Low-Dimensional Nitridosilicates Grown from Ca/Li Flux: Void Metal Ca8In2SiN4 and Semiconductor Ca3SiN3H.

Reactions of indium and silicon with lithium nitride in Ca/Li flux produce two new nitridosilicates: Ca8In2SiN4 (orthorhombic, Ibam; a = 12.904(1) Å, b = 9.688(1) Å, c = 10.899(1) Å, Z = 4) and Ca3SiN3H (monoclinic, C2/c; a = 5.236(1) Å, b = 10.461(3) Å, c = 16.389(4) Å, β = 91.182(4)°, Z = 8). Ca8In2SiN4 features isolated [SiN4]8- units and indium dimers surrounded by calcium atoms. Ca3SiN3H features infinite chains of corner-sharing SiN4 tetrahedra and distorted edge-sharing H@Ca6 octahedra. Optical properties and band structure calculations indicate that Ca8In2SiN4 is a void metal with calcium and indium states at the Fermi level and Ca3SiN3H is a semiconductor with a band gap of 3.1 eV.