The Nature of the Crystalline Fields Present in Er2(SO4)3–8H2O

The splitting of the basic state of Er2(SO4)38H2O due to the presence of the crystalline fields was calculated according to the method of Van Vleck, and Penney and Schlapp. Assuming a cubic field, the basic state in the absence of a magnetic field should split into five levels with the relative separations 0, 19, 39, 85, 89 cm—1. Meehan and Nutting have located them spectroscopically at 0, 19, 41 and 85. When the potential field constant D is assumed to be the same as experimentally determined for Nd2(SO4)3–8H2O, then there are no arbitrary constants in the calculations, and the calculated over all splitting agrees with the values found within a few percent. If the true value of D could be used, the deviation would be even less. Similar calculations were made for Dy2(SO4)38H2O. While the calculated splitting is of the same order as that found experimentally, the agreement is not good. Reasons for the lack of agreement are given. The magnetic susceptibility expressions for both salts are given and the agreement with experiment in the case of Er is excellent.