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 P 2/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 . 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).
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.