Sm2+ in oxide lattices: An unexplored chapter of crystal chemistry

The chemistry of Sm2+ in solid oxide environment is reviewed and explored b y a systematic search for crystal lattices stabilizing Sm2+ at particular r eaction conditions. It is demonstrated that SrB4O7 is representing an uniqu e lattice stabilizing Sm2+ even when crystals are prepared in air. However, when exchanging Sr by e.g. Ca, Ba, Cd, Pb, only Sm3+ doping could be trace d. Sm2+ in lattices free of nuclear spins is of interest to hyperfine optic al hole burning. In this respect we have prepared single crystals of SrSO4 doped predominantly by Sm2+. In summary, we can say that the stability of S m2+ in an oxide environment is strongly depending on local effects of coord ination and a reduction mechanism not revealed so far. In particular it rem ains unclear, why Sm2+ can be included into SrB4O7 crystals under oxidizing conditions, whereas in the rapidly cooled melt no Sm2+ could be traced.