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In this study, the impact of Nd doping on the structural, microstructural, dielectric, ferroelectric, and transport properties of Pb (1 - x) Nd x (Fe 0.5 Nb 0.5) 1 - x / 4 O 3 (PNFN) solid solutions ( x = 0 , 0.02 , 0.04 , 0.08 , and 0.1 ) is reported. For all the solid solutions, room temperature Rietveld refined X-ray diffraction (XRD) analysis reveals the monoclinic crystal structure with Cm space group. From Field emission scanning electron microscope (FESEM) studies, the polyhedral-shaped grains are found to be homogeneously distributed. Variation of dielectric properties with temperature displays the decrease of phase transition temperature (TC) with increasing Nd content. The temperature-dependent AC conductivity follows the Arrhenius behavior and the activation energies are calculated for high temperature regions. The frequency dependent AC conductivity behavior obeys the Johnscher's power law. Impedance spectroscopy results show the impact of conductivity from the bulk (grain) and displays non-Debye type of behaviour. Electric modulus demonstrates thermally activated relaxation phenomenon in the materials. Polarization vs. electric field (P-E) loops analysis confirms the ferroelectric nature of the materials. With increase in Nd concentrations, the value of remanent polarization (2Pr) increases, on the other hand, the coercive field (2Ec) value decreases. Both of these properties are suitable for enhancement of the physical properties of the multiferroic materials. [ABSTRACT FROM AUTHOR]

In this report, we have investigated the effect of BaTiO3 on the preliminary structural analysis, ferroelectric phase transition and electrical properties of (1 − x) P b (F e 0.5 N b 0.5 ) O 3 − x B a T i O 3 (P F N − B T) (x = 0 , 0.025 , 0.05, and 0.1) solid solutions. Conventional solid-state reaction technique is adopted to synthesize P F N − B T solid solution. X-ray diffraction (XRD) analysis is used to study the preliminary structural analysis, which suggests the formation of the single-phase materials. The surface morphology is studied using field emission scanning electron microscope (FESEM). The temperature-dependent dielectric properties display a broad diffuse phase transition from ferroelectric to paraelectric state and the phase transition temperature was found to be decreased with an increase in BT concentrations. Ferroelectric property of the solid solutions is confirmed by the polarization vs. electric field (P–E) loops study at room temperature. Variation of AC conductivity with frequency and temperature is also studied. The addition of BT leads to a decrease in the dielectric loss and phase transition temperature. [ABSTRACT FROM AUTHOR]

A new compound with formulation 0.4[Pb(Fe0.5Nb0.5)O3] −0.6[(Ba0.8Sr0.2)TiO3] was prepared by solid state route. The structural properties were analyzed by X-ray diffraction in terms of POWD and Rietveld analyses. X-ray photoelectron spectroscopy study provides for electronic structure. Structural vibrations and chemical compositions were analyzed by FTIR and Raman spectroscopy. Morphological and elemental analyses were done by FESEM and EDS studies. UV–Visible analysis was done to study the narrow band gap, effect of oxygen vacancy and Urbach energy. Dielectric characteristics show the diffuse phase transition. The room temperature multiferroicity was confirmed by P-E and M-H loop studies. [ABSTRACT FROM AUTHOR]

Rare earth-doped Ba0.85Ca0.15Zr0.1Ti0.9O3 (BCZT) ceramics demonstrated moderately improved properties rather than undoped counterpart. In this investigation, we report the synthesis and characterization of La3+-doped BCZT (x = 0.00, 0.02, 0.04, 0.06, and 0.08) single-phase crystals prepared by high-temperature (~ 1300 °C) solid-state reaction technique. Rare earth ions addition to BCZT affects its microstructure, phase transition, and electrical properties. All compounds were crystallized in tetragonal structure at room temperature. Scanning electron microscopy (SEM) recorded the microstructural analysis of the compounds. Temperature-dependent dielectric and impedance properties of the sintered pellet were estimated at chosen frequencies as a function of temperature. Here, efforts were made to improve the electrical properties of the material with the addition of La3+ in the BCZT system. The obtained data revealed that Curie temperature (TC) diminishes with the introduction of La3+ in BCZT ceramics. Besides, the diffusivity analysis and conductivity studies were used for better comprehension of the electrical processes in the materials. The obtained lead-free ceramics with enhanced electrical properties could be utilized in the fabrication of electronic devices. [ABSTRACT FROM AUTHOR]

