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In this research, the effects of calcination temperature in a range of 1050–1200 °C for 2 h and sintering temperature in a range of 1325-1400 °C for 2 h on phase formation, microstructure and electrical properties of lead-free Ba0.9Ca0.1TiO3 (BCT) ceramics fabricated via the solid-state combustion technique were investigated. For the XRD result, all the ceramics exhibited a coexisting phase between tetragonal and orthorhombic. The ceramic grain size tended to increase with increase of the sintering temperature. For BCT ceramic produced by the optimum sintering temperature (1375 °C for 2 h), the dielectric, ferroelectric and piezoelectric properties of εC=7393, Pr=7.60 μC/cm2,EC=5.99 kV/cm and d33=158 pC/N, respectively, were obtained. [ABSTRACT FROM AUTHOR]

Bi0.47Na0.47Ba0.06Ti1-x(Ni1/3Nb2/3)xO3 ceramics (abbreviated as BNBT1-x(NN)x, x = 0, 0.01, 0.03 and 0.05) were synthesized by solid-state combustion. The effect of x on the phase formation, microstructure and electrical properties of BNBT1-x(NN)x ceramics was examined. The XRD pattern indicated the coexistence of rhombohedral and tetragonal phases in all the specimens. Moreover, Rietveld refinement confirmed that the tetragonal phase increased from 47 to 71% when x increased from 0 to 0.05. The morphology of BNBT1-x(NN)x ceramics was observed by SEM and the ceramics grains showed polygonal shapes and the grain growth tended to be anisotropic. With (NiNb)4+ substitution, the average grain sized decreased rapidly from 1.7 to 1.0 µm and the grain size distribution was narrower as the amount of (NiNb)4+ increased. The density, remnant polarization (Pr) and coercive field (Ec) rapidly decreased with increasing x. A significant decrease in the ferroelectric properties was caused by the increasing tetragonal phase. [ABSTRACT FROM AUTHOR]

Lead-free 0.79(Bi0.5Na0.5TiO3)-0.18(Bi0.5K0.5TiO3)-0.03(BiFeO3)-x(Li2O) (BNT-BKT-BF-xLi) piezoelectric ceramics, with x between 0 and 0.4 wt.%, were prepared by the conventional solid-state reaction method. In all compositions, the samples were calcined at 800 °C for 2 h and sintered at 1100 °C for 2 h. The added Li2O affected the phase formation, microstructure, dielectric and ferroelectric properties of the BNT-BKT-BF-Li ceramics were investigated. All ceramics exhibited coexisting rhombohedral and tetragonal phases. The rhombohedral phase and the average grain size increased with increase in x. All ceramics presented polygon grain shapes with anisotropic grain growth. The depolarization temperature and the maximum temperature (Td and Tm) continuously increased with increase in Li2O content. The maximum dielectric constant (εm) decreased from 6250 to 4868 when x increased from 0 to 0.4 wt.%. The P-E hysteresis loops had their squareness factor increase with rising x, indicating a harder ferroelectric was obtained with higher Li2O doping. [ABSTRACT FROM AUTHOR]

Bi0.5(Na0.68K0.22Li0.10)0.5Ti1−xCoxO3 lead-free perovskite ceramics (BNKLT−xCo, x = 0, 0.005, 0.010, 0.015 and 0.020) were fabricated via the solid-state combustion technique. A small-amount of Co2+ ion substitution into Ti-sites led to modification of the phase formation, microstructure, electrical and magnetic properties of BNKLT ceramics. Coexisting rhombohedral and tetragonal phases were observed in all samples using the X-ray diffraction (XRD) technique. The Rietveld refinement revealed that the rhombohedral phase increased from 39% to 88% when x increased from 0 to 0.020. The average grain size increased when x increased. With increasing x, more oxygen vacancies were generated, leading to asymmetry in the bipolar strain (S−E) hysteresis loops. For the composition of x = 0.010, a high dielectric constant (εm) of 5384 and a large strain (Smax) of 0.23% with the normalized strain (d*33) of 460 pm·V−1 were achieved. The BNKLT−0Co ceramic showed diamagnetic behavior but all of the BNKLT−xCo ceramics exhibited paramagnetic behavior, measured at 50 K. [ABSTRACT FROM AUTHOR]

