Methee Promsawat

Enhanced dielectric, ferroelectric, and electrostrictive properties of Pb(Mg1/3Nb2/3)0.9Ti0.1O3 ceramics by ZnO modification

The effects of ZnO modification on the dielectric, ferroelectric, and electrostrictive properties of 0.9Pb(Mg1/3Nb2/3)O3-0.1PbTiO3 (PMNT) ceramics are systematically studied in this work. The PMNT/xZnO (with x = 0, 0.4, 2.0, 4.0, and 11.0 mol. %) ceramics of complex perovskite structure were prepared by solid state reaction and sintering process. It is found that the maximum value of the dielectric constant decreases with increasing ZnO amount up to x = 4.0 mol. %, and then significantly increases with x = 11.0 mol. %. The temperature of maximum dielectric constant tends to increase, while the diffuseness of the dielectric peak is reduced, with increasing ZnO content. The remanent polarization and the coercive field increase with increasing ZnO concentration. The induced strain and the electrostrictive coefficient reach the maximum values of 0.10% (at E = 10 kV/cm) and 12.94 × 10−16 m2/V2, respectively, with x = 2.0 mol. % ZnO. The ceramic doped with a high ZnO content (11.0 mol. %) exhibits a macroscopic...

Effect of ZnO Nano-Particulates on Structure and Properties of PZT/ZnO Ceramics

In this research, effect of ZnO nano-particles on structure, mechanical and electrical properties of PZT ceramics was investigated. X-ray diffraction result suggested that tetragonality of PZT decreased with increasing ZnO content. Density tended to increase with an addition of ZnO while grain size of the ceramics decreased. An addition of ZnO increased hardness of the ceramics. Maximum hardness was achieved at an addition of 0.5 wt% ZnO. Within the PZT/ZnO ceramics, increasing content of ZnO gradually increased fracture toughness. Electrical properties characterization of the ceramics showed that an addition of ZnO reduced dielectric constant and slightly lowered Curie temperature. Ferroelectric measurement found that an addition of < 0.5 wt% ZnO did not significantly change ferroelectric properties. However, these properties were degraded at higher content of ZnO.

Effects of ZnO nanoparticulate addition on the properties of PMNT ceramics

This research was conducted in order to study the effect of ZnO nanoparticulate addition on the properties of 0.9 Pb(Mg1/3Nb2/3)O3-0.1PbTiO3 [PMNT] ceramics. The PMNT ceramics were prepared by a solid-state reaction. The ZnO nanoparticles were added into PMNT ceramics to form PMNT/x ZnO (x = 0, 0.05, 0.1, 0.5, and 1.0 wt.%). The PMNT/x ZnO ceramics were investigated in terms of phase, microstructure, and mechanical and electrical properties. It was found that the density and grain size of PMNT ceramics tended to increase with an increasing amount of ZnO content. Moreover, a transgranular fracture was observed for the samples containing ZnO, while pure PMNT ceramics showed only a intergranular fracture. An addition of only 0.05 wt.% of ZnO was also found to enhance the hardness and dielectric and ferroelectric properties of the PMNT ceramics.

Comparative study of properties of BCZT ceramics prepared from conventional and sol-gel auto combustion powders

ABSTRACT This work studies properties of Ba0.85Ca0.15Ti0.9Zr0.1O3 (BCZT) ceramics prepared from the BCZT powders synthesized by conventional mixed oxide (so called M) and sol-gel auto combustion (so called A) methods. The M and A powders were calcined at 1200 and 900°C, respectively. Different amounts (0, 50 and 100 wt%) of A powder were added into M powder then sintered at 1450°C for 2 h. Grain size and dielectric constant (ϵr) tended to decrease with A powder content. The highest ϵr value of 5342 but slimmest was observed in the ceramic with 100 wt% A powder addition.

Electrical Properties of Sol-Gel Derived PZT/WO3 Ceramics

PZT/xWO 3 powders were prepared from the powders synthesized by a modified triol sol-gel method. XRD and TEM results suggested that fully crystallized powders were obtained at the calcination temperature of 600°C for 4 h. A reaction between PZT and WO 3 powders seemed more pronounced with increasing WO 3 content. To prepare PZT/xWO 3 ceramics, the powders were pressed and sintered at 1100°C for 6 h. Phase characterization by XRD indicated that the concentration of WO 3 affected lattice parameters and reduced c/a ratios, especially for high content of WO 3 . SEM images showed that an addition of only 0.5 wt% WO 3 significantly decreased grain size of the ceramics. Density of the ceramics, however, did not significantly depend on WO 3 concentration below 1 wt%. Addition of suitable amount of WO 3 enhanced ferroelectric properties and reduced high-temperature dielectric loss of PZT ceramic.

