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In response to the growing interest in materials exhibiting magneto-dielectric coupling across diverse application domains, we present a detailed study on the electrical behavior of Ba0.1Bi0.9(Ti0.9Zr0.1)0.1Fe0.9O3 (BBTZF) ceramic. This study includes a comprehensive analysis of temperature- and frequency-dependent dielectric behavior, along with ac impedance properties. The thermo-dielectric study in the temperature range of 300–650 K suggests the presence of an anomaly near the Neel temperature (TN = 603 K), supporting the strong magneto-dielectric coupling in BBTZF. The differential thermal study also revealed an anomaly around TN, characterized by an exothermic peak. Furthermore, the well-described experimental dielectric data as a function of frequency (100 Hz–1 MHz), by the Cole–Cole relaxation equation modified by introducing complex conductivity, demonstrated a remarkable change in the frequency of relaxation (fr) as a function of temperature in the vicinity of TN. This change is attributed to the coupling between magnetic and electric order parameters. Through the complex impedance analysis recorded at different temperatures, it was found that both the capacitance and resistance of the grain showed a change in behavior around TN, suggesting that the magneto-electric coupling is predominantly of intrinsic origin in our material. Furthermore, the intrinsic magneto-capacitance grain value is approximately − 0.36%, highlighting its potential for application in magnetoelectric devices. Finally, the ac conduction study has shown that magnetic ordering can influence the translational hopping of large polaron mechanisms. [ABSTRACT FROM AUTHOR]

We report the impact of dysprosium (Dy, with y = 0.01, 0.02, 0.05 and 0.08) substitution in (Na0.5 Bi0.5)0.94 Ba0.06TiO3 (NBT-6BT) lead-free ceramics. The structural, vibrational dielectric, ferroelectric and electrocaloric (EC) properties of all samples were systematically investigated. X-ray diffraction analysis revealed the coexistence of tetragonal (P4mm) and rhombohedral (R3c) structural phases at low content of Dy (y = 0.01, 0.02 and 0.05). The structural changes with the introduction of Dy were confirmed by Raman spectroscopy at room temperature. The evolution of the Raman spectra with temperature was found to be strongly correlated with the dielectric measurements. Higher stability of the ferroelectric (FE) phase was obtained at room temperature for the compositions y = 0.01, 0.02 and 0.05, with optimum values for y = 0.02 as remanent polarization Pr = 32µC/cm2, as well as piezoelectric coefficients d33 = 137 pC/N, kp = 0.27 and kt = 0.16, whereas a higher content of Dy (y = 0.08) induced a remarkable decrease of the ferroelectric and piezoelectric properties. Using the direct EC measurement, the ceramic corresponding to y = 0.02 exhibited a significant EC response, where ΔT = 1.2 K under 5 kV/mm. The incorporation of Dy was found to enhance the EC responsivity coefficient ζ = iT/ΔE), with a best value of ζ = 0.24 K.mm/kV for y = 0.02. [ABSTRACT FROM AUTHOR]

We reported the effect of Erbium (Er with x = 0.005, 0.01, 0.015, 0.02, 0.025 and 0.03)-substituted Ba0.8Ca0.2Ti0.975(Nb0.5Yb0.5)0.025O3 lead-free ceramics. Structural, dielectric, piezoelectric, ferroelectric and photoluminescence properties of all ceramics were systematically explored. At room temperature, X-ray diffraction (XRD) analysis showed that (Ba0.8Ca0.2)1-xEr2x/3 □ x/3Ti0.975(Nb0.5Yb0.5)0.025O3 samples (Abbreviated as BCTYN-xEr) exhibited a pure tetragonal phase for x ≤ 0.025. However, the composition (x = 0.03) showed the formation of an additional phase. The vibrational study was found to correlate strongly with XRD analysis. The dielectric properties were improved in the composition x = 0.01, where the dielectric constant was increased from 5824 for x = 0 up to 6150 for x = 0.01. The composition (x = 0.005) revealed the optimum properties with a d33 piezoelectric coefficient of 88 pC/N, a kp planar electromechanical coupling factor of 16.9% and a Pr remanent polarization of 9.25 μC/cm2. The photoluminescence (PL) results showed, at 525 nm and 550 nm, two strong green bands. As multifunctional materials, BCTYN-xEr samples represent a great potential in the applications of mechanical–electro-optical coupling and integration devices. [ABSTRACT FROM AUTHOR]

