NaZr(PO) - a cubic langbeinite-type sodium-ion solid conductor.

The synthesis of langbeinite-type phosphates with small cations such as Li or Na a high-temperature solid-state reaction is a challenging task due to the predominant formation of a related NaSICON-type phase. This work reports on the synthesis route, crystal structure, thermal behavior, and Na-conductive properties of the langbeinite-type NaZr(PO) prepared by a mechanochemically activated ion-exchange reaction between hydrothermally prepared NHZr(PO) and NaNO. The crystal structure of NaZr(PO) is refined based on X-ray diffraction data and validated by Fourier-transformed infrared spectroscopy.