Phase Formation and Melt Processing of Yb-123

Authors: Athur S.P.¹; Putman P.¹; Balachandran U.²; Salama K.¹

Source: Journal of Superconductivity: Incorporating Novel Magnetism, Volume 11, Number 5, October 1998 , pp. 525-531(7)

Publisher: Springer

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Abstract:

The formation of Yb-123 has been studied at different temperatures in air and in reduced oxygen partial pressure. It is found that the stability and/or the formation kinetics of Yb-123 phase is a major hurdle in manufacturing phase-pure Yb-123 in air. However, under reduced oxygen partial pressure, Yb-123 forms rapidly and more than 90% phase-pure Yb-123 is achieved within three sintering steps. Rods made from this powder were melt-processed in air and showed a T_c of 90 K. Kinetic studies performed by interrupting the growth during the directional solidification of these rods revealed a growth mechanism similar to that of Y-123 and a maximum growth rate of 7.2 mm/h for a stable planar interface. EPMA of the interface showed the liquid to be rich in barium cuprates with a Ba:Cu ratio of 1:3.

Keywords: Yb-123; melt processing; phase formation; reduced oxygen partial pressure

Language: English

Document Type: Research article

Affiliations: 1: Texas Center for Superconductivity and Department of Mechanical Engineering, University of Houston, Houston, Texas 77204 2: Energy Technology Division, Argonne National Laboratory, Illinois 60349

Publication date: 1998-10-01