Pichitchai Butnoi

Phase Transition and Dielectric Properties of PNNZT-BNLT Ceramics

The (1−x)Pb(Ni0.33Nb0.67)0.5Ti0.35Zr0.15O3[PNNZT] – xBi0.4871Na0.4871La0.0172TiO3[BNLT] ceramics (x = 0, 0.03, 0.06, 0.09, 0.12 and 0.15) were prepared by a two steps mixed-oxide method. XRD patterns of all ceramic samples exhibited a complete perovskite phase without pyroclore and no second phase. The BNLT addition has a significant effect on the grain growth inhibition of PNNZT-BNLT ceramics. The dielectric studies indicated that the phase transition behavior of the ceramic compositions becomes more diffuse with increasing BNLT content. The addition of BNLT content caused the increase in Tm, for example: about 16% for the 0.03 mol% BNLT sample while tanδ was reduced to about 60% compared with that of pure PNNZT sample.

Effects of Sintering Temperatures on Structural, Electrical and Mechanical Properties of BNKT Piezoelectric Ceramics

This research investigated the effects of sintering temperatures on the structural, dielectric, ferroelectric, piezoelectric and mechanical properties of lead-free Bismuth Sodium Potassium Titanate (BNKT) piezoelectric ceramics. The BNKT ceramics were prepared by solid-state mixed oxide method and sintering at temperature ranging from 1100 to 1150°C for 2 h. All ceramics sample showed highly density and reach a maximum at sintering temperature 1125°C of 5.81 g/cm3. X-ray diffraction patterns exhibited pure perovskite structure with coexisting of rhombohedral-tetragonal phases for all compositions. The microstructure was characterized by Scanning Electron Microscope (SEM), from SEM image the ceramics showed cubic-like grain shape. The average grain size increased with increasing sintering temperature. The dielectric permittivity showed the optimum sintering at 1125°C with reach a maximum dielectric constant of 4,194. Furthermore, at sintering temperature 1125°C present highest strain (Smax = 0.14%) with a large normalized strain coefficient (d*33 = Smax/Emax) of 233 pm/V.

The mechanical and electrical properties of modified-BNKT lead-free ceramics

ABSTRACT This research was conducted to study influence of ferric oxide nanoparticles on the properties of modified BNKT ceramics. The optimum sintering temperature was 1125°C at which all compositions had low porosity (0.12–0.19%). Raman and XRD showed coexisting rhombohedral and tetragonal phases throughout the entire compositional range. The Pr, d33 and g33 were slightly degraded when the additive was added. The maximum room temperature dielectric (ϵ′ = 1689, tan δ = 0.0606) and mechanical properties (HV = 5.6 GPa, HK = 4.9 GPa, E = 93 GPa and KIC = 1.58 MPa.m1/2) was obtained for the 2 vol% sample.

Electric field–induced strain behavior and ferroelectric properties of lead zirconate titanate-barium calcium zirconate titanate ceramics

ABSTRACT In this work, electric field-induced strain behavior and ferroelectric properties of xBCZT/PZT (with x = 0, 4 and 8 mol%) ceramics have been investigated. The Ec and Pr increased with increasing electric field and exhibited pinched-shape hysteresis loop at 60 kV/cm. The abnormal domain walls and switching behavior of the domains were used to discuss the above results. The strain value increased with increasing BCZT content and reached the maximum value of 0.27% (d*33 = 450 pm/V) for the 4 mol% BCZT sample. This offered an opportunity to obtain a good candidate for using in piezoelectric applications.

Effects of processing parameter on phase transition and electrical properties of lead-free BNKT piezoelectric ceramics

ABSTRACT Lead-free piezoelectric ceramics of Bi0.5(Na0.80K0.20)0.5TiO3 powders were prepared via a conventional solid-state reaction method, and effects of calcination temperature on many properties of the ceramics were investigated. XRD patterns for all ceramic samples showed coexistence between rhombohedral and tetragonal phases without any impurity. Calcination temperatures from 700 to 1000°C shifted depolarization temperature from 92 to 100°C. Dielectric and piezoelectric properties were improved and showed the optimum values for the ceramics which calcined at 800°C. The improvements of piezoelectric properties were related with the ceramic densification and MPB composition.

