The crystal structure and luminescence properties of the first lithium oxonitridolithosilicate Li₃SiNO₂:Eu²⁺

Abstract

The compound Li3SiNO2:Eu2+ was synthesized in high temperature solid-state reactions in weld shut tantalum ampules and the crystal structure of Li3SiNO2 has been determined by single-crystal X-ray diffraction. It crystallizes...

Polymorphism and polymorph-dependent luminescence properties of the first lithium oxonitridolithosilicate Li3SiNO2:Eu2+

“…As reported before, 20 it was now possible to find a synthesis pathway, which led to the growth of measurable single-crystals of Li 3 SiNO 2 . After LiSiON, the compound Li 3 SiNO 2 is only the second lithium oxonitridosilicate to be elucidated based on single-crystal diffraction data, the second after LiSiON:Eu 2+ /(Mn 2+ ) with known luminescence properties and the first, which exhibits lithium ions not only in tetrahedral coordination: in all the aforementioned compounds, lithium is exclusively fourfold coordinated and acts as part of the combined network of the tetrahedrally coordinated silicon and lithium ions.…”

“…Based on the bond length-bond strength calculations for the α-phase and considerations on coordination and linkage patterns, the positions of the oxygen and nitrogen atoms were distinguished in the refinement, particularly also because incorrectly assigned atoms resulted in significant over- or underoccupancies. 20…”

“…For this purpose, the occupation was first refined and then manually adjusted to obtain equal isotropic displacement factors for both positions. 20…”

“…For α-Li 3 SiNO 2 :Eu 2+ values above 30% have been reported. 20 Fig. 9 and 10 show that the emission peaks of the two polymorphs differ by 16 nm.…”

“…As reported, from layer A one can draw a parallel to isostructural layers in Na 2 Mn 2 S 3 and Na 6 In 2 S 6 . 20,34,35 In this work, unlike in most other cases, it was possible to obtain an indication of the positions most likely to be occupied by the Eu(II)-ions. This appeared to be feasible due to the great difference in mass between Li(I) and Eu(II), which led to remaining electron density at the Li1 and Li2 positions.…”