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

Monoclinic FePb(4)Sb(6)S(14) 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 degrees C by DTA measurements. Shiny metallic gray needle crystals grow on the surface of bulk heated at 550 degrees C. The elongated direction of each needle crystal is parallel to the c-axis. The crystal structure refinement (P2(1)/a, a = 15.750(6) A, b = 19.125(3) A, c = 4.030(4) A, beta = 91.68(8) degrees, V = 1213(1) A(3), Z = 2, D(c) = 5.651 g/cm(3), R(1) = 3.16%) reveals the presence of two rod substructures elongated parallel to the c-axis. One is the lozenge-shaped Bi(2)Te(3)-type (or called SnS archetype), [Pb(4)Sb(6)S(13)]. The other is the novel single magnetic one-dimensional (1D) straight chain, [FeS(6)]. 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 approximately 33.5 K, where Fe(2+) takes the high-spin state, t(2g)(4)e(g)(2). A possibility for the S = 2 Haldane system is discussed.