本文選題：Tb_3Al_5O_(12)(TAG) + 溶膠-凝膠法　； 參考：《西南科技大學(xué)》2017年碩士論文

【摘要】：鋱鋁石榴石基(Tb_3Al_5O_(12),TAG)陶瓷閃爍體具有密度較高,抗輻射性能良好,光輸出高,衰退時(shí)間短等優(yōu)點(diǎn),有望應(yīng)用于高能物理、核醫(yī)學(xué)、地質(zhì)勘探以及安檢等領(lǐng)域。TAG閃爍單晶存在生長(zhǎng)條件苛刻、制備周期長(zhǎng)、生產(chǎn)設(shè)備要求高、成本高、尺寸受限以及離子摻雜不均勻等問題,使得其應(yīng)用受到限制。因此,研究和制備TAG多晶陶瓷閃爍體具有重大意義。作為制備TAG多晶陶瓷閃爍體的第一步,TAG粉體必須具有高純度、良好的分散性、均勻性以及良好的燒結(jié)活性。當(dāng)前TAG粉體的制備普遍存在粉體分散性差、粒徑不均一、活化能壘高等不足,導(dǎo)致了其燒結(jié)活性低、燒結(jié)溫度高、熒光強(qiáng)度低等缺陷,對(duì)于后續(xù)的制備帶來了限制。此外,對(duì)于TAG粉體制備的具體反應(yīng)歷程也缺乏探究。因此,為了降低TAG粉體的燒結(jié)溫度,本論文首先選取了兩種反應(yīng)條件最為溫和的TAG粉體制備方法:共沉淀法與溶膠-凝膠法,成功制備出TAG粉體并對(duì)其微觀結(jié)構(gòu)及相關(guān)性能進(jìn)行了表征。發(fā)現(xiàn)溶膠-凝膠法制備的前驅(qū)體,TAG相的結(jié)晶溫度可降低到920°C遠(yuǎn)低于共沉淀法(1000°C),最終熒光強(qiáng)度也高出共沉淀法約30%。由此可見,溶膠-凝膠法在TAG粉體制備方面更具有優(yōu)勢(shì)。進(jìn)一步從原子擴(kuò)散速率角度出發(fā),通過優(yōu)化溶膠-凝膠法制備TAG粉體的工藝參數(shù),調(diào)節(jié)絡(luò)合劑檸檬酸的量改善粉體的微觀結(jié)構(gòu),為原子的短程擴(kuò)散提供通道,提高了其原子擴(kuò)散速率,有利于各相的晶化,從而降低其燒結(jié)溫度。在檸檬酸的摩爾量與金屬離子總的摩爾量的比例為1:1的情況下,制得的TAG粉體分散性、均勻性最為優(yōu)異,帶來了良好的燒結(jié)活性,與第一章制備參數(shù)相比,TAG晶相的結(jié)晶溫度降低到了877.5℃,熒光強(qiáng)度提高了約32%;同時(shí),對(duì)溶膠-凝膠法制備TAG粉體的具體反應(yīng)歷程進(jìn)行了探究。在此基礎(chǔ)上,又從各相成核的活化能壘角度出發(fā),通過引入金屬離子降低各相成核的活化能壘,從而進(jìn)一步降低了TAG粉體的燒結(jié)溫度。本研究工作首次將Fe~(3+)離子引入TAG體系,發(fā)現(xiàn)其能夠成為優(yōu)先成核位點(diǎn)從而降低各相成核的活化能壘,進(jìn)一步提高TAG粉體的燒結(jié)活性。在其最優(yōu)組成Tb_3(Al_(0.95),Fe_(0.05))_5O_(12)條件下,TAG相的結(jié)晶溫度可降低到780℃,但是Fe~(3+)離子的引入一定程度上降低了TAG體系的熒光強(qiáng)度。因此,為彌補(bǔ)Fe~(3+)離子摻雜帶來的不足,利用Ce~(3+)振動(dòng)強(qiáng)度大等優(yōu)點(diǎn),采用Fe~(3+)、Ce~(3+)兩種離子的共摻雜的方法制備了一種新型陶瓷閃爍粉體,與第一章制備參數(shù)相比,在其最優(yōu)組成Tb_(2.97)(Al_(0.95)Fe_(0.05))_5O_(12):Ce_(0.03)條件下保證其良好燒結(jié)活性的同時(shí)熒光強(qiáng)度提高了1倍。
[Abstract]:Terbium aluminum-garnet based scintillator Tbs3Al5OK12Tago ceramic scintillator is expected to be used in high energy physics and nuclear medicine because of its high density, good radiation resistance, high light output and short decay time.The application of tag scintillation single crystal in geological exploration and security inspection is limited due to its harsh growth conditions, long preparation period, high production equipment, high cost, limited size and uneven ion doping.Therefore, it is of great significance to study and prepare TAG polycrystalline ceramic scintillators.As the first step to prepare TAG polycrystalline ceramic scintillator, tag powder must have high purity, good dispersion, uniformity and good sintering activity.At present, the preparation of TAG powders has many defects, such as poor dispersion, uneven particle size, low activation energy barrier, low sintering activity, high sintering temperature and low fluorescence intensity.In addition, the specific reaction process of TAG powder preparation is also lack of exploration.Therefore, in order to reduce the sintering temperature of TAG powders, two preparation methods of TAG powders with the most mild reaction conditions, coprecipitation method and sol-gel method, were first selected in this paper.TAG powder was successfully prepared and its microstructure and related properties were characterized.It is found that the crystallization temperature of the precursor (tag) phase prepared by sol-gel method can be reduced to 920 擄C much lower than that of the coprecipitation method (1000 擄C), and the final fluorescence intensity is about 30% higher than that of the co-precipitation method.Therefore, the sol-gel method has more advantages in the preparation of TAG powders.From the angle of atomic diffusion rate, the technological parameters of preparing TAG powder by sol-gel method were optimized to improve the microstructure of the powder by adjusting the amount of citric acid, which provided a channel for the short-range diffusion of atoms.The atomic diffusion rate is increased, and the crystallization of each phase is favorable, thus lowering the sintering temperature.When the molar ratio of citric acid to metal ions is 1:1, the TAG powder has the most excellent dispersity and uniformity, and it has good sintering activity.Compared with the preparation parameters in the first chapter, the crystallization temperature of the crystal phase of tag is reduced to 877.5 鈩，

本文編號(hào)：1761310