Nonstoichiometry in the Rare-Earth Aluminum Borates

Abstract
Optical spectroscopy on one of a series (the europium compound) of the rare‐earth aluminium borates indicates appreciable nonstoichiometry, confirmed by further x‐ray studies. Detailed studies as a function of magnetic field and temperature of a particular transition (7F05D1) indicate that not only the Al3+ site but also other sites are being occupied by the rare‐earth ions. Crystal‐field splittings in 5D1 and 7F1 agree well with Judd's calculations, confirming the assignment of levels.