Discovery of Sm₂Fe₁₇N₃

Interstitial nitrogen in Sm₂Fe₁₇ expands the unit cell, producing new magnets with enhanced magnetization and Curie temperature. This is the most-cited achievement of the Group, with 700 citations since 1990!

Crystal structure of Sm2Fe17N3		The gas phase interstitial modification process

 

 

High Temperature Magnets

Current work on rare earth permanent magnets focuses on Sm-Co-TM alloys (TM = Transition Metal) containing the 1:5, 1:7, and 2:17 phases. Exchange-coupled nanocomposites of two or more ferromagnetic phases are being researched with the aim of reaching operating temperatures of 400-450ºC

Crystal structure of SmCo5

High temperature hysteresis loops for sm(CoTi)7 magnets

 

Permanent Magnet Instruments

The Group has been using permanent magnets to generate variable magnetic fields since 1990, when we were active in both the New Materials and Magnet Applications parts of the CEAM project. During Orphée Cugat’s stay in Dublin we built the first practical implementation of the nested double Halbach cylinder structure, first proposed by Herb Leupold in 1988.

 

The vibrating-sample magnetometer based on this design which generates fields of up to 1.2 T is one of our most useful instruments. A campus company, Magnetic Solutions Ltd, was formed in 1994 to market equipment based on Halbach cylinders. One of their products, the Multimag can be found in several places around the laboratory.

Facilties for permanent magnet research include arc and induction melters, a melt spinner, two high energy ball-mills, a glovebox, X-ray diffractometer, vibrating sample, SQUID and pulse magnetometers, AC susceptometer and a BH loop tracer.