Evolution of structural and magnetic properties in LaxCe2-xCo16Ti for 0 ≤x ≤ 2

Abstract

In the present work we examine the intrinsic magnetic and structural properties of the title alloys, permanent magnet materials based on the abundant rare-earth elements lanthanum and cerium, since these properties (TC, MsHa(K1, K2)) will set the upper limits on the quality of permanent magnet that can be fabricated from said alloys. Ce2Co16Ti has a high magnetic anisotropy (Ha = 65 kOe) but a relatively low saturation magnetization (Ms = 7.3 kG), and La2Co16Ti has a high Ms(9.5 kG) but Ha too low for most applications (16 kOe). Though these two end-members have previously well-known properties, changing economic conditions have made re-examination of systems containing cerium and lanthanum necessary as the economic viability of rare earth mining becomes dependent on extraction of products beyond what is currently considered useful and profitable within the rare earth elements. We find that replacing some lanthanum with cerium in La2Co16Ti increases Ha by a factor of more than two, while decreasing Ms by less than 5%. The measured Ms indicate maximum possible energy products in excess of 20 MG·Oe in these materials, which have Curie temperatures near 600 °C. Real energy products are expected to be greatest near x = 1. These findings identify LaxCe2−xCo16Ti as a promising system for development of so-called gap magnets that fill the energy product gap between expensive rare-earth magnets and current non-rare earth alternatives.