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Suprijadi Suprijadi
Badan Tenaga Nuklir Nasional
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The Effects of Atomic Substitutions (Bismuth, Gallium, Arsenic) on Electronic and Magnetic Properties of Carbon Nanotubes Aprilia, Ely; Muttaqien, Fahdzi; Purqon, Acep; Suprijadi, Suprijadi
Jurnal Matematika dan Sains Vol 20 No 1 (2015)
Publisher : Institut Teknologi Bandung

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Abstract

Investigations of carbon nanotubes (CNT) properties by substituting impurity atoms are interesting, since the the defects show different properties and potentially wide applications. In this paper, we investigate the effects of atomic substitutions (Bismuth, Gallium, Arsenic) on electronic and magnetic properties of CNT by using Density Functional Theory method with Generalized Gradient Approximation. Our results show that Bismuth and Arsenic doped on zigzag CNT (10, 0) give the band gap and magnetic moment 0.19 eV and 2 μB, respectively. In contrast, Gallium doped shows no band gap and change the semiconductor properties of zigzag edge CNT (10, 0) into metal. Furthermore, the moment magnetic for Gallium-Arsenide doped CNT (10, 0) is 1 μB. Keywords: Atomic substitution, Band gap, Carbon nanotubes (CNT), DOS, Impurity.   Pengaruh Atom Pengganti (Bismut, Galium, Arsenik) pada Sifat Elektronik dan Magnetik Karbon Nanotube Abstrak Kecacatan pada struktur CNT mengakibatkan adanya perubahan sifat elektronik dan magnetiknya. Perubahan sifat inilah yang menyebabkan CNT  menarik untuk diteliti karena berpotensi memiliki aplikasi yang luas. Pada penelitian ini, dibahas mengenai  efek dari atom pengganti (Bismut, Galium dan Arsen) pada sifat elektronik dan magnetik CNT(10,0) yang dihitung dengan menggunakan teori fungsional kerapatan dan Generalized Gradient Approximation. Hasilnya menunjukan bahwa atom pengotor Bismut dan Arsen pada CNT (10,0) menghasilkan band gap sebesar 0.19 eV dan momen magnetik sebesar 2 μB. Sedangkan atom pengotor Galium tidak menghasilkan band gap pada CNT(10,0) dan mengubah sifat semikonduktor CNT(10,0) menjadi metal. Dari perhitungan didapatkan juga magnetik momen pada CNT (10,0) dengan atom pengotor Galium dan Arsen sebesar 1 μB. Kata kunci: Atom pengganti, Band gap, Karbon nanotube, DOS, Ketidakmurnian.
A Density Functional Theory Study on using Montmorillonite to Reduce Air Pollution Wungu, Triati Dewi Kencana; Yusfi, Meqorry; Suprijadi, Suprijadi
Makara Journal of Technology Vol. 24, No. 3
Publisher : UI Scholars Hub

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Abstract

In this study, density functional theory (DFT) method is used to investigate the possibility of using a smectite clay mineral called montmorillonite (MMT) in reducing heavy metals, such as Cd, through Cd adsorption. The mechanism of Cd adsorption in MMT is observed theoretically, and the tetrahedrally isomorphic substitution on the upper layer of MMT is considered to observe the role of Al and Fe in strengthening Cd adsorption. Two types of MMT are modeled in this study: Al-MMT and Fe-MMT. The Al-MMT means that Al substitutes one atom in the upper tetrahedral layer of MMT, while Fe-MMT means that Fe substitutes one atom in the upper tetrahedral layer of MMT. According to the DFT calculation, Cd is adsorbed relatively strongly to Al-MMT compared with Fe-MMT, with Cd adsorption energy of –4.55 eV and –2.43 eV for Al-MMT and Fe-MMT, respectively. The density-of-state analysis shows that Cd helps reduce the gap between the highest valence-band energy and lowest conduction-band energy of Al-MMT and Fe-MMT. Thus, Cd/Al-MMT and Cd/Fe-MMT behave in a manner similar to a semiconductor.
Density Functional Theory Simulation of Iron-Montmorillonite as Carbon Dioxide Adsorber Ihsudha, Husni; Wungu, Triati Dewi Kencana; suprijadi, suprijadi; Morikawa, Yoshitada
Indonesian Journal of Physics Vol 34 No 2 (2023): vol 34 no 2 2023
Publisher : Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/itb.ijp.2023.34.2.5

Abstract

Carbon dioxide (CO2) is a greenhouse gas that naturally keep the Earth^s surface temperature warm but currently the levels cause environmental problem such as climate change. Carbon capture and storage (CCS) technology is built to reduce CO2 gas emissions by binding carbon dioxide molecules and then storing them or utilising them as more useful products. In this study, simulations were carried out for the addition of iron (Fe) impurities as additional cation in montmorillonite to see the increase in the ability to bind carbon gas. Density Functional Theory calculations were carried out using additional corrections such as Van der Waals (vdW) and Hubbard-U. Here we got that Fe cation can help CO2 adsorbtion compare with other site without Fe atom by adding acid cite condition. But to adsorb CO2, the structure need initial process to swell the montmorillonite interlayer to certain optimum distance.
Analysis of Temperature Sensors in a Volcanic Detection System Muid, Abdul; Sawita, I Kadek Agus Sara; Appriyana, Nazira; Albab, Alfi Nur; Tarigan, Darell Timothy; Kamal, Muhammad; Evita, Maria; Suprijadi, Suprijadi; Djamal, Mitra
Indonesian Journal of Physics Vol 36 No 1 (2025): Vol 36 No 1 2025
Publisher : Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/itb.ijp.2025.36.1.1

Abstract

Volcanoes are geological phenomena that can cause significant disasters to human life and the environment, such as eruptions, pyroclastic flows, and lahars. Therefore, early warning systems for volcanoes are crucial to reduce disaster risks and provide sufficient time for evacuation. Monitoring surface temperature and the surrounding air around volcanoes is one of the key parameters in detecting volcanic activity. Temperature increases often serve as an early indication of magmatic activity beneath the surface. This study proposes an early warning system for volcanoes based on temperature sensors integrated with fuzzy logic to monitor volcanic activity in real-time. The system consists of a wireless temperature sensor network based on the Internet of Things (IoT) connected to an IoT platform for data monitoring and analysis. The SHT31D, SHT2X, BME280 and DHT11 sensors are used to measure the ambient temperature, and the temperature data is processed using fuzzy logic methods to detect changes in volcanic activity. The system was tested in both simulation and field environments using sensor node devices consisting of several temperature sensors controlled by a microcontroller. The fuzzy logic algorithm built using 256 rules is able to classify new data from sensor nodes into one of the categories of volcano vulnerability levels, namely “Normal”, “Caution”, “Warning”, or “Evacuate”. This system has the potential to serve as a real-time temperature monitoring tool for volcanoes, supporting disaster mitigation and volcanic activity risk management.
Co-Authors Abdul Muid Albab, Alfi Nur Appriyana, Nazira Aprilia, Ely Evita, Maria Ihsudha, Husni Meqorry Yusfi Mitra Djamal Morikawa, Yoshitada Muhammad Kamal Muttaqien, Fahdzi Purqon, Acep Sawita, I Kadek Agus Sara Tarigan, Darell Timothy Triati Dewi Kencana Wungu