Structural, physical, magnetic and electrical properties of La-substituted W-type hexagonal ferrites

Lanthanum doped W-type hexaferrites BaZn2LaxFe16-xO27 (x = 0, 0.2, 0.4, 0.6, 0.8, 1.0) were synthesized by co-precipitation and sintered at 1320 degrees C. The X-ray diffraction reveals W-type hexagonal structure with few traces of secondary phase. The decrease in grain size as a function of La-concentration is attributed to the fact that La acts as a grain inhibitor. The saturation magnetization and remanance decrease due to spin canting on B-sites. The increase in coercivity follows 1/r behavior where r is the radius of grain. The DC resistivity was observed to increase from 0.59 x 10(7) to 8.42 x 10(7) Omega cm with increasing La-contents due to the unavailability of Fe3+ ions. This enhancement in resistivity makes these materials promising candidates for use at high frequencies in order to reduce eddy current losses. (C) 2011 Elsevier Ltd and Techna Group S.r.l. All rights reserved.