Nattaya Tawichai

Influence of B2O3 on electrical properties and phase transition of lead-free Ba(Ti0.9Sn0.1)O3 ceramics

The phase transition and electrical properties of Ba(Ti0.9Sn0.1)O3 ceramics with B2O3 added were investigated to explore the effect of B2O3 addition on enhanced densification and dielectric constant of these ceramics. With increasing B2O3 content, a linear reduction of ferroelectric to paraelectric transition temperature was observed. In addition, higher B2O3 concentrations enhanced a ferroelectric relaxor behavior in the ceramics. Changes in this behavior were related to densification, second-phase formation and compositional variation of the ceramics.

Phase transition behavior in (1 − x)PZT–xBiAlO3 ceramics

In this study, a new ceramic with the composition (1 − x)Pb(Zr0.52Ti0.48)O3–xBiAlO3 was fabricated using the solid state method. Phase transition characteristic and dielectric response were investigated. With increase in the content of BiAlO3, a transformation from the tetragonal to the rhombohedral phase was observed. The addition also enhanced the degree of phase transition diffuseness and produced a decrease in the ferroelectric-to-paraelectric phase transition temperature. The results suggested that BiAlO3 has a strong effect on the transition behavior of the solid solution. It is proposed that lattice distortion and compositional fluctuation are responsible for these effects.

Influence of Sintering Temperature on Dielectric and Piezoelectric Properties of B2O3 Doped Lead-Free Ba(Ti0.9Sn0.1)O3 Ceramics

Lead-free ceramics of Ba(Ti0.9Sn0.1)O3 doped with 0.5 wt% B2O3 were prepared by a conventional solid state sintering method. Dielectric and piezoelectric properties of the ceramics were investigated as a function of sintering temperature. Although density of the ceramics was observed to decrease with increasing the sintering temperature, the sample sintered at 1350°C showed maximum dielectric constant of 9900 at the phase transition temperature ∼ 36°C. Higher relative tunability of 83% was also observed at the same condition. However, the ceramics showed a lower piezoelectric coefficient (d33) at a higher sintering temperature.

STUDY OF ESR, DEFECT STRUCTURE AND SURFACE MORPHOLOGY OF Cu2+ IN CdS CRYSTALS

Cu-doped Cadmium sulfide (CdS) films were prepared by chemical bath deposition method. Various quantities of Cu were used for mixing. Surface characterization, structure, morphology and defect structures of the films were studied. The structure of all Cu-doped CdS films was a unique CdS cubic phase. The grain size of CdS was decreased when doped with Cu. The F-type defect in the undoped CdS is clearly confirmed by an ESR signal arising from the hyperfine interaction of electron spin (S=1/2) trapped in sulfur vacancies and neighboring cadmium nuclear spin (I=1/2). In the Cu-doped CdS films, the ESR peaks shift towards low fields as the copper concentration is increased. This is due to the change in crystal field experience by Cu2+ (3d9) ions while the Cd2+ signal disappears. The Cu2+ ions in the Cd1-xCuxS itself are ESR silent due to a very short relaxation time. The dark resistance increased with increasing amount of Cu concentrations up to about 0.03 M. This 0.03 M Cu-doped CdS sample also possesses the ...

Dielectric and Piezoelectric Properties of Sr Doped 0.8PZT-0.2PNN Ceramics

The solid solution of 0.8(Pb(Zr 1/2 Ti 1/2 )O 3 ) – 0.2(Pb(Ni 1/2 Nb 2/3 )O 3 ) doped with Sr were prepared by solid state route. Effect of Sr dopant on dielectric and piezoelectric properties was investigated. The dielectric constant at room temperature of the ceramics was found to increase with increasing Sr concentration. An increase in tunability was observed for the samples doped with higher Sr concentration. However, the maximum piezoelectric coefficient (d 33 ) was observed for the ceramic doped with 0.6 mol% Sr.

Characteristics of 45S5 Bioglass-Ceramics Using Natural Raw Materials

The aim of this work was to analyze the effect of using rice husk ash (RHA) and bovine bone as raw materials of glass-ceramics based on the SiO2-Na2O-CaO-P2O5 system on their physical, mechanical properties and bioactivity. All of the investigated compositions were prepared by melting the glass mixtures at 1300°C for 3 h. The resulting glass samples were heated at different temperatures ranging from 600 to 1000°C with fixed dwell-time for 2 h for crystallization. Phase identification of the prepared glass ceramics was carried out by X-Ray diffraction (XRD) and scanning electron microscope (SEM) techniques. In addition, in vitro test was carried out in stimulated body fluid (SBF). Differential thermal analysis (DTA) showed that the glass transition occurred at 505°C and crystallization at 700°C. The main crystalline phase form in most glass ceramics is a sodium calcium silicate. The optimum heat treatment temperature, at which the maximum mechanical value (620 HV) could be obtained, is around 1000°C. After incubation in SBF for 7 days, all of the samples show good bioactivity in vitro, as evident by the formation of bone like apatite phase.

Dielectric and ferroelectric properties of annealed B2O 3 doped Ba(Ti0.9Sn0.1)O3 ceramics

In the present work, the posted sintered annealing method was applied for B2O3 doped Ba(Ti0.9Sn0.1)O3 ceramics. The ceramics were fabricated via a solid state reaction method: sintered at 1350°C for 24 h followed by annealing at 1100°C for 4–32 h. Many electrical properties of the ceramics annealed at various annealing times were investigated with a variety of methods. Annealing for 4 h produced a sharper phase transition with high dielectric constant. The high dielectric constant of 27,000 was recorded at ferroelectric to paraelectric phase transition temperature of 38°C. This sample also showed a high dielectric tunability of 70%. Ferroelectric performance of the sample was also improved. The improvements in electrical properties were related to the chemical homogeneity of the sample after annealing.

Properties of Barium Stannate Titanate with Boron Oxide Addition

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.

Characterization of Lead‐Free B2O3 Doped Barium Stannate Titanate Ceramics

Lead‐free barium stannate titanate ceramics doped with 2 wt% of B 2 O 3 were prepared via a solid state sintering. The optimum condition for the preparation was carried out. Properties of the lead free material were characterized by various methods. The high dielectric constant >14000 with low tan δ 0.040 was observed at 34° C for the samples prepared at the optimum condition. Plots of dielectric permittivity as a function of temperature showed that the ceramics exhibit a diffuse ferroelectric‐paraelectric phase transition. The dielectric constant was also measured as a function of electric field. The dielectric‐electric field measurement indicated that this material exhibits a high tunability. In addition, mechanical property such as hardness was investigated. Relation between grain size and hardness of the ceramics was found to obey the Hall‐Petch equation: H v = 0.07+12.9G − 1 2 .

Electrical properties and phase transition behaviors of Sn doped 0.45PZT- 0.55PNN ceramics

Dielectric properties, and phase transition behaviors of Sn doped 0.45PbZr1/2Ti1/2O3—0.55PbNi1/3Nb2/3O3 ceramics has been investigated. The ceramics were prepared by a normal solid‐state method and were characterized, using a variety of techniques. For undoped samples, high relative permittivity of >21000 (at 1 k Hz) was found at the transition temperature of 104° C. With increasing Sn concentration, the degree of diffuse phase transition was enhanced and a linear reduction in the transition temperature was produced.