Room-temperature “ferromagnetism” found last decades in nonmagnetic nanoparticles is a puzzle that is not solved yet. In this work we report about the observation of room-temperature magnetism in powders of CaF₂ doped with CeO₂ as well as in the undoped powder but containing small amount impurity. The studied powders were obtained by grinding of bulk crystals using a sapphire mortar with a pestle. Magnetization dependences on magnetic field for the studied powder samples resemble the dependences observed in nonmagnetic oxide nanoparticles like CeO₂. The comparative study of bulk and powder fluorite samples unambiguously confirms the key role of surface defects in the observed features. XRD and TEM measurements show that powder samples have particles of different sizes from the micro down to the submicron scale. The undoped bulk fluorite as well as doped with 0.5at.% (two differently grown crystals), 2at.%, 10at.% of CeO₂ revealed only diamagnetic or paramagnetic contribution to magnetization curve whereas the powders of the same samples have ferromagnetic-like contribution on M−H curve. This work may help to get new insight in room-temperature “ferromagnetism” phenomenon of nonmagnetic nanoparticles.

近几十年来在非磁性纳米粒子中发现的室温“铁磁性”是一个尚未解决的难题。在这项工作中，我们报告了对掺杂 CeO ₂的 CaF ₂粉末以及未掺杂但含有少量杂质的粉末的室温磁性的观察。所研究的粉末是通过使用带有杵的蓝宝石研钵研磨大块晶体获得的。所研究粉末样品的磁化对磁场的依赖性类似于在非磁性氧化物纳米粒子（如 CeO _{2 ）中}观察到的依赖性. 大块和粉末萤石样品的比较研究明确证实了表面缺陷在观察到的特征中的关键作用。XRD 和 TEM 测量表明粉末样品具有从微米到亚微米级不同尺寸的颗粒。未掺杂的块状萤石以及掺杂 0.5at.%（两种不同生长的晶体）、2at.%、10at.% 的 CeO ₂仅显示对磁化曲线的抗磁性或顺磁性贡献，而相同样品的粉末具有类铁磁性对 M-H 曲线的贡献。这项工作可能有助于对非磁性纳米粒子的室温“铁磁性”现象有新的认识。