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Sr(1–x)LaxTiO3 (SLTO) nanopowder (x = 0, 0.01, 0.05, 0.07, and 0.10) were effectively synthesised by the sol-gel auto-combustion process. Bulk ceramics samples were produced by spark plasma sintering (SPS) in an Ar atmosphere. The XRD pattern of the undoped SLTO nanopowder showed the pure phase and the impurity phase (TiO2) was detected in the La-doped SLTO samples. However, the impurity phase disappeared after producing the bulk samples with the SPS process. All the samples exhibited a negative Seebeck coefficient (S). The electrical conductivity (σ) and negative Sof all the SLTO samples increased with increasing temperature and reached a maximum value at 800 K. The thermal conductivity (κ) decreased with increasing temperature and increasing La content. The SLTO with x = 0.01 showed the largest σ, negative S, power factor (S2σ) and dimensionless figure of merit (ZT) at 800 K. [ABSTRACT FROM AUTHOR]

In this research paper, we describe 0.85[0.94Bi0.5Na0.5TiO3-0.06BaTiO3]-0.15[Na0.73Bi0.09NbO3] (BNT-BT-NBN) ceramics fabricated by the solid-state combustion technique. The phase evolution, microstructure, dielectric, ferroelectric and energy storage properties were examined. The BNT-BT-NBN powders and ceramics were calcined and sintered between 650–900 °C and 1100–1175 °C, respectively, for 2 h. All samples showed a typical perovskite structure, as revealed by X-ray diffraction. The Rietveld refinement analysis of the ceramics suggested the samples sintered between 1100 and 1150 °C had coexisting R + T phases, while the R + T+C phases were observed in the ceramics sintered at 1175 °C. The average grain size of the samples increased from 0.52 to 1.39 μm with increased sintering temperature. The density of the ceramics increased from 5.12 to 5.45 g/cm3 when the sintering temperature increased from 1100 to 1150 °C, and then decreased. Increasing the sintering temperature from 1100 to 1150 °C caused the dielectric constant at Ts (εs) and the dielectric constant at Tm (εm) to increase from 1727 to 1945 and 1564 to 1750, respectively, and then εs and εm declined. All BNT-BT-NBN ceramics had good dielectric temperature stability with only a±10% change when the temperature ranged from room temperature to ∼300 °C. The optimum energy-storage properties (Wrec = 0.62 J/cm3 and η = 83.2%) were obtained from the BNT-BT-NBN ceramics sintered at 1150 °C for 2 h. This data indicates that BNT-BT-NBN ceramics can be useful as lead-free materials for high density energy-storage capacitors. [ABSTRACT FROM AUTHOR]

Lead-free Ba1-xLaxTi0.91Sn0.09O3 (BLTS) ceramics with x = 0, 0.01, 0.03 and 0.05, were prepared by the traditional solid-state sintering method with calcination and sintering temperatures of 1200 °C for 2 h and 1400 °C for 4 h, respectively. X-ray diffraction (XRD) measurements revealed that all the BLTS ceramics had pure perovskite structures with no detectable impurities. When x = 0 and 0.01, the ceramics exhibited coexisting orthorhombic (O) and tetragonal (T) phases, while the orthorhombic (O), tetragonal (T) and cubic phase (C) were detected in the BLTS ceramics with x = 0.03 and 0.05, which the Rietveld refinement analysis confirmed. Furthermore, increasing x in the BLTS ceramics led to a large decrease in the average grain size (from 45.7 to 0.9 µm). A significant decrease in the remnant polarization (Pr) accompanied by very slim hysteresis loops were observed for higher La (x ≥ 0.03) levels. This demonstrates that BLTS ceramics transition from classical ferroelectric to relaxor ferroelectric behavior due to changing occupancy of the A-site to La3+ from Ba2+. [ABSTRACT FROM AUTHOR]

Due to the substitution of complex ions into B-sites is very interesting in recent, lead-free Bi0.47Na0.47Ba0.06Ti1−x(LiNb)xO3 (BNBT1−xLNx) ceramics (with x = 0–0.04) were fabricated by the solid-state combustion method. The influence of (LiNb)4+ (x) on the phase structure, microstructure, and electrical properties was investigated. The X-ray diffraction (XRD) patterns exhibited a pure perovskite structure for all specimens. Coexisting rhombohedral and tetragonal phases were observed in all samples and the tetragonal phase increased with increased x, as analyzed by the Rietveld refinement method. The morphology of the BNBT1−xLNx ceramics, obtained by scanning electron microscopy (SEM), revealed almost-round grain shapes and anisotropic grain growth. The density and average grain sizes decreased from 5.84 to 5.54 g/cm3 and 1.7 to 0.9 µm, respectively, when x increased from 0 to 0.04. The grain size distribution decreased with increased (LiNb)4+ content. A reduction in the dielectric properties was observed, due to the phase ratio changing away from a morphotropic phase boundary (MPB), an inferior microstructure, and low density caused by (LiNb)4+ substitution. The (LiNb)4+ substitution induced the transition from non-ergodic relaxor to ergodic relaxor ferroelectric state. [ABSTRACT FROM AUTHOR]

