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"[ABSTRAKPemanfaatan panas yang tidak terpakai adalah salah satu bentuk efisiensi energi.Panas yang tidak terpakai dari industri dan transportasi dapat dikonversikanmenjadi energi listrik dengan menggunakan material termoelektrik. KeramikCa3Co2O6 dan CaMnO3 adalah salah satu contoh material. Penelitian yangdilakukan adalah percobaan sintesis keramik Ca3Co2O6 dan CaMnO3menggunakan metode proses reaksi padatan.Sintesis material menggunakan bahan baku berbasis karbonat, yaitu CaCO3,CoCO3 dan MnCO3. Sintesis dilakukan dengan mengacu pada diagram fasasistem Ca-Co-O dan Ca-Mn-O. Berdasarkan analisis termal, untuk mendapatkanfasa CaO, Co3O4 dan Mn2O3 maka bahan baku yang berbasis karbonat harusdikalsinasi pada suhu ≥ 800°C. Suhu pembentukan Ca3Co2O6 berdasarkandiagram fasa sistem Ca-Co-O dan Ca-Mn-O adalah pada rentang suhu 824-1027°C dan CaMnO3 pada rentang suhu 1100-1600°C dengan lingkunganatmosfir udara bebas.Hasil sintesis diperoleh fasa Ca3Co2O6 terbentuk paling baik pada suhu 1000°C,tetapi masih terdapat fasa lain yaitu CoO dan Co3O4. Fraksi berat masing-masingfasa adalah Ca3Co2O6 : CoO : Co3O4 = 71,1 : 21,6 : 7,3. Sedangkan pada sintesisCaMnO3, fasa CaMnO3 sudah terbentuk satu fasa pada suhu 1100°C.

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ABSTRACTHeat is one kind of energy source that can increases energy efficiency. Heat fromindustrial and transportation can be converted into electrical energy through athermoelectric material. Ca3Co2O6 and CaMnO3 ceramics are thermoelectricmaterials. The main idea of this research is synthesis of Ca3Co2O6 and CaMnO3ceramics using solid state reaction method.Synthesis of thermoelectric materials using carbonate-based raw materials. Theraw materials are CaCO3, CoCO3 and MnCO3. Synthesis of material is done withreference to the phase diagram system of Ca-Co-O and Ca-Mn-O. Based onthermal analysis, the carbonate-based raw materials must be calcined attemperature ≥ 800°C to get CaO, Co3O4 and Mn2O3 phases. The temperatureformation of Ca3Co2O6 and CaMnO3 are about 824-1027°C based on phasediagram system of Ca-Co-O and 1100-1600°C based on phase diagram system ofCa-Mn-O in air.Ca3Co2O6 phase is formed at temperatures of 1000°C, but there were some otherphase, i.e,. CoO and Co3O4. Weight fraction of each phase is Ca3Co2O6 : CoO :Co3O4 = 71,1 : 21,6 : 7,3. While CaMnO3 one phase is already formed at 1100°C.;Heat is one kind of energy source that can increases energy efficiency. Heat fromindustrial and transportation can be converted into electrical energy through athermoelectric material. Ca3Co2O6 and CaMnO3 ceramics are thermoelectricmaterials. The main idea of this research is synthesis of Ca3Co2O6 and CaMnO3ceramics using solid state reaction method.Synthesis of thermoelectric materials using carbonate-based raw materials. Theraw materials are CaCO3, CoCO3 and MnCO3. Synthesis of material is done withreference to the phase diagram system of Ca-Co-O and Ca-Mn-O. Based onthermal analysis, the carbonate-based raw materials must be calcined attemperature ≥ 800°C to get CaO, Co3O4 and Mn2O3 phases. The temperatureformation of Ca3Co2O6 and CaMnO3 are about 824-1027°C based on phasediagram system of Ca-Co-O and 1100-1600°C based on phase diagram system ofCa-Mn-O in air.Ca3Co2O6 phase is formed at temperatures of 1000°C, but there were some otherphase, i.e,. CoO and Co3O4. Weight fraction of each phase is Ca3Co2O6 : CoO :Co3O4 = 71,1 : 21,6 : 7,3. While CaMnO3 one phase is already formed at 1100°C., Heat is one kind of energy source that can increases energy efficiency. Heat fromindustrial and transportation can be converted into electrical energy through athermoelectric material. Ca3Co2O6 and CaMnO3 ceramics are thermoelectricmaterials. The main idea of this research is synthesis of Ca3Co2O6 and CaMnO3ceramics using solid state reaction method.Synthesis of thermoelectric materials using carbonate-based raw materials. Theraw materials are CaCO3, CoCO3 and MnCO3. Synthesis of material is done withreference to the phase diagram system of Ca-Co-O and Ca-Mn-O. Based onthermal analysis, the carbonate-based raw materials must be calcined attemperature ≥ 800°C to get CaO, Co3O4 and Mn2O3 phases. The temperatureformation of Ca3Co2O6 and CaMnO3 are about 824-1027°C based on phasediagram system of Ca-Co-O and 1100-1600°C based on phase diagram system ofCa-Mn-O in air.Ca3Co2O6 phase is formed at temperatures of 1000°C, but there were some otherphase, i.e,. CoO and Co3O4. Weight fraction of each phase is Ca3Co2O6 : CoO :Co3O4 = 71,1 : 21,6 : 7,3. While CaMnO3 one phase is already formed at 1100°C.]"

