Sigit Dwi Yudanto

Formation of polycrystalline MgB2 synthesized by powder in sealed tube method with different initial boron phase

Magnesium diboride, MgB2 is a new high critical temperature superconductor that discovered in the beginning of the 21st century. The MgB2 has a simple crystal structure and a high critical temperature, which can be manufactured in several forms like thin films, tapes, wires including bulk in the large scale. For that reason, the MgB2 has good prospects for various applications in the field of electronic devices. In the current work, we have explored the synthesis of MgB2 polycrystalline using powder in a sealed tube method. Different initial boron phase for the synthesized of MgB2 polycrystalline were used. These were, in addition to magnesium powders, crystalline boron, amorphous boron and combination both of them were respectively fitted in the synthesis. The raw materials were mixed in a stoichiometric ratio of Mg: B=1:2, ground using agate mortar, packed into stainless steel SS304. The pack was then sintered at temperature of 800°C for 2 hours in air atmosphere. Phase formation of MgB2 polycrystalline in difference of initial boron phase was characterized using XRD and SEM. Referring to the diffraction pattern and microstructure observation, MgB2 polycrystalline was formed, and the formation was effective when using the crystalline Mg and fully amorphous B as the raw materials. The critical temperature of the specimen was evaluated by the cryogenic magnet. The transition temperature of the MgB2 specimen synthesized using crystalline magnesium and full amorphous boron is 42.678 K (ΔTc = 0.877 K).Magnesium diboride, MgB2 is a new high critical temperature superconductor that discovered in the beginning of the 21st century. The MgB2 has a simple crystal structure and a high critical temperature, which can be manufactured in several forms like thin films, tapes, wires including bulk in the large scale. For that reason, the MgB2 has good prospects for various applications in the field of electronic devices. In the current work, we have explored the synthesis of MgB2 polycrystalline using powder in a sealed tube method. Different initial boron phase for the synthesized of MgB2 polycrystalline were used. These were, in addition to magnesium powders, crystalline boron, amorphous boron and combination both of them were respectively fitted in the synthesis. The raw materials were mixed in a stoichiometric ratio of Mg: B=1:2, ground using agate mortar, packed into stainless steel SS304. The pack was then sintered at temperature of 800°C for 2 hours in air atmosphere. Phase formation of MgB2 polycrystalline...

Fabrication of MgB2 monofilament wire by in-situ using powder-in-tube (PIT) method

In this research we have studied the making of MgB2 superconducting monofilament wire using powder-in-tube method with variation of Mg composition to B ie 0.90, 1.00 and 1.10, while Boron remains The precursor used is Mg powder (98%) and powder B (95%) Both materials are mixed and then crushed with agate mortar for 30 minutes and then put into stainless steel tube 316. The tube is then subjected to a mechanical treatment of rolling to form its monofilament wire. The wire is then cut and sintered at a temperature of 800o C for 2 hours. After that we measure the critical temperature then characterize the samples by XRD and SEM. From the result of this research it was found that in-situ wire-making by powder-in-tube method can make MgB2 superconducting monofilament wire with MgB2 as the dominant phase around 95% and MgO as the impurity phase around 5%. MgO is formed due to the oxidation occurring in the MgB2 powder inside the wire. The optimal Mg:B composition to make this wire is in the 1:2 composition Because it has a good resistivity curve with a high enough Tc Onset that is 41,67 K and Tc Zero 40,89 K. However, there is a porosity in the wire due to the volume reduction of the Mg + 2B reaction plus the evaporation of Mg.In this research we have studied the making of MgB2 superconducting monofilament wire using powder-in-tube method with variation of Mg composition to B ie 0.90, 1.00 and 1.10, while Boron remains The precursor used is Mg powder (98%) and powder B (95%) Both materials are mixed and then crushed with agate mortar for 30 minutes and then put into stainless steel tube 316. The tube is then subjected to a mechanical treatment of rolling to form its monofilament wire. The wire is then cut and sintered at a temperature of 800o C for 2 hours. After that we measure the critical temperature then characterize the samples by XRD and SEM. From the result of this research it was found that in-situ wire-making by powder-in-tube method can make MgB2 superconducting monofilament wire with MgB2 as the dominant phase around 95% and MgO as the impurity phase around 5%. MgO is formed due to the oxidation occurring in the MgB2 powder inside the wire. The optimal Mg:B composition to make this wire is in the 1:2 composition Beca...

Characterization and Studies on AC Conductivity of CaMnO3 Material

Synthesis of CaMnO3 has been performed by solid state reaction method using CaCO3 and MnCO3 powder as raw materials. The raw materials were weighed, milled, compacted into a pellet and then sintered at 1250°C. Phase of material, microstructure, and conductivity of the samples were observed. The refinement results of X-ray diffraction pattern shows that CaMnO3 formed as a single phase, which has a structure orthorhombic (P n m a) with lattice parameters, a = 5.277 A, b = 7.452 A, and c = 5,261 A. The atomic density of the refinement result is 4.591 gr.cm-3. The morphology of CaMnO3 sample has a good particle homogeneity with the particle size 1- 2 μm. The value of AC conductivity on the CaMnO3 is directly proportional with the increasing ofthe temperature. The highest value of the AC conductivity of the CaMnO3 sample is 2.8 x 10-3 S/cm at a temperature of 400°C.

Effect of Te doping on FeSe superconductor synthesized by powder-in-tube

FeSe is a superconducting material, which has the simplest crystal structure among the Fe-based superconductors. It has no arsenic element, which is very harmful to the human body. In this study, we analyzed the effects of milling time and Te doping on FeSe superconductors. The synthesis of the samples were carried out using powder-in-tube method in a SS304 stainless steel tube. After the pressing process, followed by the sintering process at 500° C for 20 hours, the samples were removed from the tubes. Later, we analyzed its crystal structures, surfaces morphology and the superconductivity properties. Δ-FeSe phase (hexagonal, non-superconductor) and β-FeSe (tetragonal, superconductor) were formed in the samples, including minor phases of Fe and Fe3Se4. Te doping changed the crystal structure from β-FeSe and Δ-FeSe into FeSe0.5Te0.5. In addition, the onset critical temperature (TC, onset) shifted to higher temperature.

Manufacture of Bi, Pb-Sr-Ca-Cu-O pellet disc using wet method

A confirmation of favorable properties of pellet disc of HTSBPSCCO is required in order to optimally do subsequent process of powder-in-tube (PIT) fabricated intosuperconductor wires. Wet method is a simple method in fabricating superconductor wire when it comes to mass production. In order to optimize this method, temperature parameter holds a decisive role in the formation of the 2223 phase of BPSCCO. We have synthesized two samples using wet method with the sintering temperature of 855°C and 865°C for 90 hours in air atmosphere.XRD analysis points out the formation of Bi-2223 phase of the sample with the sintering temperature of 855°C, whereas Bi-2212 phase is detected in the one with the sintering temperature of 865°C. The surface morphology of both samples are layers-like. According to temperature dependence of resistivity measurement results, both samples have superconductivity behavior below critical temperature (Tc). The former one (Tsintering = 855°C) has conductive-like behavior above Tcof which...