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Li 2 CaSi 2 N 4 and Li 2 SrSi 2 N 4 – a Synthetic Approach to Three‐Dimensional Lithium Nitridosilicates
Author(s) -
Zeuner Martin,
Pagano Sandro,
Hug Stephan,
Pust Philipp,
Schmiechen Sebastian,
Scheu Christina,
Schnick Wolfgang
Publication year - 2010
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201000671
Subject(s) - chemistry , lithium (medication) , lattice energy , crystallography , tantalum , alkali metal , alkaline earth metal , band gap , inorganic chemistry , crystal structure , medicine , organic chemistry , endocrinology , physics , quantum mechanics
The quaternary lithium alkaline earth nitridosilicatesLi 2 MSi 2 N 4 with M = Ca, Sr were synthesized at 900 °C by employment of liquid lithium as fluxing agent in weld shut tantalum ampoules. The title compounds crystallize in space group Pa $\bar {3}$ [Li 2 CaSi 2 N 4 : a = 1056.9(12) pm, Z = 12, R 1 = 0.0439, wR 2 = 0.0839, 412 data, 42 parameters; Li 2 SrSi 2 N 4 : a = 1071.37(12) pm, Z = 12, R 1 = 0.0476, wR 2 = 0.1227, 528 data, 42 parameters]. The structure is built up from vertex sharing [SiN 4 ] tetrahedra forming a three‐dimensional network comprising the alkaline earth and lithium ions in the voids. The network is the first example of a nitridosilicate adopting topology of Net 39 according to O'Keeffe. The two crystallographically independent M 2+ sites are highly symmetrically coordinated by six nitrogen atoms. Lattice energy calculations (MAPLE) and EDX measurements confirmed the electrostatic bonding interactions and the chemical compositions. 7 Li and 29 Si solid‐state MAS NMR spectra of Li 2 SrSi 2 N 4 are reported. Electron energy‐loss spectroscopy (EELS) elucidates further information upon the lithium incorporation.