Ph.D. Tezi Görüntüleme

Student:	Kemal ÖZTÜRK
Supervisor:	Prof. Dr. Ekrem YANMAZ
Department:	Physics
Institution:	Graduate School of Natural and Applied Sciences
University:	Karadeniz Technical University, Turkey

Title of the Thesis:	THE EFFECT OF GADOLINIUM AND YTTERBIUM DIFFUSION ON STRUCTURAL AND SUPERCONDUCTING PROPERTİES OF YBA_2CU_3O_(7-X)
Level:	Ph.D.
Acceptance Date:	20/10/2006
Number of Pages:	140
Registration Number:	di571

Summary:

This study deals with the thermal diffusion of gadolinium (Gd) and ytterbium (Yb) into the polycrystalline Y123 superconductor to understand the diffusion-induced variation of physical and structural properties. Ultimately, attempts are made to comprehend the mechanism of superconductivity and improve the properties of the superconductivity.

The Y123 samples which were diffusion-doped at various temperatures were prepared by solid-state reaction method. Values of diffusion coefficient (D) and activation energy (E_a) for Gd and Yb diffusion were determined by EDXRF method. Structural properties of the samples subjected to Gd and Yb diffusion were determined by X-ray diffraction analysis, scanning electron microscopy and optical light microscopy while electrical and magnetic properties by the R-T and M-H measurements by means of vibration sample magnetometer. Values of activation energy (U) and upper critical magnetic field (H_(c2)) were computed by use of the resistance measurements, whereas critical current density (J_c) from the magnetization measurements.

Keywords : YBa_2Cu_3O_(7-x), Gd and Yb diffusion, Activation energy, Upper critical magnetic field, M-H loops, Critical current density