In this study, the effect of sintering temperature (1000–1100 °C for 2 h) on phase formation, phase transition, microstructure and electrical properties of lead-free piezoelectric (K0.44Na0.52Li0.04)(Nb0.84Ta0.10Sb0.06)O3 (KNLNTS) solid solution with 0.3 wt%Bi2O3 + 0.4 wt%Fe2O3 + 0.2 wt%CuO additive (abbreviate as modified KNLNTS) was investigated. Modified KNLNTS ceramics were synthesized by the solid-state combustion technique using glycine as fuel. The modified KNLNTS powders were prepared using the calcination condition of 650 °C for 2 h. The XRD pattern of all sintered ceramics exhibited a pure perovskite phase. Using Rietveld refinement to analyze the phase formation showed that the modified KNLNTS ceramics had co-existing phases of orthorhombic and tetragonal in all sintered ceramics and the orthorhombic phase increased when the sintering temperature increased. The average grain size, TO-T, Tc, Pr and Ec increased with increasing sintering temperature. At the sintering temperature of 1025 °C, the modified KNLNTS ceramic showed the best electrical properties (Cε ≈ 6745, Smax ≈0.274% and d*33 ≈ 548 pm/V). The good electrical properties of the modified KNLNTS ceramics makes them good candidates for lead-free applications to replace Pb-based ceramics. [ABSTRACT FROM AUTHOR]

This work aims to investigate the effects of CuO doping (0–1.0 wt%) on the local structure of (Ba0.85Ca0.15)(Ti0.90Zr0.10)O3 (BCTZ) ceramics. These samples were prepared via the solid state combustion technique using glycine as fuel. The local structure of the samples was characterized by XANES (X-Ray Absorption Near-edge Structure) spectroscopy. The Cu, Ti K-edge and Ba L3-edge XANES measurements were performed in a fluorescent mode at ambient temperature. The XANES data revealed that the oxidation state of Ba and Ti ions in all samples was +2 and +4, respectively. Comparing the experimental Cu K-edge XANES spectra to theoretical XANES spectra simulated by FEFF program suggested that the substitution of the Cu ions for B-site ions in BCTZ lattice. [ABSTRACT FROM AUTHOR]

In this study, the effect of firing temperatures on phase formation, microstructure dielectric and magnetic properties of Ni0.6Zn0.4Fe2O4 (NZFO) ceramics were investigated. The NZFO powder were synthesized by the solid-state combustion technique using glycine as a fuel to reduce the reaction temperature. All samples were calcined in the range of 900 °C–1100 °C for 2 h and sintered in the range of 1175 °C–1275 °C for 2 h. A pure ferrite phase was found in the powders calcined above 1000 °C and the average particle size of NZFO powders was increased from 0.39 µm to 0.59 µm when the calcination temperature was increased. The x-ray diffraction (XRD) analysis results confirmed the formation of pure spinel structure with cubic phase in all the ceramic samples. The average grain size (5.54–2.80 µm) was slightly decreased, and the dielectric constant (239–13) tended to decrease with increasing sintering temperature. As the sintering temperature increased to 1250 °C, it was found that the lattice parameters (8.366–8.387 Å), the density (5.29–5.35 g/cm3), and saturation magnetization (81.51–93.92 emu/g) tended to increase after that decrease. [ABSTRACT FROM AUTHOR]

(Ba0.704Sr0.176Bi0.12)1-xZn0.08Nb0.04Ti0.88O3-Nax (BSBZNT-xNa) ceramics with x = 0, 0.01, 0.03 and 0.05 mol%, were prepared by the solid-state combustion technique. The samples were calcined and sintered at 950 °C and 1375 °C, respectively, for 2 h. The phase, microstructure, dielectric, ferroelectric and energy storage properties were investigated. The X-ray diffraction patterns of the BSBZNT-xNa powders showed a perovskite phase for all samples. When x increased from 0-0.03, the average particle size increased from 380 to 480 nm, then decreased to 420 nm. All sintered samples showed the coexistence of the orthorhombic and cubic phases. The average grain size was in the range of 2.03 to 1.39 µm. The BSBZNT-0.01Na ceramic exhibited the highest dielectric properties at room temperature (ɛr = 902, tanδ = 0.10), the lowest remanent polarization (Pr = 0.10 µC/cm2), coercive field (Ec = 0.43 kV/cm), and the highest energy storage efficiency (η ∼ 94.70%) measured under an electric field of 70 kV/cm. [ABSTRACT FROM AUTHOR]

