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The praseodymium Pr3+ doped at Bi site of Ba0.1Bi0.9(Ti0.9Zr0.1)0.1Fe0.9O3, under low concentrations (0%, 0.1%, 0.5% and 1% abbreviated as BBTZF0, Pr-BBTZF001, Pr-BBTZF005 and Pr-BBTZF01, respectively) were prepared by the solid-state reaction method. A detailed investigation has been made on structural, microstructural, ferroelectric and dielectric properties of Ba0.1(Bi1−xPrx)0.9(Ti0.9Zr0.1)0.1Fe0.9O3 ceramics. Rietveld refinement fitting revealed that the structure of these ceramics, at room temperature is rhombohedral with space group R3c. The cell volume decreased with increasing Pr-content due to the smaller ionic radius of the Pr. Temperature dependence of the dielectric constant (ε′r) of all prepared ceramics showed anomaly around TN (antiferromagnetic transition temperature); thus suggesting a magneto-electric coupling in these materials. The shift of TN with frequency is attributed to the Maxwell Wagner relaxation rather than the relaxor behavior. The P–E loop study shows the improved ferroelectric behavior and the reduced leakage current density with Pr doping. Moreover, the energy storage properties showed a clear enhancement upon the increase of the Pr concentration. The recoverable energy storage density (Wrec) of 2.75 J cm−3 with energy storage efficiency (η) of 44.52% was achieved for Pr-BBTZF01. [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]

This work presents a fundamental investigation of structural, dielectric and vibrational properties of the doped of the classical BaTi0.925(Yb0.5Nb0.5)0.075O3 (BTYN75) with a low amount of antimony Sb5+. The new lead-free ceramic BaTi0.925[Yb0.5(Nb0.8Sb0.2)0.5]0.075O3 (BTYN75-Sb) was prepared using the solid-state reaction method at 1673 K for 4 h. This ceramic was characterized by X-ray diffraction (XRD), and the XRD pattern was fitted with the Rietveld's refinement. The structural analysis of BTYN75-Sb showed the coexistence of Pm3m-cubic symmetry (33%) and P4mm-tetragonal symmetry (67%) at room temperature (RT). The dielectric properties such as dielectric constant (ε′r) and dielectric loss (tan δ) were determined. The dielectric constant was found to be ε′r = 4109 at Tm = 290 K for 1 kHz. Typical relaxor behavior of BTYN75-Sb was observed and characterized with empirical parameters: ΔTm = 4 K and γ = 1.84. Compared with the pure BTYN75, the low amount of antimony Sb5+ resulted in a slight reduction of the dielectric loss (tan δ < 0.042) over a wide temperature range [195–393 K]. The relaxor behavior and the structural properties of BTYN75-Sb were confirmed by Raman spectroscopic measurement. The relaxor BTYN75-Sb may be a promising candidate for several applications at RT and particularly for energy storage. [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]

This work presents a fundamental investigation of structural, dielectric and vibrational properties of the doped of the classical BaTi0.925(Yb0.5Nb0.5)0.075O3 (BTYN75) with a low amount of antimony Sb5+. The new lead-free ceramic BaTi0.925[Yb0.5(Nb0.8Sb0.2)0.5]0.075O3 (BTYN75-Sb) was prepared using the solid-state reaction method at 1673 K for 4 h. This ceramic was characterized by X-ray diffraction (XRD), and the XRD pattern was fitted with the Rietveld's refinement. The structural analysis of BTYN75-Sb showed the coexistence of Pm3m-cubic symmetry (33%) and P4mm-tetragonal symmetry (67%) at room temperature (RT). The dielectric properties such as dielectric constant (ε′r) and dielectric loss (tan δ) were determined. The dielectric constant was found to be ε′r = 4109 at Tm = 290 K for 1 kHz. Typical relaxor behavior of BTYN75-Sb was observed and characterized with empirical parameters: ΔTm = 4 K and γ = 1.84. Compared with the pure BTYN75, the low amount of antimony Sb5+ resulted in a slight reduction of the dielectric loss (tan δ < 0.042) over a wide temperature range [195–393 K]. The relaxor behavior and the structural properties of BTYN75-Sb were confirmed by Raman spectroscopic measurement. The relaxor BTYN75-Sb may be a promising candidate for several applications at RT and particularly for energy storage. [ABSTRACT FROM AUTHOR]