發(fā)布時(shí)間：2018-05-20 01:10

  本文選題：YAG陶瓷 + 助燒劑�。� 參考：《山東大學(xué)》2017年博士論文

【摘要】：釔鋁石榴石(Y_3Al_5O_12,YAG)是一種重要的功能性材料,在民用領(lǐng)域擁有非常廣泛的應(yīng)用,在國(guó)防科技領(lǐng)域占據(jù)非常重要的地位。作為激光增益介質(zhì),摻雜Nd~(3+)離子YAG透明激光陶瓷的很多性能優(yōu)于Nd:YAG激光晶體,是高功率激光器重要備選材料。并且,稀土離子摻雜YAG熒光粉,可用于LED光源照明。光的高透過(guò)率是實(shí)現(xiàn)Nd:YAG陶瓷激光性能的基本條件。而陶瓷的顯微結(jié)構(gòu),特別是晶粒尺寸、晶界結(jié)構(gòu)和氣孔是影響陶瓷透明度最根本因素。在激光陶瓷制備過(guò)程中,除了納米粉體的形貌、尺寸以及燒結(jié)工藝對(duì)陶瓷顯微結(jié)構(gòu)具有重要影響之外,在原料中添加助燒劑可以實(shí)現(xiàn)對(duì)顯微結(jié)構(gòu)調(diào)控。盡管大量文獻(xiàn)對(duì)助燒劑對(duì)透明激光陶瓷的結(jié)構(gòu)與性能的影響進(jìn)行了研究,但對(duì)于兩種助燒劑協(xié)同作用的研究較少。稀土摻雜YAG納米熒光粉體的尺寸、形貌和結(jié)晶程度直接影響其熒光性能。固相燒結(jié)法合成的粉體結(jié)晶性好,熒光量子效率高,但因?yàn)轭w粒大,熒光粉應(yīng)用困難;液相納米合成法合成的粉體顆粒尺寸小,但其結(jié)晶度差,熒光效率低�，F(xiàn)有納米粉體制備技術(shù)無(wú)法實(shí)現(xiàn)純度高、形貌和粒徑可控、結(jié)晶性高、分散性好的納米熒光粉體。因此,本論文研究以稀土摻雜YAG材料為主要研究對(duì)象,通過(guò)對(duì)YAG材料制備技術(shù)的研究,實(shí)現(xiàn)Nd:YAG透明激光陶瓷的顯微結(jié)構(gòu)調(diào)控和YAG:Ce納米棒的可控制備。本論文主要研究工作和結(jié)論如下:1.正硅酸乙酯(TEOS)和檸檬酸鎂(MC)的協(xié)同作用對(duì)Nd:YAG透明陶瓷微觀結(jié)構(gòu)的調(diào)控和性能提升(1)在Nd:YAG透明陶瓷制備過(guò)程中添加TEOS和MC作為助燒劑,調(diào)節(jié)其添加比例,實(shí)現(xiàn)對(duì)陶瓷晶粒大小、粒度分布和晶胞參數(shù)等微觀結(jié)構(gòu)調(diào)控。在TEOS與MC合理配比下,使其產(chǎn)生協(xié)同作用,促進(jìn)微缺陷排除和燒結(jié)周期優(yōu)化,使透明陶瓷的透過(guò)率提高并產(chǎn)出高功率激光。在Nd~(3+)摻雜量為2 at.%的YAG透明陶瓷中添加TEOS與MC配比為2:1的助燒劑,可以得到晶粒尺寸適中且粒徑分布集中、無(wú)氣孔、無(wú)雜相、晶格結(jié)構(gòu)平衡穩(wěn)定的透明陶瓷。共摻7.5 wt.%a TEOS與3.75 wt.‰MC的2 at.%Nd:YAG透明陶瓷是最優(yōu)樣品,光學(xué)透過(guò)率在1064 nm波長(zhǎng)處為83.7%,在400 nm波長(zhǎng)處為79.2%,并且其具有0.3 W的低激光輸出閾值,在約8.5 W功率808 nm波長(zhǎng)泵浦光下輸出功率超過(guò)2 W的1064 nm激光,其激光輸出斜效率為25.2%。(2)研究不同配比助燒劑,樣品微觀結(jié)構(gòu)和透明陶瓷性能之間的關(guān)系,并給出助燒劑協(xié)同作用的機(jī)理。TEOS和MC助燒劑對(duì)陶瓷微觀結(jié)構(gòu)的作用實(shí)質(zhì)是Si~(4+)和Mg~(2+)離子對(duì)Nd:YAG中Al~(3+)的取代。這種取代促進(jìn)陶瓷致密化進(jìn)程,同時(shí)協(xié)調(diào)陶瓷晶粒大小。然而,Si~(4+)、Mg~(2+)和Al~(3+)的離子半徑不一樣并且價(jià)態(tài)也有差別,這導(dǎo)致陽(yáng)離子和氧離子空位及電荷的不平衡,并導(dǎo)致晶格微畸變和晶格結(jié)構(gòu)的不穩(wěn)定。在定量情況下,適當(dāng)調(diào)節(jié)Si~(4+)和Mg~(2+)的比例,可以使電荷相互補(bǔ)償、空位相互抵消、消除不平衡狀態(tài),最終獲得優(yōu)異的Nd:YAG陶瓷。復(fù)合助燒劑的合理使用、協(xié)同作用和作用機(jī)理研究,為透明陶瓷性能提升和量化制備提供了思路。2.YAG納米粉體的可控制備及其核-殼結(jié)構(gòu)前驅(qū)體形成機(jī)理的研究(1)以Al_2O_3納米粉為模板和Al源,Y~(3+)溶液為Y源,尿素(Urea)為沉淀劑,采用半液相法制備具有Al_2O_3/Y-compound核-殼結(jié)構(gòu)的YAG納米前驅(qū)體,經(jīng)過(guò)煅燒制得尺寸均勻、成分單一、結(jié)晶性良好、分散性極佳、燒結(jié)活性好的球形YAG納米粉體。并由此粉體燒結(jié)得到Y(jié)AG透明陶瓷。通過(guò)XRD、SEM、TEM和FTIR等表征測(cè)試手段證實(shí)Al_2O_3/Y-compound核-殼結(jié)構(gòu)及其演變過(guò)程。(2)通過(guò)添加表面活性劑和調(diào)節(jié)反應(yīng)的沉淀速度,改變YAG前驅(qū)體的制備條件,討論核-殼結(jié)構(gòu)前驅(qū)體的形成機(jī)理。在反應(yīng)體系中,當(dāng)在A1_2O_3納米顆粒上引入表面活性劑后,使其表面帶負(fù)電荷,而Y-compound沉淀微核表面也帶負(fù)電荷,由于靜電排斥,Y-compound將無(wú)法組裝包覆在Al_2O_3納米顆粒上。而在沒(méi)有表面活性劑的反應(yīng)體系中,Al_2O_3納米顆粒表面帶正電荷,在靜電吸引的作用下Y-compound將預(yù)包覆Al_2O_3納米顆粒。所以靜電作用是核-殼結(jié)構(gòu)形成的一個(gè)驅(qū)動(dòng)力。采用NH_4HCO_3代替尿素作為沉淀劑來(lái)減緩反應(yīng)的沉淀速度。NH_4HC0_3的順序滴加有利于Y-compound沉淀微核自組裝并逐步長(zhǎng)大成納米顆粒,Y-compound沉淀與Al_2O_3納米顆粒分離,將不會(huì)形成核-殼結(jié)構(gòu)。而尿素在反應(yīng)之前要在反應(yīng)體系中充分溶解均勻,待體系達(dá)到其分解條件時(shí)(溫度達(dá)到83℃以上),尿素會(huì)瞬間完全分解出大量負(fù)離子基團(tuán)(HCO_3-、OH-等),這些負(fù)離子基團(tuán)在整個(gè)反應(yīng)體系內(nèi)與Y~(3+)結(jié)合生成過(guò)飽和量的Y-compound微核(爆發(fā)成核過(guò)程)。"爆發(fā)成核"得到的前驅(qū)體納米顆粒的高表面能是Al_2O_3/Y-compound核殼結(jié)構(gòu)形成的驅(qū)動(dòng)力。這種半液相法制備核-殼結(jié)構(gòu)前驅(qū)體的方法和機(jī)理,可以用于其它二元氧化物納米粉體的可控制備。3.半液相法制備納米棒狀YAG:Ce熒光粉及其機(jī)理研究與應(yīng)用(1)首次以半液相法為主要制備方法合成一維納米棒狀YAG:Ce熒光粉。采用水熱法調(diào)控合成一維棒狀NH_4Al(OH)_2CO_3并通過(guò)煅燒得到結(jié)晶性和分散性良好的納米棒狀A(yù)l_2O_3顆粒。