The four-layer Aurivillius CaBi 4 Ti 4 O 15 with introducing of La 3+ on the A-site and Mn 3+ on the B-site with the formula Ca 1-x Bi 3+x LaTi 4-x Mn x O 15 (x = 0, 0.2, 0.4, 0.6, 0.8, and 1) were synthesized by molten salt method using the mixture of sulfate salts K 2 SO 4 /Na 2 SO 4 as the flux. XRD data confirmed the formation of single-phase Aurivillius with A2 1 am orthorhombic structure for x = 0, 0.2, 0.4, and 0.6, whereas for x = 0.8 and 1, the impurity phases were observed. SEM analysis shows the anisotropic plate-like grains, which are a typical grain of Aurivillius phases. The cell volume decreases with increasing x, indicating a presence of mixed valences of Mn 3+ and Mn 4+. The dielectric constants increased with x, strongly correlated with the higher distortion of the structure, since the 6s 2 lone pair electrons of Bi 3+ cation increase. The presence of Mn 3+ unpaired electrons results in the increase of dielectric loss as increasing x.
ABSTRAKSintesis senyawa feroelektrik yang berbasis fasa Aurivillius berlapis empat (n = 4) yang didadah kation La 3+ dan Mn 3+ , Ca 1-x Bi 3,5+x La 0,5 Ti 4-x Mn x O 15 dengan x = 0; 0,2; 0,4; 0,6; 0,8 dan 1 telah dilakukan dengan teknik lelehan garam. Karakterisasi produk dengan difraksi sinar-X (XRD) menunjukkan bahwa fasa tunggal Aurivillius ditunjukkan oleh sampel dengan x = 0; 0,2; 0,4 dan 0,6. Refinement struktur dengan teknik Le Bail diketahui bahwa senyawa Aurivillius yang terbentuk sesuai dengan simetri ortorombik dan grup ruang A2 1 am. Analisis dengan Scanning Electron Microscopy (SEM) untuk semua sampel memperlihatkan morfologi sampel berupa lempengan yang merupakan ciri khas senyawa Aurivillius. Nilai konstanta dielektrik sampel dan konduktivitasnya mengalami kenaikan dengan meningkatnya x. Konduktivitas paling tinggi dimiliki oleh sampel x = 0,2 yang diperkirakan akibat adanya interaksi pertukaran ganda (double exchange) antara Mn 3+ dan Mn 4+ . Morphology analysis by scanning electron microscopy (SEM) for all samples shows the plate-like as the characteristic of Aurivillius compounds. The value of dielectric constant and conductivity of the samples increases as increase of x. The conductivity of x = 0.2 is the highest predicted due to the interaction of double exchange between Mn 3+ and Mn 4+ . Kata
The residual waste of synthesis and use of radioactive elements of gold 198Au as a radiopharmaceutical and tracer after decaying can be reused as an irradiated target material. The gold recovery process was carried out on Au-198 radioactive nano gold waste with the redox replacement method using Zn-foil as metal reducing agent. Radioactive Au-gold waste was stored until it decayed to its background, so it is not dangerous and does not interfere with the optical characterization process. The sample was dissolved with aquaregia and evaporated so that the chelating or dendrimer material can be released and oxidized. The evaporation was done to reduce acidity and obtain the salt. Furthermore, the salt solution of HAuCl4 is reduced with Zn-foil so that the pure gold deposits can be obtained through a redox process. The results of the XRF analysis showed that the gold deposits formed have fairly good purity with little Zn and Zr impurities derived from the erosion of the melting container. The yield calculation results based on ICP-OES data obtained a recovery percentage of 68.73%. The method of taking gold deposits must be increased to reduce the gold particles attached to the bar stirrer and to the melting pottery container.