Characterization of Phase Evolution, Microstructure and Electrical Properties of Sol–Gel Auto-Combustion Derived BCZT Ceramics

This work aims to study the effect of sintering temperature on properties of barium calcium zirconate titanate (BCZT) ceramics. The BCZT is a Pb-free material that shows excellent piezoelectric properties. In this study, BCZT ceramics were prepared from BCZT powders synthesized from barium nitrate, calcium nitrate, zirconium (IV) oxynitrate hydrate, titanium (IV) butoxide and citric acid precursors by the sol-gel auto-combustion method. The BCZT powder was calcined at the temperature ranging from 700 to 1000 °C. Green bodies were sintered at various temperatures (1200-1450 °C). The X-ray diffraction patterns showed only non-crystalline phase of as-burnt powder. For the calcined powders, XRD patterns showed that the amount of crystalline, perovskite phase increased with increasing calcination temperature. The crystalline particles have a spherical shape and the size in the range of 25-35 nm. For the BCZT ceramics sintered at 1200-1300 °C, the density tended to increase with increasing sintering temperature. Very high bulk densities of 5.62-5.63 g/cm3 (which were higher than those of the ceramics synthesized by the wet-chemical method) were achieved at the sintering temperature of 1400-1450 °C. Ceramics produced at these temperatures possessed fully-developed microstructures, very good dielectric properties as well as high response of polarization and strain to applied electric field.

Probing local structure of ZnO-modified Pb(Mg1/3Nb2/3)0.9Ti0.1O3 ceramic with synchrotron X-ray absorption spectroscopy technique

ABSTRACT This work aims to study the effects of ZnO modifications on local structures of Pb(Mg1/3Nb2/3)0.9Ti0.1O3 (PMNT) ceramics. Different contents of ZnO (0, 0.4, 2.0, 4.0 and 11.0 mol%) were added into PMNT ceramics. The local structures of the samples were characterized by synchrotron X-ray absorption spectroscopy (XAS). X-ray absorption near-edge structure (XANES) spectra of both Zn and Ti K-edges were displayed. The Zn K-edge energy values of all samples were in the range of 9660–9666 eV. The Zn ions incorporated in all ceramics were in the form of Zn2+. The value of Ti K-edge energy, which was equal to 4979 eV, did not change with ZnO modifications. Comparing the experimental Zn K-edge XANES spectra to the spectra simulated via FTFF program confirmed the substitution of the Zn ions for B-site ions. The intensity and the area under curve of the pre-edge peak of Ti K-edge gradually increased with increasing ZnO content up to 4.0 mol%. This suggested a gradual change in the displacement out from octahedral centers of Ti ions. This could be an evidence of the enhancement in ferroelectric order of ZnO-modified PMNT ceramics.

CNTs-added PMNT/PDMS flexible piezoelectric nanocomposite for energy harvesting application

ABSTRACT The flexible piezoelectric nanocomposites based on lead magnesium niobate titanate [Pb(Mg1/3Nb2/3)0.65Ti0.35O3; PMNT] particles in polydimethylsiloxane (PDMS) matrix were fabricated and characterized. PMNT powders are synthesized using the columbite precursor method. PMNT/PDMS flexible nanocomposites are then prepared by spin casting technique, where a small amount of carbon nanotubes (CNTs) is added into the PMNT/PDMS composite to enhance cross-links between PMNT particles and PDMS matrix. The phase and microstructure of the nanocomposite are investigated by using X-ray diffraction and scanning electron microscope (SEM). The electromechanical behavior is evaluated by using an autonomous pneumatic actuator. The flexible composite, occupying approximately 300 mm2, is capable of generating an open-circuit voltage (Voc) of 2.83 ± 0.24 V and a short-circuit current (Isc) signal of 0.33 ± 0.01 µA across 10 Ω resistor under mechanical load of 300 N. The generated electrical charges are 29026 pC. The relative dielectric constant is measured at 10 kHz and found to be 6.76 ± 1.15. The piezoelectric PMNT/PDMS composite can potentially be used in a variety of applications such as wearable sensors, actuators, and energy harvesting for converting kinetic energy into useful electrical energy.

Investigation of the effect of temperature on aging behavior of Fe-doped lead zirconate titanate

The aging degradation behavior of Fe-doped Lead zirconate titanate (PZT) subjected to different heat-treated temperatures was investigated over 1000h. The aging degradation in the piezoelectric properties of PZT was indicated by the decrease in piezoelectric charge coefficient, electric field-induced strain and remanent polarization. It was found that the aging degradation became more pronounced at temperature above 50% of the PZT’s Curie temperature. A mathematical model based on the linear logarithmic stretched exponential function was applied to explain the aging behavior. A qualitative aging model based on polar macrodomain switchability was proposed.

Enhanced sinterability and electrical properties of Bi2O3-added Ba0.85Ca0.15Zr0.1Ti0.9O3 ceramics

ABSTRACT The ceramics of Bi2O3-added Ba0.85Ca0.15Zr0.1Ti0.9O3 or BCZT-xBi (where x = 0.005, 0.01, 0.02 and 0.1 mol fraction) were fabricated from sol-gel auto-combustion derived BCZT and commercial Bi2O3 powders. In this study, BCZT-0.02Bi ceramic sintered at 1200°C for 2 h was found to be the optimum composition with high relative density and homogeneous microstructure. The temperature at maximum dielectric constant (Tmax) of this sample was near room temperature, rendering a high dielectric constant value (∼1653). Frequency dependence of Tmax suggested the relaxor behavior which was also supported by slim ferroelectric hysteresis loops. Since a relatively large breakdown voltage (> 70 kV/cm) was observed, the BCZT-0.02Bi ceramic could be a potential lead-free electrostrictive/piezoelectric material for actuator applications.