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N-Type Conductivity in Wurtzite Mn-Doped GaN thin Films Grown by Plasma Assisted MOCVD Budi Mulyanti; Agus Subagio; Edi Supriyanto; Heri Sutanto; Fitri Suryani Arsyad; Pepen Arifin; Maman Budiman; Mohamad Barmawi
Jurnal Matematika & Sains Vol 11, No 2 (2006)
Publisher : Institut Teknologi Bandung

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Abstract

Ferromagnetic semiconductor GaN:Mn thin films were successfully grown by plasma-assisted metalorganic chemical vapor deposition (PA-MOCVD) method on c-plane sapphire substrate. The films were grown at various Mn source flux in the range of 5 - 40 sccm and growth temperature which was lower than that of MOCVD themal, i.e. in the range of 625-700 °C. Cyclopentadienyl manganese tricarbonyl (CpMnT) was used as a source of Mn. X-ray diffraction patterns confirmed that GaN:Mn films are wurtzite and do not show second phase for film with Mn concentration up to 6.4% at 650 °C of growth temperature. Hall effect measurements show n-type characteristics. The carrier (electron) density tends to decreases and Hall mobility tends to with the increase of Mn concentration is increased. Hysteresis curves observed from VSM measurements indicated that all of the samples are ferromagnetic at room temperature.
Pengaruh Bentuk dan Fluktuasi Ukuran Dot terhadap Pelebaran Garis Spektral Inhomogen pada Quantum Dot Gallium Nitrida (QD GaN) Fitri Suryani Arsyad; Budi Mulyanti; Amiruddin Supu; Moehamad Barmawi
Jurnal Matematika & Sains Vol 12, No 4 (2007)
Publisher : Institut Teknologi Bandung

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Abstract

Theoretical analysis of the phenomena of the size fluctuation in Gallium Nitride quantum dot (GaN QD) is presented inthis paper. The effect of QD size fluctuation on the electron and hole energy level and the inhomogeneous linebroadening is studied. Analytical expressions for the inhomogeneous line broadening are derived for a Gaussian sizefluctuation distribution. Decreasing in the QD carrier energy level is observed when QD size increases. The peak ofoptical transition energy probability (Emax) is shifted to higher energy when dot size fluctuation (σL) increases. Theoptical transition energy distribution (fE) of cylindrical QD is at the higher energy with the inhomogeneous linebroadening (σE) wider than those of conical, ellipsoidal, as well as semi ellipsoidal QD.
Optimasi Parameter Tekanan Deposisi untuk Penumbuhan Lapisan Tipis Mikrokristal Silikon dengan Metode HWC PECVD Amiruddin Supu; I Wayan Sukarjita; Fakhruddin Fakhruddin; Fitri Suryani Arsyad; Toto Winata; Sukirno Sukirno
Jurnal Matematika & Sains Vol 13, No 4 (2008)
Publisher : Institut Teknologi Bandung

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Abstract

The Hot Wire Cell PECVD method has been developed and successfully applied to grow the hydrogenated microcrystalline silicon ( µc-Si:H) thin films. The µc-Si:H thin films were grown on the 7059 corning glass at a filament temperature of 1000 oC. Ten percents silane (SiH4) gas diluted in hydrogen (H2) gas was used as gas source. In the hot wire cell PECVD method, reactant gases are decomposed as a result of reaction with a heated filament. The filament was placed parallelly with inlet gas system and outside of electrodes. The characterization results exhibited that the deposition rate increased from 1,45 Å/s to 1,56 Å/s with increasing the deposition pressure from 700 mTorr to 1100 mTorr. The SEM image and the XRD spectrum exhibited the transition of amorphous to microcrystalline silicon at an deposition pressure of 1000 mTorr. The transition of amorphous to microcrystalline was indicated by the reduction of amorphous parts and the appearance of peak diffraction at preferential crystal orientation. The dark and photo conductivities of the obtained µc-Si:H thin films was 1,2 x10-5 S cm-1 and 2,12 x 10-3 S cm-1, respectively.
PENGARUH JUMLAH PEG 200 DAN TEMPERATUR ANNEALING TERHADAP MORFOLOGI DAN STRUKTUR NANOPARTIKEL TiO2 DENGAN METODE SINTESIS SIMPLE HEATING Tuty Emilia Agustina; Fitri Suryani Arsyad; Mikrajuddin Abdullah
Bumi Lestari Journal of Environment Vol 13 No 1 (2013)
Publisher : Environmental Research Center (PPLH) of Udayana University

