On the crystal structure and thermal decomposition of ammonium-iron(iii) bis(hydrogenphosphate)

NH4Fe(HPO4)2 and its deuterated form have been synthesized as monophasic polycrystalline materials. Their crystal structures, including hydrogen positions, were determined by Rietveld refinement and Fourier synthesis using constant-wavelength neutron powder diffraction data. In addition, the thermal decomposition of NH4Fe(HPO4)2 was found to give mixtures of Fe4(P2O7)3 and Fe(PO3)3via NH4FeP2O7 formation, the crystal structure of which has also been refined from X-ray powder diffraction data.This work has been carried out with the financial support of FEDER-MEC (MAT2006-01997, MAT2008-06542-C04-03, and Factoría Española de Cristalización-Consolider Ingenio 2010).Peer reviewe