bluuebunny/crossref_metadata_2025 huggingface dataset:
Grain Size Analysis on Ba0.65Sr0.35TiO3 Thin Films Using Design of Experiment
Authors: Retnasamy Vithyacharan , Sauli Zaliman , Vairavan Rajendaran , Taniselass Steven , Ab Aziz Muhamad Hafiz , Ehkan Phaklen , Fuad Fairul Afzal Ahmad
Published: February 2014

This paper presents the relationship between spin coating speed, heat treatment time, and annealing temperature in response to the grain size in ferroelectric Barium Strontium Titanate (BST). Many fundamental issues such as heat conduction, contact deformation, mechanical stress, and friction can be explained and distinguished through the understanding of the grain size. The investigation was done using a full factorial design of experiment (DOE). Analysis was done quantitatively by plotting the main effects graphs. The results suggest that higher spin coating speed and the annealing temperature decreases the grain size while the heat treatment time is directly proportional to the value of grain size.
Fabrication and Characterization of Stacked Self-Assembled In0.5Ga0.5As/GaAs Quantum Dots Grown by MOCVD
Authors: Aryanto Didik , Othaman Zulkafli , Ismail A. Khamim
Published: February 2014

Stacked self-assembled In0.5Ga0.5As/GaAs quantum dots (QDs) were grown using metal organic chemical vapor deposition (MOCVD). Atomic force microscopy (AFM), transmission electron microscopy (TEM) and high resolution X-ray diffraction (HR-XDR) show the effects of stacking on morphology and structure of QDs. Strains due to the buried QDs affect the shape and alignment of the successive layers. Capping of these QDs also determine the quality of the top most QDs structure.
Effects of Iron Dopants on Barium Strotium Titanate (Ba0.8Sr0.2TiO3) Thin Films
Authors: Setyadhani Riana Tri , Jamaludin Anif , Iriani Yofentina
Published: February 2014

BST thin films have been grown by Chemical Solution Deposition (CSD) method on the substrate of Pt/Si. The fabrication of BST doped by Fe have been successfully using spin coater with 4000 rpm during 30 second. Annealing process use the holding time at 3 hours, the heating rate at 5°C/min and temperature at 800°C. The ratio of Ba0.8Sr0.2TiO3 molar and Fe variant dopant (0%, 1%, 3%, and 5%) were characterized by X-Ray Diffraction (XRD) and obtaining results that show the peak shift due to variations dope. The peak shifted to the right for each increment Fe dopant. Results of addition Fe dopant also cause a differences in the magnitude of Full Width at Half Maximum (FWHM) and lattice parameters on BST ferroelectric materials. Other characterize that has been done by Scanning Electron Microsopy (SEM), it is show the thickness of the material. The resulting lattice parameters with the General Structure Analysis System (GSAS) software analysis showed that a thin films of BST and BSTF have a tetragonal structure because it has a value of a=b≠c and α=β=γ=900. Based on SEM characterization, the thickness of thin film is about 330 nm.
Transparent and Conductive Fluorinated-Tin Oxide Prepared by Atmospheric Deposition Technique
Authors: Purwanto Agus
Published: February 2014

Fluorinated tin oxide (FTO) is well known transparent conductive oxide which is widely applied for optoelectronic applications. Commercially, high-performance (FTO) film was fabricated by sputtering method or other low pressure methods. The product of these methods is expensive due to the high price of capital cost for the apparatus. To cut the price of FTO, atmospheric condition methods were developed and actively investigated using a simple device. By controlling the process conditions; such as processing temperature, precursor concentration, doping concentration, and reactor configuration; high performance FTO glass was successfully produced. The sheet resistance of the prepared FTO glass can be controlled from 9.55 – 63 Ω/□. In addition, its transparency is approximately 77 % which is ideal characteristics for the dye sensitized solar cell (DSSC) electrode application.
Defects Induced by Reactive Ion Etching in Ge Substrate
Authors: Kusumandari Kusumandari , Taoka Noriyuki , Takeuchi Wakana , Sakashita Mitsuo , Nakatsuka Osamu , Zaima Shigeaki
Published: February 2014

We investigated impacts of the Ar and CF4　plasma during reactive ion etching (RIE) on defect formation in the Ge substrates using the deep-level-transient-spectroscopy (DLTS) technique. It was found that the Ar plasma causes the roughening of the Ge surface. Moreover, the Ar plasma induces a defect with an energy level of 0.31 eV from the conduction band minimum in the Ge substrate, confirming by DLTS spectra. On the other hand, the CF4 plasma hardly induces the surface roughness of Ge. However, the CF4 plasma induces many kinds of electron and hole traps. It should be noted that the defects associated with Sb and interstitials are widely distributed to around 3-µm.
Effect of Electrolyte Composition on Corrosion Resistance in Nickel Plating Process for Coating Bonded Magnet PrFeB
Authors: Kurniawan Candra , Sholihat Hayati M.A. , Thosin Kemas Ahmad Zaini , Muljadi Muljadi , Sardjono Prijo
Published: February 2014

