Ln2GeB2O8 (Ln = Nd, Sm-Tb): a series of luminescent lanthanide(III) borogermanates with a layered structure

A series of new lanthanide borogermanates, namely, Ln(2)GeB(2)O(8) (Ln = Nd, Sm-Tb), have been synthesized by high temperature solid state reactions in platinum crucibles. They are isostructural and feature a layered [GeB2O8](6) architecture built of 1D chains of corner-sharing BO4-tetrahedra that are further bridged by GeO4-tetrahedra. The lanthanide(III) ions are located at the interlayer space and are seven-coordinated. Results of magnetic measurements indicate Sm(III), Eu(III) and Gd(III) compounds display an antiferromagnetic interaction between Ln(III) centers whereas the Tb(III) compound exhibits a ferromagnetic interaction between Tb3+ ions. Luminescent studies indicate that Eu2GeB2O8 and Tb2GeB2O8 emit strong red and green light, respectively.