Garuda - Garba Rujukan Digital

Studi Ab Initio dengan Metode GGA dan GGA + U Terpolarisasi Spin Untuk Mengkaji Sifat Elektronik dan Magnetik Kristal TiO2 pada Fasa Rutile, Anatase, dan Brookite Muhammady, Shibghatullah; Setiawan, Freddy Giovanni; Sutjahja, Inge Magdalena; Winata, Toto; Darma, Yudi
Jurnal Matematika dan Sains Vol 19 No 3 (2014)
Publisher : Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar

Kalkulasi ab initio berbasis generalized gradient approximation (GGA) dan GGA + U (U = koreksi Hubbard) terpolarisasi spin telah dilakukan untuk mempelajari sifat elektronik dan magnetik kristal TiO2 pada fasa rutile, anatase, dan brookite. Hasil perhitungan menunjukkan bahwa ketiga polimorf TiO2 memiliki sifat semikonduktor dan non-feromagnetik. Koreksi Hubbard-U berhasil memperbaiki nilai celah energi dan energi ikat orbital pada struktur anatase dan brookite. Di sisi lain, koreksi U hanya berhasil memperbaiki nilai celah energi pada struktur rutile. Rapat keadaan elektronik dari ketiga polimorf tersebut menunjukkan adanya hibridisasi orbital Ti3d and O2p, sedangkan orbital O2s terlokalisasi jauh di bawah tingkat energi Fermi. Hasil perhitungan ini dapat digunakan sebagai acuan untuk melihat perubahan / efek penambahan impuritas pada sifat elektronik dan magnetik TiO2. Kata kunci: TiO2, Rutile, Anatase, Brookite, Hibridisasi orbital, Kalkulasi ab initio, Generalized gradient approximation, Koreksi Hubbard, Terpolarisasi spin. Ab Initio Study of Electronic and Magnetic Properties of TiO2 Crystal in Rutile, Anatase and Brookite Phase using Spin-polarized GGA and GGA+U Method AbstractSpin-polarized generalized gradient approximation (GGA) and GGA + U-based (U = Hubbard correction) ab initio calculations has been used to investigate electronic and magnetic properties of TiO2 on rutile, anatase, and brookite phases. Calculation results showed that the three TiO2 polymorphs have semiconductor and non-ferromagnetic properties. Hubbard-U correction refine the energy gap and orbital bonding energy values on anatase and brookite structures. Otherwise, U correction just refine the energy gap but not refine orbital bonding energy on rutile structure. Electronic density of states of the three polymorphs show the hybridization of Ti3d and O2p orbitals, while O2s orbital is localized far below the Fermi energi level. These calculations are able to be use as references to define the effect of impurities to the properties of TiO2. Keywords: TiO2, Rutile, Anatase, Brookite, Orbital hybridization, Ab initio calculations, Generalized gradient approximation, Hubbard correction, Spin-polarized.

The Effect of Electrode Gap on the Nucleation of CaCl2.6H2O by using Sharp End Copper Electrode Putri, Risky Afandi; Swandi, Ahmad; Rahman, Annisa; Anggraeni, Radhiah; Sutjahja, Inge Magdalena; Kurnia, Daniel
Indonesian Review of Physics (IRiP) Vol 2, No 2 (2019)
Publisher : Universitas Ahmad Dahlan

The performance of the calcium chloride hexahydrate (CaCl2.6H2O) to store the sensible and latent heats is mainly determined by its nucleation or liquid to the solid phase transition. This is due to the barrier that has to be overcome when the material undergoes the nucleation process with a reduction in the entropy value. This material, with melting temperature around 29.8 Â°C, can be used as the thermal energy storage for building applications in tropical areas such as Indonesia, in order to reduce the electrical energy for aircond (AC) machines. In this paper, we report the results of an experimental study for the effect of the electrical field to the supercooling degree and time period for a phase transition. The variation in the magnitude of the electrical field was achieved by variation in the gap of the electrode for sharp end electrodes (cathode and anode), for the commonly sold copper electrode.