Despite of its excellence magnetic quality, one of the critical properties of PrFeB based permanent magnet is a low corrosion resistance so it can be oxidized easily which can reduce its magnetic properties. In this study, Nickel coating has been performed for bonded PrFeB magnet by the electroplating method using Nickel-Watts bath-type as the electrolyte to improve the corrosion resistance. The varying amount of the electrolyte compounds used to have the optimized composition indicated by the corrosion resistance measurement. The solution composition used was NiSO4 (230-380 g/L), NiCl2 (30-60 g/L), and H3BO3 (30 and 45 g/L) with a fixed value of other parameters. Characterization used including the immersion corrosion test, microstructure analysis, and magnetic properties. Based on the corrosion rate measurement, the highest corrosion resistant of Nickel coated PrFeB magnet achieved from the electrolyte composition of NiSO4: NiCl2: H3BO3 = 380: 60: 30 g/L with a plating time and current density (J) of 60 minutes and 40 mA/cm2 respectively. The corrosion rate data showed that the Nickel metal coating can improve the corrosion resistance of bonded PrFeB magnet up to 29 times than of the substrate. The SEM images showed that the thickness of the Nickel coating on the optimum electrolyte composition was in average value of 35.1 µm. The overall samples has a magnetic remanence value (Br) reached ≥ 6 kG, so it has enough properties to be applied in devices such as generators and electric motors.
Production and Characterization of Biodegradable Plastics Based on Starch of Artocarpus heterophyllus Lam Seeds
Authors: Sutikno Sutikno , Marwoto Putut , Dian Puspita Ajeng
Published: February 2014

The starch of artocarpus heterophyllus lam seeds was mixed with distilled water into a solution. The biodegradable plastics were made of starch, glycerol, and chitosan on the different volume fraction of glycerol at mixing temperature 80°C. The effect of glycerol addition on the microstructures, crystal structures, mechanical strength and thermal properties of specimens are completely reported. They were prepared based on the different volume fraction of glycerol, i.e., 2, 4 dan 6 (%Vol). The crystal structures of biodegradable plastic films were investigated using x-ray diffractometer and their thermal properties were analyzed employing thermogravimetric analysis. The biodegradabilities of specimens were obtained by soil burial test method using microorganisms. The maximum mechanical strength of biodegradable plastics is obtained about 4,7 MPa.
Characteristics of Mg-Ca-Zn Alloy Metallic Foam Based on Mg-Zn-CaH2 System
Authors: Kartika Ika , Thaha Yudi Nugraha , Pramuji Lestari Franciska , Sriyono Bambang
Published: February 2014

Mg-Ca-Zn alloy metallic foam has been recently recognized as biodegradable implant. In this present work, the characteristics of Mg-Ca-Zn alloy metallic foam which made by foaming of powder compact based on Mg-Zn-CaH2 system were investigated. Mg-Zn-CaH2 powder with nominal compositions of 97.5 weight % Mg, 2 weight % Zn, 0.5 weight % CaH2 and 96.8 weight % Mg, 2 weight % Zn, 1.2 weight % CaH2 were prepared by dry milling process for 6 h and characterized by differential thermal analysis (DTA). The prepared powders are pressed for 6.5MPa at room temperature and sintered for 2 h at various temperatures of 350 °C and 600 °C. The alloys were analyzed by x-ray diffraction and scanning electron microscope (SEM). The results indicated that addition of calcium hydride as blowing agent affects phase formation of Mg2Ca and Mg2Zn3, sintering temperature and grain refining of Mg-Ca-Zn alloy.
Synthesis of Chitosan-Gold Nanoparticles for Drug Delivery
Authors: Yazid Hanani , Yassin Amirah Mohd , Ruslan Ahmad Zahid , Alias Siti Hajar , Adnan Rohana , Md Jani Abdul Mutalib
Published: February 2014

Gold nanoparticles (Au NPs) have potential applications in catalysis, drug delivery, sensors and environmental remediation. This wide range application is due to its amenability of synthesis and functionalization, less toxicity and ease of detection. The present work focuses on functionalization of Au NPs with chitosan for further application in biomedical research. Gold nanoparticles (Au NPs) functionalized chitosan were prepared by reducing gold salt solution at various pH medium in the presence of sodium borohydride. The effect of pH and chitosan concentration on the Au particle size and distribution are studied. The results revealed the dependence of Au particle size on the pH of the solution. The smallest Au particle size is found to form in a range of 10.22 ± 2.96 nm at 0.2% chitosan concentration. In this study, we anticipate the Au NPs functionalized chitosan can be used for drug delivery applications.
Adsorption of Lead Ions onto Citric Acid Modified Rubber (Hevea brasiliansis) Leaves
Authors: Ibrahim Shariff , Hanafiah Megat Ahmad Kamal Megat , Fadzil Faisal
Published: February 2014

The removal of Pb(II) from aqueous solutions by citric acid modified rubber leaf powder (CARL) was investigated. The higher adsorptive removal of Pb(II) from aqueous solutions by CARL compared to untreated rubber leaf powder was due to the presence of more carboxylic functional groups in the former system. Batch adsorption experiments were conducted to study the effect of pH, contact time for the removal of Pb(II) from Pb(II) aqueous systems and the mechanism of adsorption process was studied by kinetic models, pseudo-first and pseudo-second order kinetic models. The functional groups on CARL played an important role in the adsorption of Pb(II). The kinetic and equilibrium adsorption data were well modeled using pseudo-first-order kinetics. Normal 0 21 false false false MS X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Calibri","sans-serif"; mso-fareast-font-family:Calibri; mso-bidi-font-family:"Times New Roman";}
Synthesis of Smart Biodegradable Hydrogels Cellulose-Acrylamide Using Radiation as Controlled Release Fertilizers
Authors: Swantomo Deni , Rochmadi Rochmadi , Basuki Kris Tri , Sudiyo Rahman
Published: February 2014

