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Ferroelectric materials exhibiting switchable and spontaneous polarization have strong potential to be utilized in various novel electronic devices. Solid solutions of different perovskite structures induce the coexistence of various phases and enhance the physical functionalities around the phase coexistence region. The construction of phase diagrams is important as they describe the material properties, which are linked to the underpinning physics determining the system. Here we present the phase diagram of (K0.5Na0.5NbO3)–(Ba0.5Sr0.5TiO3) (KNN-BST) system as a function of composition and their associated physical properties. Lead-free (1 − x)KNN–xBST (0 ≤ x ≤ 0.3) solid solution ceramics were synthesized by conventional solid-state reaction technique. The X-ray diffraction and Raman spectroscopic studies indicate composition-dependent structural phase transitions from an orthorhombic phase for x = 0 to orthorhombic + tetragonal dual-phase (for 0.025 ≤ x ≤ 0.15), then a tetragonal + cubic dual-phase (x = 0.2) and finally a cubic single phase for x ≥ 0.25 at room temperature (RT). Among these, the orthorhombic + tetragonal dual-phase system shows an enhanced value of the dielectric constant at room temperature. The phase transition temperatures, orthorhombic to tetragonal (TO-T) and tetragonal to cubic (TC), decrease with the increase in BST concentrations. The ferroelectric studies show a decrease of both 2Pr and EC values with a rise in BST concentration and x = 0.025 showed a maximum piezoelectric coefficient. [ABSTRACT FROM AUTHOR]

Here, we have studied the phase transition and magneto-electric properties of a 70 wt. % Pb(Fe0.5Nb0.5)O3–30 wt. % Co0.6Zn0.4Fe1.7Mn0.3O4 (70 wt. % PFN–30 wt. % CZFMO) multiferroic composite that exhibits a maximum magneto-electric (ME) coefficient of 26.78 mV/cm Oe at room temperature. Raman analysis confirms the formation of composite and development of strain with the shifting of Raman modes. The local symmetry breaking of end members of the composite is observed by the splitting of Raman modes. The first-order derivative of magnetization with temperature (dM/dT vs T) shows anomalies across 140 K due to the PFN phase, whereas the anomaly around 250 K is due to the spin glass transition of the CZFMO phase. The magnetization vs magnetic field (M–H) study at different temperatures reveals the existence of superparamagnetic behavior above 300 K. The temperature-dependent dielectric behavior of the composite shows an anomaly around ferroelectric phase transition (Tm) for the PFN phase along with the broad relaxation peak arising due to the CZFMO phase. The linear behavior of magnetocapacitance (MD%) with the square of magnetization (M2) suggests the existence of biquadratic ME coupling. The ME study on the composite suggests the existence of both direct and converse ME effects. [ABSTRACT FROM AUTHOR]

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]