Preparation and properties of c-axis-oriented NdBa2Cu3O7-delta films by dcsputtering

NdBa2Cu3O7-delta (NdBCO) is known to have the highest T-c, among the rare e arth REBa2Cu3O7-delta (RBCO) family, and to show higher irreversibility fie lds than YBa2Cu3O7-delta (YBCO). Recently, excellent superconducting NdBCO films have been synthesized by a laser ablation technique. In this work, th e transition temperature, phase and growth morphology of NdBCO films deposi ted on (100) SrTiO3 (STO) and (100) MgO substrates by dc sputtering have be en investigated. The transition temperature T-c is closely related with the c-axis lattice constant and shows a maximum around 1.173 nm. The c-axis la ttice constant of the films strongly depends on oxygen pressure P-o. High-T -c NdBCO films are obtained around P-o = 350 Pa. The spiral growth morpholo gy of the films is affected by deposition rate and takes place at low depos ition rate. The best film has shown a zero resistance transition temperatur e of 92.6 K. (C) 1999 Elsevier Science B.V. All rights reserved.