Smart biopolymer-based hydrogels was synthesized by graft copolymerization of acrylamide onto the rice straw cellulose backbones using simultaneous graft copolymerization by gamma radiation as initiator. Evidence of grafting was obtained from comparison of FTIR of the cellulose and grafted cellulose. The effect of acrylamide monomer concentration on grafting efficiency, gel fraction, swelling degree, crosslink density, molecular weight between crosslink (Mc), network mesh size (ξ) and Young Modulus were examined. It was found that grafting efficiency, gel fraction, crosslink density, and Young Modulus increases with increasing acrylamide concentration. Swelling degree, molecular weight between crosslink, and network mesh sizes decreases with the increasing acrylamide concentration. Furthermore, controlled release fertilizers from loaded hydrogels was analyzed in water. The urea fertilizer release mechanism from the hydrogels were Fickian diffusion. The diffusion coefficient of urea closely related to its crosslink density and network mesh sizes.
Effects of Surface Treatments on Nata de Cassava on the Tensile Strength and Morphology of Bacterial Cellulose Sheet
Authors: Cahyandari Dini , Budi Rohardjo Heru Santoso
Published: February 2014

Cellulose is natural fiber source that available abundant in the world. Besides lignin, hemi cellulose and wax, cellulose is the most component of plant. Cellulose can be produced from secretion of bacteria. Kind of bacteria that can produce cellulose are pseudomonas, Achromobacter, Alkaligene and Acetobacter, but bacteria strain that usually used to produce cellulose called bacterial cellulose is Acetobacter xylinum. Culture medium of Acetobacter xylinum are medium that contain of carbon and nitrogen. One of the medium that contain carbon and nitrogen is tapioka waste water. The gel that produce from tapioka water called nata de cassava. Cellulose fiber that produce from nata de cassava more pure than that from plant. Mechanical properties of single bacterial cellulose fiber as young’s modulus is 114 GPa and tensile strength is 78 GPa. Nata de cassava is produced with 1% sugar consentration and fermentation time is 14 days. pH of tapioka water medium is adjusting by acetic acid glacial. Nata de cassava gel washed for 2 days on running water than soaked in NaOH and NaOCl solution. Than washed on running water than dried on light pressure (0,2 MPa) and oven for an hour on 80°C. this bacterial cellulose film is ready to used as spesiment of tensile test and SEM observation. The aim of this research is to find the effect of surface treatments (Merserizing and Bleaching) on nata de cassava gel on mechanical properties and morfology of bacterial cellulose sheet. From the research find that NaOH treatment give the highest tensile strength of bacterial cellulose sheet compared to NaOCl treatment of nata de cassava.
Biodegradation of Low Density Polyethylene (LDPE) Composite Filled with Cellulose and Cellulose Acetate
Authors: Halimatuddahliana Halimatuddahliana , Rambe Ahmad Mulia
Published: February 2014

A comparative study was conducted for the biodegradation of low density polyethylene (LDPE) composites filled with cellulose (C) and cellulose acetate (CA). Composites were prepared with the content of each filler of 10% (by weight) using an extruder at processing temperature of 125°C.Biodegradation processes were done by burying in the soil and by hanging in an open environment for four months. The percentage of weight loss of pure LDPE and composites due to the degradation were observed based on the weight reduction of the composites and supported by scanning electron microscopy (SEM). The results indicated pure LDPE was not susceptible to microbial attack as the percentage of weight loss were constant. However, the composites filled with cellulose were relatively more susceptible to degradation as compared with composites filled cellulose acetate. Here, the percentage of weight loss of composites filled cellulose were higher than the composites filled cellulose acetate. On the other hand, the biodegradation processes by hanging in open environment were relatively faster than burying in soil for both types of composites. These results were confirmed by SEM which have shown some cavities.
Characterization of Photo Biocomposites for Application in Biomedical Materials
Authors: Triyono Joko , Tontowi Alva Edy , Siswomihardjo Widowati , Rochmadi Rochmadi
Published: February 2014

The purpose of this study was to perform material characterization of photo biocomposites materials consists of hydroxyapatite (HA) as a filler, (tri [ethylene glyco dimethacrilate (TEGDMA (Sigma Aldrich)) as a matrix; Camphorquinone (Sigma Aldrich) as a photoinitiator; and shellac as a coupling agent. Four ingredients then made two mixtures. The first mixture was the mixing of TEGDMA and camphorquinone and the second was shellac coated HA. Two of mixtures then were mixed to be one solution and was stirred in magnetic stirrer for 1 hour. The solution was poured into a mold and was activated by visible blue light 410 500 nm for 40 seconds in order to be polimerization processes. Materials were characterized by X-Ray Diffraction (XRD), Fourier Transform Infra-Red (FTIR) and Scanning Elektron Microscope (SEM). The materials structure were dense. This material has potential as an implant material for medical purposes.
One-Step Fabrication of Short Nanofibers by Electrospinning: Effect of Needle Size on Nanofiber Length
Authors: Fathona Indra Wahyudhin , Khairurrijal Khairurrijal , Yabuki Akihiro
Published: February 2014

The effect of needle size on the fiber length was studied and investigated. A polymer solution of cellulose acetate (CA) and organic solvent was ejected from various sizes of needle gauge then the electrospun polymer fibers were adhered on a collector plate. The diameter of fibers was ranging from 80 to 570 nm and the length could be controlled from 10 to 240 µm by increasing the needle size. The breakaway to shortened nanofibers occurred due to the imbalance of force from the surface tension of the polymer solution and the longitudinal force of the applied voltage.
Fabrication of Silver Nanoparticles and its Films and their Characterization of Structure and Electrical Conductivity
Authors: Diantoro Markus , Chasanah Alif Fitria , Nasikhudin Nasikhudin , Mufti Nandang , Fuad Abdulloh
Published: February 2014

