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Pada penelitian ini, kami melakukan sintesis polikristal Ca3Co4O9 melalui metode reaksi padat. Variasi perbandingan atomik Ca/Co sebesar 3/4,0 dan 3/4,2 diambil dengan tujuan untuk mengetahui pengaruhnya terhadap pembentukan fasa Ca3Co4O9. Proses penelitian diawali dengan penimbangan bahan baku serbuk CaCO3 dan CoCO3, digerus secara mekanik dan dikompaksi dengan tekanan 350 MPa. Sampel hasil kompaksi disinter pada suhu 850 °C selama 6 jam. Berdasarkan hasil pengujian XRD, diperoleh bahwa fasa Ca3Co4O9 meningkat dari 82,41 % menjadi 96,22 %. Parameter kisi kristal Ca3Co4O9 hasil perhitungan adalah kisi a = 0,4827 nm, kisi b = 0,4555 nm, kisi c = 1,0827 nm, dan sudut β = 98,13°.

The research has been done in the field of Field Work Practice to synthesize superconductors Bi 1,6 Pb 0,4 Sr 2 Ca 2 Cu 3 O 10+x for Meissner test using solid reaction method. The objective of this research is to make superconductor Bi 1,6 Pb 0,4 Sr 2 Ca 2 Cu 3 O 10 x with solid reaction method and to know the result of superconducting character of Bi 1,6 Pb 0,4 Sr 2 Ca 2 Cu 3 O 10 +x based on Meissner test. From the results of Meissner test that has been done on this superconductor sample looks super magnet and superconductor repel each other rejects or super magnet drift.Sehingga it can be concluded that the sample has a strong Meissner effect. From the results of Tc test using cryogenic tools obtained Tc Zero temperature of 103.4 K and Tc Onset of 116.67 K. From the data obtained it can be concluded that the sample has reached phase 2223.

We report the phase formation and electrical resistivity of MgB2 superconductor samples. Method of synthesis was conventional solid-state reaction employing crystalline β-rhombohedral boron (B) and magnesium (Mg) with a stoichiometric ratio of Mg:B=1:2. The two precursors were mixed and sintered at various temperatures from 600°C to 900°C for an hour. All samples were characterized employing XRD, SEM, and Cryogenic Magnetometer. It is shown that the MgB2 phase begins to form at a sintering temperature of 700°C. The highest peak intensity of the MgB2 phase was observed in a sample sintered at 900°C indicates the largest fraction of the superconducting phase among all synthesized samples. Electrical resistivity values were carried out to investigate the superconducting properties of the samples. It is also shown the samples sintered at a temperature of 800°C and 900°C possess superconducting properties with a critical temperature of ~ 43 K

In this work, preparation of Fe1.025Se samples was done using a solid-state reaction. Iron and selenium powder were used as raw materials. The raw materials were milled using a shaker mill for 5 hours after weighed in an atomic ratio of Fe:Se=1.025:1. To find out the formation of polycrystalline Fe1.025Se, the milled powder was then compacted in a stainless-steel tube and sintered at a temperature of 355°C (for sample 1) and 745°C (for sample 2) for 6 hours. All samples were sintered in the air atmosphere and cooled rapidly in the air. XRD was used to analyze the phase formation. Based on the diffraction pattern calculation, the sintered sample at a temperature of 745°C has a higher mass fraction of the tetragonal phase than the sample sintered at 355°C. The lattice parameters of the sample sintered at a temperature of 745°C are a = 3.7688 Å and c = 5.5236 Å. According to the resistivity measurement results, it appears that the sample sintered at 745°C has a critical temperature onset of ~13.28 K.

