Apichart Limpichaipanit

Effect of soaking time on phase formation and electrical properties of PLZT based ceramics

Lead lanthanum zirconate titanate ceramics (PLZT) are well known for their excellent dielectric, piezoelectric and ferroelectric properties and electro-optic characteristics. The solid solutions of compounds are expected to possess very interesting properties, making them promising candidates for electromechanical devices. This study describes processing and sintering conditions and electrical properties of the PLZT ceramics (9/65/35) that were successfully prepared from the respective starting materials by vibro-milling mixed-oxide method at various soaking time conditions for optimized properties. A composition and microstructure of the ceramics were investigated using X-ray diffraction and scanning electron microscopy. The dielectric properties of the densified samples were examined as a function of temperature and frequency to verify the relationships between soaking time conditions, phase formation, densification, microstructural development, dielectric, and ferroelectric characteristics.

Effect of PbO/CuO Addition to Microstructure and Electrical Properties of PLZT 9/65/35

PLZT 9/65/35 (Pb0.91La0.09(Zr0.65Ti0.35)0.9775O3) ceramics can be prepared by sintering but it is difficult to obtain dense and transparent samples. In this study, PbO/CuO (where the ratio of PbO:CuO = 4:1) was used as a sintering aid to improve sinterability of PLZT. Glassy phase formation caused by the reaction between PbO and CuO promoted grain growth and densification. PLZT 9/65/35 + x wt% PbO/CuO (where x = 0, 1.0, 3.0 and 5.0) ceramics had relaxor ferroelectric behavior. Maximum dielectric constant at 1 kHz could be tailored to optimum condition when 1.0 wt% PbO/CuO was added and the ceramic was sintered at 1200°C (ϵr = 8370 and tan δ = 0.0093).

Effect of Sintering Condition on Electrical Properties of PLZT Ceramics

Feroelectric lead lanthanum zirconate titanate (PLZT) ceramics 9/70/30 were synthesized by conventional mixed-oxide method via a vibro-milling technique. The effect of sintering temperature and two-stage sintering method on electrical properties of PLZT ceramics was investigated. The ceramic powder was uniaxially pressed in pellets and sintered at the temperatures ranging from 1200 to 1275 °C for 4hrs and two-stage sintering temperature at 1200 °C for 4 hrs. Dielectric, ferroelectric and strain properties of ceramics were characterized by LCR meter, modified Sawyer–Tower Circuit and modified Michelson interferometric technique respectively.

Optical Interferometric Technique for Induced Strain Ferroelectric Loop Study at Low Frequency

Michelson interferometric technique was modified in the setup and used to measure very small changes in optical path length for electric field induced-strain phenomena. Induced-strain is established in the sample when the beam of light propagating through the sample surface undergoes a shift in phase, which in turn leads to a change in the intensity of the interference pattern formed where the reference and probing beams recombine. In this work the electric field induced-strain was measured as a function of electric field (s-E loop) and polarization (s-P loop) of PbMg1/3Nb2/3O3 (PMN) and 0.7PbMg1/3Nb2/3O3-0.3PbZr0.52Ti0.48O3 (0.7PMN-0.3PZT) ceramics, which showed electrostrictive (quadratic shape curve) and piezoelectric (butterfly shape curve) behavior at various frequency (0.01-1Hz).

Sintering temperature-microstructure-property relationships of alumina matrix composites with silicon carbide and silica additives

Abstract Alumina-based composites were fabricated by reaction sintering from two different sintering powder mixtures: alumina with silica (SiO2) and alumina with silicon carbide (SiC; to allow oxidation to form SiO2). After sintering, SiO2 underwent complete reaction to form alumina/mullite composites. In terms of microstructure, the density and grain size of ceramic samples were investigated. The density of the composites prepared by alumina and SiC was lower than those of alumina and the composites prepared by alumina and SiO2. The grain size increased as the sintering temperature increased. In terms of mechanical properties, fracture surfaces, hardness, and fracture toughness were investigated. It was found that the fracture surface of alumina was rather intergranular, whereas the fracture surface of the composites was more transgranular. The hardness of the composites was higher than that of alumina at the same sintering temperature. However, the fracture toughness of the composites was not significantly different compared to that of alumina.

