Table of contents

Preface

We are very pleased to present the Proceedings of the 9^th Seminar on Magnetic Materials 2015 held in Palembang, South Sumatera, Indonesia on October 19^th – 21^st, 2015. The seminar aimed to be a platform on academic exchange for materials scientists, especially in magnetic materials through invited talks and distinguish lectures series. In total, we received 40 manuscripts and all of them have been reviewed by the reviewers. Those manuscripts are covering 7 topics on magnetic materials and applications meeting: magnetism and characterizations; magnetic materials applications on clean energy materials, transportation and vehicles; aerospace and defense; health care; environment and oil refining; electronics; and natural resources of magnetic materials.

Among those manuscripts, after a very intensive reviewing process, 3 papers have been accepted by the Physica B's Editors and then published in Physica B: Condensed Matter 2017, Vol. 526 of Elsevier and the other 30 manuscripts are published in the Journal of Physics Conference Series 2018, Institute of Physics (IoP).

We are really honored as the selected seminar papers were published in the regular issues of high impact factor international journals, i.e. Physica B of Elsevier. This achievement is showing the level and quality of the regional/international meeting in Indonesia, organised by the Center for Science and Technology of Advanced Materials (PSTBM) - National Nuclear Energy Agency (BATAN) Indonesia in collaboration with the Faculty of Mathematics and Natural Sciences (FMIPA) - University of Sriwijaya.

Here, we are delighted to acknowledge the incredible support from the Ministry of Industry of the Republic Indonesia (Kemenperin), the Indonesian Institute of Sciences (LIPI), the University of Indonesia (UI), the Institute Technology of Sepuluh Nopember (ITS) Surabaya, the University of Gadjah Mada (UGM) Yogyakarta, the University of Padjadjaran (Unpad) Bandung, the Institute Technology of Bandung (ITB), the Agency of the Assessment and Application of Technology (BPPT).

We hope that the present proceedings provide the valuable information to the readers in the field of magnetic materials and its applications.

Dr. Poedji Loekitowati Hariani (Unsri) and Edy Giri Rachman Putra, Ph.D (BATAN)

Chairpersons of the 9^th Seminar on Magnetic Materials

All papers published in this volume of Journal of Physics: Conference Series have been peer reviewed through processes administered by the proceedings Editors. Reviews were conducted by expert referees to the professional and scientific standards expected of a proceedings journal published by IOP Publishing.

Synthesis and characterization of NiFe₂O₄-MWNT/PVA nanocomposite films have been performed. NiFe₂O₄-MWNT as a filler of nanocomposite films was gained using a simple mixing method from an aquaeous solution containing Fe(NO₃)₃.9H₂O, Ni(NO₃)₂.6H₂O and MWNT. A wet paste-like filler was first characterized by Raman spectroscopy to confirm the presence of NiFe₂O₄ phase. Refering to the result of Raman spectra, it was known that nanocrystalline nickel ferrite (NiFe₂O₄) have been successfully synthesized.The morphological investigations using scanning electron microscopy (SEM) and energy dispersive spectroscopic (EDS) revealed that the filler has hair-like structure which correspond to the carbon nanotube with the results of atomic percentage ratio of Fe/Ni correspond to the phase formation of NiFe₂O₄. Nanocomposite films were made in 4 various concentrations (5, 10, 20, and 50 %vol filler) have been characterized in order to investigate their magnetic properties and electrical conductivity by using vibrating sample magnetometer (VSM) and Inductance-Capacitance-Resistance (LCR) meter. Based on magnetization hysteresis curves, the variation of filler addition has increased the magnetic properties of nanocomposite samples from diamagnetic into paramagnetic. It was also known that the electrical conductivity enhanced align with the increasing consentration of the filler in nanocomposite films.

Adsorption is the most extensively used technique for elimination of dye in contaminant water. Magnetically separation of toxic pollutant is becoming a potential method for water purification and obtained more effective and simple compared to conventional method of treatment. The surface-functionalized magnetic iron oxide nanoparticles with cetyl trimethyl ammonium bromide (CTAB-coated CTAB) has been investigated. CTAB-coated Fe₃O₄ were synthesized by precipitation of ferrous/ferric chloride (mole ratio 2:1) in CTAB/ammonium hydroxide solution mixture. The samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), nitrogen adsorption-desorption isothermal and Fourier transforms infrared spectroscopy. The CTAB-coated Fe₃O₄ nanoparticles exhibited ability significantly to eliminate methyl orange in water compared to uncoated Fe₃O₄. Dye adsorption equilibrium state data were fitted well to the Langmuir isotherm were obtained the favorable of constant separation factor value (RL) (0.005-0.03). The CTAB coated Fe₃O₄ followed the pseudo-second-order kinetic model, resulting in the rate constant adsorption value for the elimination of methyl orange was 0.0694 g.mg^-1.h^-1. CTAB coated Fe₃O₄ nanoparticles have relatively high saturation magnetization, which allowed their highly-efficient magnetic separation from wastewater. This investigation was concluded than CTAB-coated Fe₃O₄ nanoparticles was efficient to eliminate dye from wastewater