Lead-free Bi0.5(Na0.68K0.22Li0.10)0.5TiO3 + 0.003 mol Sm2O3 (BNKLT-Sm) ceramics were synthesized via the solid-state combustion technique with calcination temperatures between 750 and 850 °C and sintering temperatures between 1025 and 1100 °C for 2 h. The results showed that increasing the calcination temperature caused the percentage of perovskite phase and the particle size of the BNKLT-Sm powders increased. The BNKLT-Sm powder calcined at 800 °C displayed a pure perovskite structure without any impurity phases. The influence of the sintering temperature on the phase formation, microstructure and electrical properties of the ceramics was then investigated. All samples sintered at different temperatures possessed coexisting rhombohedral (R) and tetragonal (T) phases and the R phase became dominant when the sintering temperature increased. The microstructure of all ceramics showed a rectangular shape and anisotropic growth. The average grain size increased with increasing sintering temperature. Dielectric and ferroelectric behavior displayed relaxor characteristics in all samples. The maximum dielectric constant at Tm (εm) of 4777 and the highest remnant polarization (Pr) of 5.03 µC/cm2 were obtained by the densest ceramics (5.85 g/cm3), which was sintered at 1075 °C for 2 h. [ABSTRACT FROM AUTHOR]

Ba0.97Ca0.03Ti0.94Sn0.06O3 ceramics with Fe2O3 doping (BCTS-xFe; x = 0, 0.001, 0.002, 0.003, 0.004 and 0.005) were synthesized via the solid-state combustion technique. The influence of small amounts of Fe2O3 doping on the phase evolution, microstructure, electrical and magnetic properties of BCTS ceramics was investigated. We found that increasing Fe2O3 doped content changed the crystal structure from coexisting tetragonal and orthorhombic phases to a pseudo-cubic phase. The grain size, εc and Pr decreased rapidly with increasing Fe2O3 content. Moreover, TO-T and TC moved to lower temperatures and the maximum dielectric constant became significantly reduced with increased Fe2O3 doping. The BCTS ceramics with doped Fe2O3 displayed paramagnetic characteristics. [ABSTRACT FROM AUTHOR]

Binary system ceramics of 0.92Bi0.5(Na0.68K0.22Li0.10)0.5TiO3-0.08Ba0.5Sr0.5TiO3 (abbreviation as 0.92BNKLT-0.08BST) were prepared by the solid-state combustion method. Different sintering temperatures (between 1050 and 1150 °C for 2 h) were investigated for their effects on the structural phase, microstructure and electrical properties. 0.92BNKLT-0.08BST ceramics showed a pure perovskite structure with coexisting phases of rhombohedral and tetragonal, in all samples. The tetragonality and the lattice parameters increased with increasing sintering temperatures. The ceramics' grains showed polygonal shapes with anisotropic growth. The average grain size increased from approximately 0.35 to 0.83 µm when the sintering temperature increased from 1050 to 1150 °C. The highest density of 5.83 g/cm3 and the maximum dielectric constant at Tm (εm) 5006 were obtained by the sample sintered at 1100 °C for 2 h. With higher sintering temperatures, the P-E hysteresis curves exhibited more pinched loops which indicated higher relaxor behavior. A large strain of 0.21% and a high normalized strain piezoelectric coefficient ( d 33 * ), around 420 pm/V, were achieved at the sintering temperature of 1125 °C for 2 h. [ABSTRACT FROM AUTHOR]