Trial of DC Submersible Pump 12 Volt 50 Watt with Solar Power and Relationship between Water Discharge and Storage Height Ahmad Swandi; Sri Rahmadhanningsih; Sparisoma Viridi; Inge Magdalena Sutjahja
JPSE (Journal of Physical Science and Engineering) Vol 6, No 2 (2021): JPSE (Journal of Physical Science and Engineering)
Publisher : Universitas Negeri Malang

Show Abstract | Download Original | Original Source | Check in Google Scholar

One of the biggest problems for farmers in the dry season is the lack of water supply for irrigation. Currently, various types of pumps have been widely used, such as fuel pumps and pumps with PLN electricity. However, the costs required to operate these tools are pretty expensive. The solution to overcome this is using DC submersible pumps using solar panels as an energy source. The purposes of this study are to (1) determine the duration of operation of the DC submersible pump with the specifications of the battery and solar panels used, and (2) determine the productivity of the DC submersible pump in terms of the resulting discharge for various storage height conditions used. The research method used is an experimental research method using a quantitative approach. The results of this study are (1) DC submersible pump can operate for 240 minutes with 20 Ah battery at maximum voltage and uses 60 Wp solar panels, and (2) the height of the storage has an effect on the resulting discharge, there is a reduction in the resulting discharge every 0.5 meters increase in the height of the storage. Based on the analysis results, the maximum height limit for submersible pump push is 3.7 meters using a 3 per 4 inch hose. The results of this study can be a reference for farmers or users to determine the height of the water storage.DOI: 10.17977/um024v6i22021p061

Digital Simulation as Learning Aid for Heat Flow in Solid Theoretical Understanding Inge Magdalena Sutjahja; Sufiyah Assegaf; Surjamanto Wonorahardjo
JPSE (Journal of Physical Science and Engineering) Vol 5, No 1 (2020): JPSE (Journal of Physical Science and Engineering)
Publisher : Universitas Negeri Malang

Show Abstract | Download Original | Original Source | Check in Google Scholar

Understanding the physical phenomena is extremely aided by digital simulations for understanding physical phenomena that occur, especially for students in the digital era and in this new-normal period. This paper describes heat conduction in solids using the Energy2D program, starting from general formulations for heat conduction from conductors to general solids that show the mechanism of heat conduction as a diffusion process. The thermal diffusivity parameter determines heat diffusion as the ratio between thermal conductivity and multiplication between density and thermal capacity. From the practical side, heat conduction is ordinary using thermal resistance (R-value) that combines the dimensions of the material in the direction of heat flow and thermal conductivity. By taking an analogy with Ohm's law for electrical circuits, it can be determined the equivalent resistance of several thermal resistance of the material that is composed in series or parallel. A good understanding of the heat transport process in buildings is needed for the development of technologies required for the comfort of human life and energy conservation. DOI: http://dx.doi.org/10.17977/um024v5i12020p011

The Effect of Electrode Gap on the Nucleation of CaCl2.6H2O by using Sharp End Copper Electrode Risky Afandi Putri; Ahmad Swandi; Annisa Rahman; Radhiah Anggraeni; Inge Magdalena Sutjahja; Daniel Kurnia
Indonesian Review of Physics (IRiP) Vol. 2 No. 2 (2019)
Publisher : Universitas Ahmad Dahlan

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12928/irip.v2i2.1183

The performance of the calcium chloride hexahydrate (CaCl2.6H2O) to store the sensible and latent heats is mainly determined by its nucleation or liquid to the solid phase transition. This is due to the barrier that has to be overcome when the material undergoes the nucleation process with a reduction in the entropy value. This material, with melting temperature around 29.8 Â°C, can be used as the thermal energy storage for building applications in tropical areas such as Indonesia, in order to reduce the electrical energy for aircond (AC) machines. In this paper, we report the results of an experimental study for the effect of the electrical field to the supercooling degree and time period for a phase transition. The variation in the magnitude of the electrical field was achieved by variation in the gap of the electrode for sharp end electrodes (cathode and anode), for the commonly sold copper electrode.

The Change in Physical Properties of Bi2Ca2Co2O8 Thermoelectric Materials Induced by Pb and Rare-Earth Dopings Inge Magdalena Sutjahja
Indonesian Journal of Physics Vol 22 No 3 (2011): Vol. 22 No. 3, July 2011
Publisher : Institut Teknologi Bandung

