Variasi Tekanan Oksigen dalam Penumbuhan Kristal Tunggal Superkonduktor Bi2Sr2CaCu2O8+δ

Darminto Darminto, A.A. Nugroho, A.A. Menovsky, A. Rusydi, W. Loeksmanto

Abstract


Sari. Dalam tulisan ini disajikan hasil pembuatan kristral tunggal bahan superkonduktor Bi2Sr2CaCu2O8+δ dengan metode travelling solvent floating zone (TSFZ) dalam atmosfer yang benvariasi, yaitu dalam udara dan dalam oksigen (O2) 1 bar dan 2,5 bar. Variasi kadar oksigen yang terjadi dalam kristal sebagai akibat variasi atmosfer telah menyebabkan perbedaan komposisi molar dalam kristal yang terbentuk dan pembentukan fasa takmurnian. Hasil karakterisasi menuniukkan bahwa meningkatnya kadar oksigen dalam Kristal yang bersangkutan menurunkan suhu kritis (Tc) dan parameter anisotropi (γ). Penurunan anisotropi selanjutnya memperbesar medan puncak kedua(H2p) dan menggeseer garis takreversibel (Hirr) ke arah suhu dan medan magnet yang lebih tinggi dalam diagram fasa H-T, yang menunjukkan peningkatan efek pinning vorteks sebagai akibat peningkatan kadar dopan oksigen.

 

Variation of Oxygen Pressure in Growing Bi2Sr2CaCu2O8+δ Single Crystal Superconductors and its Effects

Abstract. This paper presents the results of growing Bi2Sr2CaCu2O8+δ single crystal superconductors by means of traveling  solvent floating zone (TSFZ) method in various atmospheres, namely in air and in oxygen (O2) of 1 and 2.5 bar. Variations of oxygen contents due to different atmospheres in the growing process lead to a variety of molar compositions of the as-grown crystals as well as formation of impurity phases. It is found from the result of sample characterization that the incrcase of oxygen content in the crystal lowers its critical temperature (Tc) and anisotropy (γ). Further the lowering of anisotropy incrcases the second peak field (H2p) and causes a shift of the irreversibility line (Hirr) to the higher temperature and magnetic field in the H-T phase diagram, signifying the enhancement of vortex pinning effect due to increasing concentration of oxygen dopant.


Keywords


single crystal; superconductors; oxygen doping; anisotropy; magnetic properties; pinning effect; Kristal tungggal; superkonduktor; doping oksigen; anisotropi; sifat magnetic; efek pinning.

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