本文選題：CaCu_3Ti_4O_(12)　切入點(diǎn)：BaTiO_3　出處：《吉林大學(xué)》2017年碩士論文

【摘要】：CaCu_3Ti_4O_(12)(CCTO)屬于ACu3Ti4O12家族,首次由Subramanian等人發(fā)現(xiàn)。CaCu_3Ti_4O_(12)表現(xiàn)出最特殊的性質(zhì),并且在1 kHz時(shí),具有大約12000的高介電常數(shù)(e')。它的e'從室溫到300°C幾乎與溫度無關(guān),且在102~106 Hz范圍內(nèi)與頻率無關(guān)。這些結(jié)果表明,CCTO陶瓷具有電容器應(yīng)用的潛力。由于BaTiO_3良好的特性,其在電子陶瓷和微電子領(lǐng)域是一種非常有吸引力的材料。其高介電常數(shù)(e')和低介電損耗(tanδ)使鈦酸鋇成為許多應(yīng)用的極好選擇。摻雜的鈦酸鋇已經(jīng)在半導(dǎo)體、正溫度系數(shù)電阻(PTCR)、超聲換能器、壓電器件中廣泛應(yīng)用,并且已經(jīng)成為最重要的鐵電陶瓷之一。研究了燒結(jié)時(shí)間和摻雜離子的位占據(jù)對(duì)CCTO陶瓷的高e'和高tanδ的影響。研究了Nb摻雜BaTiO_3陶瓷的結(jié)構(gòu)、微結(jié)構(gòu)、介電、電學(xué)性質(zhì)以及點(diǎn)缺陷。主要內(nèi)容如下:1、研究不同燒結(jié)時(shí)間對(duì)CCTO的微觀結(jié)構(gòu)、介電和電學(xué)性質(zhì)的影響。結(jié)果表明:CCTO陶瓷的介電性能受微觀結(jié)構(gòu)影響,隨著平均晶粒尺寸的增加,e'增加。經(jīng)阻抗和導(dǎo)納譜研究,低頻下的巨介電性質(zhì)主要是受晶界電容(C_(gb))的影響,而高頻下的介電平臺(tái)主要受晶粒電容(C_g)的影響,并且介電弛豫進(jìn)程與晶粒電阻(Rg)密切相關(guān)。隨著燒結(jié)時(shí)間延長(zhǎng),tanδ降低,tanδ與總電阻成反比,受晶界電阻(R_(gb))控制。2、單相立方結(jié)構(gòu)Ca_(1-3x/2)Tb_xCu_3Ti_4O_(12)陶瓷提高了CCTO的tanδ。這主要?dú)w功于Tb離子的摻雜修飾了CCTO的晶界的化學(xué)結(jié)構(gòu),降低了晶界的勢(shì)壘高度(φ_B),使得更多的電荷載流子能通過晶界勢(shì)壘,提高了tanδ。3、單相Ca_(1-3x/2)Tb_xCu_3Ti_(4-x)Tb_xO_(12)(CTCTT)陶瓷的晶粒生長(zhǎng)受抑制,歸結(jié)于溶解拖拽機(jī)制。拉曼(RS)表明CTCTT中存在多聲子效應(yīng),XPS表明CTCTT中以Cu~(2+)/Cu~+,Ti~(4+)/Ti~(3+)和Tb~(3+)/Tb~(4+)混合價(jià)形式存在。Tb摻雜CCTO導(dǎo)致e'降低,tanδ升高。對(duì)CTCTT的缺陷化學(xué)和阻抗譜(IS)的分析證實(shí):e'的降低和tanδ的增加主要是由于Ti位的Tb~(4+)的受主效應(yīng)導(dǎo)致CTCTT晶粒中的導(dǎo)電性降低,進(jìn)而影響內(nèi)部阻擋層電容(IBLC)效應(yīng)。4、四方結(jié)構(gòu)的Ba(Ti_(1-x/4)Nb_x)O_3(x=0.03)(BTN)陶瓷以盤狀晶粒和細(xì)晶粒共存。x=0.05的BTN陶瓷展示立方陶瓷、高密度(ρr=98%)、均勻的Nb富的細(xì)晶粒微結(jié)構(gòu),Nb離子以Nb~(5+)(百分比:80%)、Nb4+(~11%)和Nb~(3+)(~9%)的混合價(jià)形式存在。BTN陶瓷內(nèi)存在Ba空位和Ti空位。來自Nb~(5+)的施主效應(yīng)的電子補(bǔ)償在BTN中占優(yōu)勢(shì)。x=0.05的BTN高密度陶瓷是室溫電阻率ρRT=2×104Ωcm的半導(dǎo)體,而不是常規(guī)的電介質(zhì)。
[Abstract]:CaCu3Ti4Ostit belongs to the ACu3Ti4O12 family, first discovered by Subramanian et al., which shows the most special nature, and has a high dielectric constant of about 12000 at 1 kHz. Its e'is almost independent of temperature from room temperature to 300 擄C, The results show that CCTO ceramics have the potential of capacitor application. Due to the good properties of BaTiO_3, It is a very attractive material in the field of electronic ceramics and microelectronics. Its high dielectric constant and low dielectric loss make barium titanate an excellent choice for many applications. Doped barium titanate has been used in semiconductors. Positive temperature coefficient resistor PTCRs, ultrasonic transducers, piezoelectric devices are widely used. And it has become one of the most important ferroelectric ceramics. The effects of sintering time and potential occupation of doped ions on the high e' and high tan 未 of CCTO ceramics are studied. The structure, microstructure, dielectric properties of NB doped BaTiO_3 