Correlation between Magnetic Property and Cation Distribution in Z-type Hexagonal Barium-Ferrite (Ba_3Co_(2-x)Fe_(24+x)O_(41)) by Neutron Diffraction

摘要

Z-type hexagonal ferrite samples in which cobalt is partially substituted with iron, Ba_3Co_(2-x)Fe_(24+x)O_(41)) (X = 0,0.2, 0.4, 0.6), were prepared by the ceramic process under a sintering oxygen partial pressure, P_(O2) = 21.3 or 101.3 kPa, at 1573 K. The influence of the substitution ratio and oxygen partial pressure on the complex permeability was investigated by examining the cobalt distribution over various cation sites in the Z-type structure with the neutron powder diffraction analysis performed at 294 K (neutron wave length was 1.006A). The neutron diffraction pattern was studied with the Rietveld method. A significant difference in the preferential occupation of cobalt on various kind of cation sites was observed between the samples obtained under P_(O2) = 21.3 and 101.3 kPa. Almost all cobalt atoms are on the 12k octahedral site at the boundary between S- and R-blocks in the sample of x = 0, P_(O2) = 21.3 kPa. On the other hand, in the sample of x = 0, P_(O2) = 101.3 kPa, cobalt atoms are as well on other sites, the 12k octahedral site at the boundary between S- and T-blocks, the 4e tetrahedral site in S-block, the 2a octahedral site in T-block and the 2d five fold (trigonal bypiramid) site in T-block.