Synthesis, crystal structure and luminescence properties of a new samarium borate phosphate, CsNaSm(BO)(PO).

A new caesium sodium samarium borate phosphate, CsNaSm(BO)(PO), has been obtained successfully by the high-temperature solution growth (HTSG) method and single-crystal X-ray diffraction analysis reveals that it crystallizes in the orthorhombic space group Cmcm. The structure contains BO, PO, NaO and SmO polyhedra which are interconnected via corner- or edge-sharing O atoms to form a three-dimensional [NaSm(BO)(PO)] network. This network delimits large cavities where large Cs cations reside to form the total structure. Under 402 nm light excitation, CsNaSm(BO)(PO) exhibits three emission bands due to the 4f→4f transitions of Sm. Furthermore, we introduced Gd into Sm sites to optimize the Sm concentration and improve the luminescence intensity. The optimal concentration is Gd/Sm = 98/2. The luminescent lifetime of a series of CsNaGdSm(BO)(PO) phosphors shows a gradual degradation of lifetime from 2.196 to 0.872 ms for x = 0.01-0.10. The Commission Internationale de l'Eclairage (CIE) 1931 calculation reveals that CsNaGdSm(BO)(PO) can emit orange light under 402 nm excitation.