Based on our previous work of MSA influence on silver nano particles formation we have performed a series of research related to the preparation and characterization of silver nanoparticles which synthesized through coprecipitation process. The silver nano particles was transformed into silver nanoparticles films by spin coating deposition method. The silver nanoparticles were prepared from silver acetate as precursor, reductant agent phenylhydrazine, and dodecylamine as stabilizer. X-Ray Fluorescence (XRF), X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Analysis (EDAX), and Electric Four Point Probe have been used to characterize the silver nanoparticles as well as the films. The morphology and the crystal structure have been determined by means of XRD and SEM. The average grain size of silver nanoparticles is found to be 22 nm. The peaks in XRD pattern are in good agreement with that of face-centered-cubic phase of metallic silver. The electrical conductivity films were confirmed in the range of conducting material. The highest conductivity was reached at 3,88 x 109 S/cm associated to 1600 rpm of spin coater rotation.
Crystallographic and Electrical Properties of Barium Zirconium Titanate Doped by Indium and Lanthanum
Authors: Adnan Septian Rahmat , Hikam Muhammad , Rizky Edward
Published: February 2014

Barium Zirconium Titanate (BZT) films doped by Indium and Lanthanum were prepared using Chemical Solution Deposition followed by spin coating method. After deposition, the spesimen was annealed at 800 °C for 3 hours, using 3000 rpm angular spin coating speed. From crystallographic examination we found that the system is perovskite tetragonal with lattice parameters of a = 3.967 Ǻ, c = 3.988 Ǻ. On adding Indium and Lanthanum dopants, their lattice parameters have slightly increased. The spontaneous polarization of BZT is 23.13 µC/cm2, and their spontaneous polarizations increase on adding La dopant. The best spontaneous polarization is at 1 mol % dopant of Lanthanum.
A Theoretical Model of Band-to-Band Tunneling Current in an Armchair Graphene Nanoribbon Tunnel Field-Effect Transistor
Authors: Bimo Christoforus S. Putrro , Noor Fatimah A. , Abdullah Mikrajuddin , Khairurrijal Khairurrijal
Published: February 2014

Tunneling current in an armchair graphene nanoribbon (AGNR) tunnel field-effect transistor (TFET) was modeled. A linear equation was employed in describing a potential distribution within the AGNR due to its simplicity. A parabolic dispersion and an electron effective mass obtained by approximating kx 0 to the parabolic dispersion were applied to AGNR. In order to obtain electron transmittance, electron wavefunctions in AGNR were based on Airy functions. The obtained transmittance was then applied to calculate the tunneling current by employing the Landauer formula. The calculated results showed that the tunneling current increases with the AGNR width. It was also shown that the tunneling current increases as temperature decreases. In addition, the gate voltage influences the saturation condition of tunneling current in AGNR TFETs.
Determination of Thin Film Ba0.5Sr0.5TiO3 Ferroelectric Effective Mass from I-V Characteristics Calculation Using Transfer Matrix Method
Authors: Hasanah Lilik , Hamidah Ida , Hamdani Aam , Mulyanti Budi , Rusdiana Dadi , Yuwono Heru
Published: February 2014

In this paper, we present current-voltage model characterization calculation of Ba0.5Sr0.5TiO3 ferroelectric-based solar cell to determine its effective mass. Numerical calculation was done using Transfer Matrix Method (TMM). Fitting between the calculations results with experiment data can be done by approximating the Ba0.5Sr0.5TiO3 effective mass value. Ba0.5Sr0.5TiO3 effective mass can be obtained when both data fit.
Thermal Analysis and Magnetic Properties of Lanthanum Barium Manganite Perovskite
Authors: Sardjono Priyo , Wisnu Ari Adi
Published: February 2014

The lanthanum manganite is the family of magnetic materials which had the magnetic properties are varied depend on the composition. This study has been carried out synthesis and characterization of thermal and magnetic properties of the lanthanum barium manganite perovskite. The perovskite material is prepared by oxides, namely La2O3, BaCO3, and MnCO3. The mixture was milled for 10h and then sintered at temperature of 1000 °C for 10h. Thermal analysis and magnetic properties are measured by differential thermal analysis (TG-DTA) and vibrating sample magnetometer (VSM), respectively. Decomposition phase of MnCO3 become MnO occurred at temperatures around 390 °C with releasing in CO2. Since lanthanum manganite has a stable ion configuration, magnetic properties of these systems are built from MnO phase transformation become α-Mn2O3 is arrayed anti-ferromagnetic due to the presence of lanthanum in the system. And this anti-ferromagnetic behavior occurred due to magnetic interactions between Mn3+ adjacent ions through super-exchange mechanism. While lanthanum barium manganite had a less stable ion configuration, therefore magnetic properties of these systems are built from phase transformation MnO become α-Mn3O4 is arrayed ferromagnetic due to the presence of lanthanum and barium in this system. The presence of lanthanum and barium trigger in the emergence of mixed-valence Mn ions, so that occur to magnetic interaction between Mn3+ and Mn4+ through the double-exchange mechanism. We concluded that the characteristic of magnetic properties on the lanthanum barium manganite system perovskite is affected by thermal properties, fundamental properties of raw material and the result of reaction is formed.
Microstructural Studies of (Ba0.7Sr0.3Fe12O19)1-x - (Ba0.7Sr0.3TiO3)x with x = 0.2, x = 0.5 and x = 0.8 Composite System by Mechanical Alloying Process
Authors: Novizal Novizal , Manaf Azwar , Sardjono P.
Published: February 2014