In this study, the phase formation, microstructure, and electrical properties of Sr0.3(Bi0.70Na0.67Li0.03)0.5(Ti1-xNbx)O3: SBNLT-Nbx lead-free ceramics synthesized via the solid state combustion technique were examined. SBNLT-Nbx ceramics with various Nb content of x = 0, 0.01, 0.03, and 0.05 were calcined at 750 °C and sintered at 1175 °C for 2 h, respectively. The SBNLT-Nbx calcined powders showed a perovskite structure and a secondary NbO2 phase was observed with Nb5+ content of 0.03 and 0.05 mol%. All SBNLT-Nbx ceramics exhibited a pure perovskite phase with coexisting rhombohedral and tetragonal phases. The grain size was in the range of 1.17-1.34 µm. The εmax and tan δmax tended to decrease with increased x content. The best ferroelectric and energy storage properties (Pmax = 27.45 µC/cm2, Pr = 1.92 µC/cm2 and Wtotal = 0.958 J/cm3, Wrec = 0.739 J/cm3, Wloss = 0.219 J/cm3, η = 77.1%), measured under an electric field of 70 kV/cm, were observed at x = 0.01. [ABSTRACT FROM AUTHOR]

This study focused on the rare-earth hetero-valent substituted perovskite BaMO3 (M = Ce, Pr and Tb) which expected to show magnetoelectric response. In general, diamagnetic feature is presented in the 4f0 BaCeO3 system down to 2 K which is chosen as a reference in the study while BaPrO3 (4f1) and BaTbO3 (4f7) display antiferromagnetic phase transition at TN = 11.7 and 33.2 K, respectively, measured by MPMS magnetometer. At high oxygen partial pressure and donor ion-substitution (Nb5+), the BaMO3 systems demonstrate a similar defect chemistry to titanate perovskite which compensated by Ba-vacancy. Dielectric relaxation is detected for the doublet (BaPrO3 and BaTbO3) at the antiferromagnetic phase transition region. In order to examine the magnetoelectric response, the 8 Tesla of magnetic field is applied to the samples during the dielectric measurement. BaTbO3 shows a modest magnetoelectric response around 0.2% at the antiferromagnetic phase transition while that of BaPrO3 is silent. The activation energies derived from Arrhenius equation are reported to be in the range of 0.2 − 0.6 eV. [ABSTRACT FROM AUTHOR]

Lead-free multiferroic composite ceramics of 0.7BaTiO3-0.3Ni0.7Zn0.3Fe2O4 (BT-NZF) were prepared by the solid-state combustion technique. The BT and NZF powders were calcined in the range of 1100 to 1200 °C for 4 h and 900 to 1100 °C for 2 h, respectively. Afterward, BT-NZF composite ceramics were sintered between 1100 and 1250 °C for 4 h. The effect of the firing temperature on the phase formation, microstructure, electrical, and magnetic properties of BT-NZF composite ceramics was investigated. X-ray diffraction of BT and NFZ powders showed the highest purity phase were prepared the calcination temperatures of 1100 and 1050 °C, respectively. The BT-NZF composite ceramics exhibited coexisting tetragonal perovskite and cubic spinel phases. The maximum density of 5.85 g/cm3 was obtained when sintering the composite ceramics at 1125 °C. The dielectric constant at room temperature increased with increased sintering temperature. The hysteresis loops showed leakage current in all samples. Ferromagnetic properties showed the highest Ms ∼ 24.56 emu/g measured under a magnetic field of 10,000 Oe from the sample sintered at 1150 °C. [ABSTRACT FROM AUTHOR]

Lead-free (1-x)BiFeO3-xBaTiO3 ceramics (abbreviated as BF-xBT), in a composition range of 0.23 ≤ x ≤ 0.33 mol%, were prepared by the conventional solid-state reaction method. The effect of x content on phase structure, microstructure, magnetic and electrical properties of BF-xBT ceramics is also investigated. With the incorporation of x content, the coexistence of rhombohedral and tetragonal phases was observed. Field emission scanning electron microscope (FESEM) micrographs revealed that the average grain size of BF-xBT ceramics first decreased and then increased with adding x content. The fracture surface of samples showed a mode of inter-granular fracture and intra-granular fracture. The ferroelectric properties were enhanced by adding x ≥ 0.29 mol% in the BF-xBT system. The dielectric and magnetic properties were improved with a maximum value are εr = 888,711, Mmax = 0.40 emu/g, Mr = 0.17 emu/g, and Hc = 3.7 kOe at x = 0.25 mol% [ABSTRACT FROM AUTHOR]