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"Barium heksaferit disubtitusi Mn, Ba(Fe1-xMnx)12O19, telah diteliti dengan nilai x=0.00, 0.05, 0.10, 0.15, 0.20, 0.30, 0.40 dan 0.50. Sampel dipreparasi dengan metode solid state reaction dengan tahapan milling, kalsinasi dan sintering. Sampel dicampur dari bahan dasar BaCO3, Fe2O3 dan MnO2 kemudian dimilling selama 24 jam dengan atraitor ball mill. Hasil DTA didapatkan ada peak endotermik pada suhu 200°C, 300°C dan 600°C yang berhubungan dengan dehidrasi sampel, dekomposisi MnO2 dan pelepasan CO2 dari BaCO3. Sampel dikalsinasi pada suhu 1200°C selama 2 jam dengan kenaikan suhu 30C/menit. Hasil XRD setelah setelah kalsinasi menunjukkan bahwa tidak didapatkan lagi fase bahan dasar dan single phase. Hasil refinement dengan rietveld analysis didapatkan nilai parameter kisi a,b dan c. Sampel dikompaksi pada tekanan 5 MPa untuk sampel berbentuk ring dan 8MPa untuk sample berbentuk pellet pada medan magnet. Sampel disinterring pada suhu 1050°C, 1100°C, dan 1200°C selama 2 jam. Sebelum dicapai suhu sampel ditahan pada suhu 100°C, 300°C dan 600°C masing-masing selama setengah jam. Massa jenis sample diukur dengan metode Archimedes dan didapatkan bahwa massa jenis sample diatas 75% dari massa jenis teori (5.3 gram/cm3). Hasil pengukuran porositas didapatkan bahwa porositas dibawah 10%. Sample diukur sifat magnetiknya dengan permagraph. Didapatkan bahwa remanence dan energy produk berkurang ketika nilai x bertambah.

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Barium Hexaferit doped Mn, Ba(Fe1-xMnx)12O19, have been investigated for x=0.00, 0.05, 0.10, 0.15, 0.20, 0.30, 0.40 and 0.50. The preparation is carried out by solid state reaction that corresponds to milling, calcinations and sintering. The precursor BaCO3, Fe2O3 and MnO2 were mixed and milled for 24 hours using attraitor ball mill. DTA results shown there were endothermic peak at 200°C, 300°C dan 600°C that corresponds to sample dehydration, decomposition of MnO2 and releasing of CO2 from BaCO3. Samples were calcined at 12000C for 2 hours with increment 30C/minute.

XRD result showed there were no precursor phase and single phase. Lattice parameter obtained through refinement rietveld analysis. Samples were pressed by 5 MPa for ring shaped and 8 MPa for pellet shaped in magnetic field. Sample were sinterred at 1050°C, 1100°C, and 1200°C for 2 hours.

Before reached the sintering temperature was hold at 100°C, 300°C and 600°C for a half hours each. Density was measured trough arhimedes method and obtained that density was more thant 75 % theoretical density (5.30 gram/cm3). Porosity measurement result were under 10%. The sample magnetic properties was measured using permagraph. The results showed that remanence and energy product decrease as x value increase."

"Penelitian sifat-sifat bahan oksida mangan mendapat perhatian besar dari para peneliti disebabkan potensinya yang besar untuk pengembangan divais penyimpan magnetik (magnetic storage device). Bahan oksida mangan memperlihatkan sifat collosal magnetoresistive (CMR) dan menunjukkan polarisasi spin yang tinggi. Salah satu material tersebut adalah La0.7Sr0.3MnO3 (LSMO) yaitu oksida magnetik berbasis manganit. Pada penelitian ini telah di investigasi sifat-sifat magnetik bahan LSMO dengan menggunakan simulasi mikromagnetik. Simulasi dilakukan dengan dua kondisi: pertama, dengan kondisi medan nol (Ground state) dan kedua, dengan aplikasi medan luar. Pada keadaan groundstate, simulasi terdiri dari model: bola, kubus, nanodisk dan nanodisk larik (array). Struktur domain yang teramati adalah domain tunggal dan multi domain. Ukuran kritis yang diperoleh untuk model bola dan kubus sesuai dengan hasil perhitungan dengan persamaan Brown. Simulasi mikromagnetik dengan aplikasi medan luar kuasi statik telah didapatkan kurva histeresis dengan medan koersivitas untuk model nanodisk, nanodisk larik dan nanopilar. Pada model nanodisk, kurva histeresis kelihatan lebih kurus dan medan koersivitasnya berkurang dengan ketebalan disk. Pada model nanodisk larik, kurva histeresis yang didapatkan medan koersivitasnya menurun dengan kenaikan jarak antar disk. Sedangkan pada nanopilar, diaplikasikan dua pilihan medan: sejajar dengan sumbu panjang pilar dan tegak lurus dengan sumbu panjang pilar. Pada medan sejajar dengan sumbu panjang pilar, medan koersivitas menurun dengan kenaikan ukuran pilar untuk pilar persegi. Sedangkan untuk pilar silinder, medan koersivitas menurun nilainya dengan kenaikan diameter pilar silinder. Pada medan tegak lurus sumbu panjang pilar, medan koersivitas menurun nilainya hingga nol dengan kenaikan ukuran pilar sehingga mirip dengan kurva histeresis yang diperoleh saat medan mengarah ke sumbu keras (hard axis). Pada penelitian simulasi dengan menerapkan medan luar berubah dengan waktu secara ekponensial diperoleh sifat resonansi feromagnetik untuk model nanopilar LSMO. Frekuensi resonansi yang diperoleh sesuai dengan hasil perhitungan dengan persamaan Kittle’s tentang resonansi. Pada simulasi ini juga dapat dilihat perubahan struktur domain saat proses terjadinya resonansi.