Electrical Properties of Modified BNT Based Lead-Free Ceramics

The properties of modified Bi0.5Na0.5TiO3 (BNT) based lead-free ceramics were investigated. The BNT-based ceramics were prepared by a solid-state mixed oxide method Phase formation was determined by X-ray diffraction technique (XRD). The X-ray diffraction analysis of the ceramics suggested that all samples exhibited a perovskite structure without second phase. The value of dielectric constant increased with increasing in sintering temperature. Moreover, high sintering temperatures could improve ferroelectric properties of BNT base lead-free ceramics.

Electrical Properties of BNKTZ Ceramics as a Function of Calcination Temperature

In this research, the Bi0.5(Na0.80K0.20)0.5Ti0.99Ti0.10O3 were prepared via a conventional solid-state reaction method, and their properties were related with calcination temperature. The crystalline structure of BNKTZ ceramics was assessed by X-ray diffraction (XRD) method. Other physical properties, i.e. porosity, density, microstructure, and electrical properties were determined. XRD patterns for all samples showed a pure perovskite, where coexistence between rhombohedral and tetragonal phases was observed for some conditions. The optimum dielectric constant was obtained for the ceramic calcined at 800 °C. The ferroelectric and piezoelectric properties were improved and showed the highest values for the calcination temperature around 900-1000°C. The improvements of ferroelectric and piezoelectric properties were proposed to be due to the ceramics had compositions closed to MPB composition. Furthermore, density also had a contribution for the improvements.

Effect of BCZT Dopant on Ferroelectric Properties of PZT Ceramics

The ferroelectric ceramics with composition of (1-x)Pb(Zr0.52Ti0.48O3 [PZT] – x(Ba0.9Ca0.1)(Ti0.85Zr0.15)O3 [BCZT] (x = 0, 0.04, 0.08 and 0.10 ) have been successfully prepared via two-step mixed oxide method. The material systems of lead zirconate titanate (PZT) and barium calcium zirconate titanate (BCZT) have been intensive studied due to their remarkable properties of high ferroelectric and piezoelectric values. In this work, we are interesting to combine PZT with BCZT system in order to improve the electrical property of the ceramic samples. From the obtained results, it can be confirmed that ferroelectric values are significant increased with the optimum amount of the BCZT.

Effects of BST on Optical and Dielectric Properties of Na2O-B2O3-SiO2 Glasses

In this research, the effects of Ba0.7Sr0.3TiO3 (BST) on optical and dielectric properties of Na2O-B2O3-SiO2 glasses were investigated. From the study, the optically transparent glass from BST system was successfully prepared by using melt-quench method. The composition of BST used in this study are ranging between 20-60 wt.% BST. It was found that the addition of BST enhanced conductivity, but in turn reduced the percentage of transmittance in the glasses. The dielectric constant (ɛr) of the BST/Na2O-B2O3-SiO2 glasses improved with increasing the content of BST, which in turn plays an important role in controlling the properties of the BST/Na2O-B2O3-SiO2 glasses.

Influence of BCZT Dopant on Dielectric Properties of PZT Ceramics

(1-x)Pb(Zr0.52Ti0.48O3 [PZT] – x(Ba0.9Ca0.1)(Ti0.85Zr0.15)O3 [BCZT] (x = 0, 0.04, 0.08, 0.10, 0.20 and 0.30) were prepared by a two-step mixed-oxide method. XRD patterns of all ceramic samples exhibited a complete perovskite phase without impurity phase and no a second phase. The dielectric studies indicated that the phase transition behavior of the ceramic compositions becomes more diffuse with increasing BCZT contents. Moreover, The maximum dielectric constant and the transition temperature decrease with the increasing BCZT contents. The addition of BCZT contents caused the decrease of the tanδ value for 218% compared to that of pure PZT.