Wisnu Ari Adi

Effects of the geometry factor on the reflection loss characteristics of the modified lanthanum manganite

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.

Absorption Characteristics of the Electromagnetic Wave and Magnetic Properties of the La0.8Ba0.2FexMn½(1-x)Ti½(1-x)O3 (x = 0.1–0.8) Perovskite System

This paper reports on the magnetic properties and electromagnetic characterization of La0.8Ba0.2FexMn½(1-x)Ti½(1-x)O3 (x = 0.1–0.8). The La0.8Ba0.2FexMn½(1-x)Ti½(1-x)O3 (x = 0.1–0.8) materials were prepared using a mechanical alloying method. All the materials were made of analytical grade precursors of BaCO3, Fe2O3, MnCO3, TiO2, and La2O3, which were blended and mechanically milled in a planetary ball mill for 10h. The milled powders were compacted and subsequently sintered at 1000°C for 5h. All the sintered samples showed a fully crystalline structure, as confirmed using an X-ray diffractometer. It is shown that all samples consisted of LaMnO3 based as the major phase with the highest mass fraction up to 99% found in samples with x 0.3. The hysteresis loop derived from magnetic properties measurement confirmed the present of hard magnetic BaFe12O19 phase in all La0.8Ba0.2FexMn½(1-x)Ti½(1-x)O3 (x = 0.1–0.8) samples. The results of the electromagnetic wave absorption indicated that there were three absorption peaks of ~9 dB, ~8 dB, and ~23.5 dB, respectively, at respective frequencies of 9.9 GHz, 12.0 GHz, and 14.1 GHz. After calculations of reflection loss formula, the electromagnetic wave absorption was found to reach 95% at the highest peak frequency of 14.1 GHz with a sample thickness of around 1.5 mm. Thus, this study successfully synthesized a single phase of La0.8Ba0.2FexMn½(1-x)Ti½(1-x)O3 (x = 0.1–0.8) for the electromagnetic waves absorber material application. Keywords: Absorber; Electromagnetic wave; Lanthanum manganite; Magnetic; Perovskite; Substitution; Structural

Calculation of complex permeability and permittivity on Lanthanum barium manganite materials at X-band frequency

The synthesis and electromagnetic wave absorbing characterization of La_1-yBa_yMnO₃ (y = 0-1, 0) magnetic material through a mechanical milling process have been performed. The La_1-yBa_yMnO₃ (y = 0-1, 0) magnetic material was made from La₂O₃, BaCO₃, dan MnCO₃ materials. The mix was milled for 10 hours and then sintered at 1000°C for 10 hours. The results of the the hysteresis curve indicated that that La_1-yBa_yMnO₃ (y = 0-1, 0) samples are anti-ferromagnetic, and after a barium ion substituted system, this material undergoes a magnetic phase transformation becomes ferromagnetic. At y = 0, the characteristic impedance as a function of frequency is worth more than 2000 ohms, and when y = 0.2, Z characteristics began to change falls below 2000 ohms. Test results obtained by absorption of microwaves that have occurred absorption of electromagnetic waves in the frequency range between 9-15 GHz, frequency absorption peak is ~7 dB at 14.4 GHz. At the peak frequency of the electromagnetic wave absorption were calculated magnitude reaches 50% with a thickness of 1.5 mm. We concluded that the La_1-yBa_yMnO₃ (y = 0-1,0) magnetic material has been made successfully and able to absorb a microwave in the frequency range 9-15 GHz.

Preparation and Characterization of Magnetic Carbonate Apatite/Chitosan/Alginate Composite Scaffold

Treatment for bone cancer has begun to be experimented with ferrimagnetic for magnetic induction hyperthermia. On the other hand, composites of bioceramics and biopolymer have been studied for scaffold as these materials resemble the structure of bone. The current study investigated the magnetization of calcium aluminum ferrite magnetic (CaAl4Fe8O19) incorporated in carbonate apatite, alginate and chitosan, that serves as a scaffold. CaAl4Fe8O19 powder were synthesized using calcium nitrate, aluminium nitrate and ferrous chloride using the sol-gel method. Combining the carbonate apatite/chitosan/alginate compoiste and CaAl4Fe8O19using the freeze-dry method has produced carbonate apatite/alginate/chitosan/CaAl4Fe8O19 composite scaffolds. The CaAl4Fe8O19powder and the scaffolds were observed using SEM (scanning electrone microscope) and their magnetization were measured using VSM (vibrating sample magnetometer). It was shown that the scaffold is a composite structure of CaAl4Fe8O19 particles, having diameter ranging from 0.5 to 2 µm, embedded in the pore walls of the carbonate apatite/alginate/chitosan matrix. The saturation magnetization Ms and remanence magnetization Mr of the CaAl4Fe8O19particles were 20 and 2.0 emu/g, whereas, those of the magnetic scaffold were 4.3 and 2.0 emu/gr. The addition of the carbonate apatite/alginate/chitosan composite into CaAl4Fe8O19 decreased the fraction and/or magnetic of the CaAl4Fe8O19 particles.

