Inorganic-organic hybrid compound with face-sharing iodoplumbate chains showing novel dielectric relaxation

An inorganic-organic hybrid compound, [4′-methyl-1-aminopyridinium] [PbI₃] (1), has been synthesized and characterized structurally. The hybrid crystal crystallizes in space group P2₁/c, in which the Pb^{2 +} ion, surrounded by six iodides, adopts the distorted octahedral coordination geometry; the neighboring PbI₆ octahedra form the face-sharing PbI₆ octahedral chain and the organic cations are aligned into stack along c-axis direction. Hybrid compound shows normal dielectric constant (ε′ < 20) below 130 C in the frequency range of 1-10⁷ Hz, but higher dielectric constant above 160 C, especially, in the low-frequency regime. In addition, a novel dielectric relaxation process was observed in the frequency regime f < 10⁶ Hz, which exhibits the characteristic activated or Arrhenius behavior, such a dielectric relaxation process ARISES from the dynamically dipole motion of the 4′-methyl-1- aminopyridinium cations under ac electrical field.