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Recently, the investigation magnetic oxide properties has become great attention because its potential for new kind of magnetic storage devices. The materials show high spin polarization and collosal magnetoresistive effect (CMR). One of the material is La0.7Sr0.3MnO3 (LSMO), magnetic oxide based on manganite. In this study, we investigated the magnetic properties of LSMO by means of micromagnetic simulation. In this simulation, we carried out two condition; first, ground state condition (the external magnetic field is zero) and second, applied magnetic field. In the ground state, the simulation consisted of nanosphere, nanocube, nanodisk, and nanodisk arrays models. We found the domain structure were single domain and multi domain for arbitrary sizes. Also, we observed the critical size that transformation the domain structure form single domain to multi domain. Interestingly, the critical size agree to Brown’s equation. Further, we also performed the simulation with applied magnetic field; quasi-static field and time-dependent magnetic field. In the quasistatic field, we found the hysteresis curve and magnetic coercivity field for nanodisk, nanodisk arrays, and nanopillar model. In nanodisk the hysteresis curve showed more thin and the corcivity field reduce with increasing thickness. In the case of nanodisk arrays, the hysteresis curve, the coercivity decreases as increasing the interdisk distance. In the case of nanopillar, we applied the field in parallel and perpendicular the long axis of the pillar. In parallel direction, the coercivity decreased as increasing size of the pillar for square pillar. For cylindrical pillar, the coercivity decreased as increasing diameter. For the case perpendicular, we found the coercivity field decreased to zero as increasing size of the pillar. It means that the perpendicular applied field exhibited hard axis direction of the pillar. Furthermore, we also applied the nanopillar with time-dependent field such as the exponential field to observe the ferromagnetic resonance. From susceptibility spectrum of the nanopillar, we found the peak of imaginary susceptibility spectrum related to frequency resonance. Interestingly, the frequency peak followed to Kittel’s resonance and dipolar interaction that originated from the demagnetization energy, contributed to resonance in the nanopillar model."

"Strontium hexaferrite dengan komposisi nominal Sr0.6Fe,-<,..,jMn,TiyO, (x =0, y=; x = 0.4, y= 0.6; x = 0.5, y = 0.5; x = 0.6, y =0.4) disintesa dengan reaksi keadaan padat. Empat komponen serbnk BaCO,, SrCO,, Fe,O,, MnCO,, dan TiO, dicampur menggunakan High Energy Milling selama 10 jam dan disinterring pada 1050'C dalam tekanan atrnosfer selama 15 jam dan pendinginan eli tungku pemanas. X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), vibrating sample magnetometer (VSM) dan network analyzer digunakan untuk analisa struktur, sifat elektomagnetik dan penyerapan gelombang. Hasil memperlihatkan bahwa identifikasi fasa dengan penghalusan pola difrkasi XRD diperoleh fasa tunggal untuk substitusi Mn-Ti terhadap Sr0.6Fe,o, dengan x ~ y dan multi fasa terbentuk untnk x " y. Analsis mikrostrnktur dengan SEM menunjukkan variasi partikel adalah 2 - 5 um. Evaluasi terhadap karakteristik magnetik mengindikasikan bahwa terjadi penurunan koersifitas dengan kenaikan substitusi ion Mn2+ dan Ti4+ tetapi penurunan yang signifikan diperoleh terhadap saturasi magntetisasi pada substitusi Mn dan Ti dengan x :t: y. Penelitian saat ini menunjukkan penyerapan gelombang, reflection dan transmission dan juga reflection loss pada rentang frekuensi 7-16 GHz. Dilaporkan juga performansi penyerapan pada substitusi Mn dan Tipada strontium hexaferrite.

