SIFAT LISTRIK SUPERKONDUKTOR YBa2Cu3O7-x HASIL PROSES PELELEHAN DENGAN DOPANT Ti[Electrical Characterictic of YBa2Cu3O7-x Superconductor Doped by Ti Using Melting Process] - Winataputra, Didin S; MP, Yustinus; AA, Wisnu; Deswita, Deswita; Sukirman, E (Pusat Penelitian Metalurgi dan Material - LIPI, 2012)
SIFAT LISTRIK SUPERKONDUKTOR YBa2Cu3O7-x HASIL PROSES PELELEHAN DENGANDOPANT Ti. Telah dilakukan pembuatan superkonduktor YBa2Cu3O7-x (YBCO) yang didoping Ti melaluiproses modified melt textured growth (MMTG). Pembuatan cuplikan dilakukan melalui reaksi padatan dengancara menambahkan serbuk Ti ke dalam prekursor YBCO dengan variasi komposisi 0,4 % berat, 0,7 % berat, 1,0% berat dan 1,3 % berat. Proses pelelehan YBCO dilakukan pada 1100 °C selama 12 menit, kemudian didinginkan dengan cepat ke 1000 °C dan diikuti dengan pendinginan lambat ke 960 °C. Identifikasi fasa di dalam cuplikan dilakukan dengan menganalisis pola difraksi sinar-X dengan metode Rietveld. Rapat arus, Jc dan suhu kritis, Tc diukur menggunakan four point probe (FPP). Struktur mikro dan komposisi fasa cuplikan diamati dengan scanning electron microscope (SEM) dan energy dispersive x-ray spectroscopy (EDS). Hasil pengamatan menunjukkan bahwa cuplikan merupakan bahan superkonduktor Tc tinggi (STT). YBa2Cu3O7-x/Ti - fasa 123 berstruktur kristal ortorombik dari grup ruang Pmmm no. 47. Rapat arus kritis, Jc cuplikan Y-0Ti diperoleh sekitar 67 A.cm-2 dan kemudian turun terus dengan kenaikan prosentase doping Ti hingga Jc » 4 A.cm-2. Menyusutnya harga Jc disebabkan Ti tidak dapat mencegah pertumbuhan fasa 211. Bila kandungan Ti bertambah, fasa 211 juga bertambah dengan distribusi tidak homogen dan tumbuh terus serta terbentuk retakan mikro yang sejajar dan memotong butiran YBCO. Akibatnya, fasa YBCO berukuran lebih pendek dan kecil dibandingkan fasa YBCO tanpa doping Ti. Demikian juga, dengan bertambahnya kandungan Ti menyebabkan suhu kritis (Tc) berkurang dari 365 °C menjadi 350 °C. AbstractELECTRICAL CHARACTERICTIC OF YBa2Cu3O7-x SUPERCONDUCTOR DOPED BY Ti USINGMELTING PROCESS. Synthesis of YBa2Cu3O7-x (YBCO) superconductor which is doped by Ti usingmodified melt-textured growth (MMTG) method has been done. The specimen was made by solid state reaction by adding Ti powder to precursor of YBCO result with composition variation (in weight %) of 0.4, 0.7, 1 and1.3. The melt process of YBCO was done at 1100°C for 12 minutes then cooled rapidly to 1000°C followed by slow cooling to 960°C. Identification of the specimen phase was verified using x-rays diffraction (XRD) and followed by Rietveld method analysis. The critical temperature, Tc and current density, Jc were measured by means of four point probe (FPP). The microstructure and chemical composition of the specimen were observedusing scanning electron microscope (SEM) and energy dispersive x-ray spectroscopy (EDS). The result shows that the specimen was YBa2Cu3O7-x high Tc superconductor of 123-phase having orthorhombic crystal structure of Pmmm no. 47 space group. The critical current density, Jc of the specimen was obtained about 67A.cm-2 and then decreased continuously with increasing of Ti dopant till Jc » 4A.cm-2. Decreasing of Jc caused by Ti cannot prevent the growth of 211 phases. In increasing Ti content, 211 phases also increase with unhomogeneousdistribution and continue to grow. There is also formation ofmicrocracks parallel to and crossing the YBCO grains. As a result, YBCO have smaller and shorter grain size compared to YBCO grain without Ti doping. Increasing of Ti content also cause decrease from 365 °C to 350 °C.