Chittakorn Kornphom

Low Firing Temperatures and High Ferroelectric Properties of (Ba0.85Ca0.15)(Ti0.90Zr0.10)O3 Lead-Free Ceramics Synthesized by the Combustion Technique

This work studied the effect of firing conditions on phase formation, microstructure and electrical properties of (Ba0.85Ca0.15)(Ti0.90Zr0.10)O3;(abbreviated as BCTZ) ceramics, which were synthesized through the combustion technique. To reduce the reaction temperature, glycine was used as fuel with a ratio of raw material: glycine (1:1.11). BCTZ samples were calcined at 900–1200°C for 2 h and sintered at 1350 –1550°C for 2 h. Ultrafine BCTZ powder and single peroveskite phase were achieved from the sample calcined at 1050°C for 2 h.These results were obtained at a lower temperature and with shorter dwell time than those obtained using the solid state reaction method by ∼150°C and 1 h, respectively. The BCTZ ceramics exhibited a coexistence of rhombohedral and orthorhombic phase in all samples. The average particle size and the average grain size increased from 172 to 295 nm and 0.82 to 2.57 µm, respectively, when firing temperatures increased. The highest density (5.76 g/cm3), highest dielectric constant (ϵr ≅ 4485 and ϵmax ≅ 14897) and best ferroelectric properties (Pr ≅ 18.47 μC/cm2 and EC ≅ 4.52 kV/cm) were obtained from the sample sintered at 1450°C for 2 h.

The effect of firing conditions on phase formation, microstructure and dielectric properties of BNKTNb-LSb ceramics prepared via the combustion technique

The fabrication of 0.99[Bi0.5(Na0.82K0.18)0.5Ti0.995Nb0.005O3]-0.01LiSbO3 ceramics (BNKTNb-LSb) prepared by the combustion technique was studied. A single perovskite phase of BNKTNb-LSb powder was observed by the powders calcined at 700 °C for 2 h, which was lower than the solid-state reaction technique ∼150 °C. The BNKTNb-LSb ceramics showed the coexistence of a rhombohedral and tetragonal phase at a low sintering temperature. Then, the phase formation changed from a tetragonal to a pseudocubic phase when sintered at higher temperatures. The grain morphology of the BNKTNb-LSb ceramics exhibited a rather square shape and the average grain size of the ceramics was increased with increased sintering temperatures. The density, linear shrinkage, ϵr and ϵmax of the BNKTNb-LSb ceramics tended to increase with increasing sintering temperatures up to 1125 °C and then decreased. At 1125 °C, the highest density, shrinkage, ϵr and ϵmax were about 5.82 g/cm3, 18.7%, 1625 and 4465, respectively. The dielectric behavior corresponded with the XRD, density and the microstructure results.

Phase evolution and electrical properties of a new system of (1−x)[BNT–BKT–KNN]–xBCTZ lead-free piezoelectric ceramics synthesized by the solid-state combustion technique

Lead-free piezoelectric ceramics with x content from 0 to 0.1 step 0.02 were prepared via the solid-state combustion technique. The effect of x concentration on the phase evolution, microstructure and electrical properties was methodically investigated. The XRD result of showed a tetragonal phase. The coexistence phase between the rhombohedral and the tetragonal structure was observed at The phase structure at a composition between 0.08 and 0.1 was dominated by a higher rhombohedral phase. The ceramics grain exhibited a cubic shape and the average grain size decreased from 1.15 to 0.83 µm with an increase in x content from 0 to 0.1. The temperature of ϵFA and ϵSA of the ceramics tended to decrease with increasing x concentration. The MPB composition was suggested at x around 0.06 where this ceramic exhibited its highest dielectric constant good ferroelectric properties μC/cm2 and kV/cm) and excellent piezoelectric constant

Phase Formation, Microstructure and Electrical Properties of KNN-BZT Ceramics Fabricated via Combustion Technique

In this work, the effects of calcination temperature in the range of 550–800°C for 2 h and sintering temperature in the range of 1000–1100°C for 2 h on phase formation, microstructure and dielectric properties of the potassium sodium niobate-bismuth zinc titanate [0.995(K0.5Na0.5)NbO3–0.005Bi(Zn0.5Ti0.5)O3] (KNN-BZT) ceramics prepared via combustion technique were investigated. Glycine was used as fuel to reduce the reaction temperature. It was found that a single orthorhombic perovskite phase of KNN-BZT powders was observed from the sample calcined at 650°C for 2 h, which was lower than the conventional mixed oxide route ∼200°C. The single orthorhombic perovskite phase was detected in the sample sintered at the temperature lower than 1075°C. The secondary phase of Bi2Ti2O7 was found in the sample sintered at 1100°C. The microstructure of the KNN-BZT powders exhibited an almost-spherical morphology and a highly agglomerated form. The particle size was ranging from 0.2–0.3 μm and the average grain size of the ceramics increased as sintering temperature increased. The optimum condition of sintering was obtained for the sample sintered at 1075°C for 2 h. This sample exhibited maximum density (97%), highest dielectric constant (6400) and excellent ferroelectric properties (Pr = 20.5 μC/cm2 and Ec = 9.7 kV/cm).