以納米棒狀A(yù)l_2O_3顆粒為模板和A1源,Y~(3+)溶液為Y源,尿素為沉淀劑,采用半液相法制備具有核-殼結(jié)構(gòu)的納米棒狀YAG前驅(qū)體,經(jīng)煅燒得到直徑為250-400 nm長(zhǎng)度為3-5 μm的納米棒狀YAG:Ce熒光粉。所制備的納米棒狀熒光粉分散性好,結(jié)晶性高,具有相對(duì)大的比表面積和非常少的表面缺陷。采用XRD、SEM、TEM等表征測(cè)試手段揭示納米棒狀熒光粉的形成過(guò)程和成型機(jī)理。(2)一維納米棒狀YAG:Ce熒光粉的熒光性能優(yōu)于相同Ce~(3+)摻雜量的納米球狀YAG:Ce熒光粉。納米棒狀YAG:2at.%Ce~(3+)熒光粉的熒光量子產(chǎn)率(QY)為40.12%。雖然納米棒狀熒光粉的比表面積比納米球狀熒光粉的比表面積小,但是納米棒狀熒光粉的結(jié)晶性好,表面缺陷少,這是其熒光強(qiáng)度高的原因。并且,由于其特殊的棒狀結(jié)構(gòu),納米棒狀熒光粉具有兩個(gè)熒光壽命,一個(gè)對(duì)應(yīng)其本體特征的長(zhǎng)壽命和一個(gè)對(duì)應(yīng)其缺陷特征的短壽命。用納米棒狀YAG:Ce熒光粉標(biāo)記骨髓間充質(zhì)干細(xì)胞,表現(xiàn)出良好的生物相容性和熒光穩(wěn)定性。開(kāi)拓了 YAG:Ce熒光粉的應(yīng)用領(lǐng)域,顯示其重要的應(yīng)用價(jià)值。
[Abstract]:Y_3Al_5O_12 (YAG) is an important functional material. It has a very wide application in the civil field and occupies a very important position in the field of Defense Science and technology. As a laser gain medium, the doping of Nd~ (3+) ion YAG transparent laser ceramics is better than the Nd:YAG laser crystal. It is an important material for high power lasers. In addition, the rare earth ions doped YAG phosphors can be used to illuminate the LED light source. The high transmittance of the light is the basic condition for realizing the performance of the Nd:YAG ceramic laser. The microstructure of the ceramics, especially the grain size, the grain boundary structure and the porosity, is the most fundamental factor affecting the transparency of the ceramics. In the preparation of the laser ceramics, the shape of the nanometer powder is in addition to the shape of the nanometer powder. The appearance, size and sintering process have important effects on the microstructure of ceramics, and the addition of burning AIDS in the raw materials can control the microstructure. Although a large number of literatures have studied the influence of the burning AIDS on the structure and properties of transparent laser ceramics, few studies have been made on the synergistic effect of the two kinds of combustion aids. Rare earth doped YAG nano The size, morphology and crystallinity of the rice phosphor directly affect the fluorescence properties of the powder. The powders synthesized by the solid phase sintering method have good crystallinity and high fluorescence quantum efficiency, but because of the large particles and the difficulty in the application of phosphor powders, the particle size of the powders synthesized by the liquid phase nano synthesis method is small, but its crystallinity is poor and the fluorescence efficiency is low. It is impossible to realize nanofluorescence powders with high purity, controllable morphology and particle size, high crystallinity and good dispersivity. Therefore, this thesis focuses on the study of rare earth doped YAG materials. Through the research on the preparation technology of YAG materials, the microstructure and control of Nd:YAG transparent laser ceramics and the controllable preparation of YAG:Ce nanorods are realized. The research work and conclusion are as follows: 1. the synergistic effect of TEOS and MC on the microstructure of Nd:YAG transparent ceramics is regulated and improved (1) adding TEOS and MC as a burning aids to the preparation of Nd:YAG transparent ceramics, and adjusting the proportion of its addition to the grain size, particle size distribution and cell parameters of the ceramics. Structure regulation. Under the reasonable ratio of TEOS and MC, it can produce synergistic effect, promote the removal of micro defects and optimize the sintering period, improve the transmittance of the transparent ceramics and produce high power laser. In the YAG transparent ceramics with Nd~ (3+) doping amount of 2 at.