In this paper, we report our investigation on material structure analysis of (Ba0.7Sr0.3Fe12O19)1-x-(Ba0.7Sr0.3TiO3)x with x = 0.2, x = 0.5 and x = 0.8 composite system prepared by a mechanical alloying process to promote feroic properties. It is shown that the x-ray diffraction patterns of each composition for the composite materials are the same. It consisted of the mixture for the two phases. The average of particle size for each respective phase in the composite materials was found initially increased, up to 18-20 μm after mechanically milled for 40 hours, then start to decreased to a smaller size ~ 8-10 μm after 80 hrs milling time. However, a plot of particle size against the milling time for each composite phase shown a trend of further reduction in the mean particle sizes. In addition, the x-ray traces of dense pellet samples after sintering the milled powders at a temperature of 1100 °C showed broadened diffracted peaks pattern due to fine crystallites in the samples. Results of mean crystallite size determination of respective phases in the composite samples showed the same trend, a decrease with milling time toward values about 10 nm at 80 hrs milling time. Hence, sintering to the milled particles has promoted the formation of nanocrystal containing particles. When compared between the mean particle size and mean crystallite size of respective phase in the composite samples, the mean crystallite size for magnetic phase (B7S3F) was found more than 100 times smaller than the mean particle size of composite particles. However, finer mean crystallite sizes were found in the ferroelectric phase (B7S3T) in which the mean was about 200 times smaller than the mean particle size.
Micromagnetic Simulation on Ground State Domain Structures of Barium Hexaferrite (BaFe12O19)
Authors: Djuhana Dede , Oktri Dita C.C. , Kim D.H.
Published: February 2014

We have systematically investigated the domain structures of Barium Hexaferrite (BaFe12O19) by means of a micromagnetic simulation under zero external magnetic field. A hexagonal-shaped and cylindrical-shaped models are used in this simulation with respect to the diameter variation from 50 nm to 600 nm. A transition domain structure is found from a single-domain (SD) to multi-domain (MD) at a certain diameter. The hexagonal-shaped occurs in diameter 430 nm and cylindrical-shaped in diameter 410 nm. Interestingly, the domain wall of MD structure exhibits a Bloch-wall type. The domain wall width is determined by full width half maximum (FWHM) method from the transverse magnetization component data. The domain wall width from simulation showed close to Kittel’s formula
Microwave Properties of Composite Ba0.5Sr0.5Fe11.7Mn0.15Ti0.15O19/La0.7Ba0.3MnO3 Material
Authors: Repi Viktor Vekky Ronald , Manaf Azwar , Soegiono Bambang
Published: February 2014

Mn-Ti substituted Barium - Strontium Hexaferrite and Barium – Lanthanum Manganite both well established materials which have been shown poses microwave absorbtion properties. As the properties of composite system are a composition sensitive, composite materials must be properly designed to meet a specific application. In this paper, we report our recent investigation on microwave absorbtion properties of composite Ba0.5Sr0.5Fe11.7Mn0.15Ti0.15O19/La0.7Ba0.3MnO3 system. Composite components respectively Ba0.5Sr0.5Fe11.7Mn0.15Ti0.15O19 and La0.7Ba0.3MnO3 were prepared through mechanical alloying route employing a planetary ball mill for 20 hrs. The two milled powders were sintered at a temperature 1100 °C for 10 hours to ensure the crystallization towards fully crystalline materials. Composites with 2 different compositions were studied by FTIR and VNA from which results were compared with that of each component. Results of the investigation concluded that, the composite of Ba0.5Sr0.5Fe11.7Mn0.15Ti0.15O19/La0.7Ba0.3MnO3 system is a good microwave absorbing material in the frequency range 9 GHz-15 GHz, particularly, sample with coded A03B07 has a wide range frequencies absorption.
Experiment Using a Magnetically Controlled Ferrofluid Flow in a Flatplate Laminar Flow System
Authors: Fan Yi Hua , Lou Liao Yong , Chen Yu Ming
Published: February 2014

The Phenomenon of a Magnetic Controlled Ferrofluid Flow in the Flat Plate Laminar Flow System is Discussed in this Paper. the Ferrofluid Flow is One Kind of Colloid Mixture, which is Composited by the Magnetic Particles, Carrier Fluid and Surfactant. its Motion is Followed the Fluid Dynamics and can be Controlled by a Magnetic Field. from the Theoretic Analysis and the Experimental Test, the Coefficient of Viscosity of the Ferrofluid Flow will be Affected by the Magnetic Field. Thus, an Experimental Rig is Built to Test the Influences of the Gap of the Plate and the Strength and Direction of the Magnetic Field for Several Ferrofluid Flows with Different Dividing Rates of Volume. Experimental Results Showed that the Coefficient of Viscosity of the Ferrofluid Flow is Almost Not Upgrading in a Wide Gap Condition by the Magnetic Field, but as the Gap is Smaller, the Coefficient of Viscosity will be Promoted Obviously. Furthermore, Enhancing the Magnetic Field, it will be Increase the Coefficient of Viscosity of the Ferrofluid Flow. from the Experimental Results, the Relationship of the Magnetic Field, Coefficient of Viscosity of Ferrofluid Flow and the Carrier Fluid can be Confirmed.
A Simple Optimization of Triple-Junction Solar Cell nc-Si:H/a-Si:H/a-SiGe:H Using Computer Modeling and Robust Design
Authors: Abuzairi Tomy , Poespawati Nji Raden
Published: February 2014

We report for the first time a simple optimization of triple-junction solar cell nc-Si:H/a-Si:H/a-SiGe:H using computer modeling and Robust Design. Firstly we performed a computer modeling of solar cell by wxAMPS software. Subsequently, we investigated the parameters of the solar cell layers and the effect of the solar cell efficiency using Robust Design via Taguchi method, ANOVA and additive model. The results show that the a-Si:H middle absorber cell has the highest contribution of solar cell efficiency at 40.87% and the nc-Si:H n-back layer cell has the second highest contribution of solar cell efficiency at 31.15%. Moreover, the optimum condition for triple-junction solar cell is A2 B1 C2 D2 with solar cell efficiency at 15.73%. These results indicate that Robust Design succeeded predicting the best condition for optimizing triple-junction solar cell nc-Si:H/a-Si:H/a-SiGe:H.
Detailed Analysis of Shallow and Heavily-Doped Emitters for Al-BSF Bifacial Solar Cells
Authors: Sepeai Suhaila , Zaidi Saleem Hussain , Sulaiman M. Yusof , Sopian Kamaruzzaman , Ibrahim M. Adib , Desa M. Khairunaz Mat , Norizam Mat Daud
Published: February 2014