"MgB2 merupakan senyawa material superkonduktor yang berpotensi untuk diaplikasikan sebagai penghasil medan magnet kuat. Pada penelitian ini superkonduktor MgB2 difabrikasi dalam bentuk kawat dan padatan. Keberhasilan fabrikasi terletak pada terbentuknya fasa MgB2 yang minim pengotor. Preparasi material untuk superkonduktor MgB2 dilakukan melalui metode reaksi padat konvensional dengan bahan baku magnesium kristalin dan boron semikristalin. Upaya perbaikan karakteristik superkonduktor MgB2 diawali dengan mempelajari pengaruh rasio Mg:B terhadap pembentukan fasa dan sifat superkonduktornya. Berdasarkan hasil karakterisasi XRD, fraksi massa fasa MgB2 tertinggi mencapai 98,73% diperoleh dengan rasio Mg:B=0,9:2. Nilai Tc-zero mengalami kenaikan dari 41,41 K menjadi 42,28 K. Rekayasa material mencakup struktur sel fasa MgB2 dengan menggantikan atom B secara parsial dengan atom C dilakukan melalui metode reaksi padat konvensional. Rekayasa material pada proses substitusi parsial karbon nanopartikel terhadap fasa MgB2 menjadi Mg0.9(B1-xCx)2 (x=0;0,0125;0,025;0,05) menurunkan nilai konstanta kisi a. Penurunan konstanta kisi tersebut berkorelasi dengan penurunan nilai suhu kritis dari 38,83 K pada x = 0 menjadi 36,43 K pada x = 0,05. Peningkatan nilai magnetisasi diperoleh pada substitusi karbon sebesar 0,025. Dalam bentuk kawat MgB2 filamen tunggal telah berhasil diperoleh superkonduktor dengan nilai Tc-zero tertinggi sebesar 40,57 K.

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The MgB2 is a superconducting phase which may be applied as a producer of strong magnetic fields. In this study, the MgB2 superconductor was made in the form of wire and bulk. The success of the manufacture of superconducting material lies in the formation of the MgB2 phase which presents a minimum of impurities in the wire. The preparation of the materials for the superconducting MgB2 was carried out by the conventional solid-state reaction using crystalline magnesium and semicrystalline boron as raw materials. Efforts to improve the characteristics of the MgB2 superconductor begin by studying the effect of the Mg:B ratio on the formation of the MgB2 phase and its superconducting properties. Based on the results of XRD characterization, the highest mass fraction of MgB2 phase reached 98.73% obtained with a ratio of Mg:B=0.9:2. The Tc-zero value increased from 41.41 K to 42.28 K. The study involves modifying the cell structure of the MgB2 phase by partly replacing atom B with atom C through a solid-state reaction. With partial substitution of nanocarbon to B in phase MgB2 to Mg0.9(B1-xCx)2 (x=0;0.0125;0.025;0.05), the value of the lattice constant a decreased. The decrease in the lattice constant correlates with a decrease in the critical temperature value from 38.83 K at x = 0 to 36.43 K at x = 0.05. The increase in the magnetization value was obtained at the carbon substitution of 0.025. Based on the findings of this study, we were able to obtain a MgB2 monofilament wire the highest Tc-zero value of 40.57 K."