The Growth And Properties Of Diisopropylamine Perchlorate Heterostructures

Molecular ferroelectric materials have great potential for applications in piezoelectric,photovoltaic,logic,storage,and other fields due to their spontaneous polarization characteristics.In recent years,research on molecular ferroelectric materials has gradually become one of the research focuses in chemistry,materials,and physics.Molecular ferroelectric materials have various advantages such as diverse structures,convenient property design,easy performance regulation,low film forming cost,low large-scale preparation cost,good flexibility,and biodegradability.Among them,diisopropylamine bromide and diisopropylamine chloride have high Curie temperature and large spontaneous polarization value,which have enormous application potential.Diisopropylamine perchloric acid is a kind of room temperature ferroelectrics with ferroelectricity between 253 K and 343 K,although its spontaneous polarization value is not as large as that of diisopropylamine bromide and diisopropylamine chloride.In view of the excellent ferroelectric properties of diisopropylamine ferroelectrics,our research group is committed to exploring the application research of diisopropylamine ferroelectrics.Previous research by our research group has found that the preparation of micro rod shaped microcrystals from diisopropylamine perchloric acid by freeze-drying method exhibits excellent photo induced PM2.5 adsorption ability.On this basis,this paper conducted a detailed study on the properties of diisopropylamine perchlorate micro rods and analyzed the reasons for their photo induced PM2.5 adsorption properties.The specific research content is as follows:(1)Diisopropylamine perchloric acid(DIPAP)micro rod material with millimeter sized pores was synthesized by freeze-drying method.In the photo induced PM2.5 adsorption experiment,it was found that the fine DIPAP micro rod had better PM2.5 adsorption ability,while the coarse DIPAP micro rod hardly adsorbed PM2.5Raman spectroscopy testing found that the coarse DIPAP microns almost only had Raman vibration peaks of pure diisopropylamine perchloric acid,while the fine DIPAP microns also contained Raman peaks of other DIPAP phases(new DIPAP phases).Powder X-ray diffraction confirmed the existence of another DIPAP phase.This indicates that the DIPAP microns obtained by freeze-drying have a heterojunction structure composed of two phases.(2)Measurement of Raman vibrations at different positions of DIPAP microns revealed that the content of new DIPAP phases varied,resulting in a Raman peak ratio of 25%to 100%between 319 cm-1 and 464 cm-1,while this value for fine DIPAP microns was 100%.This indicates that the fine DIPAP micron rod contains more DIPAP new phases.The DSC results of DIPAP micro rods indicate that in addition to the phase transition of the original DIPAP phase,there is also a phase transition near 310K.The reversible Second order phase transition phase transition of λ shape also indicates the existence of new DIPAP phase.In addition,the emergence of new phases reduces the thermal hysteresis of the original phase,indicating a decrease in its phase transition potential barrier.(3)Multiple DSC cycle tests and analysis of pure DIPAP crystals have found that the heat treatment process can transform the original phase of DIPAP into a new phase of DIPAP.After five heating and cooling cycles,the phase transition peak of DIPAP crystal is similar to the DSC phase transition peak pattern of DIPAP micro rod.Both the heat treatment process and freeze-drying process can induce the generation of new phases in DIPAP.(4)We conducted piezoelectric microscopy tests on both coarse and fine DIPAP microns,and found that the fine DIPAP microns containing more DIPAP new phases had a larger internal bias field,which reached 4 times the coercivity field.This huge bias field may lead to a larger photoelectric effect on the fine DIPAP microns,resulting in better photo induced PM2.5 adsorption capacity.