A selective emitter structure is a promising approach to improve the cell efficiency of industrial type silicon solar cells by minimizing the losses at the front surface and in the emitter. Selective emitters can be produced by numerous processing sequences, resulting in different doping profiles. This paper focuses on the analysis of emitter formation for bifacial solar cell application. In this research, liquid phosphorus oxy-trichloride (POCl3) has been used as a diffusion source for emitter formation. The diffusion temperature was varied from 800 to 900 °C in order to determine an optimum diffusion profile. In this study, the mask-free diffusion process forms diffused emitter on both side of Si wafer. In order to determine the emitter characteristics, the sheet resistance of Si wafer after POCl3 diffusion process was measured using a four-point probe. Based on the sheet resistance value of ~47 ohm/sq, the emitter has been classified as heavily-doped emitter. The performance analysis using surface photovoltage (SPV) and spectral response presents a diffusion length of 2.19 μm. The POCl3-diffusion and screen printed Al-BSF led to bifacial solar cells with a front surface efficiency of 12.8 % and back surface efficiency of 5.08 %.
Microwave-Assisted Solid State Synthesis of Red-Emitting BCNO Phosphor and its Characteristics
Authors: Nuryadin Bebeh Wahid , Septia Ea Cahya , Iskandar Ferry , Ogi Takashi , Okuyama Kikuo , Mikrajuddin Abdullah , Khairurrijal Khairurrijal
Published: February 2014

Red-emitting BCNO phosphor has been synthesized by a microwave-assisted solid state reaction using a low-cost boric acid, urea and polyethylene glycol (PEG-20k) as the starting materials. The effects of reaction parameters: temperature, carbon and nitrogen content on material composition and photoluminescence properties were investigated. Nearly multi-phase hexagonal boron nitride, boron oxide, boron carbide and carbon graphite was observed, indicating the BCNO were successfully synthesized. The photoluminescence spectra of the phosphor excited by a UV light (365 nm) showed a broad emission band at 460 - 620 nm.
Synthesized 2,4,5-Triphenylimidazole as Precursor of Organic Light Emitting Diode (OLED) Material
Authors: Rachman Ihsan Budi , Wahyuningrum Deana
Published: February 2014

Current research based on fluorescent organic material has many advantages. One of advantages fluorescent organic material is as OLED (Organic Light Emitting Diode) based devices. OLED compound is rigid conjugated organic molecules. 2,4,5-triphenylimidazole (3) was synthesized by microwave assisted organic synthesis method. The first stage of synthesis is the synthesis of bibenzoyl (2) produced from the solventless oxidation reaction of benzoin (1) by atmospheric oxygen using MAOS (Microwave Assisted Organic Synthesis) method with chemical yields of 99.18% and melting point of bibenzoyl is 94-95 °C, and the FTIR spectrum showed the lost of -OH group peak at 3425.51 cm-1 and the strengthening of group C=O peak at 1672.25 cm-1. compound (3) was synthesized from the reactions between compound (2), benzaldehyde, ammonium acetate and acetic acid glacial by MAOS method with chemical yields of 69.04%. Melting point of compound (3) is 267-268°C and FTIR spectrum showed -NH group peak at 3038.53 cm-1 and C-N group peak at 1209.51 cm-1. Result of elucidation by 1H-NMR measurements of compound (3) showed a typical signal of -NH proton at chemical shifts of 9.31 ppm and the phenyl protons in the chemical shifts range of 7.46 to 7.94 ppm. UV-Vis and fluorescence spectra shown compound (3) has a potential as precursor compound of Organic Light Emitting Diode material.
Prelimenary Study on the Photovoltaic and Impedance Characteristics of Dye Sensitized Solar Cell (DSSC) using Polymer Gel Electrolyte
Authors: Arsyad Waode Sukmawati , Pujiarti Herlin , Wulandari Priastuti , Herman Herman , Hidayat Rahmat
Published: February 2014

Dye sensitized solar cells (DSSC) have been fabricated by using polymer gel electrolyte consisting of ionic liquids in a composite polymers of siloxane and ethylene oxide groups. The structure of those DSSCs are ITO/Ti:ZnO/TiO2/Ru-dye/gel electrolyte/Pt/ITO, with active area of about 0,5 cm2. At this preliminary work, the structure parameters and fabrication procedures had not been optimized for achieving the best performance, but it had been carefully controlled to be same for all fabricated DSSCs. Those DSSCs shows the solar cell performance similar to that observed in DSSCs fabricated in the same cell structure but using conventional electrolyte solution. They exhibit better open voltage and filling factor, which is suggested to the reduction of charge carrier recombination probably taking place at the double layer region formed at the electrode interfaces. This is consistent with their impedance spectrum which is dominated by a Warburg-like characteristics indicating a diffusion limited migration process. It seems then the cell performances is improved by the reduction of charge recombination loss but restricted by diffusion limited ion migration process.
Charge Carrier Dynamics of Active Material Solar Cell P3HT:ZnO Nanoparticles Studied by Muon Spin Relaxation (μSR)
Authors: Safriani Lusi , Risdiana Risdiana , Bahtiar A. , Aprilia Annisa , Siregar Rustam E. , Hidayat Rahmat , Saragi Tobat P.I. , Kawasaki I. , Watanabe Isao
Published: February 2014