Dielectric and Ferroelectric Behavior in 8/40/60 PLZT Ceramics

This paper describes the relationship between sintering time conditons, tetragonality from phase formation, dielectric and ferroelectric characteristics of tetragonal PLZT (lanthanum modified lead zirconate titanate) ceramics with the pressureless sintering conditions. Ferroelectric compounds of Pb0.92La0.08(Zr0.4,Ti0.6)0.98)O3, PLZT 8/40/60, were prepared using mixed-oxide synthetic route via a rapid vibro-milling method. X-ray diffraction, is used to observe the tetragonality characteristic and the presence of pyrochlore. When sintering time was increased (≥ 8 hours), pyrochlore was developed. It can be observed that with the increased sintering time, it were changed the structure and ferroelectric behavior of the PLZT ceramics.

Effect of Dielectric Properties and Elastic Strain Behavior on x/65/35 PLZT Ceramics in Lanthanum (x) Ions Contents

In this paper the effect of lanthanum addition on the phase formation, dielectric and ferroelectric characteristics of x/65/35 PLZT. This ceramics were prepared using mixed-oxide synthetic route via a rapid vibro-milling method. All samples were sintered at 1200°C for 12 h. X-ray diffraction was used to observe the crystal structure. It was found that when increasing lanthanum content, the structure remained rhombohedral. It can be seen that the change of behavior to ferroelectric relaxor with the increasing of lanthanum content resulted in the change of elastic strain

Isochromatic photoelasticity fringe patterns of PMMA in various shapes and stress applications

The research focuses on isochromatic photoelastic fringe patterns in solid materials by using reflection mode in dark field polariscope. The optical setup consists of light source, polarizers, quarter wave plates, 577 nm optical pass filter, compensator and digital camera system. The fringe patterns were produced on the sample and fractional / integer number of fringe order was observed using Babinet compensator and digital camera system. The samples were circular and rectangular shape of PMMA coated with silver spray and compressed by hydraulic system at the top and the bottom. The results of the isochromatic fringe pattern were analyzed in horizontal and vertical positions. It was found that force and the number of isochromatic photoelastic fringe order depended on shape of sample, which reflects stress distribution behavior.

Temperature and induced electric field dependence on the phase transition of 9/70/30, 9/65/35 and 9/60/40 PLZT ceramics

ABSTRACT In this work, Pb0.91La0.09(Zr1–xTix)0.9775O3 ceramics where x = 0.3, 0.35 and 0.4 (the composition near MPB) were prepared by solid solution method. After fabrication process, electrical property was measured by LCR meter. Polarization and induced strain behavior of the samples were investigated by using interferometry technique modified with Sawyer–Tower circuit at various temperatures. The results of dielectric, polarization and induced strain properties were due to the Zr/Ti ratios, which changed their behavior when temperature was varied (30–70 °C). The normal to macro-micro domains to relaxor and paraelectric phase transition was demonstrated which is related to linear or nonlinear increase of polarization and induced strain as a function of applied subswitching electric field.

Inner Filter Effect on Fluorescence Dyes Spectra in Methanol Solution

This research was conducted to study the inner filter effect on the fluorescence spectra of fluorescence dyes. The concentration effect on all of fluorescent dye solutions showed the same trend in terms of changes in fluorescence intensity spectra. At low concentrations, the fluorescence intensity increased when the concentration of fluorescent dye solution increased. However, at high concentrations, the fluorescence intensity decreased when the concentration of fluorescent dye solution increased. Interestingly, the result of fluorescence spectra in dye solutions showed that the fluorescence intensity maxima in all dye solutions were shifted to a higher wavelength (red-shift) when the concentration of fluorescent dye solution increased. The results of concentration effect on fluorescence intensity and wavelength-shift in dyes solution can be explained by inner filter effect on fluorescent dye solutions.