微小なNd-Fe-B系焼結磁石における磁化反転機構の解析: 研磨面方位および調製雰囲気による磁気特性への影響

摘要

磁区構造観察から，あたかも1磁気単位のように協同的に磁化反転する多結晶粒子集団（50～100μmサイズ）の存在が示唆されたので，本研究はそのような多結晶粒子集団を3次元的に切り出して3D微小試料とし，高感度磁力計（RSM）を用いて磁気特性を測定した．%The magnetic properties of the Nd-Fe-B magnet fine particles with diameters of 20 μm-5.5 mm were investigated using the magneto-meters of Vibrating Sample Magnetometer (VSM) and of a high sensitivity Resonating Sample Magnetometer (RSM) (max. 10~(-6)-10~(-7) emu). The coercivities disappeared in the finest 20 |im samples, but the saturated magnetizations kept 60-70% mass of the bulk sample. The deteriorations should come from the oxidation and the formation of lattice defects by mechanical polishing. The effects of polishing both in the c-plane, in the perpendicular planes along the c-axis, on the shape of the demagnetization curves, and on the coercivity were investigated.