Bi-type superconductor is a high-temperature superconductor with mainly applied in the field of electricity. Silver is used as a wire sheath which causes the price of this wire production to be high. In this study Bi(Pb)-Sr-Ca-Cu-O (BPSCCO) wires were made by using stainless-steel (SS316) tubes which is cheaper and is not change its properties by the temperature of the formation of BPSCCO at 860°C. The preparation of superconducting wire is done by the Powder-In-Tube method, sintering and withdrawing/ rolling process. TiO2 powder was added to analyze the effect on the formation of BPSCCO. Based on analyzing results, there is a dominant impurity phase that has been formed, namely Fe2.5Ti0.5O4. We found that in the use of stainless-steel tubes and the TiO2 powder (5wt%), 2223 phase was not formed. Although, small amounts of Bi2Sr2CaCu2O8 (2212) and Bi10Sr10Cu5O29 (2201) phases were found. Resistance versus temperature test using cryogenic equipment results indicate that there are symptoms of a low critical temperature around 10 K. 2212 and 2201 phases are thought to cause a low critical temperature in the samples, even though the decrease in electrical resistance does not reach zero. While the morphology of superconducting wire is quite well characterized from fairly even grains and only a small amount of porosity is formed.

Experiments have been carried out to obtain the decomposition of cobalt carbonate cobalt oxide to be used as raw material for the manufacture of calcium cobalt oxide thermoelectric materials. The experiments were performed by heating cobalt carbonate powder material (CoCO3) from Kanto Chemical with a temperature of 1000°C. Heating aims to obtain Co3O4 phase. Co3O4 phase is what will be used in the manufacture of thermoelectric materials based on the phase diagram of the system Ca-Co-O. The results of X-ray diffraction CoCO3 materials are heated to 1000°C showed that Co3O4 phase has been formed. Analysis quantitative diffraction pattern shows the diffraction peaks are the property throughout the Co3O4 phase. The crystal structure of Co3O4 is Face Centered Cubic (FCC) with space group F d -3 m. Lattice parameters of the diffraction pattern is the result of smoothing a = 8.0838 Å.

MgB2 superconductor is a superconductor with a critical temperature of around 39K and has the potential to replace Nb3Sn and NbTi as superconducting coils to produce high magnetic fields. In this study, monofilament wires have been made to analyze the doping effect of SiC and Carbon Nanotubes (CNT) in its manufacture using Powder-In-Tube (PIT) method. Stainless Steel (SS-316) tube was used as a tube filled with powders of starting materials of Mg, B, SiC and CNT. A total of 8 samples were prepared with variations in the addition of SiC, and CNT as much as 5, 10, and 15 wt %, and also the variations in the addition of Mg composition by 0 and 10 mol % from normal stoichiometric values. The samples were rolled and sintered at 800°C for 3 hours. The samples then were analyzed using SEM (Scanning Electron Microscopy) to analyze the surface morphology, XRD (X-Ray Diffractometer) to analyze the formed phases and crystal structures, and then resistivity versus temperature using cryogenic systems to analyze their superconductivity properties. Based on the results of the XRD analysis, the MgB2 phase is the major phase in the samples and the SiC doping causes the formation of minor phases of Mg2Si and Fe3C. The addition of SiC causes a decrease in crystalline properties of the MgB2 phase due to reaction with SiC, while the addition of CNT does not cause the formation of a new phase. Based on the results of the analysis of resistance versus temperature, it is seen that the addition of SiC causes a decrease in TC value. While the addition of CNT causes the improvement in the nature of superconductivity, but it also causes the decrease of its TC values.

MgB2 is a metal compound superconductor which has critical temperature value ~ 39 K. The critical temperature of MgB2 superconducting wire is higher than Nb-based superconductor, NbTi and Nb3Sn. It is a promising superconductor to replace the Nb-based superconductor that has been applied as a widely used superconducting wire. The aim of this study is to synthesize MgB2 superconductor with the various amount of Mg element using powder-in-sealed-tube method. Mg and B powders were mixed, grounded and poured into stainless steel SS304 tube. As-mixed powder was then heated at 800 C for 2 h in standard air ambient inside a sealed tube. After that, the crystal structures, surface morphology and resistivity versus temperature of all samples were characterized using X-ray diffraction (XRD), scanning electron microscopy and cryogenic system, respectively. Based on the result of XRD, the majority of MgB2 phase was formed even though there were slightly small amount of B2O phases. The critical temperature (Tc) onset of MgB2 with the addition of 0, − 5, − 10, 5 and 10 wt% Mg was calculated 42.03; 42.25; 42; and 41.8 K, accordingly. These critical temperature values are relatively higher than other studies among this type of superconductors. And then, to study the grinding effect, one of the as-calcined pellets was ground and pressed to form bulk sample again. TC,onset and TC,zero of this sample were decreased 3 and 18 K, respectively.