We report in this paper the change in the physical properties due to dopant effect in Bi2Sr2Co2O8 parent compound system. The doped samples consists of Pb-doped samples (Bi2Sr2Co2O8, x = 0, 0.5, 1.0, 1.5, and 2.0) and RE-doped samples (Bi2-xPbxCa1.9RE0.1Co2O8, RE = Y, La, Pr, Sm, Eu, Gd, and Ho). The structure of this layered oxide system consist of an alternate stack of CoO2 layer and Bi2Sr2O4 block along the c-axis with misfit structure along b-direction. From the analysis of XRD data it is found that the c-axis parameter reduced significantly in the RE-doped samples compared with those of Pb-doped samples, while the value of misfit degree almost the same. The changes in these lattice structures are accompanied by variation in the spin-state of Co-ions and electrical conductivity. We argue that these structural changes and its effect on the electrical transport properties as well as control of the magnetism plays a pivotal role in determining the thermopower in this class of magnetic thermoelectric materials through the entropy of the charge carriers. This, in turn, will determine the thermoelectric performance for application.

Cairan Ionik sebagai Penyerap Gas CO2 Yunita Anggraini; Inge Magdalena Sutjahja
ALCHEMY Jurnal Penelitian Kimia Vol 19, No 2 (2023): September
Publisher : UNIVERSITAS SEBELAS MARET (UNS)

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20961/alchemy.19.2.62225.247-260

Pemanasan global akibat emisi gas rumah kaca, terutama karbon dioksida (CO2), memiliki pengaruh yang signifikan terhadap perubahan iklim dan telah menjadi isu penting dalam beberapa tahun terakhir. Penangkapan dan pemanfaatan CO2 atau CO2 capture and utilization (CCU) adalah strategi yang efektif untuk mengurangi pemanasan global. Makalah ini bertujuan untuk memberikan gambaran singkat proses penangkapan CO2 dengan memanfaatkan cairan ionik (ionic liquid, IL). IL adalah jenis garam yang terdiri dari kation organik dan anion organik atau anorganik yang memiliki beberapa keunggulan, di antaranya volatilitas yang rendah, stabilitas termal yang cukup baik, tidak mudah korosif, laju degradasi yang rendah, dan biaya regenerasi yang rendah. Kombinasi kation-anion yang tepat membuat IL dapat digunakan sebagai pelarut untuk proses penangkapan CO2 menggantikan pelarut konvensional berbasis amina. Dalam perkembangan selanjutnya, generasi baru IL fungsional (IL berbasis basa kuat dan asam amino) dan deep eutectic solvent (DES) telah diperkenalkan sebagai larutan pengganti IL murni (IL konvensional) dengan keunggulan kapasitas penyerapan CO2 yang lebih besar, mudah terurai secara alami (biodegradable), mudah berinteraksi dengan jaringan hidup, tidak menimbulkan toksisitas (biokompatibel), dan mudah diproduksi dalam skala besar dengan biaya relatif rendah. Selain itu, dengan mempertimbangkan biokompatibilitas DES, pengembangan DES dengan mempertimbangkan aspek biologis menjadi terobosan baru yang menjanjikan sebagai bahan ramah lingkungan. Dalam hal ini DES menyerap CO2 dari gas buang dan kemudian menyediakannya sebagai sumber nutrisi bagi mikroalga.Ionic Liquid as CO2 Absorption. An increase in global warming as an impact of greenhouse gases, particularly carbon dioxide (CO2), has become an important issue in recent years. CO2 capture and utilization (CCU) are the effective strategy to mitigate global warming. This study briefly described the CO2 capture process using ionic liquid (IL). IL is a type of salt consisting of organic cations and organic or inorganic anions. IL as a solution in the CO2 capture process has several advantages, including low volatility, good thermal stability, non-corrosive, low degradation, and low regeneration costs. Using the proper cation and anion, IL acts as an effective solvent for CO2 capture, replacing amine. In subsequent developments, a new generation of functional IL (strong base and amino acid-based IL) and deep eutectic solvent (DES) has been introduced as a substitute for pure IL (conventional IL) with the advantages of more excellent CO2 absorption, biodegradable, easy to interact with live tissue, non-toxicity, biocompatible, and easy to produce on a large scale with relatively low cost. In addition, taking into account the biocompatibility of DES, the development of DES by considering the biological aspects is a promising alternative as an environmentally friendly material. In this case, DES absorbs CO2 from exhaust gases and provides it as a source of nutrition for microalgae.

