Supertetrahedral Networks and Lithium-Ion Mobility in Li2SiP2and LiSi2P3.
The new phosphidosilicates Li2SiP2and LiSi2P3were synthesized by heating the elements at 1123 K and characterized by single-crystal X-ray diffraction. Li2SiP2(I41/acd, Z=32, a=12.111(1) Å, c=18.658(2) Å) contains two interpenetrating diamond-like tetrahedral networks consisting of corner-sharing T2 supertetrahedra [(SiP4/2)4]. Sphalerite-like interpenetrating networks of uniquely bridged T4 and T5 supertetrahedra make up the complex structure of LiSi2P3(I41/a, Z=100, a=18.4757(3) Å, c=35.0982(6) Å). The lithium ions are located in the open spaces between the supertetrahedra and coordinated by four to six phosphorus atoms. Temperature-dependent7Li solid-state MAS NMR spectroscopic data indicate high mobility of the Li+ions with low activation energies of 0.10 eV in Li2SiP2and 0.07 eV in LiSi2P3.
Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstrasse 5-15 (D), 81377, München, Germany.
Arthur
A
Haffner
Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstrasse 5-15 (D), 81377, München, Germany.
Thomas
T
Bräuniger
Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstrasse 5-15 (D), 81377, München, Germany. johrendt@lmu.de.
Dirk
D
Johrendt
7Li MAS NMR spectroscopy; crystal structures; ion mobility; lithium; phosphidosilicates