This research is related to the preparation and initial characterization of gadolinium nanoparticles as a Magnetic Resonance Imaging (MRI) contrast agent. Nanomaterial-based contrast agents aim to improve clearer imaging, longer examination retention times with lower toxicity than gadolinium ion-based contrast agents, and evaluate the potential use of MRI contrast agents for early detection of cancer. Gadolinium nanoparticles were synthesized using polyol method with stabilizer and chemical reaction process at high temperature. The stabilizers used are diethylene glycol (DEG) and triethylene glycol (TEG). The reaction process was carried out at 180°C for 4 hours to obtain gadolinium nanoparticles with uniform size and shape. The results of hydrodynamic and visual measurements using DLS and HRTEM instruments on the gadolinium nanoparticles produced were 50 nm and 18 nm, respectively. The results of the characterization of the crystal structure obtained the X-ray diffraction pattern in the crystal plane (222), which is a typical for the Gd2O3 crystal phase. Characterization of chemical bonds using FTIR showed absorption at 1438-1627 cm−1, 1000-1138 cm−1 and 450-795 cm−1 indicated the presence of Gd-O bond vibrations, while absorption at 1310-1466 cm−1 indicated the presence of Gd-O-Gd bonds. This is evidenced by the similarity with the absorption peak of commercial Gd2O3. The content of free Gd3+ ions found in the synthesized products detected was only about 0.99% of the Gd3+ precursors used.
<p>Sintesis senyawa feroelektrik yang berbasis fasa Aurivillius berlapis empat (n = 4) yang didadah kation La<sup>3+</sup> dan Mn<sup>3+</sup>, Ca<sub>1-x</sub>Bi<sub>3,5+x</sub>La<sub>0,5</sub>Ti<sub>4-x</sub>Mn<sub>x</sub>O<sub>15</sub> dengan <em>x</em> = 0, 0,2, 0,4, 0,6, 0,8, dan1 telah dilakukan dengan teknik lelehan garam. Karakterisasi produk dengan difraksi sinar-X (XRD) menunjukkan bahwa fasa tunggal Aurivillius ditunjukkan oleh sampel dengan <em>x</em> = 0, 0,2, 0,4, dan 0,6. <em>Refinement</em> struktur dengan teknik <em>Le Bail</em> diketahui bahwa senyawa Aurivillius yang terbentuk sesuai dengan simetri ortorombik dan grup ruang <em>A2<sub>1</sub>am</em>. Analisis dengan <em>Scanning Electron Microscopy </em>(SEM) untuk semua sampel memperlihatkan morfologi sampel berupa lempengan yang merupakan ciri khas senyawa Aurivillius. Nilai konstanta dielektrik sampel dan konduktivitasnya mengalami kenaikan dengan meningkatnya <em>x</em>. Konduktivitas paling tinggi dimiliki oleh sampel <em>x</em> = 0,2 yang diperkirakan akibat adanya interaksi pertukaran ganda (<em>double exchange</em>) antara Mn<sup>3+</sup> dan Mn<sup>4+</sup>.</p><p><strong>Synthesis of Aurivillius Compounds Ca<sub>1-x</sub>Bi<sub>3,5 + x</sub>La<sub>0,5</sub>Ti<sub>4-x</sub>Mn<sub>x</sub>O<sub>15</sub>: Structure and Dielectric Properties</strong><strong>. </strong>Synthesis of ferroelectric compounds based on a four-phase Aurivillius phase (n = 4) which is doped with La<sup>3+</sup> and Mn<sup>3+</sup> cations, Ca<sub>1-x</sub>Bi<sub>3,5+x</sub>La<sub>0,5</sub>Ti<sub>4-x</sub>Mn<sub>x</sub>O<sub>15</sub> with <em>x</em> = 0, 0.2, 0.4, 0.6, 0 , 8, and 1 were carried out by molten salts technique. Characterization of products using X-ray diffraction (XRD) revealed that the single phase Aurivillius was shown by the samples with <em>x</em> = 0, 0,2, 0,4, and 0,6. The results of refinement show that the Aurivillius phase formed has orthorhombic symmetry with <em>A2<sub>1</sub>am</em> space group. Morphology analysis by scanning electron microscopy (SEM) for all samples shows the plate-like as the characteristic of Aurivillius compounds. The value of dielectric constant and conductivity of the samples increases as increase of x. The conductivity of <em>x</em> = 0.2 is the highest predicted due to the interaction of double exchange between Mn<sup>3+</sup> and Mn<sup>4+</sup>.<strong> </strong><strong></strong></p>
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