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Abstrak :
ANALISIS STRUKTUR KRISTAL DAN SIFAT MAGNETIK PADUAN SISTEM Ba0,5Sr0,5O.6Fe2(1-x)MnxTixO3 (x = 0, 0.25, dan 0.5). Telah dilakukan analisis struktur kristal pada bahan magnet system Ba0,5Sr0,5O.6Fe2(1-x)MnxTixO3 menggunakan difraksi sinar-x. Bahan system Ba0,5Sr0,5O.6Fe2(1-x)MnxTixO3 dibuat dengan metode reaksi padatan menggunakan proses mechanical milling dan di sintering pada suhu 1050 oC selama 15 jam dengan variasi x = 0, 0.25, dan 0.5. Hasil refinement dari pola difraksi sinar-x menunjukkan bahwa telah terbentuk single phase bahan magnet system Ba0,5Sr0,5O.6Fe2(1-x)MnxTixO3 (x = 0, 0.25, dan 0.5) dengan struktur kristal heksagonal (grup ruang P 63/m m c). Struktur heksagonal ini dibangun menjadi 4 blok sub unit yang disebut dengan 2 blok sub unit S (Fe63+O82-)2+ dan 2 blok sub unit R (Ba0.52+Sr0.52+Fe63+O112-)2- yang merupakan panjang ikatan berturut-turut Fe3+(5)?Fe3+(1)?Fe3+(5) dan Fe3+(5)?Fe3+(2)?Fe3+(5). Substitusi Mn dan Ti ke dalam atom Fe mengakibatkan volume unit sel dan jarak blok S membesar sedangkan kerapatan atomic dan jarak blok R menjadi semakin berkurang. Karakterisasi magnetic sampel Ba0,5Sr0,5O.6Fe2(1-x)MnxTixO3 (x = 0; 0,25; dan 0,5) ditandai dengan menurunnya medan coercive Hc dari 1508 Oe (x = 0) menjadi 296 Oe (x = 0,5). Dan karakterisasi uji serapan, bahwa rentang frekuensi serapan terjadi pada daerah 8 ? 11 GHz, 11 ? 13,5 GHz, dan 13.5 ? 16 GHz, dan titik puncak serapan terjadi pada frekuensi 9,3 GHz, 11,3 GHz, dan 13,7 GHz yang berturut-turut untuk sampel Ba0,5Sr0,5O.6Fe2(1-x)MnxTixO3 (x = 0; 0,25; dan 0,5). Disimpulkan bahwa telah berhasil dibuat single phase bahan magnet system Ba0,5Sr0,5O.6Fe2(1-x)MnxTixO3 (x = 0, 0.25, dan 0.5) untuk kandidat bahan absorpsi untuk gelombang elektromagnetik ultra tinggi.

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ANALYSIS OF CRYSTAL STRUCTURE AND MAGNETIC PROPERTIES ON Ba0,5Sr0,5O.6Fe2(1-x)MnxTixO3 (x = 0, 0.25, and 0.5) SYSTEM COMPOUND. The analysis of Ba0,5Sr0,5O.6Fe2(1-x)MnxTixO3 system magnetic material by using x-ray diffraction technique have been performed. The synthesis of Ba0,5Sr0,5O.6Fe2(1-x)MnxTixO3 (x = 0, 0.25, and 0.5) system magnetic material are used by solid state reaction method through the mechanical milling process and sintered at 1050 oC for 15 hours. The result of refinement of x-ray diffractions showed that the single phases of of Ba0,5Sr0,5O.6Fe2(1-x)MnxTixO3 (x = 0, 0.25, and 0.5) system magnetic materials have been formed with the crystal structure of hexagonal (space group P 63/m m c). The hexagonal with space group P63/mmc is constructed from 4 building blocks, namely two S blocks (Fe63+O82-)2+ and two R blocks (Ba0.52+Sr0.52+Fe63+O112-)2-. And then S and R blocks are bond length of Fe3+(5)?Fe3+(1)?Fe3+(5) and Fe3+(5)?Fe3+(2)?Fe3+(5), respectively. The substitution of Mn and Ti under Fe caused the volume of unit cell and S block space increase, while the atomic density and R block space decrease. Magnetic characterization show that the coercivity for x = 0 was 1567 Oe decrease drastically to 256 Oe for x = 0.5. And absorption characterization show that the bandwidth of absorption frequence was the range 8 ? 11 GHz, 11 ? 13,5 GHz, dan 13.5 ? 16 GHz, for sample of Ba0,5Sr0,5O.6Fe2(1-x)MnxTixO3 (x = 0; 0.25; dan 0.5), respectively. We conclude that the single phases of of Ba0,5Sr0,5O.6Fe2(1-x)MnxTixO3 (x = 0, 0.25, and 0.5) system magnetic materials have been synthesized with successfully.