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Abstract

The surface area of a photocatalyst is an important factor that effect decomposition process of colored wastewater. Increasing the catalyst particle surface area will increase the UV light absorbed thus enhance the photacatalysis process. Bulk TiO2 will have the higher surface area if it is made in the nano size. As a photocatalyst, nanoparticle of TiO2 is more efficient than bulk of TiO2. The nanoparticle of TiO2 can be made in various ways, for example by simple heating method. In this study, the synthesis of nanoparticle TiO2 was investigated by optimize the amount of polyethilene glycol (PEG 200) used and the annealing temperature. The amount of PEG 200 was varied between 6-18 ml. Moreover, the annealing temperature was varied in the range of 600-700oC. After synthesizing, the nanoparticles of TiO2 then characterize by using scanning electron microscope (SEM) to observe the morphology, and by using the X-ray difraction (XRD) to find the crystal structure and the particle size. Based on the characterization, it was found that the smallest nanoparticle of TiO2 have a 29 nm in size was produced by using the 12 ml of PEG at the annealing temperature of 600oC.
PENGARUH PENAMBAHAN IRON MILL-SCALE DAN TEMBAGA SEBAGAI MATERIAL PELAT BIPOLAR Nisya Ulmiah; Fitri Suryani Arsyad; Deni Shidqi Khaerudini
Jurnal Teknosains Vol 7, No 2 (2018): June
Publisher : Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22146/teknosains.36576

Abstract

Bipolar plate is an important component of proton exchange membrane fuel cell (PEMFC), which provides fuel and oxidant to reactive sites, collect produced current, and mechanical support for the cell in the stacks. This study concerns to find the optimum composition and sintering temperature of iron mills-cale in matrix aluminium as bipolar plate material. This work firstly carried out by downsizing aluminium flake from scrap into powder using high energy milling for 120 min and treated the iron mill-scale at 300 and 1000 oC for 60 min. The waste aluminium powder, after sieving of 150 mesh, was mixing with iron mill-scale containing 30 to 50 vol.% using shaker mill for 10 min. The mixed powders were then pressed 300 MPa and sintered with temperature of 500-600 oC for 60 min and flowed with N2 gas. The structural changes, physical, and mechanical properties of the sintered sample were studied by optical micrograph, density, porosity, hardness Vickers, and electrical conductivity test. The result showed that the optimum composition Fe is 40 vol. % and sinter temperature is 550 oC. Conductivity value of 45.406 S/cm and hardness 183.96 HV hasn’t meet expectation. Cu added containing 4-10 vol. % Fe aims to improve physical properties composites as bipolar plate material PEMFC. The result showed Cu 4 vol. % Fe can increase conductivity value 64.481 S/cm and hardness 340.13 HV.
The Utilization of Mg-Al/Cu as Selective Adsorbent for Cationic Synthetic Dyes Arini Fousty Badri; Neza Rahayu Palapa; Risfidian Mohadi; Mardiyanto Mardiyanto; Fitri Suryani Arsyad; Aldes Lesbani
Bulletin of Chemical Reaction Engineering & Catalysis 2021: BCREC Volume 16 Issue 4 Year 2021 (December 2021)
Publisher : Department of Chemical Engineering - Diponegoro University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.9767/bcrec.16.4.11043.696-706