Abstract: The polycrystalline materials (Li2Pb2R2W2Ti4Nb4O30 (R=Y, Eu)) of tungsten-bronze structural family have been synthesized using a high-temperature solid-state reaction (mixed-oxide) technique. The formation of the single phase compounds was checked using preliminary X-ray structural data/pattern. The nature and distribution of grains in the samples in the scanning electron micrographs (SEM) confirm the good quality of the samples used for electrical characterization. The phase transition (ferroelectric–paraelectric) in the materials was established through the detailed studies of dielectric, electric polarization and pyro-electric properties. Studies of pyroelectric properties show that the materials have reasonably high figure of merit useful for pyroelectric detector. The nature of frequency dependence of ac conductivity suggests that the materials obey Jonscher’s universal power law. [Copyright &y& Elsevier]

This paper highlights the structural, dielectric and pyroelectric properties of two complex tungsten bonze ceramics (K2Pb2Pr2W2Ti4Nb4O30and K2Pb2Pr2W2Ti4Ta4O30) which were prepared by high temperature mixed oxide method. Room temperature X-ray structural analysis confirms the formation of the compounds in single phase. SEM micrographs show uniform distribution of densely packed rod like grains. Variation of dielectric parameters with temperature and frequency shows the phase transition at 350°C and 426°C for the respective samples. Temperature dependent hysteresis loop confirms the existence of ferroelectricity in the materials. The current variation with voltage at different temperatures shows the semiconductor like behaviour of the materials. The temperature dependent dc conductivity follows the Arrhenius equation, and reveals the negative temperature coefficient of resistance (NTCR) behaviour of the materials. The current (for a fixed voltage) variation with temperature shows that the materials have high pyroelectric co-efficient and figure of merit, thus making them useful for pyroelectric sensors. [ABSTRACT FROM AUTHOR]

Abstract: A new group of tungsten bronze family Na2Pb2Eu2W2Ti4X4O30 (X=Nb, Ta) having all the valence elements (I-VI) were prepared by a high-temperature solid-state reaction technique. The formations of the compounds were confirmed by X-ray diffraction technique with an orthorhombic structure. Surface morphology of the compounds was studied by scanning electron microscope (SEM). Studies of dielectric properties (ɛ r and tan δ) of the above compounds at different frequencies in a wide temperature range (300–700K) with an impedance analyzer exhibit a ferroelectric phase transition at 580 and 394K for Na2Pb2Eu2W2Ti4Nb4O30 and Na2Pb2Eu2W2Ti4Ta4O30, respectively. Ferroelectric properties of these compounds were confirmed with polarization (hysteresis) study. [Copyright &y& Elsevier]

Abstract: The new complex polycrystalline samples of (R= Gd, Eu) were prepared by a low temperature solid-state reaction technique. Preliminary X-ray diffraction (XRD) studies of the compounds showed the formation of single-phase orthorhombic crystal structure at room temperature. Studies of dielectric properties (, ) of the above compounds at frequencies 1, 10, 100 and 1000kHz in a wide temperature range (300–700K) exhibit the ferroelectric phase transitions of diffuse type. [Copyright &y& Elsevier]

A new compound with formulation 0.4[Pb(Fe0.5Nb0.5)O3] −0.6[(Ba0.8Sr0.2)TiO3] was prepared by solid state route. The structural properties were analyzed by X-ray diffraction in terms of POWD and Rietveld analyses. X-ray photoelectron spectroscopy study provides for electronic structure. Structural vibrations and chemical compositions were analyzed by FTIR and Raman spectroscopy. Morphological and elemental analyses were done by FESEM and EDS studies. UV–Visible analysis was done to study the narrow band gap, effect of oxygen vacancy and Urbach energy. Dielectric characteristics show the diffuse phase transition. The room temperature multiferroicity was confirmed by P-E and M-H loop studies. [ABSTRACT FROM AUTHOR]

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: [•] Highly crystallized Sr3V2O8 ceramic has a structural and micro-structural stability. [•] The low values of ε r and tan δ make this material useful for microwave applications. [•] The material exhibits good ferroelectric properties suitable for memory devices. [•] The dielectric relaxation is of non Debye-type and ac conductivity obeys Jonscher power law. [•] The small value of dc activation energy suggests the conduction initiates with a small energy. [ABSTRACT FROM AUTHOR]