In this paper, the results of the superconductivity evaluation of MgB2 intermetallic-based superconducting materials prepared through mechanical alloying are reported. The formation of the MgB2 intermetallic phase took place through an intermediate phase reaction at the solid-state reaction temperature, which tends to favor single-phase materials. The annealing of mechanically milled Mg and B powders resulted in the highest mass fraction of MgB2 observed in this study, reaching more than 90% after annealing at 900 °C for 1 h. At that point, there were still second phases present consisting of Mg, MgO, and Fe2B. Improved superconducting properties were obtained in samples sintered at temperatures of 850 °C and 900 °C that had a low resistivity, low critical temperature gap values, and a high residual resistivity ratio (RRR).

Sintesis material MgB2 dengan penambahan nano-SiC telah kami lakukan menggunakan metode reaksi padat. Evaluasi penambahan nano-SiC terhadap struktur kristal dan suhu kritis MgB2 dilakukan melalui pengujian difraksi sinar-X dan cryogenic magnetometer. MgB2+x wt.% nano-SiC dengan x=0, 5, 10, dan 15 dipersiapkan dengan penggerusan manual dan disintering pada suhu 800°C selama 2 jam. Berdasarkan analisis difraksi sinar-X, penambahan nano-SiC menyebabkan penurunan nilai konstanta kisi-a dari 3,0848 Å menjadi 3,0792 Å. Distorsi pada konstanta kisi-a merupakan dampak dari karbon yang mensubstitusi boron. Hasil uji resistivitas menunjukkan bahwa penambahan nano-SiC menurunkan nilai Tc-zero dari material MgB2.

We have synthesized the FeSe and FeSe0.5Te0.5 superconductors by using a conventional solid-state reaction. The starting materials which consisted of iron, selenium, and tellurium powder were weighed in the stoichiometry ratio Fe:Se = 1:1 and Fe:Se:Te = 1:0.5:0.5. The starting materials were ground using an agate mortar for 3 h in the air. The milled powders were separated into 2 variations respectively the vacuum and powder in a sealed tube (PIST) method. For the vacuum method, the milled powders were weighed and compacted with a pressure of 165 MPa using a hydraulic press machine to form a pellet shape. For another method, the milled powders were inserted into the stainless-steel (SS316) tube and then compacted. Finally, the pellet and compacted tube were then sintered at the temperature of 745°C and 845°C for 3 h and left in the furnace to room temperature. Based on the resistivity measurement, the best sample was obtained in the FeSe0.5Te0.5 sample that sintered at the temperature of 745°C using the vacuum method. The critical temperature onset (Tconset) and critical temperature zero (Tczero) of the best sample were found at 16.66 K and 7.5 K, respectively.

The power deficit is caused by an electric current that flows inefficiently due to the high resistance on the cables. Superconductors as the materials that have zero resistivity value, can be a solution to make efficient cables. In this work, a superconductor Magnesium Diboride (MgB2) wire has been made using industrial wire drawing process. The MgB2 superconducting wire was synthesized by the powder-in-tube method. Magnesium and boron powders were ground and packed into a Stainless steel 316 tube with diameter of 8.0 mm, and then continued by carrying out the rolling process until the outer diameter became 4.0 mm. The heat treatment was carried out by pulling out the wire through tube furnace with speeding of 10 cm/2 hours at air atmosphere. The tube furnace’s temperature was kept at 800 °C during the pulling process. Then, the wire was drawn until its outer diameter became 1.8 mm. Morphology and resistivity properties of the sample were analyzed as the outer diameter of sample was 2.5 mm (sample 1) and 1.8 mm (sample 2). Morphology and resistivity properties were analyzed using SEM-EDS and four-point probes measurement method, respectively. Based on SEM images, it has analyzed that the Fe metal element in the stainless-steel tube does not react with the Mg element in the MgB2 alloy core. In addition, the structure of the forming process tends to be round and compact and there are no gaps or boundaries between the tube and powder. Based on the Tconset value obtained from this study was 42 K with a high density in its morphological form.

