Structure and Physical Properties of 1D Magnetic Chalcogenide, Jamesonite (FePb₄Sb₆S₁₄)^†

Monoclinic FePb4Sb6S14 phase, jamesonite, which is a candidate material as a S = 2 Haldane compound, has been synthesized by the direct reaction of elements under dry conditions with sealed evacuated quartz tubes. The congruent melting point was determined at 592 °C by DTA measurements. Shiny metallic gray needle crystals grow on the surface of bulk heated at 550 °C. The elongated direction of each needle crystal is parallel to the c-axis. The crystal structure refinement (P21/a, a = 15.750(6) Å, b = 19.125(3) Å, c = 4.030(4) Å, β = 91.68(8)°, V = 1213(1) Å3, Z = 2, Dc = 5.651 g/cm3, R1 = 3.16%) reveals the presence of two rod substructures elongated parallel to the c-axis. One is the lozenge-shaped Bi2Te3-type (or called SnS archetype), [Pb4Sb6S13]. The other is the novel single magnetic one-dimensional (1D) straight chain, [FeS6]. This compound shows intrinsic semiconductor behavior in the electric conductivity measurements. The optical band gap, 0.48 eV, is estimated by near-IR diffuse reflectance measurements. In the magnetic susceptibility measurements, this compound shows 1D-Heisenberg antiferromagnetic behavior with a broad peak at ∼33.5 K, where Fe2+ takes the high-spin state, t2g4eg2. A possibility for the S = 2 Haldane system is discussed.