MgFe₂O₄ has been successfully synthesized by coprecipitation method. The Precursors used are MgCl₂.6H₂O (magnesium chloride hexa-hydrate, M_r = 203.205 g/mol) and FeCl₃. 6H₂O (ferric chloride hexa-hydrate, Mr = 270.19 g/mol) and NaOH (sodium hydroxide, Mr = 39.99 g/mol) as coprecipitant. This synthesis process was done by varying the NaOH concentration, the synthesis temperature and the stirring duration. XRD analysis results showed that the grain size increases with synthesis temperature and decreases with the increase in the concentration of NaOH and the duration of stirring. The smallest grain size is 2.1 nm and the largest grain size is 10 nm. Analysis of magnetic properties MgFe₂O₄ by Vibrating Sample Magnetometer (VSM) showed that nanoparticles MgFe₂O₄ can be assumed in multidomain region, with relationships. Sample with the smallest particle size 2.1 nm, has highest Hc value 133.9 Oe. The maximum magnetization at H = 15 kOe and remanent magnetization (Mr) increase with the degree of crystallinity of the sample. Although there is also the effect of the presence of hematite phase (α-Fe₂O₃) and the grain size. Magnesium ferrite magnetic nanoparticles (MgFe₂O₄) has great potential to be applied as adsorption, sensors, drug delivery, semiconductor materials and other magnetic technology

Since Cu oxide superconductors have been discovered, the application for this type of superconductor especially in the form of superconducting tape to be used as electric cable to transport the electricity. The aim to this study is to analyse the manufacture of superconducting wire with superconducting pellets as its precursor. A pellet disc of High Temperature Superconducting (HTS) Bi,Pb-Sr-Ca-Cu-O has been made by using solid state method. This pellet has been prepared by mixing each of oxide powders together, and then sintered at 865°C for 90 hours. We have analysed the samples using X-Ray Diffractometer (XRD), Energy Dispersive x-ray Spectroscopy (EDS), Scanning Electron Microscopy (SEM) and also resistivity measurement to confirm its superconductivity. After confirmed the superconducting properties of the pellet, it was grinded into powder and inserted into silver tube with outer diameter of 10 mm and thickness of 1 mm. And then, drawn to make monofilament wire. It were then cut and inserted into another silver tube, and then re-drawing and rolled into multifilament tapes using Powder-in-Tube (PIT) method. The multifilament tapes was heated at 850°C for 12 hours. We confirmed its phase crystalline and superconductivity at pellet disc. However, when the pellet disc was made into wire and sintered at 850°C, it became amorphous and conductivity behaviour was decline. According to SEM analysis and resistivity measurement result, silver also penetrated inside the sample region of multifilament wire.

Iron oxide found in nature with high iron oxide content has potential to be utilized as raw material for magnetic application. In this study, an attempt has been made to increase hematite content through thermal oxidation or roasting in moderate temperature with additional oxygen gas to accommodate oxidation. Iron oxide powders were milled in 6 hours then washed and dried. Roasting processwere performed at four varying temperatures of 480°C, 520°C, 560°C, and 600°C with oxygen influx 3L min-1, preceded by isothermal holding at 385°C. TGA-DSC (thermogravimetric analysis – differential scanning calorimetry) and XRD (X-Ray Diffraction) characterization has been performed to understand iron oxide behavior in response to thermal oxidation at moderate temperature. It is observed that two main reactions are clearly distinguished. In DTG curve, first peak indicate reduction followed by oxidation at the second peak. XRD results has shown that the highest content of α Fe₂O₃ was achieved by roasting at 600 °C for 1 hour which produced hematite portion of 31 wt. %, yet it is still insufficient to be utilized as raw material for ferrite based magnets fabrication. To prevent reduction reaction of Fe3O4 which will retard the oxidation process, it is suggested to avoid isothermal run or lower heating rate at temperature below 406°C

Microwave absorber sheet is a composite of silicon rubber – iron oxide. The composite was prepared by silicon rubber, toluene, and magnetic powder of iron oxide. The raw material was blended in the beaker glass for 60 min and then pressed at temperature of 70 °C for 15 min. The unsure analysis showed that the sample contained carbon, oxygen, sulfur, zinc, lanthanum, barium, manganese, titanium and iron. The refinement results of x-ray diffraction pattern show that the sample is semicrystalline with the crystallinity of 46%. The sample consist of the matrix is amorphous phase and the filler is crystalline phase. The filler consist of two phases, namely iron oxide and iron metal phases. The functional groups analysis show that the sulfur addition modified the polymer by forming crosslink (bridges) between individual polymer chains and bonding between magnetic filler and rubber matrix. We concluded that this study has been successfully made a composite of silicon rubber – iron oxide for microwave absorber sheet application.

