title: Synthesis and crystal structure of cubic Ca16Si17N34.
abstract: Since the late 1960s, the exact structure of cubic calcium silicon nitride has been a source of debate. This paper offers evidence that the cubic phase CaSiN(2) described in the literature is actually Ca(16)Si(17)N(34). Presented here is a method for synthesizing single crystals of cubic-calcium silicon nitride from calcium nitride and elemental silicon under flowing nitrogen at 1500 °C. The colorless millimeter-sized crystals of Ca(16)Si(17)N(34) with a refractive index (n(25)) = 1.590 were found to be cubic (a = 14.8882 Å) and belong to the space group F43m (216). The synthesis of bulk, powdered cubic-Ca(16)Si(17)N(34) from calcium cyanamide and silicon is also discussed. Ca(16)Si(17)N(34) is a relatively air-stable refractory ceramic. In contrast to the orthorhombic phase of CaSiN(2), in which Ca(2+) sits in octahedral sites, this cubic phase has Ca(2+) in cubic sites that makes it an interesting host for new phosphors and gives rise to unique crystal field splitting.
authors.affiliation: Department of Chemistry and Biochemistry, University of California Los Angeles, 607 Charles E Young Drive East, Box 951569, Los Angeles, California 90095-1569, United States.
authors.forename: Sandra M
authors.initials: SM
authors.lastname: Hick
authors.forename: Mattheu I
authors.initials: MI
authors.lastname: Miller
authors.forename: Richard B
authors.initials: RB
authors.lastname: Kaner
authors.forename: Richard G
authors.initials: RG
authors.lastname: Blair