Abstrak :
Microstructure , crystal structure, and grain size observations on the Mg2 Al3 growth by mechanical alloying. Microstructure , crystal structure, and grain size observations on the growth of Mg2 Al3 phase by mechanical alloying have been performed. The Mg2 Al3 compound is prepared by milling process at various milling time of 10,20 and 30 h...

Abstrak :
Telah dilakukan analisis pengaruh penambahan 0.5 mol berat Mn terhadap struktur kristal dan konstanta dielektrik barium titanat. Bahan percobaan terbaik yang didapat dari sintesis metalurgi serbuk dengan temperatur sintering maksimum 950°C dan perbandingan stoichiometrinya adalah 1 : 0.5 : 0.5 mol berat bahan asal BaCO3, MnO2 dan TiO2 yang merupakan reagen dari E-Merck. Difraktogram sinar-x dengan cacah kontinu dan panjang gelombang atau X (Co Ka) = 1.7889 A yang diperoleh pada suhu kamar, dianalisis menggunakan program Kristalografi GSAS. Analisis struktur memperlihatkan bahwa bahan terdiri dari 5 (lima) fasa, struktur kristal fasa utamanya adalah BaTi0.5Mno.5O3 dengan tipe struktur perovskite BaTiO3, grup ruang tetragonal P4mm, parameter kisi masing-masing, a = 3,998 A, c = 4,022 A, reduced x2 = 1,706 , I tp = '0,176, wRp = 0,230, dengan jumlah variabel 58 . Keempat fasa pengotor tersebut adalah BaCO3, MnO2, TiO2 dan Mn3Ti2 yang masing-masing mempunyai grup ruang Pnma, P42lmnm, 1411amd dan P 631mmc. Bahan uji mempunyai nilai konstanta dielektrik minimum adalah 265,23 pada temperatur ruang dan nilai konstanta dielektrik maksimum dicapai pada temperatur 110 °C.

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The effect of 0.5 weight mole Mn on crystal structure and dielectric constant of barium titanate has been analyzed. The best sample in this study were synthesized using powder metallurgy with maximum sintering temperature at 950 °C and stoichiometric amounts of BaCO3, MnO2 and TiO2 that were reagents from E-Merck. The X-ray difractograms wich were obtained with continuous counts and X (Co Ka) = 1.7889 A at room temperature, were refined using the GSAS crystallographic soft ware package. Structural analysis shows that sample consist of 5 (five) phases where the parent phase is BaTio.5Mno.5G3 with the perovskite-type BaTiO3 structure, the space group is tetragonal P4mm, a = 3.999 A, c = 4.028 A, the goodness of fit x2 is of 1.864 with 56 refined variables and the residual parameters .Rp and wRp are of 18.8% and 24.2% respectively. The impurities phase are BaCO3, MnO2, TiO2 and Mn3Ti2 with the space group each are Prima, P 42lmnm, l 41/amd and P 63/mmc respectively. The sample has a minimum dielectric constant value is 265.23 at room temperature and maximum dielectric constant value is 519.32 at 110 °C temperature reached.

Abstrak :
Aluminium merupakan salah satu logam yang memiliki sifat mekanik yang baik. Aplikasi aluminium pada piston dalam mesin menyebabkan aluminium mengalami gesekan sehingga dapat terjadinya keausan sebelum waktunya karena karakteristik tribologi aluminium yang kurang baik. Aluminium dapat dipadukan dan dilapisi salah satunya menggunakan kobalt yang memiliki ketahanan korosi dan ketahanan aus untuk memperbaiki kekurangan dari aluminium. Pelapisan dilakukan dengan menggunakan metode elektrodeposisi karena mudah dan hemat biaya. Penambahan medan magnet selama elektrodeposisi dapat menjadi parameter yang dapat diamati pengaruhnya. Medan magnet yang diberikan secara tegak lurus terhadap katoda dapat menyebabkan adanya aliran magnetohydrodynamic yang didasarkan pada gaya Lorentz sehingga menyebabkan adanya peningkatan pada proses elektrodeposisi. Lapisan hasil elektrodeposisi dengan pengaruh medan magnet diamati menggunakan XRD didapatkan pengaruh medan magnet pada ukuran kristal yang terbentuk. Mikrostruktur lapisan yang terbentuk diamati menggunakan mikroskop optik dengan pengaruh medan magnet menyebabkan adanya perubahan pada lapisan yang terbentuk dan pengujian sifat korosi menggunakan metode linear sweep voltammetry didapatkan hasil laju korosi yang paling efektif terdapat pada sampel yang diberikan pengaruh medan magnet. ......Aluminum is a metal that has good mechanical properties. The application of aluminum to the piston in the engine causes the aluminum to experience friction so that it can prematurely wear because of the unfavorable tribological characteristics of aluminum. Aluminum can be combined and coated, one of which uses cobalt which has corrosion resistance and wear resistance to increase aluminium properties. Coating is carried out using the electrodeposition method because it is easy and cost-effective. The addition of a magnetic field during electrodeposition can be a parameter where the effect can be observed. The magnetic field applied perpendicular to the cathode can cause a magnetohydrodynamic flow based on the Lorentz force, causing an increase in the electrodeposition process. The electrodeposition result layer with the influence of a magnetic field was observed using XRD. It was obtained the effect of the magnetic field on the size of the crystals formed. The microstructure of the layer formed was observed using an optical microscope with the influence of a magnetic field causing changes in the formed layer and testing the corrosion properties using the linear sweep voltammetry method, the most effective corrosion rate results were found in samples subjected to magnetic fields.