Among the many types of natural resources that are abundant in Indonesia is iron sand. One of the products of the iron sand processing is magnetite (Fe₃O₄). The stages of separation and purification process that has been done before were extracting magnetite phase and discarding the other phases. Magnetic structure of magnetite phase of iron sand retrieved from Banten, Indonesia has been invesigated. The aims of this research is to analyze the structure of the new magnetite phase, Fe_xM_yO₄. The magnetic properties of the sample was evaluated by means of vibrating sample magnetometer (VSM). Sample characterizations was carried out by neutron activation analysis (NAA) method. The analysis result from NAA shows that there are still 17 impurities remaining, namely: M = Ti, Al, Ce, Co, Cr, Eu, La, Mg, Mn, Na, Sc, Sm, Th, V, Yb and Zn, and there are about 94% of iron sites are filled by Fe elements. The structural analysis was carried out by the help of the high resolution neutron powder diffractometer (HRPD) using a wavelength of λ = 1.8223 Å. Neutron diffraction data was analyzed by means of FullProf software. The analysis result shows that the sample hasthe chemical formula: (Fe0.97M0.03)3O4 with a cubic crystal system, space group: Fd-3m and lattice parameters: a = b = c = 8.36834 (3) Å, α = β = γ = 90°. The sample is magnetic at room temperature because the compound has a net magnetic moment, μ = 2.9(1) μB. The magnetic moments of the sample is lower than the magnetic moments of pure Fe3O4 (μ = 3.8 μB), because of about 3% of Fe sites are occupied by impurity elements. Magnetic properties of magnetite phase depend on the purity of the magnetite phase.

Has been synthesized iron sand from the Lemabang-Sumsel Area by using High Energy Milling Method. Before synthesized, extraction of Lemabang iron sand in advance by using permanent magnets and Methanol-Soap Bathed Method in order to separated iron sand and impurities. After it, iron sand milled by using High Energy Milling with variations in milling time 2 hours, 4 hours, and 6 hours. Milling time optimization done in order to see the effect of time milling on powder size and surface morphology. Then Iron sand already in milling characterized by using XRD to see crystal structure and crystal size, and SEM-EDS used to see surface morphology and composer elements. XRD's result show that, the longer of the milling time resulting the shorter of the powder size. Whereas the results of the SEM-EDS's photo, its seem that the grain morphology of the iron sand powder after milling is smoother and more homogeneous be compared before milling

The synthesis and characterization of Ba_0.6Sr_0.4Fe_12-xTi_xO₁₉ system (x = 0, 1, 2, 3) have successfully performed by mechanical milling through solid state method. Stoichiometric quantities of BaCO₃, SrCO₃, Fe₂O₃, and TiO₂ were mixed. The mixture were first milled for 48 h and sintered at 1000 °C for 5 hrs. The refinement of x-ray diffraction shows that a single phase material with a hexagonal structure and lattice parameters appears to increase with increasing Ti doping. The mechanical milling resulted in powders of all samples with mean size of 90 nm. Results of hysteresis curve shows that the samples are ferromagnetic and have low coercivity after Ti doping. Results of VNA evaluation show that the sample after Ti doping has absorption peaks with high reflection loss values at frequency ∼ 11 GHz. We concluded that this study has been successfully known effect of Ti addition on the microwave absorbing behavior of Ba_0.6Sr_0.4Fe_12-xTi_xO₁₉system at X-band frequencies.

In this study, we report the sol-gel synthesis of nanocomposite Fe₃O₄/ZnO with nanographene platelets (NGP)and characterized by suitable techniques, including field emission scanning electron microscope (FESEM), X-ray diffraction (XRD), energy dispersive X-ray analysis (EDX), UV-visible diffuse reflectance spectroscopy and vibrating sample magnetometer. The as-synthesized Fe₃O₄/ZnO/NGP nanocomposites materials were used for photocatalyst under UV as well as visible light irradiation to remove methylene blue as a model of organic polutan. The XRD spectra reveal peaks that can be attributed to cubic spinel Fe₃O₄, hexagonal wurtzite ZnO and nanographene platelets structure. The FESEM images show Fe₃O₄/ZnO uniformly decorating NGP sheets. EDX analysis signifies the formation of Fe₃O₄/ZnO/NGP. The photocatalytic activity was found to be ZnO loading dependent. Higher ZnO loading lead to higher rate of photocatalytic activity under UV light irradiation, while the opposite trend observed under visible light irradiation. The addition of NGP effectively enhanced the photocatalytic performance of Fe₃O₄/ZnO nanocomposites. Separation of Fe₃O₄/ZnO/NGP nanocomposites from the solution could be achieved by applying an external magnetic field, demonstrating the magnetic properties of the nanocomposites.