Journal of Metals Materials and Minerals, 30, 3, 9-14

The voltage of thermocouple during process contribution is determined by the absolute thermal electromotive force coefficient in each wire and the temperature difference across the section. This paper described the development of a system as a local heating method for measurements of inhomogeneities in type T thermocouples with various temperature scanning using hot air. The system could control automatically measurement voltage, temperature, distance, and speed of the stepper motor for moving the hot air scanning along with the thermocouple and control with temperature monitoring. Both the measuring and reference junctions were using an ice bath kept at 0 °C. In this paper calculation of interpretation of the measurement results of inhomogeneity using movable heating zone system of type T thermocouples and the system could detected inhomogeneity of thermocouple and there have different characteristics of voltage and seebeck effect.

MgB2 wire has been prepared by powder in tube method using magnesium and boron powder as raw materials. The powders were mixed and ground using an agate mortar for a half hour. Stainless steel SS316 tube (OD 8 mm/ID 5 mm) was filled with mixed powders, then rolled to 4 mm rectangular shape and sintered at 800 °C for 2 hours. Phases of material, microstructure, and resistivity of the specimen were identified and observed. The resistivity of the specimen was measured using the cryogenic magnet system with four point probe method. The transition temperature of the specimen was found 41.8 K (ΔT = 1.3 K).

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...

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...

In this study, we focus on the synthesis of MgB2 polycrystalline by using three different methods. MgB2 polycrystalline was prepared by conventional and mechanical alloying method. Three variations of milling method were used, which are agate mortar for a half hour; High energy ball milling (HEBM) under air atmosphere for 2 hours; and HEBM under argon for 2 hours. MgB2 polycrystalline was prepared using magnesium and boron powder with a ratio of Mg:B =1:2. After milling, the mixed powders were poured into a stainless steel SS304 tube, compacted by the press machine and sintered at 800°C for an hour in an air atmosphere. After sintering, the sample was removed from the tubes and analyzed the phase formation, microstructure, resistivity and critical temperature (Tc) of the samples. Hexagonal phase MgB2 can be seen as a dominant phase for all samples based on a qualitative analysis of X-Ray Diffraction (XRD), but there was a small amount of Mg and MgO phase as impurities. We obtained the qualitative and quantitative analysis of sample mixed with the agate mortar was the optimal sample with less impurity phase compared to other samples. Sample by using HEBM under air has the highest TConset of 42.3 K and TCzero of 41.9 K.

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...

Telah dilakukan sintesis pelet superkonduktor Bi 1.6 Pb 0.4 Sr 2 Ca 1.8 Mg 0.2 Cu 3 O 10+δ menggunakan metode padatan dan proses sintering berulang.Benda uji yang dibuat dianalisis dengan menggunakan XRD (X-ray Diffractometer) dan SEM – EDS (Scanning Elektron Microscopy - Energy Dispersive Spectroscopy). Berdasarkan analisis XRD didapatkan fase yang terbentuk adalah (Bi,Pb)-2223, (Bi,Pb)-2212, CaPbO 3 , Ca 2 PbO 4 dan MgO. Perlakuan sintering berulang pada benda uji BPSCCO doping Mg dapat meningkatkan fraksi volume (Bi,Pb)-2223 dari 37% menjadi 68%. Berdasarkan analisis SEM, didapatkan luas porositas pada morfologi permukaan benda uji sebesar 4,742%. Adapun dengan perlakuan sintering berulang menyebabkan terjadinya penurunan luas porositas dari 4,742% menjadi 2,132% hingga 1,589% untuk benda uji sintering 1 kali, 2 kali, dan 3 kali. Bentuk butir juga semakin lebih seragam akibat dari perlakuan sintering berulang yang diberikan pada sampel.