ceramics are studied. The main contents are as follows: 1. The effects of sintering time on the microstructure, dielectric and electrical properties of CCTO are studied. The results show that the dielectric properties of CCTO ceramics are affected by the microstructure. With the increase of average grain size, the results of impedance and admittance spectra show that the giant dielectric properties at low frequency are mainly affected by grain boundary capacitance C / g / g / b), while the dielectric platform at high frequency is mainly affected by grain capacitance / C g / g. The dielectric relaxation process is closely related to the grain resistance (Rg). With the increase of sintering time, the decrease of tan 未 is inversely proportional to the total resistance. Controlled by grain boundary resistance (RSP). (2) single phase cubic CaStut 1 to 3 x / 2 Tbx / 2) Ceramics have increased the tan 未 of CCTO. This is mainly due to the addition of TB ions to modify the chemical structure of CCTO's grain boundaries. By lowering the grain boundary barrier height, more charge carriers can pass through the grain boundary potential barrier, thus increasing the tan 未 .3, single phase CaBX Cu3TiTiTiK4 TbxCu3TiTiP4 TbxOT, and the grain growth of the CTCTCTCTT ceramics is inhibited, and the results show that the grain growth of the ceramics has been inhibited by the increase in the number of charge carriers passing through the grain boundary barrier, the increase in tan 未. 3 and the increase in the grain growth of the ceramics. Raman spectroscopy (RS) indicates that there are multiphonon effects in CTCTT. It shows that there is a mixed valence in CTCTT in the form of Cu~(2 / Cu / Cu / TbDX (3) and Tb~(3 / / Tbbtn4). The existence of CCTO doping leads to the increase of e' -degrade tan 未. The defect chemistry and impedance spectroscopy of CTCTT. The decrease of tan 未 and the decrease of tan 未 are mainly due to the decrease of conductivity in CTCTT grains due to the acceptor effect of Tb~(4 at Ti position. Furthermore, the internal barrier layer capacitance (IBLC) effect .4. the tetragonal Baantitike 1-x / 4nbsp / 4 NbxSZ / 4 NbxSX / 0. 03 BTN ceramics exhibit cubic ceramics with disk-shaped and fine-grained BTN ceramics. There are Ba vacancies and Ti vacancies in BTN ceramics in the form of mixed valence in the form of Nb~(5 (percentage: 80% Nb4 + 11) and Nb~(3. The electronic compensation of donor effect from Nb~(5) is in the form of Ba vacancies and Ti vacancies in BTN ceramics. The high density BTN ceramics with advantage. X0. 05 are semiconductors with resistivity 蟻 RT=2 脳 104 惟 cm at room temperature. Instead of conventional dielectric.
【學(xué)位授予單位】：吉林大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TQ174.1

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