A new barium-containing alkali metal silicate fluoride NaBa3Si2O7F with deep-UV optical property

Abstract

A new silicate fluoride, NaBa 3 Si 2 O 7 F, has been successfully synthesized by a high-temperature solution method. It crystallizes in the orthorhombic space group Cmcm (No. 63). NaBa 3 Si 2 O 7 F is the first barium-containing alkali metal silicate fluoride with the [NaO 6 ] polyhedra, the [BaO 8 F] polyhedra and isolated [Si 2 O 7 ] units. The optical characterizations indicate that NaBa 3 Si 2 O 7 F possesses wide transparent window and available luminescence properties. To confirm the coordination surroundings of anionic groups and its thermostability, infrared spectroscopy and thermal behaviors were also analyzed, which proved the existence of tetrahedronly coordinated silicium atoms and the good stability of NaBa 3 Si 2 O 7 F at high temperature. First-principles calculation was also implemented for better understanding the relationship between the structure of NaBa 3 Si 2 O 7 F and its property. Additionally, to further explore the structural novelty of NaBa 3 Si 2 O 7 F, the comparison of the anionic structures was carried out in mixed alkali and alkaline-earth metal silicate fluorides. Interestingly, the result indicates the isolated [Si 2 O 7 ] dimer is rare among the above systems, which enriches the structural chemistry of silicate fluorides.

Eu2+ activated NaBa3Si2O7F: A new efficient blue‐emitting luminescent material for solid‐state lighting and display

“…According to the report of Pan et al., 32 the crystal structure of the NBSOF prepared by solid‐state action is shown in Figure 1A. It is clear that each Si atom forms [SiO 4 ] tetrahedron with four neighboring O atoms, and every two [SiO 4 ] tetrahedrons are connected by sharing O atom to form [Si 2 O 7 ] dimer.…”

“…According to the report of Pan et al, 32 sites and Ba sites. In order to characterize structure of the as-prepared materials, the Rietveld refinement XRD pattern of NBSOF was obtained as shown in Figure 1B.…”

“…The new barium‐containing silicate fluoride NaBa 3 Si 2 O 7 F (NBSOF), as one member of alkaline‐earth silicate fluorides, was first reported by Pan et al. in 2019 32 . NBSOF crystallizes in the orthomorphic system and the basic structure consists of [NaO6] octahedrons and isolated [Si 2 O 7 ] units, which shows that it has good stability, and the Na and Ba sites could provide suitable location for Eu 2+ .…”

“…26,27 Especially, the higher electronegativity of fluorides can efficiently enhance the emission intensity of phosphor. 26,28 32 NBSOF crystallizes in the orthomorphic system and the basic structure consists of [NaO6] octahedrons and isolated [Si 2 O 7 ] units, which shows that it has good stability, and the Na and Ba sites could provide suitable location for Eu 2+ . According to the above analysis of structure, the NBSOF can be highly expected to be a good luminescence matrix for phosphor.…”

α-, β-Pb4B2O7 and α-, β-Pb4B6O13: Polymorphism drives changes in structure and performance

“…However, unlike the fixed coordination number of four for the Si atom in silicates (SiO 4 tetrahedra), the coordination number of the B atom in borates can be either three (BO 3 triangles) or four (BO 4 tetrahedra). As a result, the structure of borates is more complicated and variable than that of silicates [39][40][41][42][43][44]. For the cations, it was found that Pb 2+ with lone pair electrons could exhibit variable coordination numbers from 2-10 and form diverse coordination polyhedra with holodirected or hemidirected geometries.…”