Portal de Periódicos da CAPES

La16[Si8N22][SiON3]2 – A nitridosilicate with isolated, corner-sharing and edge-sharing tetrahedra

2008; Elsevier BV; Volume: 11; Issue: 2 Linguagem: Inglês

10.1016/j.solidstatesciences.2008.08.008

1873-3085

Christian Schmolke, Saskia Lupart, Wolfgang Schnick,

Rare-earth and actinide compounds

The mixed anion oxonitridosilicate La16[Si8N22][SiON3]2 has been synthesized by the reaction of LaN, finely ground SiO2 and silicon diimide (Si(NH)2) at 1600 °C in a radiofrequency furnace. The structure has been determined by single-crystal X-ray diffraction (La16[Si8N22][SiON3]2, P1¯, a = 5.718(2), b = 11.391(2), c = 13.435(3) Å, α = 112.02(3), β = 90.19(3), γ = 90.58(3)°, V = 811.1(3) Å3, Z = 2, R1 = 0.027, 4460 independent reflections, 258 refined parameters). Besides La3+ and non-condensed [SiON3]7− tetrahedra, there are chains of both corner-sharing and edge-sharing SiN4 tetrahedra with additional Q1-type SiN4 groups attached to all non-edge-sharing SiN4 units of the chain. The resulting infinite chains are alternately built up of pairs of edge-sharing [Si2N6]10− units that are linked by a common nitrogen atom to two corner-sharing single branched Q3-type SiN4 tetrahedra. According to its low degree of condensation, La16[Si8N22][SiON3]2 is moisture sensitive and undergoes rapid hydrolysis on exposure to air. Rietveld refinement of X-ray powder diffraction data is in accordance with the results of the single-crystal X-ray structure determination.