In this study, magnetic recyclable catalyst Fe₃O₄/CuO/ZnO/nanographene platelets (Fe₃O₄/CuO/ZnO/NGP) and Fe₃O₄/CuO/TiO₂/nanographene platelets (Fe₃O₄/CuO/TiO₂/NGP) composites were synthesized by simple hydrothermal method. Methylene blue was used as a model of textile dye to evaluate their catalytic activities. A range of analytical techniques including X-ray diffraction, energy-dispersive X-ray spectroscopy and vibrating sample magnetometer were employed to reveal the crystal structure, composition and property of the nanocomposites. The catalytic performance was evaluated by degradation of methylene blue in aqueous solution under UV light and ultrasonic irradiation simultaneously. X-ray diffraction results revealed that cubic spinel Fe₃O₄, monoclinic CuO, hexagonal wurtzite ZnO and graphene platelets exist in Fe₃O₄/CuO/ZnO/NGP, while in Fe₃O₄/CuO/TiO₂/NGP nanocomposites instead of hexagonal wurtzite ZnO, anatase TiO₂ is observed. These results confirmed that the nanocomposites were the desired materials. In addition, all samples exhibited ferromagnetic behavior at room temperature and could be rapidly separated from aqueous solution for repeated use under external magnetic field. From the degradation of methylene blue, it is found that the as-prepared nanocomposites exhibited excellent catalytic activity compared with nanocomposite synthesized without nanographene platelets. The nanocomposites still retain the 100% of the initial activity after it has been used four times repeatedly.

Rare Earth Elements (REE) is one of the natural resources that are very strategic and high economic value. REE applications in industry are continues to grow such as LCD (liquid crystal display), LED (light emitting diode), magnet and hybrid batteries (NiMH batteries; Misch metal; Ce, La, Nd). This resulted in REE demand continues to increase up to 10%. Increased demand is not matched by the number of Rare Earth production in the world. This happens because the Chinese as the main actor in the producer REE world production (95%) restricting the export of Rare Earth up to 35% so that the world price of LTJ bounced up. Research & development processing, and purification REE continue to obtain high purity Rare Earth Metals. Baking process the mineral carrier of REE (raw material minerals) with solid NaOH using a muffle furnace has been carried out. The research aims to determine the effect of temperature and grain size of the monazite sand on the decomposition reaction monazite sand and reaction kinetics. The raw materials used are monazite sands containing rare earth oxides as much as 55.1% and 11.01% phosphate. At monazite sand baking using solid NaOH will occur monazite sand decomposition process and the release of the existing phosphate. The results showed that the optimal conditions baking process at a temperature of 400°C and 200 mesh particle size obtained 91.40% phosphate inseparable.

The synthesis and characterization of composite rubber – lanthanum manganite modification have been performed. The composite was prepared by rubber elastomer thermoplastics, stearic acid, ZnO, n-cyclohexyl-2-benzothiazyl sulphenamide (CBS), sulfur, and magnetic powder of La_0.8Ba_0.2(Fe, Mn, Ti)O₃. The raw material was mixed by open two-roll mixing for 32 min and then pressed at temperature of 140 °C for 30 min. The element analysis showed that the sample contained carbon, oxygen, sulfur, zinc, lathanum, barium, manganese, titanium and iron. The refinement results of x-ray diffraction pattern show that the sample issemicrystalline with the crystallinity of 46%. The sample consist of the matrix is amorphose phase and the filler is crystalline phase. The filler consist of two phases, namely ZnO and La_0.8Ba_0.2(Fe, Mn,Ti)O₃ phases. The functional groups analysis show that the sulfur addition modified the polymer by forming crosslink (bridges) between individual polymer chains and bonding between magnetic filler and rubber matrix. We concluded that this study has been successfully made a composite of rubber – La_0.8Ba_0.2(Fe, Mn,Ti)O₃ for microwave absorber sheet application.

