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Journal : Jurnal Matematika

Pengaruh Temperatur Penumbuhan terhadap Struktur Kristal dan Morfologi Film Tipis TiO2:Eu yang Ditumbuhkan dengan Metode MOCVD [The Effect of Growth Temperature on the Crystall Structure and Morphology of the Thin Film TiO2:Eu Grown with MOCVD Method] Edy Supriyanto; Goib Wiranto; Hery Sutanto; Agus Subagio; Mikrajuddin Abdullah; Maman Budiman; Pepen Arifin; Sukirno Sukirno; Mohamad Barmawi
Jurnal Matematika & Sains Vol 12, No 2 (2007)
Publisher : Institut Teknologi Bandung

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Thin film of TiO2:Eu had been grown on an n-type Si(100) substrate using Metalorganic Chemical Vapor Deposition (MOCVD) method with titanium (IV) isopropoxide [Ti{OCH(CH3)2}4] 99.99% and europium nitrate [Eu(NO3)3.6H2O] 99.99% as the metal organic precursors. The tetrahydrofuran (THF) was used as a solvent for the precursor. X-ray Diffraction (XRD) analysis showed that the TiO2:Eu thin film grown at temperature of 450 οC had crystal planes of rutile (200), rutile (002) and anatase (211), whereas film grown at 500 οC resulted in a crystal plane of rutile (002) with columnar grain and surface morphology relatively smooth. On the other hand, film grown at temperature of 550 οC has rutile (200) and rutile (002) planes. The surface morphology of thin films TiO2:Eu was affected by Eu atom concentration. The roughness of surface morphology increased with increasing Eu content and therefore the grains became larger. It can be concluded that the crystal structure and surface morphology properties of the films depended significantly on the substrate temperature.
Size Dependent Phase Transition in BaTiO3 and PbTiO3: a General Theory Based on a Simple Ising Model Mikrajuddin Abdullah
Jurnal Matematika & Sains Vol 9, No 1 (2004)
Publisher : Institut Teknologi Bandung

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A general theory based on simple Ising model has been developed to explain the effect of size on the phase transition in BaTiO3 and PbTiO3. The model can explain very well the presence of critical temperature for the occurrence of tetragonal ⇔ cubic structure, the presence of critical size where this transition to occur. Size dependent of the transition is induced by the dependence of dipole-dipole interaction in the sample on the size.
Gelation Model for Porosity Dependent Fluid Permeability in Porous Materials Mikrajuddin Abdullah; Khairurrijal Khairurrijal
Jurnal Matematika & Sains Vol 14, No 1 (2009)
Publisher : Institut Teknologi Bandung

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A statistical theory of gel formation in a polymer matrix was used to explain the dependence of liquid permeability in porous materials. A porous material was modeled as a dispersion of bubbles in a solid matrix. Bubbles were treated as monomers and formation of infinite connected bubbles was treated as the formation of gels in polymer. The theoretical predictions were in agreement with the observed data for basalt andesits. The model can easily predict the percolation threshold of porosity at which the permeability increases suddenly, which depends on the effective number of nearest bubbles around a selected bubble. Around the percolation threshold, the permeability satisfies a scaling relationship with a critical exponent of t » 1.2. It is also identified that the critical exponent and fractal dimension of pores, D, satisfy t » 0.8 (1 + 1/D).
Dinamika Paket Gelombang Elektron yang Menerobos Penghalang Trapesium dengan Ketebalan Nanometer Maharati Hamida; Khairurrijal Khairurrijal; Mikrajuddin Abdullah
Jurnal Matematika & Sains Vol 11, No 2 (2006)
Publisher : Institut Teknologi Bandung

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A simulation of the dynamics of electrone wave packet tunneling through a potential barrier in a MOS (metal-oxide-semiconductor) diode was performed by solving the time-dependent Schrödinger equation using the finite difference method. The wave packet is initially located in the semiconductor layer then moves toward to the oxide layer and probably tunnels through and/or is reflected by the oxide layer. The wave packet is deformed when it reaches the oxide layer. It is found that the higher the wave packet energy, the faster the wave packet moves and the higher the probability of transmitting the wave packet for the same bias voltage. It was also found that at low energy, the increase of bias voltage does not increase significantly the probability of finding the transmitted wave packet. At high energy, however, the probability of finding the transmitted wave packet becomes higher with increasing the bias voltage.
Aktivitas Fotokatalitik TiO2 yang Dilapiskan pada Polipropilena Berbentuk Lembaran dan Butiran Sutisna, Sutisna; Rokhmat, Mamat; Wibowo, Edy; Rahmayanti, Handika Dany; Khairurrijal, Khairurrijal; Abdullah, Mikrajuddin
Jurnal Matematika dan Sains Vol 22 No 1 (2017)
Publisher : Institut Teknologi Bandung

