Suan Sunandha Science and Technology Journal

Study of Physical and Optical Properties of Cobalt Oxide-Doped Glass Prepared by Microwave Melting Technique

Pattraporn Saengka — 2025-03-13

This research investigates the physical and optical properties of cobalt oxide-doped glass prepared using the microwave melting technique. The glass composition was formulated according to the ratio (50-x)B₂O₃: 10SiO₂: 30ZnO : 10Na₂O : xCoO, where x represents the cobalt oxide concentration (0.00, 0.01, 0.05, 0.10, 0.15, and 0.20 mol%). Glass samples were prepared using the microwave melting technique, applying 1,000 watts of power for 20 minutes. The melted glass was then poured into a graphite mold and annealed at 500°C. The results showed that both density and refractive index increased with rising CoO concentration, while molar volume decreased. The absorption spectra of the glass, in the wavelength range of 250-1,100 nm, increased with higher CoO concentrations. Additionally, the CIE L*a*b* values indicated a blue color.

Study of the effect of doping dysprosium ions in soda lime silicoborate glasses using microwave techniques for white-light-emitting diodes (WLEDs)

Nattaporn Mahingsa — 2025-03-13

Soda lime silicoborate glasses doped with dysprosium ions (Dy³⁺) were synthesized with a glass composition of 55.0B₂O₃: 25.0SiO₂: 10.0Na₂O: 10.0CaO: xDy₂O₃ (where x represents the concentration of Dy₂O₃, varying from 0.0 to 2.0 mol%). The synthesis was carried out using a microwave technique and the physical, optical and luminescence properties of the obtained glasses were investigated. The results showed that the density and refractive index increased, while the molar volume decreased with higher Dy₂O₃ concentration. The absorption spectra indicated that these glasses exhibited absorption in the UV-visible and near-infrared light regions. When excited at 388 nm, the glass emitted light at wavelengths of 481, 575, and 663 nm. The emission intensity increased with increasing Dy₂O₃ concentration up to 0.5 mol%, after which it decreased due to the concentration quenching effect. The CIE 1931 chromaticity diagram confirmed that the glasses emitted light in the white region. Likewise, the glasses exhibited CCT values that fall within the bright white color region, with temperature values ranging from 4309 to 4393 K. The Y/B ratio was calculaed from the luminscence spectraindicating the level of asymmetry in the prepared glasses. The decay time showed a non-exponential behavior, indicating cross -relaxation between Dy³⁺-Dy³⁺ ions, and the decay curve was fitted using the IH model S = 10 (quadrupole-quadrupole). The Judd-Ofelt (JO) parameters (W₂, W₄ and W₆) were calculated from the absorption spectra, and the radiative transition probabilities (A_R), stimulated emission cross-sections (σ(λ_p)) and branching ratios (β_R) were obtained from the JO parameters. The results confirm the suitability of these glass samples for use in WLEDs and as laser medium.

Evaluating a Small-scale Membrane Technology for Removing Salinity in Village Water Supply at Dan Kuntot, Nakhon Ratchasima

Saranbhak Chuersuwan — 2025-03-13

This study evaluates the use of a solar-powered membrane separation device to remove salinity from a village water supply in Dan Kuntot District. Water quality from surface water, freshwater, and tap water were tested for pH, temperature, turbidity, salinity, conductivity, and total dissolved solids (TDS). The results showed that surface water had high levels of salinity (1.6-2.1 ppt), conductivity (3495-3982 µS/cm, and TDS (2097-2351 mg/L). The surface water had a pH in the range of 5.7 to 6.2, temperatures of 27.6 to 29.3 Celsius, and turbidity of 6.8 to 10.1 NTU. The freshwater from the village water supply had a comparable pH (5.5-6.9). Turbidity levels were low (0.25-0.27 NTU). Conductivity and TDS levels were a bit lower to 3342-3415 µS/cm and 2005-2049 mg/L, respectively. Salinity levels remained high, 1.6 ppt. The village water treatment process cannot remove salt molecules. The tap water had an undetected salinity level after the freshwater passed through the membrane device. Conductivity and TDS were much lower, ranging from 14 to 19 µS/cm and 9 to 12 mg/L, respectively. The solar-powered small membrane separation could remove salinity as high as 2.1 ppt down to undetected level. The device could separate salt molecules using membrane technology, significantly reducing salinity levels in the tap water. Conductivity and TDS levels were also considerably lower in the tap water, with more than a 99 percent reduction. However, the produced water had low pH levels. Adding alkalinity would bring the pH close to neutral.

Passion Fruit Juice Beads Production by Reverse Spherification Technique: Effect of Concentration and Soaking Time of Calcium Lactate Solution

Songchai Wiriyaumpaiwong — 2025-03-13

This research investigates the impact of calcium lactate concentration and soaking time on the qualities of passion fruit juice beads produced through reverse spherification. Passion fruit juice, xanthan gum, and calcium lactate are dropped into a sodium alginate solution to form beads, which are then immersed in a 0.5-1.0% (w/v) calcium lactate solution for 5-10 minutes. Results indicate that beads soaked in a 1% (w/v) calcium lactate solution for 5 minutes exhibit the smallest droplet size and highest roundness. Increased calcium lactate concentration and soaking time enhance springiness, while hardness, cohesiveness, gumminess, and chewiness decrease. Sensory evaluation shows that beads soaked in a 1% (w/v) calcium lactate solution for 10 minutes have superior taste, texture, and overall preference compared to unsoaked beads.

Oxidation Behavior of Nanostructure CrAlN Thin Films

Nirun Witit-anun — 2025-03-13

In this research, the nanostructure chromium aluminium nitride (CrAlN) thin films were prepared on silicon (100) substrate by reactive DC magnetron sputtering technique with Cr-Al alloy target and then annealing in air at different temperatures (500 - 900 °C) to investigate the oxidation behavior. The films' oxidation rate and oxidation activation energy were also calculated using parabolic relations and the Arrhenius equation. The X-ray diffraction (XRD) indicated that a solid solution CrAlN structure was found for the as-deposited thin film whereas the mixed oxide phase of Cr₂O₃ and Cr₅O₁₂ structures were discovered in the XRD spectra upon oxidation temperature at 800 °C. The XRD patterns were verified by the Energy dispersive X-ray spectroscopy (EDS) examination, which demonstrated the obvious increase of oxygen concentration at oxidation temperature from 800 °C due to the oxidation mechanism. The oxidation behavior was also confirmed by field-emission scanning electron microscopy (FE-SEM) analysis which the grain aggregation was observed while the cross-sectional microstructure of the thin films revealed that a very thin dense oxide layer was formed on the CrAlN layer. The oxide thickness increased from 648 nm to 1044 nm with increasing annealing temperature. The thin films began oxidizing above 800 °C, resulting in a porous structure. It was discovered that the as-deposited thin film exhibited a high-temperature oxidation resistance at 800 °C. The oxidation rate increased from 1.43 × 10^-13 to 3.78 × 10^-13 cm/s² and was obtained from an annealing temperature of 800 °C. The oxidation activation energy calculated from the Arrhenius plot was 99.85 kJ/mol. The nanoindentation technique also reported that the hardness of the films decreased from 15.92 to 0.03 GPa through the annealing temperature.