Abstract

Mg-Al-LDH is a chemical compound produced through co-precipitation technique and modified with Cu(NO3)2.6H2O to form Mg-Al/Cu. However, the research on the capability of these compounds for adsorbing mixtures of cationic dyes as well as malachite green (MG), methylene blue (MB), and Rodhamine-B (Rh-B) has not been carried out. Therefore, this research aims to determine the performance of Mg-Al-LDH and Mg-Al/Cu for removing cationic dyes. The materials used were characterized by using XRD powder, FT-IR, and N2 adsorption desorption. The Adsorption process was conducted by batch system and several effects were investigated, such as kinetic parameter, isotherm, and the temperature condition. The stability feature of Mg-Al-LDH and Mg-Al/Cu was obtained from the regeneration process in the five cycles. The results presented that Mg-Al/Cu was effectively produced, which was indicated by the formation of layer at 10.792° (003), 22.94° (006), 35.53° (112), 55.78° (110), and  56.59° (116). Mg-Al-LDH and Mg-Al/Cu were found to adsorbed MG than the other cationic dyes with adsorption capacity of 68.996 mg/g and 104.167 mg/g, respectively. The unique properties of Mg-Al/Cu includes, structural stability towards the reuse of adsorbent subsequently for five times, without significant decrease of adsorption capacity. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0). 
Preparation of Hydrochar from Salacca zalacca Peels by Hydrothermal Carbonization: Study of Adsorption on Congo Red Dyes and Regeneration Ability Mauizatul Hasanah; Alfan Wijaya; Fitri Suryani Arsyad; Risfidian Mohadi; Aldes Lesbani
Science and Technology Indonesia Vol. 7 No. 3 (2022): July
Publisher : Research Center of Inorganic Materials and Coordination Complexes, FMIPA Universitas Sriwijaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (3498.283 KB) | DOI: 10.26554/sti.2022.7.3.372-378

Abstract

Hydrochar of Salacca zalacca peels (HC-SP) is prepared by hydrothermal carbonization treatment of Salacca zalacca peels (SP) obtained from local fruits at Palembang, South Sumatera, Indonesia, with the resulting yield weight reaching 90%. Materials are characterized using the XRD diffraction, FTIR spectrum, and SEM-EDX. The XRD pattern shows the characteristics of the formation of amorphous compounds. The FTIR spectrum confirms the presence of functional groups O-H, C-H, C=C, and C-O. Data of SEM-EDX show that materials have heterogeneous morphologies, form aggregates, and in HC-SP materials there is an increase in carbon content from the initial material. The capacity of SP in the congo red (CR) adsorption process is 33.003 mg/g and increases to 133.333 mg/g in HC-SP. The maximum dye adsorbed was achieved at pH 4. The adsorption kinetics followed PSO with the equilibrium adsorption occurring at 90 minutes, and the adsorption isotherm followed the Langmuir isotherm with the value of R2 closer to the value of 1. A positive 4H value indicated that the adsorption is an endothermic process. In contrast, an 4S value suggested that the degree of irregularity in the adsorption process is small in large concentrations. Based on data regeneration ability, materials of SP and HC-SP can be used in the three cycles regeneration process of the CR adsorption process. The adsorption process of CR occurs physically and chemically based on enthalpy values and FT-IR data after being adsorbed with CR.
Catalytic Oxidative Desulfurization of Dibenzothiophene by Composites Based Ni/Al-Oxide Nur Ahmad; Alfan Wijaya; Amri; Erni Salasia Fitri; Fitri Suryani Arsyad; Risfidian Mohadi; Aldes Lesbani
Science and Technology Indonesia Vol. 7 No. 3 (2022): July
Publisher : Research Center of Inorganic Materials and Coordination Complexes, FMIPA Universitas Sriwijaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (1788.962 KB) | DOI: 10.26554/sti.2022.7.3.385-391

