High-pressure synthesis, crystal structure and photoluminescence properties of a new terbium silicate: Na2Tb1.08Ca2.92Si6O18H0.8. Issue 79 (27th October 2017) - Bao, Xinjian
Abstract : New terbium silicate Na2 Tb1.08 Ca2.92 Si6 O18 H0.8 was synthesized at high pressure condition. The structure was and the photoluminescence properties were also investigated suggesting a strong green emission with the lifetime 2.498(7) ms. Abstract : The crystal properties of a terbium silicate Na2 Tb1.08 Ca2.92 Si6 O18 H0.8 synthesized at 1 GPa and 800 °C using a piston-cylinder apparatus is reported. Our single-crystal X-ray analysis shows that this new compound is triclinic with the space group P̄ 1 ( Z = 1), and its unit-cell parameters are a = 7.056(3) Å, b = 7.075(3) Å, c = 8.029(3) Å, α = 102.381(5)°, β = 95.387(6)°, γ = 90.552(6)°, and V = 389.6(2) Å 3 . This structure consists of octahedral double chains of the compositions [Ca0.875 Tb0.125 O6 ] and [Ca0.585 Tb0.415 O6 ]. The double chains are linked by tetrasilicate chains via vertex oxygen atoms to form a 3D framework with 6-membered (2 octahedra and 4 tetrahedra) ring channels along the b -axis where the Na + cations locate. The luminescence properties of the Na2 Tb1.08 Ca2.92 Si6 O18 H0.8 phase are also investigated. This phase, with most of its Tb in 3+, emits mainly from one transition, 5 D4 → 7 F5 (542 and 552 nm). The room temperature fluorescence decay curves are fit well by an exponential function, yielding a lifetime value of about 2.498(7) ms.