The effect of doping element Zr on anisotropy and microstructure of SmCo7-xZrx.

Ab initio density functional calculations, transmission electron microscope, and x-ray diffraction (XRD) were used to study the dominant factor of increased coercivity for the doping effect in SmCo7-xZrx (x = 0 to 0.3). Simulated values of saturated magnetization are 940 emu/cm3 for SmCo7 and 799 emu/cm3 for SmCo6.7Zr0.3, which agree with experimental results within 6%. The calculated anisotropy constant (for 2e) increases from 1.151 × 107 erg/cm3 for SmCo7 to 1.934 × 107 erg/cm3 for SmCo6.7Zr0.3. The grain sizes remain almost the same by adding ∼4% (atomic percent) Zr through the analyses of XRD. The increased anisotropy is the dominated factor for enhancing the coercivity in SmCo6.7Zr0.3. In addition, both results of Rietveld refinements of XRD data and ab initio calculations show that Zr situating at 2e/3g positions are more stable than 2e/2e locations, which were suggested conventionally. [ABSTRACT FROM AUTHOR]