Synthesis, crystal structure and magnetic properties of Li0.44Eu3[B3N6]

Abstract

Li0.44Eu3[B3N6] was synthesized from the metathesis reaction of Li-3[BN2] and EuCI3 at 850 degrees C. Li0.44EU3-[B3N6] crystallizes in the trigonal space group R (3) over barc (No. 167) with a=12.0225(2) angstrom, c=6.8556(2) angstrom and Z=6. In the crystal structure, isolated, planar cyclic [B3N6](9-) units are charge-balanced by the mixed-valence Eu3+/Eu2+ and Li+ cations. Li+ occupies partially (44%) the Wyckoff site 6b and is sandwiched between the [B3N6](9-) anions. Mossbauer spectroscopy results show the resonance lines of Eu2+ and Eu3+, respectively, indicating the heterogeneous mixed valency of the Eu atoms. X-Band ESR investigations between 5 and 300 K reveal an intense signal over the whole temperature range originating from Eu2+. Magnetic susceptibility measurements indicate a Curie-Weiss behavior with an experimental effective magnetic moment of (mu eff)=8.28 (mu B) per formula unit.