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Strontium hexaferrite with nominal compositions Sr0.6Fe,-{"':Y~xTiy03 (x ~ 0, y o=Q; x ~ 0.4, y ~ 0.6; x ~ 0.5, y ~ 0.5; x ~0.6, y ~ 0.4) have been synthesized by solid state reaction. The four components powder were BaCO,, S!CO,, Fe,O,, MnCO,, and Ti02 mixed with High Energy Milling for 10 hours and sintered at I 050'C in the air at atmosphere pressure for 15 hour and furnace cooling. X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), resonance vibrating sample magnetometer (R· VSM) and vector network analyzer were used to analyze its structure, electromagnetic and microwave absorption properties. The result showed that, phase identification by refinement results ofXRD pattern confirmed single phase was obtained for Mn-Ti substituted Sr0.6Fe20, with x ~ y and multiphase formed for x" y. The microstructure analyses by SEM showed that the varied particle sizes of 2 -- 5 ~-tm. Evaluation on the magnetic characteristic indicated that coercivity decreased as the number ofMn2"~" and Ti +ions increased but significant decrease in saturation magnetization obtained for Mn and Ti substitution with x ::1:- y. Present investigation demonstrates that microwave absorber. reflection and transmission as well as reflection loss in the frequency range 7-16 GHz were derived Absorption performance ofMn and Ti substituted strontium hexaferrite are also reported."

"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 mass fraction of main phase in doped samples decreased 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."

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Telah dilakukan penelitian mengenai struktur kristal, morfologi dan sifat magnetic bahan Nd1-xSrxMnO3 (x = 0, 0.2, 0.4, 0.6, 0.8, 1) dengan metode sol-gel. Divariasikan substitusi Sr terhadap senyawa NdMnO3. Efek dari substitusi Sr terhadap NdMnO3 didapatkan dari perbedaan struktur kristal, morfologi, dan sifa magnetic setiap variasi komposisi Sr. Dengan karakterisasi struktur kristal menggunakan X-Ray Diffractometer (XRD) dan karakterisasi morfologi menggunakan Scanning Electron Microscope (SEM) serta karakterisasi sifat magnetik menggunakan Vibrating Sample Magnetometer (VSM). Hasil XRD menunjukkan bahwa komposisi Sr di NdMnO3 tidak mengubah struktur kristal dari perovskite tersebut, tetapi parameter kisi dari struktur kristal berubah tiap komposisi Sr nya. Bentuk dan ukuran grain partikel juga sangat berbeda tiap komposisi Sr nya, hal ini menunjukkan bahwa komposisi Sr di NdMnO3 memang dapat mengubah strukur kristal, morfologi, dan sifat magnetik manganit perovskite NdMnO3.

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Research on the crystal structure, morphology and magnetic properties of Nd1- xSrxMnO3 (x = 0, 0.2, 0.4, 0.6, 0.8, 1) was carried out using the sol-gel method. The Sr substitution of NdMnO3 was varied. The effect of Sr substitution on NdMnO3 was obtained from differences in crystal structure, morphology, and magnetic properties for each variation in the composition of Sr. With characterization of crystal structure using X-Ray Diffractometer (XRD) and morphological characterization using Scanning Electron Microscope (SEM) and characterization of magnetic properties using a Vibrating Sample Magnetometer (VSM). XRD results showed that the Sr composition in NdMnO3 change the crystal structure of the perovskite and the lattice parameters of the crystal structure changed with each Sr. composition. The shape and grain size of the particles are also very different for each Sr. composition, this shows that the Sr composition in NdMnO3 can indeed change the crystal structure, morphology, and magnetic properties of the NdMnO3 perovskite manganite.

 

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"This book is both a course book and a monograph. The first chapter briefly introduces the history, background and technology of EPM. In the second chapter, the concept of transport phenomena is concisely introduced and in the third chapter the essential part of magnetohydrodynamics is transcribed and readers are shown that the concept of transport phenomena does not only apply to heat, mass and momentum, but also magnetic field. The fourth chapter describes electromagnetic processing of electrically conductive materials such as electromagnetic levitation, mixing, brake, and etc., which are caused by the Lorentz force. The fifth chapter treats magnetic processing of organic and non-organic materials such as magnetic levitation, crystal orientation, structural alignment and etc., which are induced by the magnetization force. This part is a new academic field named magneto-science, which focuses on the development of super-conducting magnets."