[13a-D62-1~11] 6.4 薄膜新材料

▲ [13a-D62-2] Optimization of Thin Film Growth of Doped NEG-123 Superconductor

〇(PC)Shiv Jee Singh¹、Paolo Mele¹、Miryala Muralidhar² (1.Muroran Inst Tech、2.Shibaura Inst Tech)

キーワード：High temperature Superconductor, Transition temperature, Critical current density

Oxygen controlled melt growth (OCMG) processed (Nd,Eu,Gd)Ba₂Cu₃O_y “NEG-123” doped with very small amount of nanometer sized particles like TiO₃, MoO₃ and Nb₂O₅ exhibited an improvement in pinning performance. As a result, a high critical current density (J_c) value of ~10⁵ A/cm² was achieved at 90.2 K. Technical applications of high T_c superconductors (HTS) also require the development of simple methods to produce with appropriate superconducting properties. We have studied and optimized the superconducting properties of doped REBa₂Cu₃O_y “RE123” thin film composites by nanoparticles based on a control of the growth conditions. In this study, we focus on (Nd_0.33Eu_0.33Gd_0.33)Ba₂Cu₃O_y (NEG-123) + Gd₂BaCuO₅ (Gd-211), which has reported excellent critical current density (J_c) in the bulk form, and fabricated NEG-123 + Gd-211 thin film with high superconducting properties. NEG-123 + Gd-211 films have grown on STO (SrTiO₃) substrate by PLD method. We shall discuss the optimization of growth of thin film on different heating temperature inside chamber in a very broad range of temperature from 700 to 900°C, the distance between target and substrate, and the O₂ pressure inside the chamber. A broad spectrum of characterizations involving X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), magneto-resistance, magnetization and specific heat measurements have been undertaken on these films. All these thin films are characterized under exactly same conditions and our study shows that the grown film at 800°C has showed the transition temperature (T_c) of 93K as similar to that reported value for the polycrystalline sample. We will also demonstrate and discuss the effect of O₂ gas annealing of thin film inside the furnace at different pressure and annealing time and will conclude the best conditions to grow the high quality thin film of NEG-123+Gd-211 with high superconducting properties