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Journal : Science and Technology Indonesia

Significant Reduction in Lattice Thermal Conductivity of (PbTe)0.95 - (PbS)0.05 Thermoelectric Materials Through Liquid Silicon Quenching Ginting, Dianta; Nurlela, Ai; Nanto, Dwi; Mashadi; Sudiro, Toto; Kristiantoro, Tony; Rhye, Jong-Soo
Science and Technology Indonesia Vol. 10 No. 4 (2025): October
Publisher : Research Center of Inorganic Materials and Coordination Complexes, FMIPA Universitas Sriwijaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.26554/sti.2025.10.4.1087-1095

Abstract

Thermoelectric materials are game-changers, that have the ability to transform waste heat into electrical energy, making them a potential renewable energy solution to reduce reliance on fossil fuels. The standard metric for evaluating thermoelectric materials is the dimensionless figure of merit, ZT, which is markedly influenced by lattice thermal conductivity (ĸl ). Higher thermal transport through the lattice lowers the ZT value, reducing the material’s efficiency. Therefore, finding ways to decrease ????l is critical for boosting thermoelectric performance. In our research, we explored an innovative approach by applying a quenching technique using liquid silicon to reduce thermal conductivity (ĸT ) due to lattice vibrations. We compared the lattice conductivity (ĸl ) of materials with and without this liquid silicon quenching process. The results were striking: at 300 K, quenching lowers the lattice thermal conductivity by about 40.1 %, and at 800 K, it is still reduced by roughly 24.7%compared with pristine PbTe. Even more impressive, when compared to non-quenched (PbTe)0.95 − (PbS)0.05 alloys, at 300 K, the silicon-quenched sample attains an additional ĸl reduction of roughly 16.1 %, while at 800 K the extra decrease is about 13.0%. These findings highlight that liquid silicon quenching is a highly effective method for lowering ĸl of PbTe thermoelectric materials. This approach paves the way for developing next-generation thermoelectric materials that are more efficient, particularly for eco-friendly waste heat recovery applications. Our work opens new possibilities for sustainable energy innovation.
Sustainable Corrosion Protection of Stainless Steel 316L in Marine Environment Using Electrophoretically Deposited Garlic Extract Green Inhibitor: Electrochemical and Surface Analysis Arwati, IG. Ayu; Ginting, Dianta; Feriyanto, Dafit; Golwa, Gian Villany; Yuliarty, Popi; Tarigan, Kontan; Damar, Stenlly; Khuzaimah; Mashadi, Mashadi
Science and Technology Indonesia Vol. 11 No. 2 (2026): April
Publisher : Research Center of Inorganic Materials and Coordination Complexes, FMIPA Universitas Sriwijaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.26554/sti.2026.11.2.447-456

Abstract

The increasing demand for sustainable and environmentally friendly corrosion inhibitors has driven research toward green alternatives to conventional toxic inhibitors. This study investigates the corrosion protection performance of garlic extract (Allium sativum) as an eco-friendly green inhibitor for stainless steel 316L in 3.5% NaCl marine environment. The inhibition efficiency was evaluated using electrochemical potentiodynamic polarization techniques, complemented by comprehensive surface characterization through scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX), Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy, electrochemical impedance spectroscopy (EIS), and cyclic voltammetry analysis. Electrophoretic deposition (EPD) was employed to apply garlic extract concentrations of 8, 10, and 12 mL onto SS316L specimens. Results demonstrated significant corrosion rate reduction from 0.0082732 mmpy (unprotected specimen) to 0.0014547 mmpy with 12 mL garlic extract treatment, achieving maximum inhibition efficiency of 82%. EIS revealed substantial increase in charge transfer resistance (>170 kΩ), while electrochemical analysis demonstrated mixed-type inhibition behavior with reduced corrosion current densities. SEM-EDX confirmed the formation of protective Fe2+-allicin complex layers on the metal surface, while Raman spectroscopy showed substantial reduction in corrosion products (a-Fe2O3 and y-FeOOH) formation. Cyclic voltammetry demonstrated a five-order-of-magnitude reduction in diffusion rate, confirming exceptional barrier properties. The superior performance is attributed to the chemisorption of sulfur and oxygen-containing compounds in allicin molecules onto active steel sites, forming stable protective films. This green inhibitor demonstrates excellent potential for sustainable corrosion protection in marine and industrial applications, offering an environmentally benign alternative to synthetic inhibitors.