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.

A four-step process was proposed to manufacture monofilament wire Bi,Pb-Sr-Ca-Cu-O using silver (Ag) sheath fabricated by Powder-In-Tube (PIT) method in which the thickness of wire were subjected to rolling from 10 mm ? to2 mm ? and heated at temperature of 860 ?C in 24 h. The effect of the rolling and heating process on the properties of four samples Ag-sheathed Bi,Pb-Sr-Ca-Cu-O wires in each step were studied. In x-ray diffraction (XRD) patterns of monofilament wire fabricated by PIT method in which the repeated heating process involved in rolling can alter the precursor phase. At a first and second deformation process, samples sintered at 860 ?C in 24 h still contained the constituent elements of precursor powders. Third deformation step were shown to have superconducting phase Bi,Pb-Sr-Ca-Cu-O 2212. According to resistivity measurement analysis, rolling and repeated heating process were shown to have a critical effect on superconductivity. First, second and fourth rolling were found to have no superconductivity, while third rolling were found to exhibit superconductivity of which its value of critical temperature monofilament wire (Tc,onset) was 90 K. Furthermore, according to Scanning Electron Microscopy (SEM) analysis, the rolling and repeated heating process were observed to have important effect on morphology of samples. Wire superconductors on first and second rolling were shown to have crack and high porosity, but after third rolling the crack and porosity were diminished. Overall the deformation process have yielded promising results particularly when the superconducting phase Bi,Pb-Sr-Ca-Cu-O 2212 were found optimum in third deformation process.

Telah dilakukan percobaan pemurnian Metallurgical Grade Silicon (MG-Si) atau silikon tingkat metalurgi melalui proses pelindian. Proses pelindian menggunakan campuran larutan asam pada konsentrasi 2,45 mol/L HCl + 1,2 mol/L HF yang dilakukan dengan memvariasikan waktu pelindian pada suhu 60°C dengan kecepatan putar 300 rpm. Hasil percobaan menunjukkan bahwa proses pelindian MG-Si dengan menggunakan campuran larutan asam pada konsentrasi 2,45 M HCl + 1,2 M HF dapat menurunkan unsur pengotor yang terkandung di dalam MG-Si dan meningkatkan kemurnian seiring peningkatan waktu pelindian. Pada proses pelindian 12 jam, efisiensi ekstraksi unsur pengotor Al dan Fe mencapai 99,99%, sedangkan untuk unsur Ti mencapai 99,96%. Persentase efektivitas dari larutan pelindian selama 12 jam mencapai 99,96%. Pencapaian tersebut berpeluang untuk ditingkatkan dengan memvariasikan konsentrasi maupun waktu pelindian sehingga diperoleh nilai optimal.