This article reports the effect of Cu2+ substitution on the phase formation, morphology and electrical behavior of Bi0.5Na0.34K0.11Li0.05Ti(1-x)CuxO3 with 0 ≤ x ≤ 0.020 (BNKLT-xCu) ceramics prepared by the solid state combustion technique with glycine used as the fuel. All samples were prepared with a calcination temperature and a sintering temperature of 750 °C and 1025 °C, respectively for 2 h. The XRD results of all compositions revealed a single perovskite structure and that Cu2+ diffused efficiently into B-sites of the lattice, producing a BNKLT-xCu solid solution. The phase formation of the BNKLT-xCu ceramics showed coexisting rhombohedral (R) and tetragonal (T) phases in all samples. The highest measured density of the BNKLT ceramics was 5.99 g/cm3 and good dielectric properties measured at the temperature of the maximum dielectric constant (εm = 4723 and tanδ = 0.054), were obtained by the sample with Cu2+ substituted at x = 0.010. The BNKLT-xCu ceramics with Cu2+ ≥ 0.005 showed pinched P-E loops, and the negative strain of the S-E loops started to disappear, owing to the Cu2+ induced transformation from the ferroelectric (FE) phase to the ergodic relaxor (ER) phase. With Cu2+ levels of 0.010, the d*33 value increased to 705 pm/V, indicating that this sample was near the FE–ER phase boundary with induced high strain. Substituting an appropriate amount of Cu2+ improved the densification of BNKLT-xCu ceramics as capillary forces in the liquid phase during sintering pulled the grains together, which increased the εm values. [ABSTRACT FROM AUTHOR]

Herein, the effect of Fe3+ ions substitution on the phase evolution, microstructure, electrical, and magnetic properties of Bi0.5(Na0.68K0.22Li0.10)0.5Ti1−xFexO3 (BNKLT‐xFe) ceramics with 0 ≤ x ≤ 0.020 is investigated. The BNKLT‐xFe ceramics are synthesized via the solid‐state combustion method. All BNKLT‐xFe compositions use a calcination temperature of 750 °C for 2 h and a sintering temperature of 1025 °C for 2 h. The X‐ray diffraction (XRD) and Raman spectra illustrate coexisting rhombohedral (R) and tetragonal (T) phases in all compositions and the R phase increases with increasing Fe content. The X‐ray absorption spectroscopy (XAS) technique confirms that the local R symmetry increases from 38.8% to 67.0% with increasing x content from 0 to 0.020. The average grain size gradually increases from 0.52 to 0.84 μm when the x content increases from 0 to 0.020. At x = 0.010, the ceramic has high ferroelectric properties (Pr ≈ 26.8 μC cm−2, Ec ≈ 20.4 kV cm−1) and the highest normalized strain (d33*) of 386 pm V−1. In addition, the maximum value of the temperature‐dependent dielectric constant of 6136 is found at x = 0.015. Although BNKLT‐0Fe ceramic show diamagnetic behavior, paramagnetic behavior is observed in all Fe3+ substituted samples. [ABSTRACT FROM AUTHOR]

The fabrication of 0.62[0.75Pb(Mg1/3Nb2/3)O3-0.25Pb(Yb1/2Nb1/2)O3]-0.38PbTiO3ceramics (abbreviated PMN-PYbN-PT) by combustion technique using one step calcination was studied. Glycine was used as fuel to reduce the reaction temperature. The phase formation, microstructure, density and dielectric properties were investigated. It was shown that calcination method is more effective than conventional solid state reaction. The crystal structure of PMN-PYbN-PT ceramics exhibited a single rhombohedral perovskite phase in samples sintered at temperature T < 1200°C. The pyrochlore phase was found in the samples sintered at 1200°C. The average grain size of the ceramics increases with increasing sintering temperature. The density and the maximum dielectric constant increases with increasing sintering temperatures up to 1150°C, and then decreases at higher temperatures. The maximum density (8.04 g/cm3), highest dielectric constant (19000) and excellent ferroelectric properties (Pr∼ 41.05 μC/cm2andEc∼ 8.1 kV/cm) were obtained for the sample sintered at 1150°C. [ABSTRACT FROM PUBLISHER]