La_0.67Ba_0.33Mn_1-xNi_xO₃ with x = 0.0; 0.1; 0.2; 0.4 were prepared from powder of La₂O₃, BaCO₃, MnCO₃, and NiO by the solid-state reaction method. All the powder is mixed by using Planetary Ball Milling for 25 hours. After that, all the samples are compacted, calcinatedat 800°C for 10 hours and sintered 1350°C for 20 hours. Phase identification was carried out by using XRD spectrometer and refined by using High Scorer Plus. The results showed that La_0.67Ba_0.33Mn_1-xNixO₃ were single phases for all x compositions. The crystal structureswereorthorhombic. The resistivity and magnetoresistance (MR) properties were evaluated by using FPP (Four Points Probe) method, while magnetization was measured by using permagraph spectrometer. From the magnetoresistance results, we observed that the samples showed different sensitivity's responds for each x value. By increasing of x values, the magnetoresistances tend to change from negative magnetoresistance to positive magnetoresistance. Besides, the sensitivity's responds of magnetoresistance were increased by increasing the x values. The highest sensitivity was for x = 0.4. The permeagraph results showed that all the samples were paramagnetic at room temperature due to substitution of Ni. We concluded that the doping of Ni gives effect to the resistivity and magnetoresistance of the samples and also to the sensitivity's responds as a candidate of magnetoresistance sensor's material.

Synthesis of composite titanium dioxide with iron oxide magnetic material (Fe₃O₄/TiO₂ composite) has been successfully carried out by precipitation method. Photocatalytic performance test of this composite Fe₃O₄/TiO₂ was performed for degradation process of the methylene blue solution with the experiment parameters consist of the solution pH, lighting time, type of light, amount of catalyst, and the concentration of methylene blue. The experimental results showed that the Fe₃O₄ addition in TiO₂ catalyst can simplify recovery process of the catalyst, and able to broaden the absorption area up to visible light, so that the degradation process can be carried out with UV and visible light. Degradation of methylene blue by Fe₃O₄/TiO₂ composite in under sunlight more effectively compared UV light.

Now days, heavy metal pollution has become one of the most serious environmental problems. The magnetic nanoparticles (MNPs) have received great attention to solving the problems as adsorbent materials due to their unique physical and chemical properties. CoFe₂O₄ MNPs was prepared by co-precipitation method, and its application for removal of Cu(II), Fe(II) and Ni(II) ions from wastewater. The various structural as well as morphological properties were characterized by x-ray diffraction (XRD), transmission electron microscopy (TEM), and vibrating sample magnetometer (VSM) analysis. Factor of affecting adsorption including temperature, contact time, particles size, magnetic properties and additional Polyethylene glycol (PEG-4000) as coating agent of adsorbent were further investigated. The results show that maximum Fe(II) was adsorbed at all of various parameters. Adsorption process of heavy metal ions from wastewater was known as increase as temperature range from RT to 60°C, but decrease at 120°C for Cu(II) and Ni(II). The maximum adsorption of Cu(II) and Ni(II) also occurs at the smallest particle size, 4nm. On the other hand, percentage of removing metal ions using PEG-coated MNPs decrease comparing to Co-MNPs without coating, for Cu(II), Fe(II), and Ni(II) is 97.1%, 100%, and 99.6%, respectively. The ability of Co-MNPs for removing metal ions decrease after coated using PEG-4000 maybe due to the small surface area and existence of polymer as nonmagnetic. Furthermore, the result of this experiment revealed that CoFe₂O₄ MNPs can be used as the effective adsorbent to remove metal ions in the wastewater.

The preparation of NdFeB has been conducted in a dry and wet milling condition using a planetary ball mill (PBM) for ½, 1, 2, 3, 4, and 5 hours. The dry and wet milling was performed in an argon gas and toluent, respectively with ball and powder ratio of 10:1. The milled powder was dried in the vacuum condition of 11 mBar at the temperature of 60°C for 10 hours. 5wt.%Celuna (WE-518) was used as binder, mixed with magnetic powder and anisotropically pressed at 25 kgf/cm². Curing process was conducted in a vacuum chamber of 11 mBar at temperature of 180°C for 1 hour. The particle diameter and the true density of NdFeB powder were measured by using PSA and Pycnometer, respectively. The morphology and phase composition were characterized using SEM and XRD, respectively. The obtained results show that the optimum milling time of NdFeB powder is 3 hours using wet milling method. The results also concluded that the powder true density of 7.79 g/cm³, the bulk density of 5.98 g/cm³ and the mean particle diameter of 9.59 μm can be achieved. The SEM image confirmed that the milling process has an effect in reducing the particles size. But the milling process lead to a damage in the crystal structure of the material, resulting in decreasing the magnetic flux density. The half hour dry milling is capable to produce a maximum magnetic flux density of 1816 Gauss.

