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FF9.30.1

Preparation and Characterization of (C4H9NH3)2MCl4 (M=Mn, Cu) Liling Guo, Yadong Dai, Mingjie Hu, Hanxing Liu*, Shixi Ouyang State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan 430070, P. R. China ABSTRACT With the preparation of organic-inorganic layered perovskite-type compounds (C4H9NH3)2MCl4 (M = Mn, Cu) in solutions, X-ray diffraction (XRD), scanning electron microscopy (SEM),thermal gravimetry (TG) and differential scanning calorimetry (DSC) have been used to characterize the obtained powders. XRD patterns demonstrate that the two compounds have obvious layered structures and SEM pictures reveal that both (C4H9NH3)2MnCl4 and (C4H9NH3)2CuCl4 take on obvious sheet-like microstructure. TG&DSC curves indicate that (C4H9NH3)2CuCl4 decomposes at much lower temperature than (C4H9NH3)2MnCl4.This is ascribed to weakening interactions between its organic and inorganic components , which is presumably due to the Jahn-Teller distortion of [CuCl6] octahedra. INTRODUCTION Layered organic-inorganic hybrid perovskites have been studied intensively due to the potential applications of their unique electrical, magnetic, and optical properties, for example, (RNH3)2MCl4 (M = Mn, Cu) where R is an n-alkyl chain or an aromatic group known as ferromagnets or antiferromagets and also high Tc superconductors [1,2]. These compounds have a two-dimensional structure (Fig.1) consisting of extended corner-sharing metal halide octahedra layers (i.e. [MCl6] inorganic anions), alternating with organic cation bilayers (i.e. protonated primary amines). Notably, interaction between the organic and inorganic components of the perovskite structures is significantly influential in the relative stability of various crystals, whereas interactions between the organic R groups, as van der Waals interactions, are much weaker [3,4] though they can either stabilize or destabilize the perovskite structures.

Figure1 Structure scheme of (C4H9NH3)2MCl4. c-axis length is two times of d-space value

FF9.30.2

This paper reports the preparation of (C4H9NH3)2MCl4 (M = Mn, Cu) by reactions in solution and characterization of their structures by XRD and SEM. In addition, unit cell parameters derived from Pawley Refinement program are used to analyse the decrease of d-space value in (C4H9NH3)2CuCl4 caused by the Jahn-Teller distortion of the [CuCl6] octahedra. This increases the repulsion of Cl- in the c-axis direction and weakens the interactions between organic and inorganic components of the compound, which results in its lower thermal stability confirmed by TG&DSC curves. EXPERIMENTAL DETAILS Sample Preparation (C4H9NH3)2MnCl4 is synthesized by a reaction in aqueous HCl solution. The process involves adding the C4H9NH2·HCl into the light green MnCl2 acid solution after dissolving MnCl2·4H2O in aqueous HCl (37%wt) at 70℃ in a water bath and mixing C4H9NH2 with aqueous HCl to get protonated primary amine C4H9NH2·HCl. The stoicheiometric molar ratio of MnCl2·4H2O to C4H9NH2 is 1:2, whil