本文選題：分子基鐵電體　切入點：鐵電動力學　出處：《華東師范大學》2017年博士論文　論文類型：學位論文

【摘要】：鐵電體是一類具有自發(fā)極化并且極化方向可以隨外電場發(fā)生反轉的固體(晶體或聚合物)或液晶材料,在電子領域具有重要的應用,如電容器、非易失性存儲器、場效應晶體管、傳感器、電容器等。自從1920年第一個鐵電體羅息鹽問世以來,鐵電材料的發(fā)展和應用主要集中在無機鐵電體和少數有機聚合物鐵電體�，F代電子學發(fā)展的趨勢之一是制備純有機電子器件,因此有機鐵電體成為近年來鐵電材料的研究熱點,它們的發(fā)展不僅給材料化學帶來了新的挑戰(zhàn),同時由于它們的輕便、柔韌和無毒等優(yōu)點,也為鐵電體在有機電子領域的應用提供了新的思路。隨著研究的大量開展,幾種性能良好的小分子鐵電體陸續(xù)被發(fā)現,打破了人們對小分子鐵電材料居里溫度低、自發(fā)極化小的傳統(tǒng)認識,為其實際應用提供了可能。此外,當鐵電性與光學、磁性等性質結合時,自發(fā)電極化成為操控物質光學、磁性的新途徑,同時也使得利用光和磁場來調控其自發(fā)極化成為可能。此類多功能材料,如熒光鐵電材料、磁電耦合材料等,無論在基礎研究方面,還是在光電器件、自旋電子學、磁電傳感等應用方面都有著重要的研究意義。本文從系統(tǒng)研究二異丙胺鹽類分子基鐵電晶體的鐵電特性、制備金屬有機配合物單晶、磁性元素摻雜分子基鐵電晶體三個方面入手,在分子基鐵電單晶的制備及性能調控方面取得了以下研究成果:1.研究了溶液法直接制備二異丙胺溴(DIPAB)鐵電單晶的條件,結果表明影響DIPAB晶型的關鍵因素是晶體生長過程中溶劑/環(huán)境中的水分:在無水條件下重結晶得到鐵電相的晶體,而在含水條件下得到順電相的晶體。在此基礎上,通過熱蒸發(fā)法在不同襯底上成功制備了均勻的DIPAB薄膜。2.首次對小分子鐵電體DIPAB晶體的電滯回線動力學進行了研究,發(fā)現電滯回線面積A隨頻率f具有三個階段的變化,不同于無機材料中常見的單峰曲線變化,結合DIPAB的結構特點,認為這可能是由于晶體中同時存在有序-無序振動和離子位移型鐵電起源。通過數據擬合,得到了三個階段A與f和電場E0之間的指數關系式。3.制備了六種不同陰離子(HF2-,Cl-,Br-,I-,NO3-,ClO4-)的二異丙胺(DIPA+)鹽晶體并研究了陰離子對晶體的相變溫度和鐵電性能的影響,結果表明這些晶體的鐵電性與陰離子的電負性和結構密切相關:對于鹵素陰離子來說,電負性越大,晶體相變溫度越高,極化強度越大;DIPA-C104不符合此規(guī)律是由于其相變源于C104-離子而不是DIPA+陽離子的有序-無序振動。密度泛函理論計算結果與實驗結果符合。4.制備了有機-無機雜化DIPA2MnBr4單晶,晶體在420 K附近發(fā)生結構相變,電滯回線和PFM測試表明DIPA2MnBr4具有室溫鐵電性。此外,DIPA2MnBr4晶體在紫外燈下發(fā)強綠色熒光,量子產率高達62%,并且對醇類氣體具有靈敏的熒光響應和良好的可重復性。5.以錳(Ⅱ)為金屬中心,分別制備了一系列含不同有機胺配體的胺-錳(Ⅱ)-氯配合物和含不同鹵素離子的吡咯烷-錳(Ⅱ)-鹵素配合物的單晶,研究了有機配體和鹵素離子對配合物結構和磁性、熒光等性質的影響。結果表明有機配體和鹵素離子均能調控配合物的結構及性質。6.研究了巴豆酸單晶、巴豆酸鈷(II)和巴豆酸錳(Ⅱ)配合物晶體的結構和性質。隨后,借鑒無機半導體摻雜的概念,制備了(1:10)、(1:5)的錳(Ⅱ)和鈷(Ⅱ)摻雜巴豆酸的晶體,所得到的摻雜晶體同時具有磁性和近室溫鐵電性,在外磁場作用下,錳(Ⅱ)摻雜巴豆酸(1:5)晶體的介電常數隨溫度發(fā)生明顯的突變,并且突變隨磁場強度增加而向高溫移動,表明晶體內可能存在磁電耦合。
[Abstract]:Ferroelectrics is a kind of solid and spontaneous polarization polarization direction can be reversed with the external electric field occurs (crystal or polymer) or liquid crystal materials have important applications in the field of electronics, such as capacitors, nonvolatile memory, field effect transistors, sensors, capacitors and so on. Since 1920 the first ferroelectric Luo the advent of the development and application of salt making, ferroelectric materials mainly focused on inorganic organic polymer ferroelectrics and ferroelectrics. One of the few modern electronics is the development trend of preparation of pure organic electronic devices, so organic ferroelectric ferroelectric materials has become a hot research topic in recent years, their development is not only to material chemistry has brought new challenges, at the same time because of their lightweight, flexible and non-toxic, but also provides a new way for the application of ferroelectrics in the field of organic electronics. With the research carried out a lot, some good performance Small molecular ferroelectrics have been discovered, people broke the Curie temperature of small molecule of ferroelectric materials is low, the traditional understanding of small spontaneous polarization, provides a possibility for the practical application. In addition, when the combination of ferroelectric and optical, magnetic properties, self generating polarization is the new way to manipulate matter optical, magnetic, and at the same time makes use of optical and magnetic field to control the spontaneous polarization becomes possible. This kind of multifunctional materials, such as fluorescent ferroelectric materials, magnetoelectric materials, both in terms of basic research, or in optoelectronic devices, spintronics, has important significance on magnetoelectric and other applications. The ferroelectric properties of system two isopropylamine salt molecules based ferroelectric crystals, preparation of metal organic complexes of single crystal, the three aspects of molecular