%, the proportion of TEOS and MC is 2:1, and the grain size is moderate and the particle size can be obtained. A transparent ceramic with a concentration, no pores, no heterozygosity and a stable and stable lattice structure. The best sample is mixed with 7.5 wt.%a TEOS and 3.75 wt. per 1000 MC. The optical transmittance is 83.7% at the 1064 nm wavelength and 79.2% at the 400 nm wavelength, and it has a low laser output threshold of 0.3 W, at about 8.5 W power 808 nm wavelength pump. The output power of 1064 nm laser with output power of more than 2 W is 25.2%. (2), the relationship between the microstructure of the sample and the properties of the transparent ceramics is studied. The mechanism of the synergism of the CO combustion agent,.TEOS and the effect of MC on the microstructure of ceramics is the essence of Si~ (4+) and Mg~ (2+) ions to Al~ in Nd:YAG. Instead of 3+, this substitution promotes the process of ceramic densification and coordinates the size of the ceramic grains. However, the ionic radius of Si~ (4+), Mg~ (2+) and Al~ (3+) is different and the valence state is different, which leads to the imbalance of the vacancy and charge of the cation and oxygen ions, and leads to the lattice micro distortion and the instability of the lattice structure. When the ratio of Si~ (4+) and Mg~ (2+) is adjusted, the charge can be compensated each other, the vacancy counteracts each other, and the unbalance state is eliminated. Finally, the excellent Nd:YAG ceramics are obtained. The rational use of the compound sintering aids, the synergism and the mechanism of action are studied. The control of the.2.YAG nano powder is provided for the improvement of the performance of the transparent ceramics and the preparation of the quantitative preparation of the.2.YAG. Study on the formation mechanism of the precursor of its core shell structure (1) using Al_2O_3 nanometer powder as template and Al source, Y~ (3+) solution as Y source and urea (Urea) as precipitant, the YAG nano precursor with Al_2O_3/Y-compound nuclear shell structure was prepared by semi liquid phase method. After calcining, the scale is uniform, the composition is single, crystallization is good, dispersion is excellent, sintering live. Good spherical YAG nano powder. And the powder is sintered to get YAG transparent ceramics. The nucleation and shell structure and evolution process of Al_2O_3/Y-compound are confirmed by XRD, SEM, TEM and FTIR. (2) the preparation conditions of the precursor of YAG are changed by adding the surface active agent and the precipitation rate of the reaction, and the precursor of the nuclear shell structure is discussed. In the reaction system, when the surface active agent is introduced on the A1_2O_3 nanoparticles, the surface is negatively charged, and the Y-compound precipitated micronucleus surface is negatively charged. Because of electrostatic exclusion, Y-compound will not be coated on the Al_2O_3 nanoparticles. In the reaction system without surfactant, Al_2O_3 nanoscale will be in the reaction system. The particle surface has positive charge and the Y-compound will be precoated with Al_2O_3 