The crystal structure and magnetic properties of the synthetic langbeinite KBaFe 2(PO 4) 3

Powder neutron diffraction data have been used to refine the crystal structure of KBaFe ₂(PO ₄) ₃ at 4.2 K; space group P2 ₁3, a₀ = 9.8732(1) Å. The material is isostructural with the mineral langbeinite, having two crystallographically distinct, octahedrally coordinated Fe ³⁺ ions in the asymmetric unit. Mössbauer effect spectroscopy and magnetic susceptibility measurements show that KBaFe ₂(PO ₄) ₃ orders as an L-type ferrimagnet with 3.9 < T_C < 4.2 K. The variation of H_int has been monitored by Mössbauer spectroscopy in the temperature range 1.3 < T < 4.2 K.