[22a-E205-1~12] 10.5 Application of magnetic field

[22a-E205-10] Determination of crystal forms in DyBa₂Cu₃O_7-δ powder by in-situ X-ray diffraction measurements under static and rotating magnetic fields

〇Fumiko Kimura¹, Shintaro Adachi¹, Shigeru Horii¹, Tsunehisa Kimura² (1.Kyoto Univ. Adv. Sci., 2.Fukui Univ. Tech.)

Keywords:high temperature superconductor, magnetic orientation, X-ray diffraction

The superconducting properties of DyBa₂Cu₃O_7-δ (0 ≤ δ ≤ 1), which is a superconducting ceramic with a high critical temperature, are sensitive to the amount of oxygen. Since the crystal structure depends on the amount of oxygen, powder XRD can be used to evaluate the superconducting characteristics of the sample. Dy123 is tetragonal and does not show superconductivity when the amount of oxygen is low. On the other hand, when the amount of oxygen is large, it becomes orthorhombic and shows superconductivity. Especially if the value is close to the transition region of the crystal system, it may be a mixture of orthorhombic crystals with slightly different a-axis and b-axis lengths and tetragonal crystals with equal a-axis and b-axis lengths. In such cases, the evaluation of the crystal structure becomes complicated and the evaluation of the sample by powder XRD becomes difficult.
On the other hand, it has been reported that the distinction between tetragonal system and orthorhombic system can be made by utilizing the difference in magnetic susceptibility anisotropy between the two crystal systems. In this study, we report the crystal system of Dy123 crystals near the transition point by 2D (two-dimensional) XRD diffraction images obtained from the magnetic field orientation of the crystallite suspension.