Abstract: The deuterated form of ammonium iron(III) bis (hydrogenphosphate), ND4Fe(DPO4)2, was investigated in detail from neutron powder diffraction data with a wavelength ? = 4.724 Å. The material undergoes two successive magnetic phase transitions which are associated with the Fe3+ magnetic moments. One at TC = 17.82 ± 0.05 K is attributed to the ferrimagnetic order with the magnetic moments, ?FI = 4.19 ± 0.02 ?B at 4 K, lying on the crystallographic plane ac. The other transition is found to be at Tt = 3.52 ± 0.05 K due to an antiferromagnetic arrangement, with an equal moment antiphase structure that is characterized by a long-period propagation vector close to vec kAF ? (1/16,0,1/16) and a magnetic moment for the Fe3+ ions of ?AF = 4.41 ± 0.03 ?B at 1.5 K. The low symmetry of its triclinic crystal structure and the complex pattern of competing superexchange pathways seem to be responsible for the existence of this double magnetic phase transition.

Authorship

Download reference