In this experimental work Vibration Sample Magnetometer (VSM) was used to study the magnetization property of ultrasonic assisted sinter material ODS Fe-Cr containing dispersoid particles Y₂O₃. The results of magnetization diagram analysis showed an anisotropy with saturation values 150 and 200 emu/gr for the angles 270 and 360°, respectively. Although higher saturation level, the alloy exhibits exceptionally small hysteresis loop with very low remanence and coercivity. As powder Fe-Cr mixture before sintering has maximum saturation 200 emu/gr. Properties combination of anisotropy, the absent of hysteresis loop and high saturation value has been opened new research opportunity on application of Fe-Cr based ODS material in field of sensors and magnetic assisted electro mechanic parts such as transformers and motors.

Partially Zn-substituted for Cu in electron-doped superconducting cuprates of Eu_1.85Ce_0.15Cu_1-yZn_y4+α-δ (ECCZO) with y = 0, 0.01, 0.02, 0.05 and various δ values have been studied in order to elucidate the effect of nonmagnetic impurity of Zn to their structure and resistivity properties in the electron-doped cuprates. It has been found that the main peaks of T' structures are clearly observed in all samples. Superconductivity disappeared with Zn substitution for Cu in electron-doped system of ECCZO.

Ni-substituted to perovskites La_0.67Ba_0.33Mn_1-xNi_xO₃ with x = 0; 0.01; 0.02; 0.03; 0.04; and 0.05, have been done and investigated by x-ray diffraction spectrometer, permagraph spectrometer, and four-point probe (FPP) measurements. X-ray diffraction spectrometer result refined by high score software. All samples show an orthorhombic structure at room temperature. At room temperature the cell parameter a, b and c of the samples seem to be constant although the doping of Ni was increased. The permagraph spectrometer results showed that all the samples were paramagnet at room temperature since magnetic remanence is zero for all samples. The four-point probe (FPP) results negative magnetoresistance and positive magnetoresistance. The negative magnetoresistance appears at x = 0 with ratio 15.625% and the positive magnetoresistance appears at x = 0.01 until 0.05 with maximum ratio 18.341% for x = 0.01. Theseevidences showed that highest sensitivity's respond for resistivity change before and after applying external magnetic fields to perform magnetoresistance phenomena is for x = 0.01.

The synthesis and characterization of high purity of Fe₃O₄ and α-Fe₂O₃ from iron sand has been carried out. Iron sand samples retrieved from Banten, Indonesia. The iron sand powder was milled for 10 hours at room temperature by using high energy milling (HEM) and then was separated according to its type using magnetic separator. The iron sand powders are dissolved in acid chloride solution so that is formed a solution of iron chloride, and this solution is sprinkled with sodium hydroxide to obtain fine powders. The fine powders which formed were washed again with de-ionized water and sintered in the electric chamber furnace at 750 °C in the air at atmosphere pressure for 5 hours. The elemental analysis results using neutron activation analysis (NAA) is obtained that the fine powders contain the dominant of iron (Fe). The refinement results of X-ray diffraction pattern shows that the fine powders have a single phase of Fe₃O₄, and then after sintering changed to α-Fe₂O₃ single phase. The microstructure analysis showed that the particle of Fe₃O₄ and α-Fe₂O₃ shaped respectively like spherical and polygonal with the similarly particle sizes and homogeneously on the surface of the samples. We concluded that this study has successfully performed the process of purifying iron sand to obtain fine powders of Fe₃O₄ and α-Fe₂O₃ with high purity. The first section in your paper

Magnetic properties of α-Fe2O3 partly filled MWNT/Polyvinyl Alcohol (PVA) composites film have been studied by Raman spectroscopy, Fourier Transform InfraRed (FTIR) spectroscopy, Transmission Electron Microscopy (TEM), Vibrating Sample Magnetometer (VSM), Four Point Probe (FPP). The Composite films were prepared by simply mixing between α-Fe2O3 –filled Multiwalled Carbon Nanotube(MWNT) dispersed in Sodium Dodecyl Sulphate (SDS) with 10% PVA solution for 4 variation concentration with a total volume 5 ml. The result of Raman Spectroscopy on precursor sample showing the existence of α-Fe2O3 phase and MWNT. From FTIR spectroscopy on the film samples observed the attachment of the PVA with iron oxide and MWNT. The paramagnetic properties of the samples film were investigated by means of Vibrating Sample Magnetometer (VSM). The higher value of magnetoresistanceratiowas +40% on the sample with percolation threshold Pc = 0.51 wt%. The interaction between α-Fe2O3 filled MWNT in matrix polymer PVA made shrinkage or decreased the localization length inside the grain of composites film.

