Synthetic and Structural Investigations on the System Na1-xEux[Li3-2xSi1-xAl3xO4-4xN4x]

During the investigation of a solid-solution series between the alkali lithosilicate Na[Li3SiO4] and the hypothetical nitridolithoaluminate Eu[LiAl3N4] with the generalized sum formula Na1-xEux[Li3-2xSi1-xAl3xO4-4xN4x], a hitherto unknown oxo-nitride has been synthesized. The new material with the composition Na1-xEux[Li3-2xSi1-xAl3xO4-4xN4x] (x = 0.22) crystallizes in the tetragonal space group I4/m (no. 87) with a = 7.704(2) and c = 3.1584(6) angstrom. 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) (approximate to 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[Li3SiO4]-structure type and their emission maxima can be shifted in the spectral range from 469 nm up to 588 nm.