nanoparticles under the action of electrostatic attraction. So the electrostatic action is a driving force of the nucleation and shell structure. The sequential addition of NH_4HCO_3 instead of urea as a precipitator to slow down the precipitation rate.NH_4HC0_3 is advantageous to Y-compound precipitation micronucleus self assembly and gradually longer. Dacheng nanoparticles, the separation of Y-compound precipitation and Al_2O_3 nanoparticles, will not form a nuclear shell structure, and urea will be fully dissolved in the reaction system before the reaction. When the system reaches its decomposition conditions (the temperature is above 83 degrees C), the urea will completely decompose a large number of negative ions (HCO_3-, OH-, etc.), these negative ions. The group is combined with Y~ (3+) in the whole reaction system to produce Y-compound micronucleus (nucleation process). The high surface energy of the precursor nanoparticles is the driving force of the Al_2O_3/Y-compound nuclear shell structure. The method and mechanism of the semi liquid phase method to prepare the core shell precursor can be used in other parts. Study and application of nano rod like YAG:Ce phosphor prepared by.3. semi liquid phase preparation by.3. semi liquid phase method and its mechanism study and application (1) one dimensional nano rod like YAG:Ce phosphor was synthesized by semi liquid phase method for the first time. The one-dimensional bar like NH_4Al (OH) _2CO_3 was synthesized by hydrothermal method and the crystallization and dispersion were obtained by calcining. Good nano rod like Al_2O_3 particles were used as the template and A1 source, Y~ (3+) solution as Y source and urea as precipitator. The nano rod like YAG precursor with nuclear shell structure was prepared by semi liquid phase method. The nanometer rod like YAG:Ce fluorescent powder with a diameter of 250-400 nm with a diameter of 3-5 micron was calcined. The nano rod like fluorine was prepared. The light powder has good dispersibility, high crystallinity, relatively large specific surface area and very few surface defects. The forming process and forming mechanism of nano rod like phosphor are revealed by XRD, SEM, TEM and other characterization tests. (2) the fluorescence properties of one dimensional nanoscale YAG:Ce phosphor are superior to that of the same Ce~ (3+) doped nanoscale YAG:Ce phosphor. The fluorescence quantum yield (QY) of the rice rod like YAG:2at.%Ce~ (3+) phosphor is 40.12%., although the specific surface area of the nano rod like phosphor is smaller than that of the nanoscale phosphor, but the crystallinity of the nano rod like phosphor is good and the surface defect is few. This is the reason for its high fluorescence intensity. And, because of its special bar like structure, nanoscale rod like structure. The phosphor has two fluorescence lifetimes, a long life corresponding to its noumenal characteristics and a short lifetime corresponding to its defect characteristics. The labeling of bone marrow mesenchymal stem cells with nano rod like YAG:Ce phosphor shows good biocompatibility and fluorescence stability. The application field of YAG:Ce phosphor has been opened up and its important application price is shown. Value.
【學(xué)位授予單位】：山東大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2017
【分類號(hào)】：TQ174.1

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