Sintesis Zn0.5Mg0.5TiO3 dengan Variasi Rasio Mol Serbuk (Zn+Mg):Ti Menggunakan Metode Pencampuran Larutan pada Suhu 600ºC

Dalam penelitian ini telah dilakukan sintesis serbuk larutan padat Zn0.5Mg0.5TiO3 dengan metode pencampuran larutan dalam jumlah yang relatif tinggi (>90 % berat). Bahan dasar yang digunakan dalam sintesis adalah serbuk-serbuk Mg dan Ti, sedangkan Zn digunakan sebagai bahan aditif dengan variasi rasio mol serbuk yang digunakan antara 1,03:1 ≤ (Zn+Mg):Ti ≤ 1,18:1. Prekursor dibuat dengan melarutkan masing-masing serbuk Mg, Zn, dan Ti ke dalam HCl 37%, mencampurkan ketiga larutan dan mengeringkan campuran di udara pada suhu 110ºC serta terakhir mengkalsinasi serbuk hasil pengeringan pada suhu 600ºC selama ½ jam. Uji komposisi serbuk hasil sintesis tersebut dilakukan dengan difraksi sinar-x. Identifikasi fasa pada serbuk hasil sintesis menunjukkan bahwa seluruh variasi rasio mol menghasilkan fasa Zn0.5Mg0.5TiO3 dan rutil. Ukuran kristal fasa Zn0.5Mg0.5TiO3 dengan rasio mol 1,03:1 dan 1,05:1 berturut-turut adalah 20 dan 29 nm. Variasi mol yang menghasilkan fraksi berat Zn0.5Mg0.5TiO3 terbesar adalah 1,12:1, yaitu sebesar 91%

RLFC: Random Access Light Field Compression using Key Views and Bounded Integer Encoding

We present a new hierarchical compression scheme for encoding light field images (LFI) that is suitable for interactive rendering. Our method (RLFC) exploits redundancies in the light field images by constructing a tree structure. The top level (root) of the tree captures the common high-level details across the LFI, and other levels (children) of the tree capture specific low-level details of the LFI. Our decompressing algorithm corresponds to tree traversal operations and gathers the values stored at different levels of the tree. Furthermore, we use bounded integer sequence encoding which provides random access and fast hardware decoding for compressing the blocks of children of the tree. We have evaluated our method for 4D two-plane parameterized light fields. The compression rates vary from 0.08 - 2.5 bits per pixel (bpp), resulting in compression ratios of around 200:1 to 20:1 for a PSNR quality of 40 to 50 dB. The decompression times for decoding the blocks of LFI are 1 - 3 microseconds per channel on an NVIDIA GTX-960 and we can render new views with a resolution of 512X512 at 200 fps. Our overall scheme is simple to implement and involves only bit manipulations and integer arithmetic operations.Comment: Accepted for publication at Symposium on Interactive 3D Graphics and Games (I3D '19

Nanostructure and Magnetic Field Ordering in Aqueous Fe3O4 Ferrofluids: A Small-Angle Neutron Scattering Study

Despite the importance of reducing production costs, investigating the hierarchical nanostructure and magnetic field ordering of Fe3O4 ferrofluids is also important to improve its application performance. Therefore, we proposed an inexpensive synthesis method in producing the Fe3O4 ferrofluids and investigated their detailed nanostructure as the effect of liquid carrier composition as well as their magnetic field ordering. In the present work, the Fe3O4 ferrofluids were successfully prepared through a coprecipitation route using a central precursor of natural Fe3O4 from iron sand. The nanostructural behaviors of the Fe3O4 ferrofluids, as the effects of the dilution of the Fe3O4 particles with H2O as a carrier liquid, were examined using a small-angle neutron spectrometer (SANS). The Fe3O4 nanopowders were also prepared for comparison. A single lognormal spherical distribution and a mass fractal model were applied to fit the neutron scattering data of the Fe3O4 ferrofluids. The increasing carrier liquid composition of the fluids during dilution process was able to reduce the fractal dimension and led to a shorter length of aggregation chains. However, it did not change the size of the primary particles or building block (approximately 3.8 nm) of the Fe3O4 particles. The neutron scattering of the Fe3O4 ferrofluids under an external magnetic field in the range of 0 to 1 T exhibited in a standard way of anisotropic phenomenon originating from the nanostructural ordering of the Fe3O4 particles. On the other hand, the Fe3O4 powders did not show anisotropic scattering under an external field in the same range. Furthermore, the magnetization curve of the Fe3O4 ferrofluids and nanopowders exhibited a proper superparamagnetic character at room temperature with the respective saturation magnetization of 4.4 emu/g and 34.7 emu/g

