Synthesis And Ferroelectric-dielectric Properties Of Amantadines And Fluoroethylamine Halogenated Perovskites Compounds

1.In recent years,the research of molecular ferroelectrics has attracted extensive attention since they are light-weight,environmentally friendly?no contain lead,etc.?,flexible and easily synthesize compared with ceramic ferroelectrics,thus they are expected to replace ceramic ferroelectrics and became a research hotspot in research of functional materials..In this paper,four adamantane compounds,nine perovskite compounds and four azole compounds were successfully synthesized.The structures,optical and ferroelectric properties of these compounds were deeply studied by single crystal diffraction,dielectric,DSC,SHGand ferroelectric measurements.The main contents include:We introduce the properties and applications of crystals,such as structural symmetry,dielectric,thermal properties,SHG effect and ferroelectric,phase transition materials and their applications are introduced.And further illustrate the definition and classification of phase transition.We cite examples to state the research status of molecular ferroelectric and dielectric materials,and describethe significance of the selected subject and the research progress of this work.2.The cage structure of amantadine contains a lot of C atoms with sp³ hybridized orbitals.This flexible structure is conducive to the generation of rotational motion of molecules,which leading to happen of the structural phasetransition.By using amantadine carboxylic acid and amantadine,four compounds with reversible structural phase transitions were designed and constructed.A new ferroelectric compound C₁₁H₁₅O₂·C₅H₁₁N₂O?1?with giant strong nonlinear effect was synthesized from amantadine carboxylic acid and l-proline amide.Compound 1 undergoes a reversible structural phase transition near 130 K.The dipole moment from amine group to carboxylic acid produces spontaneous polarization,whose spontaneous polarizability is 0.15 uC/cm² and the nonlinear effect intensity is three times of that KDP.Compound 2C₁₁H₁₆O₂·C₅H₈N₂?2?is composed of two amantadine carboxylic acid molecules and a 3,5-dimethylpyrazole molecule,which undergoes a reversible structural phase transition near 260 K.We obtained a neutral adduction C₁₁H₁₆O₂·C₆H₁₂N₄·CHCl₃?3?by the reaction of amantadic acid and hexamethylenetetramine.3 shows a reversible phase transition with symmetry breaking near 265 K.Amines are commonly used to construct molecular ferroelectricity and dielectric materials.Amantadine was protonated by high chlorine acid to form compound C₁₁H₁₉N·ClO₄?4?with reversible structural phase transition.3.Nine new perovskite halogenides with reversible phase transitions were synthesized by using cadmium chloride,manganese chloride and copper chloride as the backbone,and2-fluoroethylamine,2,2-difluoroethylamine,2,2-trifluoroethylamine as organic amine cations.Compounds?FC₂H₄NH₃?₂CdCl₄?5?and?FC₂H₄NH₃?₂MnCl₄?6?display phase transitions in the vicinity of room temperature,and compounds?FC₂H₄NH₃?₂CuCl₄?7?,?F₂C₂H₃NH₃?₂CdCl₄?8?,?F₂C₂H₃NH₃?₂MnCl₄?9?,?F₃C₂H₂NH₃?₂CdCl₄?11?,?F₃C₂H₂NH₃?₂MnCl₄?12?and?F₃C₂H₂NH₃?₂CuCl₄?13?all undergo phase transitions at high temperature,while compound?F₂C₂H₃NH₃?₂CuCl₄?10?shows phase transition at low temperature.The thermal anomalies,the switchable dielectric behavior and the phase transition mechanism of the nine compounds were analyzed,the results show that these structural phase transitions mainly caused by the order-disorder motions of amine and the distortion of molecular framework.The step dielectric behaviors of these perovskite compounds near the phase transition temperature indicate they have potential applications in dielectric switches,and provide a new method for designing molecular ferroelectric materials or solid state phase transition materials with other performance.4.We report three azole compounds with reversible phase transitions by reaction of 1,2-dimethyl imidazole,imidazole,triazole and acid.Among them,compounds C₅H₉N₂·PF₆?14?and C₄H₄O₄·C₂H₃N₃?16?exhibit very large dielectric relaxation dependence on temperature.Besides,a new metal organic copper tetrazolium complex C₁₂H₆N₇·CuSO₄?17?with high nitrogen structure was prepared by hydrothermal reaction of 5,5'-dicyano-3,3'-bipyridine,sodium azide and CuSO₄,which hasa beautiful butterfly hairpin structure,thus we believe that it possesses potential application in energetic materials.