鉍層狀鈣鈦礦氧化物（n=6、7）材料中的A、B位改性研究
發(fā)布時(shí)間：2018-10-11 09:35
【摘要】：具有Aurivillius結(jié)構(gòu)的含鉍層狀氧化物材料(Bi4Bin-3Fen-3Ti3O3n+3,n-BFTO)是一種可以在室溫或室溫以上同時(shí)表現(xiàn)出鐵電性和鐵磁性的單相多鐵材料,在高密度存儲(chǔ)、傳感、自旋電子器件等領(lǐng)域有著很大的潛在應(yīng)用價(jià)值。 值得注意的是,現(xiàn)有n-BFTO材料的鐵電、鐵磁性能相對(duì)較弱,并且與材料的層數(shù)有緊密的聯(lián)系。為進(jìn)一步提高n-BFTO的多鐵性能,本文主要進(jìn)行以下研究,包括：1)結(jié)構(gòu)層數(shù)對(duì)B位Co部分取代Fe的BFTO材料鐵磁性能的影響；2)優(yōu)選了具有七層結(jié)構(gòu)的BFTO,對(duì)其分別進(jìn)行A位或者B位摻雜取代,以及A、B位共摻雜取代,研究對(duì)應(yīng)陶瓷材料的物相結(jié)構(gòu)、鐵電、鐵磁、介電、發(fā)光等性能；3)對(duì)A、B位共摻雜取代的具有六層結(jié)構(gòu)的BFTO的鐵電、鐵磁、漏電等性能進(jìn)行研究,并與7層結(jié)構(gòu)的材料相對(duì)比,進(jìn)一步討論層數(shù)對(duì)材料多鐵性能的影響。論文主要結(jié)果如下： 第一章：主要介紹了多鐵材料的相關(guān)概念,BFTO材料的研究發(fā)展歷史,以及BFTO陶瓷常用的制備方法和性能表征手段。 第二章：通過(guò)固定B位Co取代濃度的方式,探討n-BFTO材料的結(jié)構(gòu)層數(shù)對(duì)材料鐵磁性能的影響。研究發(fā)現(xiàn)隨著層數(shù)的增加,Fe-O-Co耦合數(shù)會(huì)增加,因而導(dǎo)致鐵磁性能提高。此外與偶數(shù)層材料相比,奇數(shù)層材料中更有利于獲得好的鐵磁性。這主要是因?yàn)楹笳呤墙Y(jié)構(gòu)對(duì)稱(chēng)性更低的單斜相,更有利于增強(qiáng)Fe-O-Co間的耦合強(qiáng)度從而提高鐵磁性能。 第三章：研究了在B位鈷摻雜的濃度對(duì)Bi8Fe4Ti3O24(7-BFTO)陶瓷結(jié)構(gòu)、鐵電、鐵磁和介電性能的影響。發(fā)現(xiàn)在7-BFTO材料中,Co對(duì)Fe的最大可取代量并不是由材料的容忍因子決定(Fe和Co離子半徑非常接近,從容忍因子上來(lái)講,是可以完全互相取代的),而熱力學(xué)因素的影響可能更大。要保證材料的穩(wěn)定七層結(jié)構(gòu),Co和Fe的最大原子個(gè)數(shù)比為0.4:3.6,否則合成過(guò)程中材料的結(jié)構(gòu)會(huì)出現(xiàn)坍塌并會(huì)伴隨著雜相的出現(xiàn)。對(duì)于保持有七層穩(wěn)定結(jié)構(gòu)的材料,Co對(duì)Fe的取代量越多,鐵磁性能越好,材料最優(yōu)的鐵磁性能在Co:Fe=0.4:3.6時(shí)出現(xiàn),而鐵電性能最優(yōu)出現(xiàn)在Co:Fe=0.33.7處,前者主要由最大的磁性耦合離子對(duì)數(shù)目決定,而后者取決于Co取代鐵對(duì)材料結(jié)構(gòu)和漏電性的影響。 第四章：研究Eu和Co在A、B位共摻雜時(shí)7-BFTO陶瓷材料中的熒光、鐵電和鐵磁性能。我們發(fā)現(xiàn)在這種層狀結(jié)構(gòu)材料中,稀土離子發(fā)光的濃度淬滅作用可以得到一定程度上的抑制,這可能是由于BFTO材料獨(dú)特的層狀結(jié)構(gòu)對(duì)晶胞內(nèi)稀土離子相互之間距離和所處格位有著一定的調(diào)控作用。另外Eu的摻雜對(duì)材料的鐵電鐵磁性能也有較為明顯的影響。 第五章利用貴金屬的表面等離激元,來(lái)增強(qiáng)稀土離子摻雜的7-BFTO (BLnFTO)材料中光致發(fā)光強(qiáng)度。設(shè)計(jì)并制備了具有核-殼-殼結(jié)構(gòu)Ag/SiO2/BLnFTO的材料。但是實(shí)驗(yàn)發(fā)現(xiàn)以Ag作為提供表面等離激元的中心不是很合適,這主要是因?yàn)锳g在樣品進(jìn)行熱處理時(shí),容易發(fā)生氧化并從材料中擴(kuò)散消失等問(wèn)題,不利于材料的性能和使用壽命。 第六章：主要研究了在La、Co共摻的Bi6-xLaxFe1.5Co1.5Ti3O21(6-BLFCT)材料中,鐵磁和鐵電性能隨著La摻雜濃度的變化關(guān)系。發(fā)現(xiàn)鐵磁和鐵電性能在一定的La摻雜濃度范圍內(nèi)會(huì)隨著La的增加而增大,都在x=0.75處達(dá)到最大,這是由于La摻雜對(duì)于材料晶體結(jié)構(gòu)的修飾以及晶體結(jié)構(gòu)對(duì)磁耦合結(jié)構(gòu)的影響。之后系統(tǒng)研究了La摻雜對(duì)材料中主要離子的價(jià)態(tài)和導(dǎo)電性的影響,也發(fā)現(xiàn)高價(jià)離子最穩(wěn)定和導(dǎo)電率最低時(shí)都是La:Bi=0.75:6.25。 最后第七章是全文內(nèi)容的總結(jié)以及對(duì)未來(lái)工作的展望。
[Abstract]:Bi4Bin-3Fen-3Ti3O3n + 3, n-BFTO with Aurivilius structure is a single-phase polyiron material which can exhibit ferroelectricity and ferromagnetism at room temperature or at room temperature, and has great potential application value in the fields of high density storage, sensing, spin electronics and so on. Notably, the iron and ferromagnetic properties of the existing n-BFTO material are relatively weak and are closely related to the number of layers of material In order to further improve the multi-iron performance of n-BFTO, this paper mainly studies the following research, including: 1) the effect of the number of structural layers on the ferromagnetic properties of the BFTO material substituted by the B-bit Co part; 2) the BFTO with the seven-layer structure is preferred, and the A-bit or the B-bit doping are respectively carried out to replace the Fe-based BFTO material. A, B-bit co-doping is substituted to study properties such as phase structure, ferroelectric, ferromagnetic, dielectric, luminescence and other properties of the corresponding ceramic materials; 3) the