A New Borate-phosphate Compound CsNa2Lu2(BO3)(PO4)2: Crystal Structure and Tb3+ Doped Luminescence①

ABSTRACT Composite borate-phosphate compounds have always attracted much attention for their structure diversity and interesting properties. In this work, a new borate-phosphate CsNa 2 Lu 2 (BO 3 )(PO 4 ) 2 (CNLBP) was found for the first time and its structure was characterized by single-crystal X-ray diffraction method. It crystallizes in orthorhombic system , space group Cmcm with a = 6.8750(5), b = 14.6919(1), c = 10.5581(7) Å, V = 1066.44(1) Å 3 , Z = 4, M r = 777.58, D c = 4.843 g/cm 3 , F (000) = 1368, µ (Mo Kα ) = 22.20 mm −1 , R ( F 2 > 2σ( F 2 )) = 0.0173 and wR ( F 2 ) = 0.0367. The structure of CNLBP features a chain framework of [Lu 2 (BO 3 )(PO 4 ) 2 ] ∞ that delimits 1D tunnels filled by Na + and Cs + ions. Phosphors CNLBP: x Tb ( x = 0, 0.1, 0.2, 0.4, 0.6, 0.8, 1.0) were prepared, and it can emit bright green light under near-UV excitation due to the 5 D 4 → 7 F j (j = 6, 5, 4, 3) transition of Tb 3+ . Due to the large separation of Lu 3+ ions in CNLBP structure lattice, the optimal concentration of Tb 3+ is 80%, and concentration quenching occurs only for the full Tb 3+ concentration.