Ca14Si19 – a Zintl Phase with a Novel Twodimensional Silicon Framework

Ca14Si19 is an overlooked binary phase in the Ca/Si system with a novel type of twodimensional silicon framework (R3c, a = 867.85(6), c = 6852.8(8) pm, Z = 6). The basic building units are 3,3,3‐barrelanes Si11 which are linked by Si3 bridges to form a twodimensional silicon framework leaving space for interstitial calcium atoms. The thickness of the silicon layers is about 800 pm. The compound is a semiconductor with a band gap of about EG = 0.1 eV and a diamagnetic moment of χmole = −9 · 10−4 cm3mol−1. According to the relatively high linking of silicon atoms the reaction with air and moisture is fairly slow.