Abstrak :
Microstructural identification of synthesized steel with significant local content has been carried out. Alloy ingot was prepared using a casting technique. The samples were then formed into bulk steel by a machining process. A high resolution powder neutron diffractometer (HRPD) was used as an equipment for characterization. By applying neutron diffraction techniques, a ferritic steel profile can be resulted in as well as ‘minor peaks’ belong to impurities formed in the sample. These impurities can be identified as small amounts of Al2O3 54SiO2, Al4C3, SiC and Cr23C6. Scanning transmission electron microscopy (STEM) combined with energy dispersive X-ray spectroscopy (EDX) confirmed and revealed neutron identified phase distributions. Joint Committee on Powder Diffraction Standards (JCPDS) least square curves calibration can precisely calculate the dhkl parameters of each reflection plane. As a comparison, another sample of alloy ingot was also investigated using neutron diffraction. The pattern was free from crystal impurities. Rietveld refinements provide satisfactory goodness of fits Rwp = 10.42% and reliability factor S = 1.7. This was so-called a ‘real bulky’ sample of a 73Fe24Cr2Si0.8Mn0.1Ni ferritic steel alloy.

Abstrak :
Characteristic of thermal property, electrical property and crystal structure of sic ceramic with additif clay addition. Ceramic sic has been made from raw materials Sic technics and clay as additive. Clay composition is 0,1,3,4 % weight, where function of clay is as a binder and it can not influence properties of Sic....

Abstrak :
KARAKTERISASI LAPISAN PENYERAP DAPAT BAKAR PADA PERMUKAAN PELET UO2 + DOPAN TiO2. Lapisan penyerap dapat bakar pada permukaan pelet UO2 + dopan TiO2 telah berhasil dibuat dengan menggunakan mertoda RF sputtering. Penelitian ini bertujuan untuk mendapatkan karakter mikrostruktur pelet UO2 + dopan, ketebalan, kekerasan mikro, komposisi kimia dan struktur kristal lapisan penyerap dapat bakar pada permukaan pelet UO2. Penentuan mikrostruktur dan ketebalan lapisan dilakukan dengan menggunakan mikroskop optik, kekerasan lapisan dengan metode kekerasan mikro Vickers, komposisi kimia dengan spektrometri XRF dan struktur kristal dengan difraksi sinar-X. Hasil penelitian menunjukan bahwa semakin besar kandungan TiO2 dalam pelet maka semakin besar ukuran butir dalam mikrostruktur pelet dan semakin tebal lapisan yang terbentuk pada permukaan pelet UO2. Kekerasan lapisan permukaan pelet UO2 + dopan TiO2 sinter relatif sama dan tidak bergantung pada konsentrasi dopan TiO2. Lapisan permukaan pelet UO2 + 0,3 % TiO2, pelet UO2 + 0,5 % TiO2 dan pelet UO2 + 0,7 % TiO2 sinter mengandung unsur zirkonium masing-masing 1,97 mg, 2,47 mg dan 4,81 mg. Lapisan penyerap dapat bakar pada permukaan pelet UO2 + dopan TiO2 sinter mempunyai fasa ZrB2 dengan struktur kristal heksagonal.

CHARACTERIZATION OF BURNABLE ABSORBER LAYER ON THE SURFACE OF UO2 + DOPED TiO2 PELLETS. Burnable absorber layer on the surface of UO2 + doped TiO2 pellets have successfully created using RF sputtering methods. The objective of this research is to obtain of microstructure characters of UO2 + doped TiO2 pellets, thickness, micro hardness, chemical composition and crystal structure of burnable absorber layer on the surface of UO2 pellets. The methods used are the microstructure and layer thickness using optical microscopy, layer hardness with micro Vickers hardness method, chemical composition by XRF spectrometry, and crystal structure by X-ray diffraction. The results showed that the larger of TiO2 content in the pellets then the greater of the grain size in the microstructure of the pellets and the thicker of the layer formed on the surface of UO2 pellets. The hardness of surface layer of UO2 + doped TiO2 sintered pellets are equal and does not depend on the dopant concentration of TiO2. The surface layer of UO2 + 0.3 % TiO2, UO2 + 0.5 % TiO2 and UO2 + 0.7 % TiO2 sintered pellets are containing zirconium respectively 1.97 mg, 2.47 mg and 4.81 mg. Burnable absorber layer on the surface of UO2 + doped TiO2 sintered pellets have ZrB2 phase with a hexagonal crystal structure.