Nanocomposites and nanomaterials
Magnetic properties of polycrystalline Ce2O3
K. Lamonova1, Yu. Pashkevich1, T. Charoonsuk2, T. Kolodiazhnyi3
1O. O. Galkin Donetsk Institute for Physics and Engineering of the NAS of Ukrain, Nauky ave., 46, Kyiv-03680, Ukraine
e-mail: k.v.lamonova@ukr.netm
2Electroceramic Research Laboratory, College of Nanotechnology, King Mongkut’s Institute of Technology Ladkrabang, Bangkok 10520, Thailand
3National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki, 305-0044, Japan
Ce2O3 compound with an orange-ochre color has been prepared by firing CeO2 powder of 99.99% purity in hydrogen gas atmosphere at 1500 C for 6 hours with one intermediate re-grinding. Phase purity was confirmed by laboratory x-ray diffraction. The A-type hexagonal Ce2O3 phase has the P2/m1 space group symmetry with two formula units in the primitive cell.
Magnetic susceptibility, χ, of the powder has been measured at 0.005, 0.02, 0.05 and 0.1 T in the 2–300 K temperature range. It was revealed that: (i) there is a kink of the magnetic susceptibility near T ≈ 6.2 K; (ii) there is no difference between zero-field cooled and field-cooled data which implies no detectable ferromagnetic contribution. The high-temperature magnetic susceptibility is of the Curie-Weiss law with the Weiss constant θW ≈ -95 K and effective magnetic moment of Ce3+ ion is about 2.57 μB that is comparable to the free ion value of 2.54 μB. 

The temperature dependence of magnetic susceptibility induced by Ce3+ ions has been simulated by the modified crystal field theory [1]. The calculations showed that the features of the χ(T) curve near 3.5 K can be explained by the out of phase displacements of the neighboring Ce3+ ions as temperature decreases (Fig).

1.	Lamonova K. V., Zhitlukhina E. S., Babkin R. Y., Orel S. M., Ovchinnikov S. G., and Pashkevich Yu. G. // J. Phys. Chem. A – 2011. – 115. – P. 13596. 

Fig. Experimental (0.005 T) and calculation temperature dependences of magnetic susceptibility.