Influence of sintering temperature on properties of BNKLLT–6 wt% BCTZ binary lead-free piezoelectric ceramic prepared through the solid-state combustion technique

ABSTRACT In this work, a new binary 94 wt%[Bi0.5(Na0.68K0.22Li0.1)0.5TiO3 + 0.10 wt% of La2O3]–6 wt% [(Ba0.85Ca0.15)(Ti0.90Zr0.10)O3] [BNKLLT–6 wt% BCTZ] ceramic was fabricated by the solid-state combustion technique and glycine was used as the fuel. The effect of sintering temperature in the range of 1075–1175 °C for 2 h on phase evolution, microstructure and electrical properties was investigated. The phase formation exhibited a coexistence structure between rhombohedral and tetragonal at low sintering temperature. As the sintering temperature increased, the phase formation changed to pseudo-cubic phase. The average grain size of the ceramics was increased with the increasing sintering temperature. Density, ϵr, ϵSA and TFA of BNKLLT–6 wt% BCTZ ceramics increased while the TSA decreased when the sintering temperature increased up to 1125 °C, while after this temperature the opposite trends occurred. At a sintering temperature of 1125 °C, the BNKLLT-6 wt% BCTZ sample showed the highest theoretical density (95.8%), maximum dielectric constant ϵSA (5278), highest d33 (227 pC/N) and fair ferroelectric properties (Pr = 24.5 µC/cm2 and Ec = 15.45 kV/cm).

Fabrication of Pyrochlore Phase Free PMN-PZT Ceramics via the Combustion Technique

A ferroelectric ceramic, 0.3Pb(Mg1/3Nb2/3)O3-0.7Pb(Zr0.48Ti0.52)O3 (PMN-PZT) with a pyrochlore-free phase was prepared by the combustion technique using glycine as fuel. The crystal structure, microstructure, dielectric and ferroelectric properties of the samples were investigated. It was found that the single peroveskite phase of PMN-PZT powders was obtained from the sample calcined at 850°C for 2 h. The purity phase was detected in all ceramic samples. The microstructures of the PMN-PZT powders exhibited an irregular shape and an agglomerated form and the average particle size increased with the increase of calcination temperature. The Tc trended to decrease while the average grain size increased when sintering temperature increased. At 1200°C, the ceramic exhibited maximum density (97%), highest dielectric constant (25000) and excellent ferroelectric properties (Pr = 24 μC/cm2 and Ec = 4.5 kV/cm). The combustion technique is easier and can produce these ceramics more economically than other techniques.

Phase formation and piezoelectric properties of (Pb0·95Ba0·05)(Zr1−xTix)O3 ceramics fabricated by solid state reaction technique

Abstract This work studied the crystal structure, microstructure and piezoelectric properties of Lead Barium Zirconate Titanate [(Pb0·95Ba0·05)(Zr1−xTix)O3; (PBZT)] ceramics with 0≤x≤0·50 step 0·05 prepared by the solid state reaction method. PBZT samples were calcined in the range of 900–1000°C for 1 h and sintered at 1200°C for 3 h. The crystal structure, microstructure and piezoelectric properties were analysed by an X-ray diffractometer (XRD), scanning electron microscope (SEM) and d33 meter. It was found that the PBZT ceramics are indexed in the orthorhombic structure for x = 0, the rhombohedral structure for 0·05≤x≤0·30, the coexisting of rhombohedral and tetragonal structure for 0·35≤x≤0·45 and the tetragonal structure for x = 0·50. The average grain size and the density are around 1·20–2·59 μm and 7·52–7·67 g cm−3 respectively. The highest piezoelectric coefficient is 129 pC/N obtained by x = 0·40.

Dielectric and ferroelectric properties of PMN–PT–PZ ceramics prepared via combustion technique

Abstract The fabrication of 0·53Pb (Mg1/3Nb2/3)O3–0·37PbTiO3–0·10PbZrO3 (PMN–PT–PZ) ferroelectric ceramics using the combustion technique and the effects of firing conditions on the phase structure, microstructure and electrical properties of the powders and ceramics were studied. Glycine was used as a fuel to reduce the reaction temperature. It was found that a single perovskite phase of PMN–PT–PZ powders was obtained from the sample calcined at 900°C for 2 h. The conventional technique uses two steps in the calcination process. The use of glycine in the combustion technique reduced the process to one step. The morphology of the PMN–PT–PZ powders showed an almost spherical shape and the average particle size increased from 0·12 to 2·51 μm when the calcination temperature was increased from 700 to 1000°C. The pure PMN–PT–PZ ceramics exhibited coexistant phases of the rhombohedral and the tetragonal perovskite phase in the samples sintered at a temperature lower than 1100°C. A second phase of pyrochlore was found in the samples sintered at temperatures higher than 1150°C. The PMN-PT-PZ ceramics sintered at 1100°C for 2 h exhibited the highest density, highest linear shrinkage and highest dielectric constant at Tc of 7·72 g cm−3, 16·13% and 18337 respectively. The densest PMN-PT-PZ ceramic exhibited good ferroelectric properties of (using an electric field at 30 kV cm−1) Pr = 26·9 μC cm−2 and Ec = 4·5 kV cm−1.

Fabrication of 0.62[0.75PMN-0.25PYbN]-0.38PT Ceramics Using One Step Calcination via Combustion Technique

The fabrication of 0.62[0.75Pb(Mg1/3Nb2/3)O3-0.25Pb(Yb1/2Nb1/2)O3]-0.38PbTiO3 ceramics (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/cm2and Ec ∼ 8.1 kV/cm) were obtained for the sample sintered at 1150°C.