Synthetic and Structural Investigations on the System Na_1–xEu_x[Li_3‐2xSi_1‐xAl_3xO_4‐4xN_4x]

Abstract

During the investigation of a solid‐solution series between the alkali lithosilicate Na[Li 3 SiO 4 ] and the hypothetical nitridolithoaluminate Eu[LiAl 3 N 4 ] with the generalized sum formula Na 1– x Eu x [Li 3–2 x Si 1‐ x Al 3 x O 4–4 x N 4 x ], a hitherto unknown oxo‐nitride has been synthesized. The new material with the composition Na 1– x Eu x [Li 3–2 x Si 1‐ x Al 3 x O 4–4 x N 4 x ] ( x = 0.22) crystallizes in the tetragonal space group I 4/ m (no. 87) with a = 7.704(2) and c = 3.1584(6) Å. To the best of our knowledge this is the first synthesis of a litho‐alumo‐oxo‐nitridosilicate containing either alkali‐, or rare‐earth metals. Upon excitation of this novel compound with near UV to blue light, a broadband amber emission with a maximum at 612 nm and a full width at half maximum of 2835 cm ‐1 (≈ 105 nm) is observed. Furthermore, single‐crystals of the solid‐solution series could be synthesized on the oxygen‐rich side between 0 < x < 0.2. The thereby received phosphors crystallize in the Na[Li 3 SiO 4 ]‐structure type and their emission maxima can be shifted in the spectral range from 469 nm up to 588 nm.