磁性材料 中性子回折によるＺ型六方晶Ｂａフェライト（Ｂａ３Ｃｏ２−ｘＦｅ２４＋ｘＯ４１）の陽イオン分布と磁気構造の解析

Abstract

The cation distribution and magnetic structure of the Z-type hexagonal ferrite with various compositions (x=0, 0.2, 0.4 in Ba3Co2-xFe24+xO41) prepared under oxygen partial pressure, Po2=101.3 kPa, at 1573K, were studied by neutron powder diffraction analysis (wave length of the neutron was 1.006 A). To examine magnetic Bragg reflections, neutron diffraction patterns were measured within temperature range between 294 and 773K for the sample with composition x=0.4. Two significant reflections were observed at 2θ=11.5 and 13.5°in the pattern at 294 K though no peaks at 773 K. These magnetic reflections were observed for any other samples at 294 K. The peak at 28 = 11.5° corresponded to the magnetic reflections of (0010), (101) and (104) planes and the other at 13.5° the magnetic reflections of (0012) and (106) planes, respectively. The cation distribution for all the samples was determined by the Rietveld analysis of the neutron diffraction patterns measured at 294 K. The preferential distributions of cobalt ions were found. Cobalt ions partially occupy 12k octahedral site at the boundary between S-block and T-block, 4e tetrahedral site in S-block, 2a octahedral site in T-block and 2c five fold (trigonal bypiramid) site in T-block for the sample of x=0.