Poly (3-hexylthiohene) (P3HT) has attracted much attention due to their chemical and thermal stability as well as their potential to be used as an active material in solar cells. Recently, hybrid solar cell has been developed due to the combining advantages of organic material (P3HT) and inorganic material such as nanoparticle zinc oxide (ZnO). ZnO is an inorganic material with high electron mobility and easy to prepare as electron acceptor to dissociate excitons formed in conjugated polymer as the active material of solar cells. ZnO also can be prepared as a nanoparticle that can resolve a problem of small exciton diffusion length of P3HT. However, the clearly explanation about the effect of ZnO to the charge carrier dynamics in P3HT is not fully understanding yet. We have studied charge carrier dynamics in active material of solar cell P3HT:ZnO along and perpendicular to the chain by means of longitudinal field (LF) muon-spin-relaxation (μSR) method to elucidate the intra and inter-chain charge carrier in polymer hybrid P3HT:ZnO. We found the charge carrier transport changes from intra-chain to inter-chain diffusion. One dimensional intra-chain diffusion is observed in the samples at low temperatures, while three dimensional inter-chain is observed at high temperatures.
Dimensional Analysis of Grid Pattern on a Nematic Liquid Crystal
Authors: Wahyuni Dwiria , Kusumawardany Intan R. , Hartini Sri , Yusuf Yusril
Published: February 2014

Grid pattern (GP) was observed on planarly aligned nematic liquid crystal 4-methoxy-benziledene-4-n-buthyl-aniline (MBBA) when it applied by certain frequency and certain voltage which exceeds a threshold voltage, VGP. The GP appeared due to convective movement of MBBA molecules. Dimensions on GP were distinguished into length and width of GP rectangular shape. Width-area of GP is product of the length and the width. Dimensional analysis carried on image processing used ImageJ software. Observation on the pattern showed that the frequency affected GP dimensions, which were proportional to the GP length and inversely proportional to the GP width. Variation on frequency also showed that the frequency was inversely proportional to GP width-area that formed on image, but was proportional to sample thickness.
Structural, Chemical Composition and Optical Properties of CdTe Fabricated by Vacuum Evaporation Technique
Authors: Ariswan Ariswan
Published: February 2014

CdTe polycrystalline thin films have been fabricated by vacuum evaporation technique. Their properties have been investigated using X-ray diffraction, energy dispersive spectroscopy, scanning electron microscope and uv-vis spectroscopy. The results showed that the CdTe thin films crystalized at hexagonal structure with lattice parameters a and c 6.45 Å and 7.66 Å respectively. The EDS results showed that the chemical composition is nonstoichiometry, slightly rich of Tellerium with Cd/Te of 0,9. It has a uniform shape with color homogenity and has an optical band gap at room temperature about 1.47 eV. Keywords:Vacuum evaporation, polycrystalline, cadmium telluride, thin films.
The Influence of Sandblasting and Electropolishing on the Surface Hardness of AISI 316L Stainless Steel
Authors: Suyitno Suyitno , Ishak Ishak
Published: February 2014

The purpose of this study is to analyze the effect of sandblasting and electropolishing on microstructure and hardness of stainless steel AISI 316L. The equipment used was sandblasting machine with a working pressure of 5-7 kg/cm2 with a duration of 10 minutes. The silica sand was used with size of 500-800 μm. The equipment used in the electropolishing process is the DC power supply with a maximum output of 2x100A. Anode and cathode material were stainless steel AISI 316L. Electrolyte solution consisted of 96% mass fraction of sulfuric acid and 85% mass fraction of phosphoric acid with a ratio of 1:1. The parameters used in the electropolish process were voltage of electrical, distance of electrodes and duration of electropolishing process. The results show that increasing the voltage, decreasing the distance, and increasing the duration of the electropolishing process increase the hardness up to 69%.
Preparation and Characterization of Magnetite-Silica Nano-Composite as Adsorbents for Removal of Methylene Blue Dyes from Environmental Water Samples
Authors: Fisli Adel , Yusuf Saeful , Ridwan Ridwan , Krisnandi Yuni K. , Gunlazuardi Jarnuzi
Published: February 2014

Magnetite-silica nanocomposites (Fe3O4/SiO2) have been synthesized and characterized and were used as an effective sorbent material for dyes removal from environmental water samples. They were prepared by a simple procedure via a co precipitation of iron (II) and iron (III) ion mixture in ammonium hydroxide and then was impregnated by a sodium silicate. The prepared samples were characterized using Zeta potential, XRD, VSM, TEM, EDS, and porosity analysis. The result of characterization showed that Fe3O4 nanoparticles have been coated by silica. The composite have been superparamagnetic behaviour at room temperature and contain both meso-and microporosity system. Mesoporosity contributes dominantly to the pore volume. Adsorption performance of magnetic-silica nanoparticles were examined its ability to adsorp methylene blue dye in aqueous solution. The 20 mg/L of initial concentration of methelene blue, 1 gr/L adsorbent in solution and under shakker for 5 hour, the remain of methylene blue in solution was 13,3% for Fe3O4/SiO2 (3:1), 30,2% for Fe3O4/SiO2 (2:1) and 24,2 % for Fe3O4/SiO2 (1:1). The composite was effective to adsorb dyes in water and can be easily recovered from treated water with helping of magnetic bar.
Adsorption Mechanism of Carbon Monoxide on PtRu and PtRuMo Surfaces in the Density Functional Theory Perspective
Authors: Cahyanto Wahyu Tri
Published: February 2014

