Magnetic and structural properties of commercial Sm2(Co,Fe,Cu,Zr)17-based magnets

A newly developed ${\mathrm{Sm(Co,Fe,Cu,Zr)}}_z$ magnet, with $\text{z≈7,}$ has a lower temperature coefficient of coercivity β, as compared with other commercial magnets with $\text{z≈7.7.}$ It was found that the initial magnetization curve for the newly developed magnet is typical of pure uniform domain wall pinning, while for the commercial magnets nucleation and domain wall pinning occur simultaneously, although domain wall pinning is still the dominant mechanism. It was also found that the magnetic viscosity parameter $S_v$ has similar temperature dependence with the coercivity. Transmission electron microscope studies showed that the smaller cell size contributes to the low temperature coefficient of coercivity.