Pinning centres in NEG-123 active at liquid oxygen temperature (90.2 K)

Abstract

We present a new type of (Nd,Eu,Gd)Ba2Cu3Oy ‘NEG-123’ material for superconducting permanent magnets for use at liquid oxygen temperature(90.2 K). This material exhibits an exceptionally high flux pinning up to the close vicinity ofTc. The improvement of the flux pinning was achieved by externally added ball-milledsecondary phase particles that partially transformed during the technological process to anew type of nanometre-scale Zr-rich particles. The critical current density improved by oneorder of magnitude at 77 and 90 K as compared to those of other RE-123 type materials.The exceptional trapped field at 90.2 K enabled a levitation experiment at liquid oxygentemperature, which proved that these materials can be used as superconducting permanentmagnets at 90 K. We point out that this technology can be easily adapted for massproduction.