Supalak Manotham

Properties of 0.94Bi0.5Na0.5TiO3–0.06BiAlO3 Ceramics Prepared by Two Steps Sintering Technique

In this research, 0.94Bi0.5Na0.5TiO3–0.06BiAlO3 ceramics were prepared by the conventional solid-state reaction and the two steps sintering. X-ray diffraction analysis revealed that both samples showed a pure perovskite phase. Scanning electron microscopy study revealed that both ceramics had similar microstructure. The two steps sintering affects the phase transition temperature of the ceramics. Dielectric and ferroelectric properties of the two steps sintering samples are better than that of the conventional sample. The results were related to the densification and the degree of crystallinity of the samples.

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.

Processing and Properties of Biphasic Calcium Phosphates Bioceramics Derived from Biowaste Materials

Properties of biphasic calcium phosphates bioceramics derived from biowaste materials were investigated. The hydroxyapatite (HA) powder was synthesized from bovine bone via thermal treatment while β-tricalcium phosphate (β-TCP) powder was synthesized from mussel shells via solid state solution. Pure HA and β-TCP were successful obtained. The HA and β-TCP were mixed together and sintered at 1100 - 1350°C. The effects of the sintering temperature and the ratio of HA/ β-TCP on the properties of the studied samples were investigated. The sintering temperature at 1250°C presented the maximum value of density and hardness. X-ray analysis of BCP ceramics sintered at 1250°C presented multiple phases of calcium phosphate. Average grain sizes of the studied samples decreased as the ratio of HA increased.

Influence of Sintering Temperature on Structure and Electrical Properties of Modified-BNKT Lead-Free Piezoelectric Ceramics

In this research, the effects of sintering temperature on phase structure, densification, microstructure, and electrical properties of modified-BNKT ceramics were investigated. Conventional sintering of lead-free 0.97Bi0.5(Na0.80K0.20)0.5TiO3-0.03(Ba0.70Sr0.30)O3 or 0.97BNKT-0.03BSrT ceramic was investigated to clarify the optimal sintering temperature for densification and electrical properties. All ceramics were prepared by a conventional mixed oxide and sintered at various temperatures from 1100 to 1150°C. XRD pattern indicated all ceramics exhibited a single perovskite without any secondary phases. The maximum density of 5.80 g/cm3 with relative density of 99.32% were observed for the ceramic sintered at 1125°C. Grain size tended to increase with increasing the sintering temperature. The good dielectric (Td = 121 °C, Tm = 320 °C and e¢max = 4982) and ferroelectric properties (Pr = 16.66 µC/cm2, Ec = 17.85 kV/cm and Rsq = 0.74) were obtained for the ceramic sintered at optimum sintering temperature of 1125°C.

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.

Effects of Dwell Time Sintering on Microstructure, Piezoelectric and Mechanical Properties of Modified BNT-Based Ceramics

The properties of modified Bi0.5Na0.5TiO3 (BNT) based lead-free ceramics were investigated. The BNT-based ceramics were prepared by a two-steps sintering method. The ceramics were sintered at T1=1373 K and T2= 1173 K for various dwell times (0, 2, 4, and 8h). The properties of the ceramics were characterized by many techniques. The ceramic samples exhibited a pure perovskite phase with rhombohedral symmetry. The microstructural analysis by a scanning electron microscopy (SEM), indicated that all ceramics had a similar microstructure. Piezoelectric and mechanical properties of the ceramics were improved at a suitable dwell time at T2.