High-temperature synthesis, crystal structure, optical properties, and magnetism of the carbidonitridosilicates Ho2[Si4N6C] and Tb2[Si4N6C]

The novel carbidonitridosilicates Ho2[Si4N6C] and Tb2[Si4N6C] were obtained by the reaction of the respective lanthanoid metal with carbon and Si(NH)2 in a radiofrequency furnace at the temperature of 1700 uC. According to the single-crystal structure analysis of Ho2[Si4N6C] (P21/c, Z~4, a~593.14(1), b~989.74(1), c~1188.59(2) pm, b~119.58(4)u, R1~0.0355, wR2~0.0879, 2187 F values, 119 parameters) the compound contains a condensed network of corner-sharing star like [C(SiN3)4] units. The holmium ions are situated in channels along [100]. The UV–VIS absorption spectrum of Ho2[Si4N6C] shows the typical Ho 3z