PROBLEM TO BE SOLVED: To provide a core-shell type cerium oxide fine particles or a dispersion containing them, and methods of manufacturing those.SOLUTION: Provided are core-shell type cerium oxide particles which have an average particle size of 30-200 nm and a coefficient of variation of the fine particles of 0.25 or smaller, and in which the shape of secondary particles in the core part is spherical, and a polymer is attached to their surfaces the dispersion of the cerium oxide fine particles a dried powder of the dispersion of the cerium oxide fine particles and a method of manufacturing the core-shell type cerium oxide fine particles including a process for obtaining a mixture by mixing a cerium salt and the polymer with an organic solvent and a process for precipitating the core-shell type cerium oxide fine particles by heating while refluxing the mixture at a prescribed temperature, in which the cerium salt is cerium nitrate and the particle size of the fine particles are controlled based on the size of molecular weight of the polymer.COPYRIGHT: (C)2008,JPO&INPIT【課題】コアシェル型酸化セリウム微粒子、それを含有する分散液及びそれらの製造方法を提供する。【解決手段】粒子径の平均が30-200nmであるコアシェル型酸化セリウム微粒子であって、該微粒子の変動係数が0.25以下で、コア部分の二次粒子の形状が球状であり、その表面に高分子が付着している、前記微粒子、該酸化セリウム微粒子の分散液、該酸化セリウム微粒子分散液の乾燥粉体、及び、セリウムの塩と高分子を有機溶媒に混合して混合物を得る工程と、その混合物を所定の温度で加熱・還流してコアシェル型酸化セリウム微粒子を析出する工程とを有する、コアシェル型酸化セリウム微粒子又はその分散液の製造方法であって、前記セリウムの塩が、硝酸セリウムであり、かつ、前記高分子の分子量の大きさによって前記微粒子の粒径を制御することからなるコアシェル型酸化セリウム微粒子の製造方法。【選択図】図8