Adsorption mechanism of carbon monoxide (CO) on PtRu and PtRuMo alloy surfaces is investigated using density functional theory (DFT). It includes evaluation of binding configuration and the adsorption strength. The results show that CO preferentially adsorbs onto the 3 fold hollow site of the PtRu-surface, while on the PtRuMo surface we observe the shift from the fcc hollow site to near the bridge site. We also note that adsorption energy of CO on the PtRuMo is stronger than that of adsorption on the PtRu surface. From the charge transfer analysis, we conclude that the stronger binding energy is caused by the more charge transferred to the surface-adsorbate bonding region brought by alloying Mo to the PtRu.
Hydrothermal Synthesis and Visible-Light-Driven Photocatalytic Activity of Allophane – Wakefieldite-(Ce) Composite
Authors: Hojamberdiev Mirabbos , Makinose Yuki , Katsumata Kenichi , Isobe Toshihiro , Matsushita Nobuhiro , Okada Kiyoshi
Published: February 2014

In this study, highly adsorptive mechanically-mixed and as-synthesized allophane–wakefieldite-(Ce) composites were prepared by mechanical mixing and hydrothermal synthesis, respectively. The results from X-ray diffraction and Raman spectroscopy analyses show that the mechanically-mixed composite has higher crystallinity than the as-synthesized composite. The nanoparticles of wakefieldite-(Ce) were homogenously distributed with allophane in the as-synthesized composite. The specific surface areas of the mechanically-mixed and as-synthesized composites are 164 m2/g and 191 m2/g, respectively. The photocatalytic activity of the samples was evaluated for the degradation of acetaldehyde (AcH) gas under visible light. Both composites demonstrated higher photocatalytic activity than individual wakefieldite-(Ce) and allophane because allophane in the composites played an important role in the adsorption of acetaldehyde gas molecules and the mediation between the gas phase and the wakefieldite-(Ce) surface.
Study of Internal Response of Epoxy due to Compressive Load via Experiment and Simulation Using Abaqus FEA Software
Authors: Aditya Irfan Dwi , Widayani Widayani , Viridi Sparisoma , Khotimah Siti Nurul
Published: February 2014

Epoxy is widely used primarily as a matrix material in the manufacture of Polymer Matrix Composites (PMC). Epoxy behavior under compression load has to be understood before the mechanical behavior of PMCs can be accurately predicted. Simulation model combined with experiment and image analysis are used to investigate internal response of epoxy resins polymeric materials subject to compressive loads. To investigate epoxy response to compressive load, small carbon-based material rods are inserted in the epoxy. The samples are held in one side and subjected to compressive load on the other side. All the samples swell at load sides. Image analysis on the carbon-based rods figures out the internal response, which seems to be isotropy in lateral direction. The results are compared to simulation results using Abaqus FEA. Similar condition is obtained when a brittle thin material is stuck to the top of the model.
Development of Geopolymer Utilizing Inorganic Waste Materials
Authors: Samadhi Tjokorde Walmiki , Pratama Pambudi Pajar , Muan Nurhidayati
Published: February 2014

Geopolymers, which are produced by the reaction between aluminosilicate solid precursors and concentrated alkali solutions, is an environmentally attractive construction material due to its much smaller carbon footprint compared to ordinary Portland cement (OPC), and its ability to consume a wide range of solid inorganic waste materials. This work describes the synthesis of geopolymers utilizing local aluminosilicate materials and the evaluation of several key engineering properties of the geopolymer product as a construction cement. A simple 22 factorial experiment is undertaken to measure the effect of types aluminosilicate solids (metakaolin produced by calcining a Belitung kaolin at 750 °C, and coal fly ash from an East Java baseload powerplant) and alkali activators (NaOH and KOH solutions) on the initial and final setting time of the geopolymer cement mortar. All geopolymer mortar samples exhibit longer setting times compared to OPC mortars. Statistical analysis indicates that KOH produces faster initial setting than NaOH, while fly ash produces faster setting times compared to metakaolin. A 23 factorial experiment is conducted subsequently, adding curing temperature (60 and 80 °C) to the experimental factors. The key engineering property measured in the second experiment is the compressive strength of geopolymer mortars. ANOVA treatment of the measured data indicates that all three experimental factors significantly impacts the compressive strength. Consistent with the preceding experiment, the use of fly ash and KOH significantly increases the strength of the geopolymer mortar. Higher curing temperature is also found to increase the strength. The use of metakaolin as geopolymer precursor produces compressive strength approximately 50% than that of the OPC mortar, while fly ash produces a geopolymer mortar strength that is at least as good as OPC.
Improving the Physico-Mechanical Properties of Eco-Friendly Composite Made from Bamboo
Authors: Widyorini Ragil , Puspa Yudha Ari , Isnan Ramadhanu , Awaluddin Ali , Agus Prayitno Tibertius , Ngadianto Agus , Umemura Kenji
Published: February 2014

This research focused on physical and mechanical properties of biocomposite made from bamboo and citric acid as natural binder. Bamboo particles was mixed with citric acid at 0 – 40 wt% resin content based on air-dried particles and each mixture was hot pressed at 180 °C for 10 min. The result showed that addition of citric acid could improve significantly the physical and mechanical properties of particleboard. The thickness swelling was 50 % for bamboo binderless particleboard (0 wt%), whereas it decreased to 7 % under a resin content of 10 wt%. The optimum resin content in this study was 30 wt%, while the modulus of rupture dan the modulus of elasticity were 14 MPa and 4.5 GPa, respectively. The ester linkages were detected by Fourier transform infrared spectroscopy, indicating that carboxyl groups from citric acid reacted with hydroxyl groups from bamboo to produce better properties of particleboard, especially its dimensional stability. Based on these results, it was concluded that citric acid could be as a potential natural binder for bamboo particleboard.