Analysis of Structural and Microstructure of Lanthanum Ferrite by Modifying Iron Sand for Microwave Absorber Material Application

Analysis crystal structure of lanthanum ferrite by modifying iron sand has been carried out. Lanthanum ferrite included one of the functional materials which had composition of ABO3 perovskite system. The lanthanum ferrite is prepared by iron sand and lanthanum oxide powders. The mixture was milled for 10h with the various composition of lanthanum content. The samples are sintered at a temperature of 1000 °C for 10h. The microstructure analyses showed that the particle shapes was polygonal with the varied particle sizes and uniform distribution on the surface of the sample. The phase composition of refinement result showed that the lanthanum ferrite formed empirical compound of La0.8Mg0.2Fe0.7Ti0.2Si0.1O3. The La0.8Mg0.2Fe0.7Ti0.2Si0.1O3 phase has a structure orthorombic (P b n m) with lattice parameters a = 5.513(1) Å, b = 5.549(1) Å and c = 7.849(2) Å, α = β = γ = 90°, the unit cell volume of V = 240.2(9) Å3, and the atomic density of ρ = 6.293 gr/cm3. We concluded that this study has been successfully synthesized lanthanum ferrite material from modifying iron sand and has been understood changes in the parameters of the crystal structure and phase composition of this material. It was a great opportunity that the material can be used as a material candidate of absorber electromagnetic waves.

Structural investigation and microwave characteristics of (Ba0.2La0.8)Fe0.2Mn0.4Ti0.4O3 absorbing materials

Synthesis and characterization of (Ba0.2La0.8)Fe0.2Mn0.4Ti0.4O3 absorbing material by mechanical alloying process has been performed. The absorbing material was prepared by oxide materials, namely BaCO3, La2O3, TiO2, Fe2O3, and MnCO3. The mixture was milled for 10 h and then sintered at a temperature of 1000 ° C for 10 h. The refinement results of x-ray diffraction pattern of lanthanum manganite substituted with barium showed that the sample consisted of two phases, namely, La0.9125MnO3 phase which has a structure monoclinic (I12/a1) with lattice parameters a = 5.527(1) A, b = 5.572(1) A and c = 7.810(1) A, α = γ = 90° and β = 89.88(5)°, the unit cell volume of V = 240.57(8) A3, and the atomic density of ρ = 6.238 gr.cm−3. The microstructure analyses showed that the particle shapes was polygonal with the varied particle sizes of 1 ∼ 3 μm distributed homogeneously on the surface of the samples. The results of the electromagnetic wave absorption curve analysis by using a vector network analyzer (VNA) showed...

STRUCTURE ANALYSIS OF SINGLE PHASE SISTEM Ba 1-X La X MnO 3 (0

The synthesis and characterization of La 1-X Ba X MnO 3 with (x = 0, 0.1, 0.2 and 0.3) magnetic materials by mechanical alloying process have been carried out. This magnetic materials is prepared by oxides, namely BaCO 3 , La 2 O 3 , and MnCO 3 . The mixture was milled for 10 hours then sintered at a temperature of 1,000 °C for 10 hours. The refinement results of X-Ray Diffraction pattern of Lanthanum manganite substituted with Barium for x = 0.1 and 0.2 showed that the sample consisted of single phase, namely, La 0.9125 MnO 3 phase. LaMnO 3 phase has a monoclinic structure (I12/a1) with lattice parameters a = 5.4638(7) A, b = 5.5116(6) A and c = 7.768(1) A, α = β = 90 o and γ = 90.786(9) o , the unit cell volume of V = 233.93(3) A 3 , and the atomic density of ρ = 6.449 g.cm -3 . The concluded that ability of Barium atom substitution in the Lanthanum atom in this system only up to the limit x ~ 0.2 formed the Ba 0.2 La 0.8 MnO 3 structure. The addition of the element bariumfurthermore (x > 0.2) will form two phases, namely La 0.8 Ba 0.2 MnO 3 and BaMnO 3 phases. Keywords: Ba-La Manganite, Crystal structure, Magnetic.