Ln_2GeB_2O_8 (Ln = Nd, Sm-Tb): A series of luminescent lanthanide(iii) borogermanates with a layered structure

摘要

A series of new lanthanide borogermanates, namely, Ln_2GeB _2O_8 (Ln = Nd, Sm-Tb), have been synthesized by high temperature solid state reactions in platinum crucibles. They are isostructural and feature a layered [GeB_2O_8]~(6-) architecture built of 1D chains of corner-sharing BO_4-tetrahedra that are further bridged by GeO_4-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 Tb~(3+) ions. Luminescent studies indicate that Eu_2GeB_2O_8 and Tb _2GeB_2O_8 emit strong red and green light, respectively.