Van Vleck paramagnetism of the trivalent Eu ions

Magnetic susceptibilities of Eu2O3, EuF3 and EuBO3 have been measured over the wide temperature range 5–650 K. The Van Vleck paramagnetism, with the ground state of 7F0 (S=3, L=3), has been investigated comprehensively. The temperature independent paramagnetism emerges manifestly below approximately 100 K. The variation of the susceptibility with temperature for EuBO3 is in satisfactory agreement with the coupling constant λ=471K, where the spin–orbit interaction is λL·SλL·S for the Russell–Saunders coupling on the basis of Van Vleck theory with one parameter λλ. The value of λ=490K can fit the susceptibility data of EuF3. The deviation from the theory arises in Eu2O3. This discrepancy originates mainly from the influence of the crystalline field. Susceptibility of Gd2O3, having the ground state of 8S7/2 (S=7/2, L=0), is also presented as a magnetic standard compound in comparison with these results.