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The sheet and granule of polypropylene (PP) have been used as the support material for TiO2 catalyst. The TiO2 powder was coated to the polymer surface using a combination of electrostatic and heating methods (for the PP sheet) and thermal milling method (for PP granule). The photocatalytic testing of catalysts conducted on a 300 ml solution of Methylene Blue (MB) with initial concentration of 25 ppm. Under solar ilumination, the catalyst sheets have a higher photocatalytic activity than the catalyst granules.
Pengaruh Perbandingan Molaritas Prekursor terhadap Fotoluminesensi BCNO yang Disintesis dengan Metode Hidrotermal Septia Mahen, Ea Cahya; Nuryadin, Bebeh Wahid Nuryadin Wahid; Iskandar, Ferry; Abdullah, Mikrajuddin; Khairurrijal, Khairurrijal
Jurnal Matematika dan Sains Vol 18 No 3 (2013)
Publisher : Institut Teknologi Bandung

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Abstrak Fosfor BCNO yang terdispersi pada likuid telah berhasil disintesis menggunakan metode hidrotermal. Bahan dasar (prekursor) yang digunakan adalah asam borat [B(OH)3] sebagai sumber boron, urea [(NH2)2CO] sebagai sumber nitrogen, dan asam sitrat (C6H8O7)sebagai sumber karbon. Dalam penelitian ini, telah dilakukan variasi rasio molar nitrogen terhadap boron (N/B) dan rasio molar karbon terhadap boron (C/B) dan pengaruhnya terhadap pendaran fosfor BCNO yang dihasilkan. Hasil karakterisasi spektrum fotoluminesen dari sampel yang dibuat menunjukkan bahwa pendaran fosfor BCNO mempunyai puncak emisi tunggal disekitar warna biru (~450 nm) ketika dieksitasi dengan sinar UV(365 nm). Intensitas pendaran dipengaruhi oleh kadar karbon terhadap kandungan boron (C/B) dan kadar nitrogen terhadap kandungan boron (N/B). Penambahan kadar karbon dan nitrogen diketahui dapat meningkatkan intensitas pendaran. Sedangkan intensitas optimum pendaran fosfor BCNO dicapai pada saat ratio molar C/B = 1 dan N/B =20. Kata kunci: Fosfor BCNO, Spektrum fotoluminesen, Metode hidrotermal. Influence of Precursor Molar Ratio on the BCNO Photoluminescence synthesized by Hydrothermal Method Abstract BCNO phosphor which is dispersed into liquid has been successfully synthesized by using hydrothermal method. The precursor consists of the borate acid [B(OH)3] as boron source, urea [(NH2)2CO] as nitrogen source, and citric acid (C6H8O7) as carbon source. In this research, molar ratio variations of nitrogen and carbon  towards boron (N/B and C/B), and their influence on resulted BCNO phosphor luminescence were done. The characterization results of the sample shows the single peak of BCNO phorphorous luminescence around blue color (~450 nm) on the photoluminescence spectrum, when excited by UV light (365nm). The photoluminescence intensity was affected by the ratio N/B and C/B. The increase of carbon and nitrogen ratio can increase the photoluminescence intensity. The optimum intensity of BCNO phosphor photoluminescence was obtained at the molar ratio N/B = 20 and C/B =1. Keywords : BCNO phosphor, Photoluminescence spectrum, Hydrothermal method.
Fabrikasi Transparant Conducting Film Berbahan Dasar Grafit pada Substrat Plastik dengan Proses Mekanik Rahman, Dui Yanto; Sustini, Euis; Abdullah, Mikrajuddin
Jurnal Matematika dan Sains Vol 22 No 1 (2017)
Publisher : Institut Teknologi Bandung

