Crystal structures of A2FeCl5⋅H2O (A=Rb+, Cs+) and field dependent superconducting susceptometer measurements

Abstract

Crystal structures and low field principal crystal axis magnetic measurements are reported for the antiferromagnetic iron (III) salts A₂FeCl₅⋅H₂O; A=Rb⁺, Cs⁺. The two compounds undergo a zero field paramagnetic to antiferromagnetic phase transition at 6.5 K (A=Cs⁺) and 10.05 K (A=Rb⁺). The spin flop magnetic phase is observed in high field measurements. The magnetic field‐temperature phase diagrams are reported. All magnetic measurements were recorded on a superconducting susceptometer. The bicritical points are 6.25 K, 14.5 kOe (A=Cs⁺), 9.75 K, 17.8 KOe (A=Rb⁺). Crystal data for Cs₂FeCl₅⋅H₂O: space group Cmcm, Z=4, a=7.442(3) Å, b=17.307(7) Å, c=8.077(7) Å, V=1040 ų, R=5.2%, 561 reflections. Crystal data for Rb₂FeCl₅⋅H₂O, space group Pnma, Z=4, a=13.825(4) Å, b=9.918(3) Å, c=7.100(2) Å, V=4.9 ų, 5.7%, 712 reflections.