Papers by Author: Athipong Ngamjarurojana

Abstract: The 0-3 lead-free bismuth sodium titanate-bismuth potassium titanate-barium titanate (BNBK) ceramic/Portland cement composites (PC) were fabricated by pressing and curing method. The influence of BNBK particle size on the dielectric and acoustic properties of 0-3 BNBK-PC composites was studied. BNBK of various median particle sizes (75, 212 and 425 μm) at 50% by volume were mixed with Portland cement to produce the 0-3 BNBK-PC composites. The dielectric constant results of composites were found to increase with increasing BNBK particle size and the dielectric constant of composite with 425 μm particle size at 1 kHz was 196. The 0-3 BNBK-PC composites in the range tested have an acoustic impedance match with concrete structure.

Abstract: The optical spectroscopic properties of fluorescent materials were investigated using laser induced fluorescence technique. The fluorescent creams were used in this research. The sample materials were illuminated by UV laser excitation source. Then, the fluorescence spectra were recorded and analyzed by fiber optics spectrometer complied with the CIE 1931 XYZ color space which is essential for color management. The result showed that the characteristics of fluorescence spectra such as intensity, wavelength position and bandwidth in each fluorescent creams exhibited distinct characteristics in each species.

Abstract: In this study, the fringe pattern distribution of various loads on circular disk of homogeneous acrylic in different thicknesses by using reflection polariscope technique was carried out. The load was pressed at the top and the bottom to produce the fringe patterns, which were recorded by digital camera. Then the results were analyzed. The number of isochromatic fringe pattern depends on the magnitude of force acting on the circular disk and these relation is linearly. The application of these research is used to predict stress distribution on the transparent material in the case of different dimension of the circular disk shape.

Abstract: 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.

Abstract: The experiment was conducted to study the stress distribution on a homogeneous plastic using photoelastic analysis system where the stress was observed by reflection polariscope. The circular disk of homogeneous plastic was used for study in this research. The sample was pressed at the top and bottom. The fringe patterns were produced from sample on the model being stressed, which could be observed in the bright field and dark field. The fringe patterns were recorded by digital camera. Then the results were analyzed; the fringe pattern looked different when applying various magnitudes of force because the stress distribution in sample was changed in homogeneous plastic.

Abstract: Structure–property relationship has been performed in the lanthanum-modified lead–zirconate–titanate (PLZT) with a lanthanum content 8 and Zr/Ti ratio 40/60. The X-ray diffraction analysis, scanning electron microscopy, and sintering behavior have evidently demonstrated that it is possible to tailor the structural properties of PLZT 8/40/60. Structure of PLZT 8/40/60 had pure perovskite with tetragonal without secondary phase. Tetragonality (c/a) was observed in the range of 1.01093-1.02095. SEM micrographs were shown a development of mean grain size to clarify the development of grain after sintering processing. The result shows that increasing of sintering temperature resulted in mean grain size increasing from 1.70 to 3.08 μm. Ferroelectricity of PLZT ceramics were normal ferroelectric and dielectric constant increased with the increasing sintering temperature.

Abstract: In this study, leadbased ferroelectric ceramics Pb_0.91La_0.09Zr_0.65Ti_0.35O₃ PLZT (9/65/35) were fabricated by solid solution method. The electrical and mechanical properties were measured by modified Michelson interferometer and Sawyer-Tower circuit to investigate electric field induced strain and polarization (s-P-E) of PLZT (9/65/35) at 30-70 °C. The induced strain and polarization were changed when the temperature was increased indicating the change of spontaneous polarization inside the ferroelectric materials.

Abstract: 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.

Abstract: This research was conducted to improve the ferroelectric properties of PZT based ceramics by studying the effect of sintering conditions in terms of temperature and soaking time (time of sintering) on the ferroelectric properties of ceramics in the 0.8Pb (Zr_1/2Ti_1/2)O₃-0.2Pb (Zn_1/3Nb_2/3)O₃ system prepared by vibro-milling mixed-oxide method. The XRD patterns of specimens showed perovskite structure for all compositions. The pyrochlore phase was not observed in this system. The sintering temperature and soaking time affects the ferroelectric properties of ceramics by the optimum sintering condition for 0.8PZT-0.2PZN ceramic is sintered at 1250°C for 2h.

Abstract: In this study, Bismuth-based glasses were prepared and doped with various concentration of potassium chromate. They were melted in an electrical furnace at 1250°C for 4 hours then pressed with fire frame to plate shape and annealed at 500°C for 10 min. Optical spectra were used to analyze color shade of glasses. Homogeneity of glasses was analyzed by birefringence technique. Glasses color was changed from colorless to slightly and opaque green with an increasing amount of potassium dichromate and birefringence result showed that the glasses are non-homogenous.