The new compound K4Sc2P4Se14 was synthesized via the polychalcogenide flux method. It crystallizes in the space group C2/c, and the structure is composed of 1/∞[Sc2P4Se14 4-] chains that are separated by K+ cations. The structural motif features two [PSe4]3- units and one [P2Se6]4- unit bridging the Sc centers and has not been reported for any other compound. The 1/∞[Sc2P4Se14 4-] chains pack in a crosshatched pattern perpendicular to the c axis of the crystal, forming channels for half of the K+ atoms while the other half occupy empty space between the chains. The orange-yellow crystals of K4Sc2P4Se14 are air-sensitive and gradually turn red over the course of a couple hours. The band gap of the phase is 2.25(2) eV, and Raman spectroscopy shows the symmetric stretches of the selenophosphate groups to be at 231 and 216 cm-1 for the [PSe4]3- and [P2Se6]4- units, respectively. Solid-state 31P MAS NMR of K4Sc2P4Se14 shows two prominent peaks at 11.31 and -23.07 ppm and one minor peak at -106.36 ppm, most likely due to degradation of the product or an unknown second phase.
ASJC Scopus subject areas
- Inorganic Chemistry
- Physical and Theoretical Chemistry