ic020530r_si_001.cif (50.5 kB)
The Crystal Structure and Magnetic Properties of a New Ferrimagnetic Semiconductor: Ca21Mn4Sb18
dataset
posted on 2003-02-14, 00:00 authored by Aaron P. Holm, Marilyn M. Olmstead, Susan M. KauzlarichSingle crystals of the new transition metal Zintl phase, Ca21Mn4Sb18, were prepared by high temperature melt
synthesis. The crystal structure was determined by single crystal X-ray diffraction to be monoclinic in the space
group C2/c. Crystal information was obtained at 90 K, and unit cell parameters were determined (a = 17.100(2)
Å, b = 17.073(2) Å, c = 16.857(2) Å, β = 92.999(2)°, Z = 2, R1 = 0.0540, wR2 = 0.1437). The structure can
be described as containing 4 discreet units per formula unit: 1 linear [Mn4Sb10]22- anion, 2 dumbbell-shaped
[Sb2]4- anions, 4 individual Sb3- anions, and 21 Ca2+ cations. The [Mn4Sb10]22- anion contains four edge-shared
MnSb4 tetrahedra with distances between Mn ions of 3.388(4) Å, 2.782(4) Å, and 2.760(4) Å. Electron counting
suggests that the Mn are 2+. Temperature dependent magnetization shows a ferromagnetic-like transition temperature
at ∼52 K which is suppressed with increasing magnetic field. The paramagnetic regime is best fit to a ferrimagnetic
model, providing a total effective moment of 4.04(2) μB, significantly less than that expected for 4 Mn2+ ions (11.8
μB). Temperature dependent resistivity shows that this compound is a semiconductor with an activation energy of
0.159(2) eV (100−300 K).