Naphat Albutt

Effect of hybrid doping on dielectric behavior of barium titanate ceramics

ABSTRACT Hybrid-doped BaTiO3 ferroelectric polycrystalline ceramic samples were synthesized by solid state reaction. The concentration of La3+ was fixed 1 mol% while that of Sm3+ varied from 1 to 4 mol%. The effect of the replacement, which can be either lanthanum or samarium, in a cationic site on structural and physical properties of BaTiO3 was investigated. The dielectric permittivity changed significantly with temperature in a wide temperature rang. It was found that the dielectric behavior can be ascribed to the change in defect concentrations in different lattice locations in BaTiO3 structure.

Phase Transition and Microstructure Development of BaTiO3 by Thermal Development of BaTiO3 by Thermal Decomposition Method

The thermal decomposition was used to prepare BaTiO3 powders. Using BaCO3 and TiO2 powders as precursors and heat treatment in the temperature range of 600-1000 °C for 6 hr. The final product (BaTiO3) proceeds through a trace amount of Ba2TiO4. The phase transformation was investigated by X-ray diffraction (XRD) as a function of sintering temperature. The results show that the microstructures of BaTiO3 were developed during sintering at different temperature. In additional, the particle growth of BaCO3 and TiO2 are the major factors to affect of the particle growth mechanism.

The Grain Structure of Nd Doped Y2NiMnO6 Ceramics Sintered at High Temperature

The granular structure of ceramic material influences the electrical properties. Ceramics of YMNO (Y2NiMnO6) doped with Nd were produced by compression and sintering. Grain size was determined from SEM image analysis. Generally, As the Nd dopant concentration was increased, the grain size increased with sintering time. However, at the highest dopant levels of 30% and 20% Nd, a large range in grain size was observed with regions of defective growth. In contrast, a more uniform grain growth was seen for the 10% Nd doped ceramic at all sintering times.

Development of Low-Cost Abbe Refractometer

Refractive index and Abbe number are major physical properties of optical materials including glasses and transparent polymers. Refractive index is, in fact, not a constant number and is varied as a function of optical wavelength. The full refractive index spectrum can be obtained using a spectrometer. However, for optical component designers, three refractive indices at the wavelengths of 486.1 nm, 589.3 nm and 656.3 nm are usually sufficient for most of the design tasks, since the rest of the spectrum can be predicted by mathematical models and interpolation. In this paper, we propose a simple optical instrumental setup that determines the refractive indices at three wavelengths and the Abbe number of solid and liquid materials.

Compact Fluorescence Microscope for Smartphone and Tablet

Microscope add-on toolkits for smartphone and tablet have become more widely available in the market. Although, these are sufficient to meet the demand and requirements of standard users, e.g. educational usage, these devices, in fact, do not meet the medical and biological requirements where fluorescence imaging plays a crucial role. In this paper, we introduce our innovative design in compact fluorescence microscope for smartphone and tablet. The device enables users to take fluorescent images at several excitation wavelengths using compact sources and filters.

Gas Detector System for Industrial Use

Early detection of hazardous or flammable gasses/volatiles reduces the potential risks to personnel, such as development of respiratory problems. A simple robust resistive sensor device is presented with a sensing film of poly (styreneco-maleic acid) containing carbon nanotubes as the conductive medium. The response of the sensor was assessed with several volatile solvents and an industrial printer ink. All vapours were detected by increased resistance of the sensor film, and the ink vapour elicited the largest response. A warning system for volatile solvents could be based on this sensor design for use in industrial environments.

Complete Phase Change of Y2NiMnO6 Ceramics Doped with TiO2 at High Temperature

Determining the structure of ceramic materials is essential in order to fully characterize the electrical properties and improve existing materials. YMNO ceramics (Y2NiMnO6) prepared by compression and sintering were doped with TiO2 and analyzed using XRD and SEM. The calcined sample prior to sintering contained phases of the YMNO double perovskite and TiO2. Following sintering at 1400°C, the perovskite structure was replaced by Y2Ti2O7 fcc structure, and the grain size was found to increase with sintering time up to 18 hours. This sets a limit to the amount of TiO2 which can be used to successfully dope the YMNO ceramic.

Theoretical Investigation of Surface Plasmon Resonance (SPR)-Based Acoustic Sensor

We report a theoretical investigation of a surface plasmon resonance (SPR)-based acoustic sensor for optical detection of ultrasound. The structure being studied is arranged in the Krestchmann configuration and the detection is performed by observing the change of refractive index of water next to the SPR metal. The acoustic pressure is simulated using COMSOL. The simulation results illustrate an insight into mechanism of pressure variation on the surface of SPR sensor due to a constructive interference of the ultrasound. This leads to a local refractive index change of water. The local refractive index change is calculated by converting the incident pressure to water density using IAPWS-95 formulation. Then, the water density is converted to the refractive index using Lorentz-Lorenz formulation. Here we report the change in the refractive index of the water to pressure, dn/dp, which is calculated to be 1.4 x 10-10 Pa-1, which is very close to the dn/dp reported by M. W. Sigrist 1986. We also investigated the effect of temperature and wavelength on the dn/dp and found that the variation in temperature and wavelength does not show any significant effect on the dn/dp relationship. We also discuss the effect of quality factor (Q) and possible improvements to enhance the sensitivity of SPR-based acoustic sensor.

Adsorption of Pb(II) from Solution by Mangosteen Peel Charcoal Powder

This research investigates the use of charcoal produced from waste peels of the mangosteen (Garcinia mangostana L.) fruit as adsorbents of lead contaminants for cost effective wastewater treatment. Test solutions of lead (Pb (NO3)2) were prepared over 0.003 M to 0.5 M, to observe a color change KI was added to the solution. Charcoal from mangosteen peel was added in powder form or as flakes. We found that at least 1.5 g of charcoal was required to adsorb lead from 20 ml of a 0.015 M (Pb (NO3)2) solution, as indicated by low sediment and reduced color change.

Back Focal Plane Confocal Ptychography

This paper illustrates how the amplitude and phase of back focal plane distribution can be recovered in a confocal microscope system from several intensity images in the image plane. These will have a wide range of uses for imaging and sensing. We believe this method is complementary to the V(z) technique where the sample is defocused. The field generated in the back focal plane may be processed by virtual propagation which averages noise in a highly efficient manner. In this paper, we demonstrate that the phase information on the back focal plane can be recovered using ptychography with no need to modify the optical configuration and employ an interferometer. This phase information plays a crucial role in sensitivity of surface plasmons resonance biosensing systems.