SrB4O7 ∶ Sm2+: crystal chemistry, Czochralski growth and optical hole burning

Abstract

The crystal chemistry of the Sm3+ to Sm2+ reduction in tetraborate lattices was investigated. In crystalline SrB4O7 in air it is mainly Sm2+ that is incorporated from a melt or glass containing predominantly Sm3+. For the process in air, a reduction and pick-up mechanism is assumed to take place at the crystal/nutrient interface. Stabilization of Sm2+ in SrB4O7 at high temperature and in an oxidizing atmosphere seems to be a particular property of the system, because no Sm2+ inclusion could be observed along the series MB4O7 (M = Ca, Ba, Cd, Pb), if similar reaction conditions were applied. So far, there is only one other oxide lattice (BaB8O13) known where at high temperatures significant amounts of Sm2+ are obtained for reactions in the air.