Papers by Author: Uraiwan Intatha

Abstract: Lead-free (K_0.5Na_0.5)NbO₃ (KNN) piezoelectric ceramics were studied and synthesized by the seed-induced method. NaNbO₃ crystal was used as seed and prepared by molten salt synthesis (MSS). The average particles size of NaNbO₃ seed crystal was about 1-3 mm. Then, the NaNbO₃ seed was mixed with KNN powder and ball milled for 24 h. The mixed powder was calcined at 700-900 °C and sintered at 1100 °C. The phase structure and morphology of the ceramics were investigated by X-ray diffraction and scanning electron microscope and the electrical properties were studied. The results indicated that all samples showed a pure perovskite phase. The highest density of the ceramic was 93% compared to the theoretical density. The results showed that NaNbO₃seed crystal improved piezoelectric properties of KNN ceramics.

Abstract: Ba_0.85Ca_0.15Zr_0.1Ti_0.9O₃ (BCZT) ceramics were produced by using the seed-induced method. The nano-particle BZ (BaZrO₃) seeds were mixed with BaCO₃, CaCO₃, ZrO₂ and TiO₂ powder for preparing by the mixed oxide method. The XRD results indicated that all powder and sintered ceramic samples showed a pure perovskite phase with coexistence between rhombohedral and tetragonal phase. As the BZ seed content increased, the density of ceramics tended to decrease from 5.61 g/cm³ to 5.37 g/cm³. The average grain size of the ceramics was in the range of 12.15 -13.50 mm. The dielectric loss (tand) was less than 0.03 for all samples at room temperature (at 1 kHz). Other electrical properties, including dielectric constant (ε_r), remnant polarization (P_r), and piezoelectric charge coefficient (d₃₃) values decreased with increasing BZ seed doping with relates to the decreasing grain size and density of BCZT ceramics. However, the values of coercive field (E_c) decreased and piezoelectric voltage coefficient (g₃₃) increased with BZ seed doping.

Abstract: The study was conducted to find out the effect of particle sizes of BaTiO₃ (BT) seed on the microstructure and electrical properties of (Ba_0.85Ca_0.15)(Zr_0.1Ti_0.9)O₃ (BCZT) ceramics. The BT seeds were prepared by the molten salt method. Results indicated that the BT seed powder showed a single pure perovskite phase when using a low temperature of ~750°C. The particle sizes of BT seeds increased from ~381 to ~600 nm with increasing heating temperatures from 750 to 900°C. After that, the different BT seeds were mixed with BaCO₃, CaCo₃, ZrO₂ and TiO₃ via the solid state reaction method. The mixed powder was calcined and sintered at 1200 °C for 2 h and 1450 °C for 4 h, respectively. The microstructure, phase formation and electrical properties were investigated. All ceramic samples showed a pure perovskite phase. The density and average grain size values of ceramics were in the range of 5.36-5.47 g/cm³ and 9.83-11.86 μm, respectively. The highest values of dielectric constant (ε_r), piezoelectric constant (d₃₃) were 3393 and 452 pC/N, respectively which obtained at the sample of BT-seed size 372 nm doped.

Abstract: Ba_0.85Sr_0.15Ti_0.90Zr_0.10O₃ (BSZT) ceramics doped Sn was prepared by seed-induced method. The seed was prepared by molten salt method, NaCl-KCl (1:1 by mole) eutectic mixtures was used as the flux. The BSZT added seed with doped SnO were calcined at 1250 °C for 3 hrs and sintered at 1400 °C for 2 hrs, respectively. The phase formation and morphology of these samples were characterized via X-ray powder diffraction and scanning electron microscopy, respectively. From the above studies, it has been concluded that the maximum dielectric constant is 19147 at BSZT ceramics prepared by seed-induce method.