The present paper reports the effect of Yttrium substitution on the structural, microstructure, dielectric, ferroelectric, and electrocaloric (EC) properties of the lead-free (Na0.5 Bi0.5)0.94 Ba0.06TiO3 (abbreviated as NBT-6BT) ceramics. For a small quantity of Yttrium (x = 0.01 and 0.05), the X-ray diffraction and Raman spectra exhibit the coexistence of rhombohedral and tetragonal phases at room temperature. However, with x = 0.08 composition, a structural change to pseudo-cubic phase was identified. By adding a small amount of Yttrium, the ferroelectric properties were improved by increasing the remnant polarization from (Pr = 27µC/cm2) for x = 0 up to (Pr = 36µC/cm2) for x = 0.01. This resulted in an improvement of 30% in the estimated ferroelectric parameters as well as an improvement in the piezoelectric properties, as measured by the value of d33 of 130 pC/N. The electrocaloric temperature change (ΔT) is calculated by a direct method using Differential Scanning Calorimetry (DSC) to be at more than 1 K at 5 kV/mm for x = 0.01. Despite the minimal amount employed, our observations lead us to say that the introduction of Yttrium into the NBT-6BT ceramic has directly affected the properties of this material. Nevertheless, with a higher content of Yttrium (x = 0.08), a sudden decrease of both ferroelectric and EC effect was observed. The declined properties at higher contents may originate from the structural change which can influence the polar distribution in the structure. [ABSTRACT FROM AUTHOR]

Structural, dielectric, and ferroelectric properties, and electrocaloric effects of pure and Gd doped (Na0.5Bi0.5)0.94Ba0.06TiO3 ceramics prepared by the conventional solid-solid method have been carried out. The X-ray diffraction analysis confirms a pure perovskite structure with the coexistence of tetragonal and rhombohedra structures in both powders. The thermal and frequency dependences of the dielectric constants of both ceramics revealed relaxor behavior. The two compounds exhibited two phase transitions: ferroelectric/antiferroelectric (FE/AFE) transition followed by an antiferroelectric/paraelectric (AFE/PE) transition at higher temperatures. Remarkably, we noticed that the small amount of Gd doping (2%) highly enhanced the dielectric properties of the parent compound by about 71%. The phase diagram was as well influenced by the Gd doping, where the FE/AFE transition temperature rose from 90 in the parent compound to 115°C in the doped one whereas the AFE/PE transition temperature was decreased from 320 to 270°C, respectively. The direct electrocaloric measurements performed on both compounds showed that the ferroelectric/antiferroelectric phase transition was accompanied by a significant electrocaloric effect. The Gd3+ doping improved the electrocaloric properties of the parent compound, where a remarkable temperature variation of 1.4K was obtained in the doped ceramic. The results of the direct electrocaloric measurements will be compared and discussed with those derived from the indirect method. [ABSTRACT FROM AUTHOR]

This paper deals with Ca and Zr co-doped BaTiO (BCTZ) ( x = 0.1, 0.13, 0.2 and y = 0.05, 0.1, 0.15). These ceramics were prepared using the conventional solid state method. The symmetry, dielectric properties, Raman spectroscopy, ferroelectric behavior and piezoelectric effect were examined. X-ray diffraction (XRD) results display that morphotropic boundary occurs from tetragonal to orthorhombic region of BCZT and polymorphic phase transitions from tetragonal to orthorhombic, orthorhombic to rhombohedral regions of BCZT. The evolution of the Raman spectra was investigated as a function of compositions at room temperature, in correlation with XRD analysis and dielectric measurements. We note that the substitution of Ca in Ba site and Zr ions in Ti site slightly decreased the cubic-tetragonal temperature transition ( T ) and increased the orthorhombic-tetragonal ( T ) and rhombohedral-orthorhombic ( T ) temperatures transitions. The ferroelectric properties were examined by a P- E hysteresis loop. The two parameters Δ T and Δ T are defined as Δ T = T − T and Δ T = T − T , they come close to T for x = 0.13, y = 0.1, which reveals that this composition is around the polymorphic phase. The excellent piezoelectric coefficient of d = 288 pC N, the electromechanical coupling factor k = 40%, high constant dielectric 9105, coercive field E = 0.32 (KV mm) and remanent polarization P = 0.1 (µc mm) were obtained for composition x = 0.13, y = 0.1. [ABSTRACT FROM AUTHOR]