AgNi3(PO4)(HPO4)2: an alluaudite-like structure.

The new title phosphate, silver trinickel phosphate bis(hydrogenphosphate), has been synthesized by the hydrothermal method. It has an alluaudite-like structure but shows some differences owing to the presence of the H atoms. The structure is isomorphous with the compounds of general formula AM(3)(XO(4))(HXO(4))(2) (A is Na or Ag, M is Co, Zn or Mn, and X is As or P), with the Ag atom, one Ni atom and one P atom lying on twofold axes.