Abstract

In the present study, composite layer double hydroxide-metal oxide (Ni/Al-TiO2 and Ni/Al-ZnO) was successfully prepared and used as catalyst of oxidative desulfurization of dibenzothiophene. Characterization of catalyst was used XRD, FTIR, and SEM-EDS. The structure of Ni/Al-LDH, TiO2, and ZnO in composite Ni/Al-TiO2 and Ni/Al-ZnO was consistent, which also indicated that the preparation of composite did not change the form of precursors. FTIR spectra of Ni/Al-TiO2 and Ni/Al-ZnO absorption band at 3398, 1639, 1339, 832, 731, and 682 cm−1. The catalysts have an irregular structure, TiO2 and ZnO adhere to the surface of Ni/Al LDH. The percent mass of Ti and Zn on the composite at 29.3% and 18.2%, respectively. The acidity of Ni/Al LDH increased after being composited with TiO2 and ZnO. The optimum reaction time, dosage catalyst, and temperature were 30 min, 0.25 g, and 50°C, respectively, and n-hexane as a solvent. The percentage conversion of dibenzothiophene on Ni/Al-LDH, TiO2, ZnO, Ni/Al-TiO2, and Ni/Al-ZnO were 99.44%, 91.92%, 95.36%, 99.88%, and 99.90%, respectively. The catalysts are heterogeneous system and the advantage is that can be used for reusability. After 3 times catalytic reactions, the conversion of dibenzothiophene still retains more than 80%, even Ni/Al-TiO2 and Ni/Al-ZnO composites still 97.79% and 98.99%, respectively.
Highly Efficient Catalytic Oxidative Desulfurization of Dibenzothiophene using Layered Double Hydroxide Modified Polyoxometalate Catalyst Nur Ahmad; Muhammad Badaruddin; Nova Yuliasari; Fitri Suryani Arsyad; Aldes Lesbani
Bulletin of Chemical Reaction Engineering & Catalysis 2022: BCREC Volume 17 Issue 4 Year 2022 (December 2022)
Publisher : Department of Chemical Engineering - Diponegoro University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.9767/bcrec.17.4.16373.821-830

Abstract

Layered double hydroxide-modified polyoxometalate (ZnAl-PW) was prepared and used for the oxidative desulfurization of dibenzothiophene. XRD patterns of ZnAl-LDH and PW are still present in ZnAl-PW. The bands of ZnAl-PW in wavenumber 3276, 1637, 1363, 1050, 952, 887, and 667 cm-1. The typical surface of ZnAl-LDH and ZnAl-PW can be observed not smooth in different sized with irregular shapes. The average diameter distribution of ZnAl-LDH and ZnAl-PW is 14 nm and 47 nm, respectively. For dibenzothiophene with 500 ppm, conversion on ZnAl-LDH, PW, and ZnAl-PW was 94.71%, 95.88%, and 99.16%, respectively. Conversion of dibenzothiophene in line with the acidity of ZnAl-LDH, PW, and ZnAl-PW were 0.399, 1.635, and 3.023 mmol/gram, respectively. The most effective catalyst dosage for the desulfurization of dibenzothiophene on ZnAl-LDH, PW, and ZnAl-PW is 0.25 g. The unchanged dibenzothiophene concentration indicates a heterogeneous system. ZnAl-LDH, PW, and ZnAl-PW are truly heterogeneous catalysts. After 3 cycles of oxidative desulfurization, the percentage conversion of dibenzothiophene on ZnAl-LDH, PW, and ZnAl-PW were 77.42 %, 65.98%, and 86.38%, respectively. Copyright © 2022 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0). 
Pengaruh Annealing Terhadap Tingkat Kestabilan Efisiensi Sel Surya p-i-n a-Si:H Doping Delta Amiruddin Supu; Dilla M; Jasruddin Daud Malago; Fitri Suryani Arsyad; Toto Winata; M. Barmawi
Indonesian Journal of Physics Vol 12 No 3 (2001): Vol. 12 No.3, Juli 2001
Publisher : Institut Teknologi Bandung

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Abstract

Hydrogenated amorphous silicon (a-Si:H) solar cells with δ-doped p-layer have been fabricated using double chamber Plasma Enhanced Chemical Vapor Deposition (PECVD). 10 % Silane (SiH4), diborane (B2H6) and phosphine (PH3) gases in hydrogen (H2) gas were used as gas sources. δ-Doped p-layer was deposited by using very thin boron layer as dopant source. Current (I) - voltage (V) characteristic measurement was done using xenon lamp as light source with power of 250 watts and voltage of 24 volts. The result shows that the efficiency of δ-doped p-i-n a-Si:H solar cell without annealing decreases from 5.39 % to 3.49 % as the illumination time increases from 0 hours to 2.5 hours. The stable efficiency obtained is3.6 %. It means that there is an efficiency drop of 33.15 %. Solar cell efficiency annealed at temperature of 150OC decreases from 8.59 % to 6.69 % as the illumination time increases from 0 hours to 2.5 hours. Its stable efficiency obtained is 7.11 %. It means that there is an efficiency drop of 17.23 %. Thus the annealing process decreases the efficiency drop.