Magnetic and Structural Characteristics of PrCo13-xSix Alloys and their Nitrides

摘要

PrCo13-xSix alloys with 0 <= x <= 4.5 have been synthesized and studied attemperatures from 10 to 1273 K and infields up to 17 kOe. The structure and magnetic properties of the alloys vary significantly with changes in Si content x. In the alloys with x = 0, TMA and XRD studies show the phases present to be Pr2Co17 and Co. For x = 1.5 or 2.0, the alloys are essentially single-phase fcc materials (NaZn13 structure type). At larger values of x the ternary alloy formed in a bet structure (Ce2Ni17Si0 structure type). Replacement of Co by Si in PrCo13 results in a drop in T sub c from 1318 K (for LaCo13) to approx. 900 K for fcc Pr(Co.Si)13 alloy and to approx. 20 K for bct Pr(Co.Si)sub 13 alloys. There is also a large drop in magnetization from 104.6 emu/g for the alloy with x = 1.5 to 19.2 emu/g for the alloys with x = 4.0. A bct alloy (x = 3.5) showed negligible magnetic anisotropy. Si doping sharply reduces the Co moment. Si doping also reduces tbe Pr moment to 1.5 micrometer sub s (fcc alloys) and to 1.8 micrometers sub s (bct alloys). Nitrogenation fails to improve Pr(Co.Si)13 alloys as permanent magnet materials.