本文選題：分子基鐵電體　切入點(diǎn)：鐵電動(dòng)力學(xué)　出處：《華東師范大學(xué)》2017年博士論文　論文類(lèi)型：學(xué)位論文

【摘要】：鐵電體是一類(lèi)具有自發(fā)極化并且極化方向可以隨外電場(chǎng)發(fā)生反轉(zhuǎn)的固體(晶體或聚合物)或液晶材料,在電子領(lǐng)域具有重要的應(yīng)用,如電容器、非易失性存儲(chǔ)器、場(chǎng)效應(yīng)晶體管、傳感器、電容器等。自從1920年第一個(gè)鐵電體羅息鹽問(wèn)世以來(lái),鐵電材料的發(fā)展和應(yīng)用主要集中在無(wú)機(jī)鐵電體和少數(shù)有機(jī)聚合物鐵電體�，F(xiàn)代電子學(xué)發(fā)展的趨勢(shì)之一是制備純有機(jī)電子器件,因此有機(jī)鐵電體成為近年來(lái)鐵電材料的研究熱點(diǎn),它們的發(fā)展不僅給材料化學(xué)帶來(lái)了新的挑戰(zhàn),同時(shí)由于它們的輕便、柔韌和無(wú)毒等優(yōu)點(diǎn),也為鐵電體在有機(jī)電子領(lǐng)域的應(yīng)用提供了新的思路。隨著研究的大量開(kāi)展,幾種性能良好的小分子鐵電體陸續(xù)被發(fā)現(xiàn),打破了人們對(duì)小分子鐵電材料居里溫度低、自發(fā)極化小的傳統(tǒng)認(rèn)識(shí),為其實(shí)際應(yīng)用提供了可能。此外,當(dāng)鐵電性與光學(xué)、磁性等性質(zhì)結(jié)合時(shí),自發(fā)電極化成為操控物質(zhì)光學(xué)、磁性的新途徑,同時(shí)也使得利用光和磁場(chǎng)來(lái)調(diào)控其自發(fā)極化成為可能。此類(lèi)多功能材料,如熒光鐵電材料、磁電耦合材料等,無(wú)論在基礎(chǔ)研究方面,還是在光電器件、自旋電子學(xué)、磁電傳感等應(yīng)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(lèi)分子基鐵電晶體的鐵電特性、制備金屬有機(jī)配合物單晶、磁性元素?fù)诫s分子基鐵電晶體三個(gè)方面入手,在分子基鐵電單晶的制備及性能調(diào)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(jié)果表明影響DIPAB晶型的關(guān)鍵因素是晶體生長(zhǎng)過(guò)程中溶劑/環(huán)境中的水分:在無(wú)水條件下重結(jié)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(chǔ)上,通過(guò)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(duì)小分子鐵電體DIPAB晶體的電滯回線動(dòng)力學(xué)進(jìn)行了研究,發(fā)現(xiàn)電滯回線面積A隨頻率f具有三個(gè)階段的變化,不同于無(wú)機(jī)材料中常見(jiàn)的單峰曲線變化,結(jié)合DIPAB的結(jié)構(gòu)特點(diǎn),認(rèn)為這可能是由于晶體中同時(shí)存在有序-無(wú)序振動(dòng)和離子位移型鐵電起源。通過(guò)數(shù)據(jù)擬合,得到了三個(gè)階段A與f和電場(chǎng)E0之間的指數(shù)關(guān)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(duì)晶體的相變溫度和鐵電性能的影響,結(jié)果表明這些晶體的鐵電性與陰離子的電負(fù)性和結(jié)構(gòu)密切相關(guān):對(duì)于鹵素陰離子來(lái)說(shuō),電負(fù)性越大,晶體相變溫度越高,極化強(qiáng)度越大;DIPA-C104不符合此規(guī)律是由于其相變?cè)从贑104-離子而不是DIPA+陽(yáng)離子的有序-無(wú)序振動(dòng)。密度泛函理論計(jì)算結(jié)果與實(shí)驗(yàn)結(jié)果符合。4.制備了有機(jī)-無(wú)機(jī)雜化DIPA2MnBr4單晶,晶體在420 K附近發(fā)生結(jié)構(gòu)相變,電滯回線和PFM測(cè)試表明DIPA2MnBr4具有室溫鐵電性。此外,DIPA2MnBr4晶體在紫外燈下發(fā)強(qiáng)綠色熒光,量子產(chǎn)率高達(dá)62%,并且對(duì)醇類(lèi)氣體具有靈敏的熒光響應(yīng)和良好的可重復(fù)性。5.以錳(Ⅱ)為金屬中心,分別制備了一系列含不同有機(jī)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(jī)配體和鹵素離子對(duì)配合物結(jié)構(gòu)和磁性、熒光等性質(zhì)的影響。結(jié)果表明有機(jī)配體和鹵素離子均能調(diào)控配合物的結(jié)構(gòu)及性質(zhì)。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(jié)構(gòu)和性質(zhì)。隨后,借鑒無(wú)機(jī)半導(dǎo)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(shí)具有磁性和近室溫鐵電性,在外磁場(chǎng)作用下,錳(Ⅱ)摻雜巴豆酸(1:5)晶體的介電常數(shù)隨溫度發(fā)生明顯的突變,并且突變隨磁場(chǎng)強(qiáng)度增加而向高溫移動(dòng),表明晶體內(nèi)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(xué)位授予單位】：華東師范大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2017
【分類(lèi)號(hào)】：TM221

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本文編號(hào)：1593364