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Transparent Conducting Film (TCF) employing graphite powder as conducting material has been successfully fabricated by using extremely cheap and simple method.  This method doesn’t use heating and transfer process which is commonly used in fabrication of Transparent Conducting Film. Graphite powder was directly deposited on the surface of plastic using circle motion of tube shaped-metal which its surface was covered with thick tissue. The film thickness was varied to investigate the influence of it to the transmittance and resistance of the film. The transmittance and resistance measurement was carried out under UV-Vis electrometer and I-V El-Kahfi equipment assistance, and finally the transmittance of 60% and resistance of 24,4 kΩ was gained for one time of coating, While 9 times of coating produced 13% of transmittance and 773 Ω of resistance.
Sintesis Nanokomposit -Fe2O3/SiO2 dengan Metode Salt-Assisted Spray Pyrolysis untuk Menurunkan Viskositas Minyak Berat Anrokhi, Mohamad Samsul; Nuryadin, Bebeh Wahid; Abdullah, Mikrajuddin; Khairurrijal, Khairurrijal; Iskandar, Ferry
Jurnal Matematika dan Sains Vol 22 No 1 (2017)
Publisher : Institut Teknologi Bandung

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A α-Fe2O3/SiO2 nanocomposite as aquathermolisys catalyst material at heavy oil has been synthesized and optimized by using  Salt-Assisted Spray Pyrolysis method. The α-Fe2O3/SiO2 nanocomposite is obtained by thermal decomposition from the precursor.  The precursor is made of FeCl3, SiO2 and NaCl and water as a solvent. Concentration of FeCl3, SiO2, and NaCl are 1:1:5 in order. the composition of SiO2 in the composite is 0%, 25% and 50% of total mass, respectively. the droplets were transported to the furnace reactor using air as a carrier gas with a fixed flow rate at 5 liter/min and the furnace’s temperature is 800 °C in order to get the pyrolysis reaction. The resulted powder is then characterized by using XRD, SEM and Chatalytic aquathermolysis test. The result of XRD characterization shows that crystal peaks of α-Fe2O3 has been formed. SEM result shows nanocomposite morphology of α-Fe2O3/SiO2 with circle particle form with average particle diametre of α-Fe2O3, SiO2 25% and SiO2 50% of total mass are 765 nm, 850 nm, and 746 nm, respectively. Catalytic Aquathermolysis test showed catalyst α-Fe2O3/SiO2 50%  has catalytic properties better than catalytic properties of α-Fe2O3/SiO2 and α-Fe2O3/SiO2 25%.
Analisis Regresi Sifat Tanah Terhadap Rebound Tiang Pancang Amalia, Nadya; Rokhmat, Mamat; Sutisna, Sutisna; Viridi, Sparisoma; Abdullah, Mikrajuddin
Jurnal Matematika dan Sains Vol 22 No 1 (2017)
Publisher : Institut Teknologi Bandung

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The behavior of soil around driven pile during pile driving process directly affect the driving process. Two categories of stress are produced during the driving process, i.e. stress along the pile shaft (shear stress) and stress at the end of the pile (compression stress). Since soil is a porous medium, shear and compressive stresses during the driving process will force water to come out of the pores in the soil. Related to hammering and low permeability of the soil at rebound zones such as clay, water can not flow out of the pores and can not be dissipated instantly. As a result, a high pore water pressure will be generated along the shaft and at the end of the pile. Pile coating with titanium dioxide (TiO2) is able to make the pile to be driven deeper than pile without coating with the same count of hammer strokes for pile driving in clay soils. Uniquely, the coating does not give effect to the pile driving in non-cohesive soils. This indicates that the coating is capable in minimizing pile rebound. Regression model is used in this study to identify the characteristics of engineering soil parameters which may cause the rebound phenomenon.
Pengembangan Material Sorben Berbasis Zeolite dan Clay Alam se-bagai Media Desalinasi Air Laut Wibowo, Edy; Rokhmat, Mamat; Sutisna, Sutisna; Khairurrijal, Khairurrijal; Abdullah, Mikrajuddin
Jurnal Matematika dan Sains Vol 22 No 1 (2017)
Publisher : Institut Teknologi Bandung

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We have developed a sorbent based natural materials for seawater desalination application. We used clays, soil, rock and zeolite as raw materials. We conducted a thermal activation process to improve the sorption ability of the materials. The sorption ability of materials were tested to reduce the salinity of seawater and it is expressed by the reduction efficiency. The highest reduction efficiency (4%) was obtained from the activation of the soil at temperature of 600 ° C and the zeolite at a temperature of 200 ° C. It can be seen that the reduction efficiency was linearly increased with the increase of the doses of sorbent. We observed that the sorption ability of zeolite can be enhanced through thermal activation at a relatively low temperature so that it was potentially used as a low-cost sorbent material for seawater desalination.