Synthesis of High-Purity Ceramic Nano-Powders Using Dissolution Method

A set of ceramic powders has been synthesized using a “bottom-up” approach which is denoted here as the dissolution method. The raw materials were metal powders or minerals. The dissolution media were strong acid or base solutions. In the case of metallic raw materials, magnesium and titanium powders were separately dissolved in hydrochloric acid to obtain their precursors. They were then dried, washed, and calcined in air at various temperatures to produce pure MgO and TiO2 nano-powders. Pure MgTiO3 nano-powders by mixing the precursors at the stoichiometric ratio and calcining the dried mixture at a temperature as low as 700°C have also been successfully synthesized. In the mineral case, local zircon sand was used as the raw material. A standard procedure to extract the “clean” and pure zircon powder was applied which included washing, magnetic separation, and reactions using hydrochloric acid and sodium hydroxide. A pure zircon nano-powder was obtained by applying mechanical ball-milling to the zircon powder. The zircon powder was also chemically dissociated to give amorphous silica (SiO2), cristobalite, amorphous zirconia (ZrO2), and nanometric tetragonal zirconia powders

Analysis of Crystal Structure and Dielectric of Zn2+ Ion Doped Nanoparticle Magnetite Based on Iron Sand Synthesized by Coprecipitation Method

Zn2+ ion doped Fe3O4 nanoparticles based on iron sand have been successfully synthesized by coprecipitation method at low temperature. The starting materials were iron sand, ZnCl2, HCl, and NH4OH. Characterizations were conducted by means of X-Ray Flourescence (XRF), X-Ray Diffraction (XRD) and digital capacitance meter AD5822. XRF identification confirms that the elemental composition of all samples is appropriate with the stoichiometry calculation. Phase formation identification by using High Score Plus and DDView+PDF2 software reveals that all samples crystallize in cubic spinel structure. Rietveld refinement analysis bymeans of Reitica yields the doping of Zn2+ ion on Fe3O4 increases the lattice parameter with crystal size in the order of nanometer. This is in line with theoretical predictions as a consequence of the influence of Zn2+ ionic radii that replace Fe2+. Furthermore, dielectricity analysis shows that the higher the amount of Zn2+ doped Fe3O4 nanoparticles the higher the dielectric constant. This mechanism is ionic polarization phenomenom as consequence of the decreasing in the crystal volume and the atomic distance that lead to increase the moment of dipole

ANALISIS UKURAN DAN KORELASI NANO PARTIKEL Fe3O4 DALAM FLUIDA MAGNETIK DENGAN TEKNIK HAMBURAN NEUTRON SUDUT KECIL

ANALISIS UKURAN DAN KORELASI NANO PARTIKEL Fe3O4 DALAM FLUIDA MAGNETIK DENGAN TEKNIK HAMBURAN NEUTRON SUDUT KECIL. Telah dilakukan analisis ukuran dan korelasi nanopartikel Fe3O4 dalam fluida magnetik menggunakan Teknik Hamburan Neutron Sudut Kecil. Analisis ukuran partikel dilakukan dengan pendekatan daerah Guinier untuk memperoleh ukuran jari-jari girasi dalam partikel yang selanjutnya digunakan untuk menentukan rerata jari-jari partikel magnetit. Ukuran jari-jari partikel magnetit berkisar antara 17,8 nmhingga 53,6 nm. Pendekatan dengan model Poly Core Shell Ratio menunjukkan harga ukuran rerata jari-jari partikel sebesar 25 nm dengan polidispersitas sebesar 0,4. Pengaruh konsentrasi fluida magnetik terhadap ketebalan lapisan surfaktan tidak menunjukkan perubahan harga yang signifikan yaitu sebesar 6 Å hingga 8 Å dan dalamkisaran variasi 0,5Mhingga 3M belum ditemukan adanya korelasi antar partikel magnetit dalam fluida magnetik

KAJIAN STRUKTUR KRISTAL DAN DIELEKTRISITAS NANOPARTIKEL MAGNETITE BERBASIS PASIR BESI DOPING Zn2+ HASIL SINTESIS METODE KOPRESIPITASI

KAJIAN STRUKTUR KRISTAL DAN DIELEKTRISITAS NANOPARTIKEL MAGNETITE BERBASIS PASIR BESI DOPING Zn2+ HASIL SINTESIS METODE KOPRESIPITASI. Nanopartikel Fe3O4 berbasis pasir besi doping ion Zn2+ telah berhasil disintesis melalui metode kopresipitasi pada suhu rendah. Bahan-bahan yang digunakan adalah pasir besi sebagai bahan utama, ZnCl2, HCl dan NH4OH. Karakterisasi dilakukan menggunakan X-Ray Flourescence (XRF), X-Ray Diffraction (XRD) dan kapasitansi meter digital AD5822. Hasil uji XRF menunjukkan bahwa komposisi unsur sampel sesuai dengan stoikiometri. Identifikasi fasa menggunakan sotware High Score Plus dan DDView+PDF2 menunjukan bahwa seluruh sampel terbentuk dalam fasa spinel kubik. Hasil analisis refinement menggunakan sofware Reitica menunjukkan semakin banyak doping ion Zn2+ pada Fe3O4, nilai parameter kisi kristal juga meningkat dengan ukuran kristal berorde nanometer. Hal ini sebagai konsekuensi dari pengaruh ukuran jari-jari ion Zn2+ yang menggantikan ion Fe2+. Sementara hasil uji dielekrisitas menunjukkan dengan meningkatnya doping ion Zn2+ pada Fe3O4, nilai dielektrisitasnya juga meningkat. Mekanisme ini adalah fenomena polarisasi ionik sebagai akibat dari menurunnya volume kristal dan jarak antar atom, sehingga momen dipol semakin besar