Abstract: Recent years, propolis has plenty of biological and pharmacological properties and its mechanisms of action have been widely investigated. There is a substantive database on the biological activity and toxicity of propolis indicating it may have many antibiotic, antifungal, antiviral and antitumor properties, among other attributes. The one-step incorporation of propolis into nanofibrous mats of polycaprolactone (PCL) by electrospinning was demonstrated. In this research, the preparation of the PCL nanofibers films added ethanolic extract propolis (EEP) by electrospinning technique was studied. The EEP content was varied from 0, 2, 4, 6, 8 and 10%. The morphology was observed by a scanning electron microscope (SEM). The functional group was investigated by FT-IR

Abstract: In this study, barium stannate titanate ceramics with an addition of boron oxide were synthesized via a solid-state sintering method. The effect of sintering aid on electrical and mechanical properties of barium stannate titanate ceramics was investigated. It was found that, the ceramic with 2 wt% boron oxide showed the lowest porosity and the highest dielectric constant of ~ 13700 at room temperature. In addition, an increase in the boron oxide content was observed to enhance the hardness of the ceramics. These results may be helpful in the multilayer capacitor applications.

Abstract: Binary system of 0.45Pb(Zr1/2Ti1/2)O3–0.55Pb(Ni1/3Nb2/3)O3with a composition close to the morphotropic phase boundary were investigated as a function of Sn doping (0.0-8.0 mole%). X-ray analysis showed that pure perovskite phase was observed for all samples. The density of the ceramic samples was increased with an increase of Sn concentration. However, microstructural analysis showed that Sn-doping has not a significant impact on grain size. Moreover, the increasing Sn-contant can reduce the remanent polarization but increase the dielectic contant.

Abstract: In this work, preparation conditions and effect of ZrO2 doped BaFe0.5Nb0.5O3 ceramics were studied. Relationship between structure and dielectric properties was investigated. Single-phase cubic BFN powder was synthesized by solid-state reaction at 1200°C for 4 hours with heating and cooling rate of 5°C/min. Various amount of ZrO2 doped from 0.1 to 0.5 %weight were used for doping. After that BFN ceramics were formed via uniaxial pressing and sintered at 1300°C for 4 hours with heating and cooling rate of 5°C/min. Physical properties, microstructure, phase evolution and dielectric properties were studied to find out the optimum conditions for high voltage capacitor applications.

Abstract: BaFe0.5Nb0.5O3 (BFN) exhibits very high dielectric constant over a wide temperature range. However, these materials normally require high-temperature sintering to achieve a maximum densification. The aim of this study is to determine the effect of potassium fluoride salt on the sintering and dielectric properties of BFN ceramics. The results show that KF additive lower the sintering temperature by 100-200°C without affecting the formation of BFN phase. Ceramics doped with 1% KF show optimum densities of about 95% of the theoretical value when sintered at 1300°C. The addition of fluoride salt in the BFN ceramics causes very broad dielectric constant curves over a wide temperature range indicating the diffuse phase transition characteristic. Furthermore, this addition also reduces in the dielectric loss when compared with pure BFN ceramics

Abstract: In this research work, the investigation of the morphotropic phase boundary, physical properties and electrical properties of lead- free piezoelectric materials of bismuth sodium titanium oxide: (Bi0.5Na0.5)TiO3 (BNT) and potassium niobium oxide : KNbO3 (KN) in the ceramic system of (1-x)BNT- xKN where x= 0.00, 0.03, 0.05, 0.08, 0.10 and 0.15 by modified mixed oxide method was carried out. The BNT and KN powders were prepared separately using calcination technique with optimum calcination temperature for producing both BNT and KN powders of about 800°C. XRD results revealed that the BNT-KN ceramics with low KN content of x less than 0.05 contain ferroelectric perovskite phase with rhombohedral symmetries while the higher KN content ceramics have mixed symmetries between rhombohedral and orthorhombic. From the evidences including phases, microstructures and dielectric data of the BNT-KN ceramics, it may be assumed that the morphotropic phase boundary may be at around the composition of x = 0.05.