Effect of BaCeO₃ and BaSnO₃ Additives on Microstructural Development and Critical Current Density of Melt Textured YBa₂Cu₃O₇₋ₓ

Improvement of superconducting properties, such as critical current density Jc and trapped magnetic field, of melt textured YBa2Cu3O7-x (Y123) require introducing of effective pinning sites, e.g., nonsuperconducting inclusions, twin boundaries and other defects. It has been shown that addition of small quantities of BaCeO3 (\u3c0.5 wt%) into Y123 results in an increase of the Jc. However, higher cerium concentrations affect the solidification process and inhibit the growth of melt textured Y123 single crystals. In this study, the effect of BaCeO3 additions on the growth and microstructural development of melt textured Y123 single crystals were investigated. The relationship between the solidification kinetics, microstructural development and superconducting properties of Y123 melt textured single crystals with cerium additives is discussed

Neodymium Oxide Doped Melt Textured YBa₂Cu₃O₇₋ₓ Single Crystals

Processing, microstructure and property relationships in neodymium oxide doped high temperature superconducting YBa2Cu3O7-x (Y123) were investigated. It has been observed that a small amount (~ 0.25 - 1 mol%) of Nd2O3 results in the formation of nanosized secondary phases which may have a significant effect on the superconducting properties of melt textured Y123 single crystals. It was further observed that addition of Nd2O3 greater than 1 mol% leads to multiple nucleation during solidification of Y123 and results in polycrystalline samples. Melt textured single crystals of Y123 with \u3c 1 mol% were successfully grown and characterized with respect to microstructural development and superconducting properties

FLYWHEEL ENERGY STORAGE SYSTEMS WITH SUPERCONDUCTING BEARINGS FOR UTILITY APPLICATIONS

This project’s mission was to achieve significant advances in the practical application of bulk high-temperature superconductor (HTS) materials to energy-storage systems. The ultimate product was planned as an operational prototype of a flywheel system on an HTS suspension. While the final prototype flywheel did not complete the final offsite demonstration phase of the program, invaluable lessons learned were captured on the laboratory demonstration units that will lead to the successful deployment of a future HTS-stabilized, composite-flywheel energy-storage system (FESS)

Evaluation of YBa₂Cu₃O₇₋ₓ Bulk Superconductors for High Field Magnet Applications

Processing of YBCO single crystals was carried out by solidification of semi-liquid YBCO composition using a seeding technique. Microstructural characterization of the pinning centers was investigated by transmission electron microscopy. Characterization of single crystals was carried out, relating grain size and shape to the corresponding flux profiles. Current densities were calculated based on measured trapped fields. Once circulating currents were established, flux pumping and quenching experiments were conducted. These large single crystals will be incorporated into electromagnetic forming devices for use in the military and commercial aircraft manufacturing and service industries

Design, Fabrication, and Test of a 5-kWh/100-kW Flywheel Energy Storage Utilizing a High-Temperature Superconducting Bearing

The summaries of this project are: (1) Program goal is to design, develop, and demonstrate a 100 kW UPS flywheel electricity system; (2) flywheel system spin tested up to 15,000 RPM in a sensorless, closed loop mode; (3) testing identified a manufacturing deficiency in the motor stator--overheats at high speed, limiting maximum power capability; (4) successfully spin tested direct cooled HTS bearing up to 14,500 RPM (limited by Eddy current clutch set-up); (5) Testing confirmed commercial feasibility of this bearing design--Eddy Current losses are within acceptable limits; and (6) Boeing's investment in flywheel test facilities increased the spin-test capabilities to one of the highest in the nation

Final Scientific/Technical Report

Boeing Phantom Works and its team originally proposed a three-year Phase III SPI project to develop a 30-kWh flywheel with a 100 kW power capability as a power risk management system (RMS) for power users and providers. The chief objectives for the Risk Management System Flywheel were to (1) demonstrate its ability to protect a critical load such as a small data center from swings in power availability, cost, and power factor and (2) show that the RMS flywheel can perform these functions with reduced noise, emissions, and operating costs when compared with non-HTS competitors including batteries, diesel generators, and microturbines

The Effect of Platinum and Excess 211 Phase on the Loss of the Liquid Phase in Melt Textured Yba₂Cu₃O₇₋ₓ

Platinum is an important additive in YBa/sub 2/Cu/sub 3/O/sub 7-x/ [123] powders for melt processing and growth of large oriented crystals, but its role in liquid loss during the growth cycle is poorly understood. A series of experiments were conducted to determine how platinum effects liquid loss, and to study the solubility limit of platinum in 123. Both atomically mixed and solid state platinum sources were compared. Crystals were grown on a nonreactive setter so that liquid loss could be clearly distinguished by weight from reaction products with the setter. Based on weight loss studies there was little difference between atomically added platinum and by adding platinum powder to the 123 powder. In samples with no excess Y/sub 2/BaCuO/sub 5/ (211), weight loss due to liquid loss was at a minimum of 3.8 percent with 0.3 weight percent platinum content. Examination with an electron microprobe reveals different microstructures for the two different methods of platinum additions

Processing of Erbium Doped High-T\u3csub\u3ec\u3c/sub\u3e Superconductor Yba₂Cu₃O₇₋ₓ Single Crystals For Improved Flux Pinning

The effect of selected rare earth (RE) oxide addition on growth behavior of large single crystals and the superconducting properties of YBa2Cu3O7-x (Y123) was investigated. the results show that even a small amount (%) of rare earth addition can have a significant effect on the flux pinning capacity of Y123 single crystals. It was further observed that for Nd and Yb the continuous crystal growth became very unstable for additions greater then 1 mol % while crystal growth remains stable even for additions up to 30 mol % Er2BaCuO5. Magnetization measurements on RE-doped Y123 single domains revealed relatively high Jc, values as compared to undoped Y123 single crystals