High-pressure synthesis, crystal structure and photoluminescence properties of a new terbium silicate: Na₂Tb_1.08Ca_2.92Si₆O₁₈H_0.8

Abstract

The crystal properties of a terbium silicate Na 2 Tb 1.08 Ca 2.92 Si 6 O 18 H 0.8 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 P1 (Z ¼ 1), and its unit-cell parameters are a ¼ 7.

Rb1.66Cs1.34Tb[Si5.43Ge0.57O15]·H2O, a New Member of the OD-Family of Natural and Synthetic Layered Silicates: Topology-Symmetry Analysis and Structure Prediction

“…There are no silicate-germanates with Tb in the nature or synthetic compounds according to [1,2]. However, there are a lot of original synthetic Tb-silicates with different anionic radicals [2,3]: ortho-NaTb 9 (SiO 4 ) 6 O 2 [4], KTb 9 (SiO 4 ) 6 O 2 and Cd 2 Tb 8 (SiO 4 ) 6 O 2 [5] (structural type of apatite), Na 5 Tb 4 (OH)[SiO 4 ] 4 [6]; diortho-Tb 2 Si 2 O 7 [7], K 3 TbSi 2 O 7 [8], Tb 4 S 3 Si 2 O 7 [9]; triortho-K 3 TbSi 3 O 8 (OH) 2 [10]; tetraortho-groups Ba 2 Tb 2 Si 4 O 13 [11]; six-membered rings Na 3 Tb 3 Si 6 O 18 •H 2 O (synthetic gerenite) [12]; chains-unbranched Rb 2 TbGaSi 4 O 12 [13], wollastonite Na 2 Tb 1.08 Ca 2.92 Si 6 O 18 H 0.8 [14] and spiral Na 3 TbSi 3 O 9 •3H 2 O [15]; layers in Cs 3 TbSi 4 O 10 F 2 [16] [19]. For some of these compounds, the luminescence properties were investigated [6,10,[13][14][15]18,19].…”