Bi 1.6 Pb 0.4 Sr 2 Ca 2 Cu 3 O 10+δ with the addition of carbon nanotubes (CNT) and TiO2 have been synthesized using solid state reaction method with the repeated sintering process. 0.1 wt % of CNT and 5 wt% of TiO2 have been added to analyze the effect on the synthesizing of 2223 phases. The samples were analyzed using XRD (X-ray diffractometer) and SEM (Scanning Electron Microscopy). Based on the XRD results, 2223 and 2212 were formed. The addition of CNTs and TiO2 reduced the intensity of 2223 phases. This is due to the addition of CNTs and TiO2 as an impurity and prevent the formation of the phases. Also, the repeated sintering process led to the increase of 2223 phase, and the decrease of 2212 phase. However, the repeated sintering process in the B-CNT and B-TiO samples eliminates the impurities phase thus increasing the volume fraction 2223 and decreasing the volume fraction 2212. Based on morphological structure through SEM observation, the addition of CNT in the Bi(Pb)-2223 samples formed longer plates with large porosity spaces while the addition of TiO 2 formed clumps on the Bi(Pb)-2223 morphological structure. However, the repeated sintering process improves the morphological structure of B-CNT and B-TiO becomes increasingly denser and the smaller porosity space. Abstrak Telah dilakukan sintesis Bi 1 , 6 Pb 0 , 4 Sr 2 Ca 2 Cu 3 O 10+δ dengan penambahan CNT ( carbon nanotube ) dan penambahan TiO 2 menggunakan metode reaksi padatan dengan proses sintering berulang. Penambahan CNT sebesar 0,1 %berat dan TiO 2 sebesar 5 %berat dan sintering berulang dilakukan untuk mempelajari pengaruhnya terhadap pembentukan fasa 2223 beserta pengotornya, dan mempelajari perubahan morfologi Bi 1 , 6 Pb 0 , 4 Sr 2 Ca 2 Cu 3 O 10+δ . Bi 1 , 6 Pb 0 , 4 Sr 2 Ca 2 Cu 3 O 10+δ yang dibuat dianalisis dengan XRD ( x -ray diffractometer ) dan SEM ( s canning e le c tron m icroscopy ). Berdasarkan hasil XRD, penambahan 0,1 %berat CNT dan TiO 2 sebesar 5 %berat pada superkonduktor Bi(Pb)-2223 diketahui menghasilkan fasa 2223, fasa 2212, dan juga fasa pengotor. Namun proses sintering berulang mampu mengurangi fasa impuritas, meningkatkan fraksi volume 2223, serta menurunkan fraksi volume 2212. Berdasarkan pengamatan struktur morfologi melalui SEM, penambahan CNT pada superkonduktor Bi(Pb)-2223 membentuk serpihan memanjang dengan ruang porositas yang besar sedangkan penambahan TiO 2 membentuk gumpalan pada struktur morfologi Bi(Pb)-2223. Proses sintering berulang mampu memperbaiki struktur morfologi B-CNT dan B-TiO menjadi semakin rapat dan ruang porositas yang semakin kecil.

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.

CaMnO 3 merupakan senyawa oksida dengan potensi aplikasi yang cukup luas, salah satunya yaitu thermoelectric . Sintesis CaMnO 3 menggunakan bahan baku gugus karbonat berhasil dilakukan melalui metode reaksi padatan. Sintesis diawali dengan pencampuran kedua bahan baku secara stoikiometri dan dilanjutkan dengan penggerusan, kalsinasi, peletisasi dan penyinteran pada variasi suhu 1100, 1200 dan 1250 o C. Pengamatan XRD menunjukkan kecenderungan pola difraksi yang sama pada tiap temperatur serta menunjukkan terbentuknya fasa tunggal CaMnO 3 . Nilai parameter kisi kristal CaMnO 3 hasil penghalusan menggunakan metode Rietvield dengan sistem kristal orthorombic dan space group Pnma adalah a = ~5,26 A; b = ~7,44 A; dan c = ~5,27 A. Mikrostruktur yang ditampilkan oleh mikroskop elektron menunjukkan bahwa semakin tinggi suhu, ukuran butir akan semakin kecil dan kerapatan butir semakin meningkat. Abstract CaMnO3 is metal oxide compound with wide potential applications i.e thermoelectric. Synthesis of CaMnO3 using carbonat groups material has been succesfully carried out through solid state reaction method. It is started by mixing of both CaCO3 and MnCo3 raw materials at a stoichimometri composition and followed by grinding, calcinating, pelletizing and sintering at various temperatures of 1100 oC, 1200 oC and 1250 oC. XRay diffraction results for all specimens show similar pattern at each temperature condition, namely the formation of single phase CaMnO3. Crystal lattice from refinement with Rietviled method that has been identified in orthorombic crystal system and Pnma space group was a = ~5,26 A; b = ~7,44 A; dan c = ~5,27 A. Microstructure of CaMnO3 phase shows that increasing temperature will increase grain density and reduce grain space.