Synthesis of CaMnO₃ has been performed by solid state reaction method using CaCO₃ and MnCO₃ powder as raw materials. The raw materials were weighed, milled, compacted into a pellet and then sintered at 1250°C. Phase of material, microstructure, and conductivity of the samples were observed. The refinement results of X-ray diffraction pattern shows that CaMnO₃ formed as a single phase, which has a structure orthorhombic (P n m a) with lattice parameters, a = 5.277 Å, b = 7.452 Å, and c = 5,261 Å. The atomic density of the refinement result is 4.591 gr.cm^-3. The morphology of CaMnO₃ sample has a good particle homogeneity with the particle size 1- 2 μm. The value of AC conductivity on the CaMnO₃ is directly proportional with the increasing ofthe temperature. The highest value of the AC conductivity of the CaMnO₃ sample is 2.8 x 10^-3 S/cm at a temperature of 400°C.

In this study, Titania nanotube (TiNT) had been modified by combining it with carbon nanotube (CNT) and magnetic material, Fe₃O₄, forming magnetically modified composite (TiNT/CNT/Fe₃O₄). Magnetic properties were added to the composite to overcome photocatalytic application problem for waste water treatment case, especially the catalyst recovery issue. Prior to the modifications, TiNT was synthesized from TiO₂ P25 using hydrothermal process at 130 °C for 6 h. TiNT and CNT were then combined using hetero agglomeration process in acid condition to obtain TiNT/CNT composite. Various amount of Fe₃O₄ nanoparticles were then composed on the surface of TiNT/CNT using ultrasonic assisted in-situ process, producing TiNT/CNT/Fe₃O₄ magnetic composites. The samples were analyzed with various characterizations: zeta potential, FT-IR, FE-SEM/EDX, XRD, and VSM. Experimental results show that TiNT/CNT/Fe₃O₄ composite with good crystallinity and morphology had been successfully synthesized. The optimal amount of Fe₃O₄ in TiNT/CNT/Fe₃O₄ magnetic composite was 0.3 times the amount of TiNT to minimize the photodissolution effect, while the composite was still categorized as superparamagnetic materials (with the saturation magnetization value of 21.1 emu/g and coercivity of 84.4 oe). The magnetic separation test also confirmed that prepared magnetic composites could be effectively separated from the test solution.

The isotropic magnets Barium Hexsaferit has been made by using a sintering process and the composition of Fe₂O₃ on barium hexaferrite was carried by the addition of Fe₂O₃ (0, 0:25, and 0.5, % wt). The raw materials were used such as: commercial powder BaFe₁₂O₁₉ and hematite Fe₂O₃ from e-Merck. Both the raw materials were weighed according to the composition, and then refined for 48 hrs by using ball mill. After milling processes, the mixed powder was measured particle size distribution by using Laser Particle Size Analyzer, and it was obtained average particle size about 17,15 μm. After that, the powders were mixed with 2 % white. Celuona WE 518 as a binder, then the sample powders were formed by using cold pressing with a force about 5 tons becomes pellets with a diameter of 13.10 mm and thickness of 7.12 mm. Then samples pellet were sintered by using Electrical Thermolyne Furnace at temperature: 1150 ° C and holding time for 2 hours. The sintered samples were measured microstructure by using XRD, magnetic properties by using Permeagraph and Gausmeter. The variation of composition Fe₂O₃ on barium ferrite can influence significantly on crystal structure and magnetic properties. It was found two phases such as: BaFe₁₂O₁₉ phase and Fe₂O₃ phase on the samples with the addition of 0.5 % Fe₂O₃, but for sample without the addition of Fe₂O₃ and with 0.24% Fe₂O₃ have only single phase BaFe₁₂O₁₉. The results of measurement magnetic properties show that Magnet BaFe12O19, with addition 0.25% wt. Fe₂O₃ has high value for flux magnetic density and Br, but the Hc value of magnet BaFe12O19 becomes 2 times higher with the addition of 0.5% wt. Fe₂O₃.

