction technique. X-ray diffraction (XRD) study confirmed the formation of single-phase orthorhombic compounds in the crystal system at room temperature. Microstructural analysis of the surface of the compounds by scanning electron microscopy (SEM) suggests that small grains are uniformly distributed on the surface of the samples. Detailed studies of the dielectric properties suggest that they have undergone a phase transition well above the room temperature. Measurements of electrical conductivity (dc) as a function of temperature confirm the semiconducting properties of the compounds much above the room temperature with negative temperature coefficient of resistance (NTCR) behaviour. [Copyright &y& Elsevier]

Abstract: A ferroelectric ceramic based on Te-modified BaSnO3 with a general formula BaSn1−x Te x O3 (x =0, 0.05, 0.10, 0.15) has been synthesized by a high-temperature solid-state reaction technique. Thermal analysis (DTA, TGA and DTG) was carried out to optimize calcination temperature and other experimental conditions of material formation. Preliminary structural analysis indicates that crystal structure of the material is basically cubic and remains unaffected even on Te-doping. Microstructural analysis of the sample reveals polycrystalline nature and substantial modification in surface properties of the materials on Te-doping. Detailed studies of dielectric properties of the compounds as a function of temperature showed a ferroelectric–paraelectric phase transition. It has been observed that the value of peak dielectric constant (ɛ max) and Curie temperature are strongly dependent on frequency and dopant concentration. An evidence of relaxor property has also been noticed for each concentration of the Te-dopant. Studies of electrical conductivity of the Te-doped BaSnO3 show a substantial enhancement in its value at elevated temperatures. [Copyright &y& Elsevier]

Two new compounds Bi 2 GdZrVO 9 and Bi 2 DyZrVO 9 of the Aurivillius family having two pseudo perovskite units per cell are processed by the solid-state reaction method. The effect of the lanthanides at the A-site and a combination of transition elements at the B-site of the bismuth layer structured compounds are discussed in detail. The Nyquist plots confirm the contribution of only grain to the polarization mechanism, and thus the depression angle was obtained to estimate its deviation from the Debye behavior. The activation energy estimated for the relaxation process, conduction process, and the grain resistance suggests the involvement of ionization of oxygen vacancy in these processes. The dielectric properties of both the samples were studied in detail and found to have better values as compared to those of the other members of the bismuth layer family. The conductivity analysis using Jonscher's power law is employed to ascertain the conduction mechanism in the samples. Figure and its inset represent the temperature variance of ε ′ r and the hysteresis loop respectively. [Display omitted] • Bi 2 GdZrVO 9 and Bi 2 DyZrVO 9 were synthesized by the mixed oxide reaction method and crystallized in the orthorhombic system. • Impedance analysis of both the samples substantiates the role of only grain effect towards the total polarization. • The ε ′ r of BGdZrV and BDyZrV are 557 and 307 respectively as compare to that of 170 for Bi 3 TiNbO 9 at 1 MHz and 525°C. • Jonscher's power law favors the OLPT mechanism in BGdZrV and the CBH mechanism in the BDyZrV conduction process. [ABSTRACT FROM AUTHOR]

This investigation involves the synthesis and study of dielectric, structural and impedance properties of polycrystalline Bi(Ni 2/5 Ti 2/5 Fe 1/5)O 3 (symbolized as BNTF) nano-ceramic. The BNTF polycrystalline sample was fabricated through the use of a conventional solid-state reaction route. X-ray structural examination reveals that the parent compound (i.e., BiFeO 3) crystallizes in the rhombohedral structure (space group-R3c) while that the BNTF compound crystallizes in orthorhombic symmetry. The substitution of NiTiO 3 into BiFeO 3 enhances various properties and reduces electrical leakage current. The average crystallite size is calculated to be 29 nm. The room temperature textures and surface morphologies of the specimen were verified by field-emission scanning electron microscope, and show uniform grains distribution on sample surfaces. Dielectric parameters (constant and tangent-loss) and impedance spectroscopy parameters of NiTiO 3 modified BiFeO 3 compound were investigated over a wide temperature range (25–500 °C) at different frequency (25 kHz-500 kHz), which offers several interesting features of BNTF material suitable for further device applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • Improved ε r and ac-conductivity of Sn-modified lead germanate. • Temperature-dependent dielectric and electrical properties. • Decreased E a and revealed conduction mechanism of PGSO at higher temperatures. • NTCR behavior of PGSO for high-sensitivity thermistors and sensors. • Thermistor constant (β) of 1662 K in 250 °C-300 °C. A solid-state reaction was used to synthesize the tin modified lead germanate: Pb 5 Ge 1.5 Sn 1.5 O 11 (PGSO). The composition was modified to enhance its dielectric and electrical properties. The PGSO sample was characterized by various analytical techniques, such as XRD for structural analysis and FTIR for additional structural information. The surface morphology and features of PGSO were examined by SEM, while its band gap was determined by UV–Visible-Diffuse Reflectance Spectroscopy absorbance spectra. The impedance, dielectric behaviour, AC conductivity, activation energy, and modulus of PGSO were also studied. The temperature dependence of the dielectric constant and AC conductivity showed an increase with increasing temperature. The electrical resistivity (R) decreased as the temperature increased from 100 °C to 300 °C, exhibiting a NTCR behaviour for PGSO sample, which could be applied as a high temperature thermistor and sensor, and could be used to fabricate a high sensitivity, low-cost thermistor. The circuit parameters such as bulk resistance (R b), frequency factor (n), and bulk capacitance (C b) were determined by fitting the Nyquist plot using an equivalent circuit (CQR)(CR). [ABSTRACT FROM AUTHOR]