properties of iron, ferromagnetic, and electric leakage of the BFTO, which are replaced by the A and B co-doping, are studied and compared with the material of the 7-layer structure. In contrast, it is further discussed that the number of layers on the multi-iron performance of the material Impact. Main results of the thesis The first chapter is as follows: Chapter 1: It mainly introduces the related concepts of multi-iron materials, the research and development history of BFTO materials, and the preparation methods and properties of BFTO ceramics. The second chapter discusses the structure and number of n-BFTO materials by fixing B-bit Co substitution concentration. The results show that the coupling number of Fe-O-Co increases with the increase of the number of layers. in addition to an even layer material, that odd layer material is more advantageous, Good ferromagnetic properties are obtained. This is mainly because the latter is a phase with lower structural symmetry and is more conducive to enhancing the coupling strength between Fe-O-Co. In the third chapter, the structure of Bi8Fe4Ti3O24 (7-BFTO) ceramic and iron were studied. In the 7-BFTO material, the maximum substitutability of Co to Fe is not determined by the tolerance factor of the material (Fe and Co ion radii are very close, from the tolerance factor, they can be completely replaced with each other), and heat The influence of mechanical factors may be greater. To ensure the stable seven-layer structure of the material, the maximum atomic number of Co and Fe is 0. 4: 3. 6. Otherwise, the structure of the material in the synthesis process will occur. In the case of Co: Fe = 0. 4: 3. 6, the better the ferroelectricity can be found in Co: Fe = 0. 33. 7, the former is the largest. the number of magnetic coupling ions is determined and the latter depends on the co-substituted iron pair, The effects of Eu and Co in A and B co-doped 7-BFTO ceramics were studied. In this layered structure, the concentration quenching of rare earth ions can be suppressed to some extent, which may be due to the unique layered structure of BFTO material and the distance between the rare earth ions in the unit cell. and the doping of the Eu is different to the iron of the material. In the fifth chapter, the 7-BFTO doped with rare earth ions is enhanced by using the surface plasmon and the like of the noble metal. Photoluminescence intensity in (BLnFTO) material, design and preparation of nuclear-shell-shell structure Ag/ SiO2/ BLnFTO materials. However, it is found that Ag is not very suitable as the center of the excitation element, such as surface, because Ag can easily oxidize and disappear from the material when the sample is subjected to heat treatment. Six-xLaxFe1. 5Co1. 5Ti3O21 (6-BLFCT) materials co-doped with La and Co were studied. The ferromagnetic and ferroelectric properties can vary with the La doping concentration. It is found that the ferromagnetic and ferroelectric properties can increase with the increase of La in a certain La doping concentration range, reaching the maximum at x = 0. 75, which is due to the La doping on the material crystal. The effect of structure modification and crystal structure on the structure of magnetic coupling is studied. The influence of La doping on valence state and conductivity of main ions in material is studied, and the most stable and conductive rate of high valence ions is also found. The minimum time is La: Bi = 0. 75: 6. 25.