based magnetic elements doped ferroelectric crystal with in molecule based ferroelectric single crystal preparation and property control The following results are obtained: 1. the study of the solution method to directly prepare two isopropyl amine bromide (DIPAB) ferroelectric single crystal conditions, results show that the key factors affecting the DIPAB crystal is water / solvent in the process of crystal growth in the environment: under anhydrous conditions obtained by recrystallization of ferroelectric crystals in aqueous conditions get the paraelectric crystal. On this basis, through thermal evaporation on different substrates of DIPAB thin films were prepared for the first time on the.2. uniform small molecule ferroelectric crystal DIPAB hysteresis kinetics were studied, found that changes in the hysteresis loop area A with frequency f has three stages, the single peak curve of different in the inorganic material in common, combined with the structural characteristics of DIPAB, that this may be due to order-disorder vibration and displacement of ion type ferroelectric crystals exist in the origin at the same time. By fitting the data obtained three stages with F and A Six different kinds of anions prepared the exponential relationship between the.3. field E0 (HF2-, Cl-, Br-, I-, NO3-, ClO4-) two isopropylamine (DIPA+) and to study the effect of salt crystal anion on the crystal phase transition temperature and ferroelectric properties, results show that the ferroelectric properties of these crystals is closely related with the anion electronegativity and structure for halogen anion, the larger the electronegativity, the phase transition temperature is higher, the greater the intensity of polarization; DIPA-C104 does not comply with this rule is because the phase transformation from C104- ion instead of DIPA+ cation order disorder vibration. The density functional theory calculation results accord with the experimental results of organic inorganic hybrid DIPA2MnBr4 single crystal was prepared by.4., the crystal phase transition occurs near 420 K, hysteresis loop and PFM test shows that DIPA2MnBr4 has room temperature ferroelectricity. In addition, DIPA2MnBr4 crystal strong green fluorescence under UV light, quantum yield up to 62 %, and has the alcohols gas sensitive fluorescence response and good repeatability of.5. with manganese (II) metal center, were prepared by a series of different organic amine ligands containing amine - manganese (II) - chloride complexes containing different halide ions and pyrrolidine - manganese (II) - halogen study on complexes of single crystal, organic ligands and halogen ions on the structure and magnetic properties of complexes, effects of fluorescent properties. The results show that organic ligands and halogen ions can crotonic acid crystal study on regulation of.6. structure and properties of complexes of cobalt (II), crotonic acid and crotonic acid manganese (II) structure and properties the crystal structure of the complexes. Then, based on the concept of inorganic semiconductor doping, preparation of (1:10) (1:5), Mn (II) and cobalt (II) doped crotonic acid crystals doped crystals obtained with magnetic and ferroelectric properties near room temperature, the external magnetic field under the action of manganese (II crotonic acid (1:5) doped) crystal The dielectric constant abruptly changes with the temperature, and the mutation moves to the high temperature with the increase of the magnetic field intensity. It indicates that there may be a magnetoelectric coupling in the crystal.

【學位授予單位】：華東師范大學
【學位級別】：博士
【學位授予年份】：2017
【分類號】：TM221

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本文編號：1593364