The manganese modified Bi 0.5 K 0.5 TiO 3 ceramic (i.e., Bi 0.5 K 0.5 Ti 0.80 Mn 0.20 O 3) was synthesized by a standard solid-state reaction route. Rietveld refinement of X-ray diffraction data confirms that the compound crystallizes in the tetragonal symmetry with P4bm space group. The substitution of 20% Mn ions at the Ti-sites results in a substantial increase in the dielectric constant and a decrease in the dielectric loss in the compound making the material attractive for high-frequency device applications. The analysis of complex impedance and modulus spectroscopy confirms the non-Debye type of relaxation mechanisms in the material with contribution from both the grain and grain boundary to the electrical properties. The AC conductivity data are analyzed to determine the activation energy of the charge carriers participating in the conduction process and to predict the dominant conduction mechanism in the sample. • Rietveld refinement confirms the tetragonal structure of the compound. •NTCR behavior was observed. •Impedance and Modulus spectroscopy confirms the non Deby type relaxation nature of the material. [ABSTRACT FROM AUTHOR]

In this present communication, a polycrystalline lead-free system with composition Bi 0.60 Li 0.40 Fe 0.60 Nb 0.40 O 3 (BLFNO termed further) is synthesized using a cheap conventional ceramic processing route. It featured with resistive, capacitive and dielectric properties of the synthesized composition. Room temperature XRD (X-ray diffraction) technique used to determine the single phase formation, structure and lattice parameters. The SEM micrograph reveals the non-uniform distribution of grains with highly dense grain growth. The complex impedance and modulus technique help to analyze the electrical properties of the sample. The frequency and temperature dependent electrical characteristics occurring in the sample were carried out in a wide temperature (25–500 °C) and frequency (1 kHz-1MHz) range. The Nyquist plot depicts the contribution of both grain and grain boundary effect in the prepared composition. The temperature dependent AC conductivity shows the activation energy for conduction. The frequency dependent electrical modulus and impedance analysis suggest non–Debye type relaxation behavior in the sample. Image 1 • Tetragonal phase has been confirmed using XRD analysis. • The CIS spectra show the non-Debye type of mechanism and contribution of grains and grain boundaries. • P-E loop suggests ferroelectricity in the prepared sample. [ABSTRACT FROM AUTHOR]

The polycrystalline 0.7Bi(Fe 0.98 Ga 0.02)O 3 -0.30BaTiO 3 (BFG-BTO) ceramic was processed by high temperature reaction route. The room temperature X-ray spectra suggest a tetragonal symmetry. The structural refinement was also carried out. The high densification of sample formation is depicted from a scanning of the natural surface of the sample. The electrical properties were measured using a complex impedance method over a wide range of frequencies and temperatures. The overlapping large-polaron tunnelling model type of conduction mechanism is obtained from the frequency dependent ac conductivity plots. The relaxation mechanism is studied with the help of various spectroscopic tools (modulus and dielectric). The Nyquist plot indicates the non-Debye characteristics and the combined contribution of both grain and grain boundary towards the resistive property of the sample. Image 1062858 • The BFG-BTO is synthesized by cheap cost ceramic processing. • Dielectric properties with respect to temperature is investigated. • The complex impedance plots shows grain and grain boundary effects in the BFG-BTO. • A well defined relaxation mechanism was identified by modulus analysis. [ABSTRACT FROM AUTHOR]

The structural, electrical and multiferroic characteristics of (Ba 1- x La x ) (Ti 1- x Fe x )O 3 (i.e., (1- x ) BaTiO 3 - x LaFeO 3 ) with ( x  = 0.0–0.5) were investigated. The samples prepared through a chemico-thermal route were found to crystallize in a tetragonal structure similar to that of its parent BaTiO 3 . Elemental content, surface morphology and vibrational characteristics (from Raman spectra) of the samples were also analyzed. The temperature dependence of dielectric characteristics of all the materials has been studied using a multi-peak Gaussian model. The dielectric peaks are attributed to the magnetic transitions of LaFeO 3 and the ferroelectric-paraelectric transition of BaTiO 3 . The existence of multiple transitions in (Ba 1- x La x ) (Ti 1- x Fe x )O 3 compounds leads to higher values of dielectric constant in a wide range of temperature. Due to the high dielectric or tangent loss of the materials with higher x content, these materials might be suitable for use as microwave absorber. The relaxation and conduction mechanism of all the materials have been investigated. The multiferroic characteristics of the samples have been analyzed with room temperature P-E, M − H and M-E plot. [ABSTRACT FROM AUTHOR]

