Pr Doped YBCO Films Produced by Pulsed Laser Deposition

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0946-HH09-09

Pr Doped YBCO Films Produced by Pulsed Laser Deposition B. Craig Harrison1, Joseph W. Kell1, Paul N. Barnes1, Timothy J. Haugan1, Chakrapani V. Varanasi1,2, Manisha V. Rane3, Frank Ramos3, and Iman Maartense2,4 1 Air Force Research Laboratory, 2645 5th st., bldg. 450, WPAFB, OH, 45433 2 University of Dayton Research Institute, Dayton, OH, 45469 3 Albany State University, 251 Fuller Road, Albany, NY, 12203 4 Air Force Research Laboratory, bldg. 652, WPAFB, OH, 45433

ABSTRACT Pr doped YBa2Cu3O7-d targets with composition Y1-xPrxBa2Cu3O7-d where x = 0.0001, 0.001, 0.01, and 0.1 were prepared from oxide powders and used to deposit thin films by pulsed laser deposition using conditions previously optimized for pure YBa2Cu3O7-d. The Pr dopant was found to be dispersed throughout the film by secondary ion mass spectrometry and the doped films had an increased density of nanoparticles on the surface. The pinning force of the doped samples was found to decrease with increasing concentration of Pr; however, several concentrations displayed pinning forces that surpassed pure YBCO. At 0.01% Pr concentration, the doped film displayed a significant enhancement over pure YBa2Cu3O7-d for nearly the full range of 0 – 9 T. This study was conducted in order to determine a method of doping YBa2Cu3O7-d to achieve high in-field critical current densities while allowing the processing conditions to remain unchanged. INTRODUCTION YBa2Cu3O7-d (YBCO) in the form of a biaxially aligned film on a buffered metallic substrate is currently being pursued as a high temperature superconductor (HTS) coated conductor for a variety of power applications. Some of the applications under consideration, such as motors and generators, will subject coated conductor to large magnetic fields where the performance of YBCO is suppressed1. Although a critical current density (Jc) of ~106 A/cm2 is regularly attained in YBCO thin films under self-field conditions, magnetic fields in excess of 1T applied along the c-axis direction tend to reduce the Jc by an order of magnitude. Therefore, further improvement to the Jc is desired in order to use YBCO coated conductor in the full spectrum of high field applications as well as to minimize the size and weight of the power systems.

One possible method of achieving the desired Jc(H) values is to incorporate well-dispersed, artificial, magnetic flux pinning centers into the YBCO lattice2-7. These pinning centers can consist of nonsuperconducting particulates2-4 or secondary superconducting phases5-7. Doping YBCO with rare earth (RE) elements can lead to the formation of both types of pinning centers. Nonsuperconducting particulates form when the RE elements react to form a nonsuperconducting phase, while secondary superconducting phases form when other RE elements substitute for yttrium in the crystal lattice. Due to the difference in ionic radius between the other RE elements and Y, replacement atoms may cause strain induced improvements. Modest improvements can be achieved with substitution in quantities

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