【學(xué)位授予單位】：中國(guó)科學(xué)技術(shù)大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2015
【分類(lèi)號(hào)】：TB34;TM271
本文編號(hào)：2263717
[Abstract]:Bi4Bin-3Fen-3Ti3O3n + 3, n-BFTO with Aurivilius structure is a single-phase polyiron material which can exhibit ferroelectricity and ferromagnetism at room temperature or at room temperature, and has great potential application value in the fields of high density storage, sensing, spin electronics and so on. Notably, the iron and ferromagnetic properties of the existing n-BFTO material are relatively weak and are closely related to the number of layers of material In order to further improve the multi-iron performance of n-BFTO, this paper mainly studies the following research, including: 1) the effect of the number of structural layers on the ferromagnetic properties of the BFTO material substituted by the B-bit Co part; 2) the BFTO with the seven-layer structure is preferred, and the A-bit or the B-bit doping are respectively carried out to replace the Fe-based BFTO material. A, B-bit co-doping is substituted to study properties such as phase structure, ferroelectric, ferromagnetic, dielectric, luminescence and other properties of the corresponding ceramic materials; 3) the properties of iron, ferromagnetic, and electric leakage of the BFTO, which are replaced by the A and B co-doping, are studied and compared with the material of the 7-layer structure. In contrast, it is further discussed that the number of layers on the multi-iron performance of the material Impact. Main results of the thesis The first chapter is as follows: Chapter 1: It mainly introduces the related concepts of multi-iron materials, the research and development history of BFTO materials, and the preparation methods and properties of BFTO ceramics. The second chapter discusses the structure and number of n-BFTO materials by fixing B-bit Co substitution concentration. The results show that the coupling number of Fe-O-Co increases with the increase of the number of layers. in addition to an even layer material, that odd layer material is more advantageous, Good ferromagnetic properties are obtained. This is mainly because the latter is a phase with lower structural symmetry and is more conducive to enhancing the coupling strength between Fe-O-Co. In the third chapter, the structure of Bi8Fe4Ti3O24 (7-BFTO) ceramic and iron were studied. In the 7-BFTO material, the maximum substitutability of Co to Fe is not determined by the tolerance factor of the material (Fe and Co ion radii are very close, from the tolerance factor, they can be completely replaced with each other), and heat The influence of mechanical factors may be greater. To ensure the stable seven-layer structure of the material, the maximum atomic number of Co and Fe is 0. 4: 3. 6. Otherwise, the structure of the material in the synthesis process will occur. In the case of Co: Fe = 0. 4: 3. 6, the better the ferroelectricity can be found in Co: Fe = 0. 33. 7, the former is the largest. the number of magnetic coupling ions is determined and the latter depends on the co-substituted iron pair, The effects of Eu and Co in A and B co-doped 7-BFTO ceramics were studied. In this layered structure, the concentration quenching of rare earth ions can be suppressed to some extent, which may be due to the unique layered structure of BFTO material and the distance between the rare earth ions in the unit cell. and the doping of the Eu is different to the iron of the material. In the fifth chapter, the 7-BFTO doped with rare earth ions is enhanced by using the surface plasmon and the like of the noble metal. Photoluminescence intensity in (BLnFTO) material, design and preparation of nuclear-shell-shell structure Ag/ SiO2/ BLnFTO materials. However, it is found that Ag is not very suitable as the center of the excitation element, such as surface, because Ag can easily oxidize and disappear from the material when the sample is subjected to heat treatment. Six-xLaxFe1. 5Co1. 5Ti3O21 (6-BLFCT) materials co-doped with La and Co were studied. The ferromagnetic and ferroelectric properties can vary with the La doping concentration. It is found that the ferromagnetic and ferroelectric properties can increase with the increase of La in a certain La doping concentration range, reaching the maximum at x = 0. 75, which is due to the La doping on the material crystal. The effect of structure modification and crystal structure on the structure of magnetic coupling is studied. The influence of La doping on valence state and conductivity of main ions in material is studied, and the most stable and conductive rate of high valence ions is also found. The minimum time is La: Bi = 0. 75: 6. 25.
【學(xué)位授予單位】：中國(guó)科學(xué)技術(shù)大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2015
【分類(lèi)號(hào)】：TB34;TM271
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