Barium hexaferrite is known as a permanent magnet that has hexagonal or granules morphologies. Magnetic field of barium hexaferrite can be increased by changing its morphology. A rod-shaped barium hexaferrite is expected to result in higher magnetic field compared to granules even though the volumes of both are the same. This study aims to synthesize a rod-shaped barium hexaferrite and to evaluate its magnetic properties. Barium hexaferrite was synthesized using sol-gel method by mixing barium nitrate and iron (III) nitrate nonahydrate with molar ratio of 1:12. Chitosan 1% was added as dispersant and starch 0.5% (w/v) was used as template with variation in volume (5%, 10% and 15% (v/v)). The solution was dried at 100°C for 48 hours and resulting xerogel was then calcined at 1000°C for 2 hours to obtain barium hexaferrite powder. X-Ray D result demonstrated the presence of barium hexaferrite with small fraction of hematite and pure barium hexaferrite. Scanning electron microscopy images showed different concentrations of starch generated different size and morphologies of resulting barium hexaferrite. A rod shaped barium hexaferrite was formed for all samples that prepared using starch template, however hexagonal shape was still found in all samples. The size of resulting barium hexaferrite is decrease by increasing the concentration of starch. Theparticle size of barium hexaferrite measured was 125nm thickness with of 500nmlength for 5% starch, 109 nm thickness and 406 nm length for 10% starch and 62.5 nm thickness and 406 nm length for 15% starch, Barium hexaferrite synthesized without using starch and chitosan produced hexagonal morphology with the thickness of 240-574 nm and length of 574-957 nm. Vibrating Sample Magnetometer showed hysteresis curve as the percentage variation of starch was used, higher amount of starch used tends to increase the values of saturation and remanence. Avery significant increase in coercivity value amounted to 457.1% occurred in the use of 10% starch. It can be concluded that starch can be used as rod-shaped template in sol-gel method to produce barium hexaferrite. By using chitosan and starch in the process of synthesis of barium hexaferrite using sol-gel method can increase the value of the magnetization and the coercivity barium hexaferrite.

The Nd_0.33Eu_0.33Gd_0.33Ba₂Cu₃O_7-∂ (NEG-123) nanoparticles have been successfully synthesized by wet-mixing method using HNO₃ as dissolving agent. The NEG-123 samples are divided into two which were treated differently. The first and second samples were mixed respectively, for one and 24 hours. All the samples were then calcined at 600°C for 3 hours, and sintered at relatively low temperature (750 to 900°C), each for 30 minutes. Samples were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), and vibrating sample magnetometer (VSM). Rietveld analysis shows the lattice parameter of a-axis decreases with the increasing sintering temperature from 750 to 900°C, while the lattice parameter of b and c-axes increases. Further, it was known based on the XRD analysis that the higher the sintering temperature, the greater the peak intensities and average crystal size. The NEG-123 samples with the average crystal size of hundreds nanometer exhibit paramagnetism, while those with average crystal size of ten nanometers demonstrate superparamagnetism at room temperature.

The synthesis and characterization of modified lanthanum manganite materials by using mechanical milling technique have been performed. This magnetic material is prepared by oxides, namely lanthanum oxide, barium carbonate, iron oxide, titanium dioxide, and manganese carbonate. The mixture was milled for 10h, compacted at 5000 psi into pellets with three kinds of different thickness (d = 1.5, 2.0 and 4.0 mm, respectively) and then sintered at temperature of 1000 °C for 10h. The refinement results of x-ray diffraction pattern showed that the sample is single phase. The sample had composition in accordance to stochiometry composition. The geometry factor consists of the particle morphology observed using scanning electron microscope and thickness measured millimeter device. The microstructure analyses shows that the particle shapes was aggregates with the particle sizes distributed homogeneously on the surface of the sample. The results of the microwave absorption indicated that there were three of absorption peak frequency at 9.9 GHz, 12.0 GHz, and 14.1 GHz. The microwave absorption of the sample increases with increasing thickness of absorption area. We concluded that the increasing thickness of absorption region resulted new resonance frequencies, and the new resonance frequencies are joined to each other to form a wider resonance frequency and it is known as a broadband absorber. The first section in your paper.

Ferrite nanoparticles have become interesting materials originating from their performances in many applications. In this paper, the preparation metal-doped ferrites in the system of Fe_2.9Cr_0.1O₄ nanopowders is reported. The Cr_0.1Fe_2.9O₄ nanopowders were utilized to produce ferrofluids. The Indonesian sand was used as a raw material to prepare the samples using co-precipitation route. The Fe_2.9Cr_0.1O₄ particles structured in cubic spinel with the particle size and lattice parameter of about 9.4 nm and 8.36 Å, respectively. The band gap energy of the Cr_0.1Fe_2.9O₄ nanopowders was 2.26 eV. Furthermore, the saturation magnetization of the powder was higher than that of the fluid as the effect of particle size and aggregation.

In this paper, the authors report the fabrication of Zn_0.2Fe_2.8O₄ particles from Indonesian sand in the forms of nanopowder and magnetic fluid. The fabrication was conducted by employing a combined coprecipitation-sonochemical method. The analysis of the XRD data presented that the Zn_0.2Fe_2.8O₄ was crystallized in a spinel structure with a lattice parameter of about 8.378 Å. The data analysis of the TEM image showed the Zn_0.2Fe_2.8O₄ particles distributed in nanometric size with a spherical shape. The magnetic investigation showed that the magnetic nanopowder and fluid both had superparamagnetic character. Moreover, the band gap of the Zn_0.2Fe_2.8O₄ particles was about 2.28 eV. These characters open a significant opportunity for the prepared samples to be applied for sensory and antibacterial applications.