Abstract

Distribution of chemical elements in polycrystalline BaFe_12–xTi_xO₁₉ and BaFe_12–xMn_xO₁₉ barium ferrite samples is studied. The samples are prepared by solid-phase synthesis at 1400 °C from stoichiometric mixtures of oxides and carbonates. The XRD data indicate that all the studied samples have one crystalline phase characteristic of the M-type hexaferrite structure. The Curie temperatures are determined by differential scanning calorimetry. It is shown that replacing iron with Ti and Mn atoms diminishes the temperature of magnetic phase transition. The difference in bulk and surface atomic composition between the studied ferrites are established by XRD and XPS. It is shown that barium can exhibit surface segregation. The replacement of iron by manganese in the barium hexaferrite structure leads to surface segregation of barium, while the replacement by titanium hinders the segregation.

中文翻译：

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钛和锰的添加对六方铁氧体中钡表面偏析的影响

摘要

研究了多晶BaFe _{12– x} Ti _x O ₁₉和BaFe _{12– x} Mn _x O ₁₉钡铁氧体样品中化学元素的分布。样品是在 1400 °C 下由氧化物和碳酸盐的化学计量混合物通过固相合成制备的。XRD数据表明，所有研究的样品都具有M型六方铁氧体结构的一种晶相特征。居里温度通过差示扫描量热法测定。结果表明，用 Ti 和 Mn 原子代替铁会降低磁相变温度。通过 XRD 和 XPS 确定了所研究的铁氧体之间体积和表面原子组成的差异。结果表明，钡可以表现出表面偏析。钡六方铁氧体结构中锰取代铁导致钡的表面偏析，而钛取代则阻碍偏析。