Synthesis and Characterization of the Layered K2NiF4 Type(CnH2n+1NH3)2PbCl4 System

摘要

Layered K2NiF4-type (CnH2n+1NH3)2PbCl4(n=6, 8 and 10) system, or alkylammonium tetrachloroplumbate compound, has been synthesized from PbCl2 and CnH2n+1NH3Cl solutions under argon ambient pressure for 12hrs at 90 ∩. The crystal structure of the compound has been analyzed using X-ray powder diffraction in the range of 5 ⅹ ÷2ト÷ 55 ⅹ , and all samples assigned to an orthorhombic system. Local distances of the Pb-Cl bond have been determined by Pb LIII-edge extended X-ray absorption fine structure (EXAFS) spectroscopy. The vibration modes of alkylammonium chains and the absorption peaks of an exciton have been examined by FT-IR and UV-Vis. reflectance spectra, respectively. The phase transition temperatures of the compounds have been studied by using DSC. According to the thermal analysis, two phase transition temperatures have been observed in the compositions of n=8 and 10.