Bertin Tchoula Tchokonte, MoiseBashir, Aiman Kamal Hamed2018-08-022024-05-142018-08-022024-05-142017https://hdl.handle.net/10566/15005Philosophiae Doctor - PhD (Physics)Rare-earth (RE) elements possess an incompletely lled 4f shell, which is very small compared to typical interatomic distances. As a result of this, RE elements and compounds exhibit characteristic properties, which deviate signi cantly from those of other systems containing for instance the 3d transition elements with expanded 3d shells. As a result of a small radius of the 4f shell, the 4f electron does not participate in chemical bounding. Instead, the 4f electron together with the nucleus act virtually as an e ective nucleus. From chemical point of view all RE behave similarly. The overlap of the neighbouring f shells is extremely small. The magnetic moments associated with the 4f shell may be treated as well localized moments in contrast to the 3d which are itinerant.enThesisUniversity of the Western Cape