Pengaruh Penambahan Nukleator SrCl2.6H2O dan Pengental HEC terhadap Efek Supercooling dan Pemisahan Fase PCM CaCl2.6H2O Sri Rahayu Alfitri Usna; Inge Magdalena Sutjahja; Daniel Kurnia
Wahana Fisika Vol 6, No 2 (2021): December
Publisher : Universitas Pendidikan Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.17509/wafi.v6i2.40317

Kalsium klorida heksahidrat (CaCl2.6H2O) merupakan salah satu material berubah fase (Phase Change Material, PCM). Material ini termasuk dalam kelompok PCM inorganic garam hidrat dengan temperatur lebur 29 °C dan entalpi yang cukup tinggi yaitu 190 kJ/kg, sehingga berpotensi sebagai medium penyimpan energi termal laten (latent thermal energy storage, latent TES). Penelitian ini bertujuan untuk mengetahui pengaruh penambahan 1% berat agen nukleator stronsium klorida heksahidrat (SrCl2.6H2O) dan 1-2% berat agen pengental hidroksietil selulosa (HEC) pada CaCl2.6H2O untuk meminimalkan efek supercooling dan pemisahan fase, serta percepatan proses nukleasi. Dari hasil eksperimen yang dilakukan, penambahan 1% berat SrCl2.6H2O dapat mengurangi efek supercooling secara signifikan, efek pemisahan fase sekitar 70% hingga iterasi ke-38, serta percepatan proses nukleasi CaCl2.6H2O dibandingkan tanpa penambahan SrCl2.6H2O. Sedangkan untuk komposisi SrCl2.6H2O (1% berat) + HEC (1-2% berat) juga mampu mengurangi efek supercooling secara signifikan, begitu pula dengan efek pemisahan fasenya yakni sekitar 60% hingga iterasi ke-38.

Implementation of Project-Based Science Learning to Improve Literacy of School Managers About New Renewable Energy in West Halmahera Swandi, Ahmad; Viridi, Sparisoma; Rahmadhanningsih, Sri; Sutjahja, Inge Magdalena; Sari, Juwita
Kasuari: Physics Education Journal (KPEJ) Vol. 7 No. 2 (2024): December 2024
Publisher : Universitas Papua, Jurusan Pendidikan Fisika FKIP Unipa

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.37891/kpej.v7i2.575

Renewable energy is a very important solution in overcoming the limitations of electrical energy in schools. The number of schools that have not received electricity in West Halmahera is still quite large, this hampers various daily activities in the school environment. Therefore, it is very important to provide understanding and skills about the application of new and renewable energy, especially for school managers. This study aims to improve the scientific literacy of school managers in West Halmahera about New and Renewable Energy. The type of research used is a pre-experimental research design with One-Group Pretest-Postets Design. The research sample was taken from the population of school administrators in West Halmahera with 20 school administrators. The analysis of the research results was carried out in a quantitative descriptive manner. Based on the results of the initial and final tests, an N-Gain value of 0.41 was obtained which indicates that there is an increase in literacy about renewable energy in the medium category. In addition, the results of observations show that the activity of school managers in participating in activities is quite good, which is indicated by the percentage above 70%.

Efek Surfaktan pada Stabilitas Nanofluid Nickekl Ferrite Mahmudi, Riyadi Adnan; Yusuf, Akhmad; Sutjahja, Inge Magdalena
Jurnal Ilmu Fisika Vol 17 No 1 (2025): March 2025
Publisher : Jurusan Fisika FMIPA Universitas Andalas

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.25077/jif.17.1.31-40.2025

Nanofluid stability is a critical factor for the effective application of nanofluids in various fields. One simple and effective method to enhance nanofluid stability is through the addition of surfactants. This study examines the effect of different surfactants on the stability of nickel ferrite (NiFe₂O₄)/water nanofluid. The nanofluids were synthesis using the two-step method, and the surfactants investigated inculded oleic acid, polyethylene glycol 400, tetrabutylammonium bromide, gum arabic, and citric acid. Different concentrations for each surfactant were tested by adjusting the nanoparticles-to-surfactant ratio. The suspension stability was evaluated through visual observation, Zeta potential measurements, and thermal conductivity analysis. The most stable NiFe₂O₄/water nanofluid was achieved using citric acid surfactant, with a nanoparticles-to-surfactant volume ratio of 1:0.25, a Zeta potential value of -35.0 mV and an average thermal conductivity of 0.585 ± 0.007 W/m·K. The results of this study are important for developing nanofluid and magnetic nanofluid systems with optimum conductive heat transfer performance.

Title

Found 10 Documents
Search

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Title Search

Found 10 Documents Search

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Title

Found 10 Documents
Search