Addition of alternate phase nanoparticle dispersions to enhance flux pinning of Y-Ba-Cu-O thin films

Abstract

The public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this bu den estimate or any other aspect of this collection of information, including suggestions for reducing this burden, This is a work of the U.S. Government and is not subject to copyright protection in the United States. ABSTRACTNanoparticle dispersions of various phases were added to YBa2Cu307, (YBCO or 123) thin films by multilayer pulsed laser deposition, to determine their effect on flux pinning. The different pinning materials examined include Y2BaCu05 (Y211 or green-phase), La2BaCu05 (La211 or brown-phase),Y 203, Ce02, and MgO, with lattice constant mismatches varying from 0.5% to 12% with respect to YBCO. Y211 and Y203 provided significant pinning increases at temperatures of 65 K and 77 K, however other phases provided enhancements only at 65 K (for Ce0 2 and La211) for limited range of applied field strengths. An interesting correlation between T e transition widths and pinning strengths was observed. The additions produced markedly different nanoparticle and film microstructures,as well as superconducting properties. SUBJECT TERMS

Deposition of (Y2BaCuO5/YBa2Cu3O7−x)×N multilayer films on Ni-based textured substrates

“…Transition temperatures of multilayer {(211 $1.2 nm /123 $11 nm ) · N, N = 20-25} and 123-only samples were virtually the same $89-90 K measured at AFRL by ac susceptibility methods [16] and at ORNL by transport methods. This is slightly different from T c measurements on single crystals where a small decrease of $1-2 K was measured for similar multilayer compared to 123 films [15].…”

“…Buffered Ni 0.97 W 0.03 (Ni-W) substrates were prepared at Oak Ridge National Laboratory (ORNL) and American Superconductor Corporation (AMSC) using similar procedures [11], and buffered Ni substrates were prepared at Air Force Research Laboratory (AFRL) [16] [11,16]. Buffered Ni substrates were prepared with a cap layer of CeO 2 $70 nm thick, an intermediate layer of YSZ $500 nm thick, and a seed layer of CeO 2 $70 nm, using pulsed laser deposition (PLD) for all buffer layers [16].…”

“…Buffered Ni substrates were prepared with a cap layer of CeO 2 $70 nm thick, an intermediate layer of YSZ $500 nm thick, and a seed layer of CeO 2 $70 nm, using pulsed laser deposition (PLD) for all buffer layers [16].…”

Superconducting Properties of (M x /YBa2Cu3O7−δy )N Multilayer Films with Variable Layer Thickness x

“…[2][3][4] Many methods of introducing defects can be considered to increase flux pinning in YBCO, [2][3][4] and recent efforts have studied the use of (M x /123 y ) N heterostructures to introduce~3 to 20 nm-size island-growth nanoparticles or even larger-diameter plate-like defects into the films. [5][6][7][8][9][10][11][12][13][14][15][16][17] A number of different second-phase additions M have been tested, including M = green-phase 211, 5-12 Y 2 O 3 , 11,12,14,15 CeO 2 , [11][12][13] IrZrO 3 , 16 BaZrO 3 , 17 and other phases with negative effects on T c and/or J c (H) including M = La211, 11,12 MgO, 11,12 and Sm123. 12 Studies of (M x /123 y ) N heterostructures can provide basic information about the relative pinning properties of different M phases, and specific parameters of flux pinning such as the effects of different layer spacings.…”

“…[5][6][7][8][9][10][11][12][13][14][15][16][17] This paper presents a systematic comparison of film properties for selected M phases and different x layer thickness. A significant result observed is that the surface coverage is an important constant factor to optimize flux pinning, regardless of the M phase.…”