A polycrystalline vanadium doped lead free dielectric material of Bi(Zn 2/3 V 1/3 )O 3 (BZV) has been prepared using a standard high-temperature solid state reaction technique. Its temperature and frequency dependent capacitive, conductive and resistive characteristics are outlined though experimental investigation. The formation of single phase compound of BZV material with orthorhombic crystal symmetry is identified through X-ray diffraction data analysis, and the homogeneous distribution of grains are realized through scanning electron micrograph. The acquaintance of frequency–temperature dependent electrical parameters with the obtained micrograph provides the experimental evidence of contributions of grain as well as grain boundary in its capacitive and resistive characteristics. The negative temperature coefficient of resistance behaviour of the material is revealed from impedance characteristic, and non-Debye type relaxation has been realized from the Nyquist plot. The charge carriers of this electronic compound have both long & short range order that has been validated from the complex modulus and impedance analysis. The prepared electronic material substantiate some important dielectric features which props up the material as promising component for electronic devices. [ABSTRACT FROM AUTHOR]

The rapid evolution of modern technology for the sustainable development of human beings demands eco-friendly, flexible, cost-effective, and lightweight smart materials. Ceramics-polymer composites are those novel materials with improved features, which fulfill the prerequisite conditions for application in flexible devices. Pristine PVDF is one of such electroactive flexible polymers which exhibits good dielectric, ferroelectric and piezoelectric properties. But, its functional properties in the perspective of device application still need improvement and this can be achieved by adding filler to the pure PVDF. In this communication, we have reported the influence of Hafnia-Zirconia (HZ) ceramics (0.19HfO 2 -0.81ZrO 2) filler on structural, microstructural, dielectric, and electrical properties of pure PVDF matrix. The polymer-ceramics flexible composites are synthesized by an eco-friendly and cost-effective method i.e., solution casting method. The phase formation of flexible composites is confirmed from the room temperature XRD spectra. The degree of crystallinity increases with an increase in filler content. The degree of β-phase crystallinity is found to be maximum for 5 wt% of the ceramics filler. An enhanced dielectric constant of ~53 and 20 was observed (as expected) for 5 and 10 wt% of HZ ceramics filler respectively at 100 Hz due to the enrichment of polar β-phase for these two ceramics-polymer composites. The influence of filler content on the dielectric properties was explained based on the percolation model. Relaxation and conduction mechanisms of flexible composites are analyzed from the impedance spectroscopy and ac conductivity study, respectively. • Ceramics-polymer flexible composite films were prepared by solution casting method. • (0.19HfO 2 -0.81ZrO 2) ceramics filler of various weight% was added to PVDF matrix. • Improved polar β-phase and degree of crystallinity obtained for studied samples. • Enhanced dielectric constant with reasonable tangent loss was obtained. • Relaxation mechanisms are analyzed from impedance spectroscopy. [ABSTRACT FROM AUTHOR]

Abstract: Pb[(Mg3/4Co1/4)1/3Nb2/3]O3 (PMCN) ceramic was prepared by a columbite precursor method. The structural analysis revealed the cubic phase of PMCN at room temperature. Dielectric studies of the compound indicated the relaxor behaviour with diffuse phase transition (DPT). The transition temperature (T m) was found to be at −22 °C at 1 kHz. The frequency dependence of T m has been modeled using Vogel–Fulcher relation. The dielectric relaxation in PMCN is found analogous to the magnetic relaxation in spin-glass system. Complex impedance analysis indicated multi-Debye-type dielectric relaxation in PMCN and relaxation frequency shifts to higher frequencies with the increase in temperature. [Copyright &y& Elsevier]

Single phase perovskite ceramic Pb(Mg1/4Cd1/12Nb2/3)O3 (PMCN) was prepared by the high temperature solid-state reaction method. Dielectric constant and loss tangent were measured over a frequency range 1 kHz–1 MHz in the temperature region -50 –115 °C. Dielectric studies revealed the relaxor behaviour with diffuse phase transition. The frequency dependence of the temperature of the permittivity maximum (Tm′) has been modeled using Vogel–Fulcher relation. The dielectric relaxation in PMCN is found to be analogous to the magnetic relaxation in spin-glass system. [Copyright &y& Elsevier]

Polycrystalline samples of (Pb0.92R0.08)(Zr0.6Ti0.4)0.98O3 (R=La, Nd, Sm, Eu, Gd, Dy, Er and Yb) (PRZT) were sol-gel grown. The structural and microstructural properties of the compounds were examined through XRD, SEM, and TEM techniques. Detail analyses of the dielectric constant at different temperatures (30–430 °C) at 104 Hz suggest that the compounds (except Yb doped PZT) undergo diffuse phase transition of the second order. Piezoelectric and polarization studies provided some interesting physical parameters useful for device applications. [Copyright &y& Elsevier]