本文選題：獨居石 + 鐠��； 參考：《西南科技大學》2015年碩士論文

【摘要】：本文用鑭系元素鐠(Pr)模擬三價次錒系核素镎(Np),以Ce2(C2O4)3?10H2O、Pr6O11和NH4H2PO4為原料,通過固相反應合成了摻鐠鈰獨居石固溶體Ce1-xPrxPO4(x=0-1),采用熱壓燒結(jié)制備了摻鐠鈰獨居石陶瓷固化體(Ce0.5Pr0.5PO4),借助失重-差示掃描量熱(TG-DSC)、X射線衍射(XRD)、場發(fā)射掃描電鏡(FESEM)、能譜(EDS)等分析測試手段,研究了鈰獨居石(Ce PO4)與鐠獨居石(Pr PO4)的相互固溶規(guī)律,研究了Ce1-xPrxPO4(x=0-1)獨居石固溶體及其陶瓷固化體的較佳制備工藝,分析了其相組成、密度及顯微結(jié)構等。結(jié)果表明:采用二次研磨/煅燒工藝,制備單相獨居石固溶體Ce1-xPrxPO4(x=0-1)的較佳煅燒工藝為1200oC下煅燒6h;隨著Pr含量的增加,獨居石固溶體Ce1-xPrxPO4(x=0-1)的晶胞參數(shù)a、b、c和晶胞體積V呈線性減小,晶胞參數(shù)?呈線性增加;熱壓燒結(jié)制備Ce0.5Pr0.5PO4獨居石陶瓷固化體的較佳工藝為1150oC保溫2h(30MPa),固化體相對密度可達到99%以上,物相為Ce0.5Pr0.5PO4獨居石固溶體,其晶粒間緊密結(jié)合,晶界較模糊。采用MCC-1靜態(tài)浸出實驗法,通過水熱反應釜裝置模擬深地質(zhì)處置環(huán)境,借助電感耦合等離子體發(fā)射光譜-質(zhì)譜(ICP-MS),研究熱壓燒結(jié)Ce0.5Pr0.5PO4陶瓷固化體的化學穩(wěn)定性。結(jié)果表明:熱壓燒結(jié)的Ce0.5Pr0.5PO4陶瓷固化體中的Ce元素和Pr元素均具有良好的化學穩(wěn)定性。42d時,Ce元素的歸一化浸出率≤9.93×10-6g·m-2·d-1,浸出率≤1.90×10-12g·m-1;Pr元素的歸一化浸出率≤7.74×10-5g·m-2·d-1,浸出率≤1.48×10-11g·m-1。p H值對熱壓燒結(jié)Ce0.5Pr0.5PO4陶瓷固化體中Ce元素和Pr元素的歸一化浸出率和浸出率有一定影響。Ce元素和Pr元素在弱酸性環(huán)境(p H=5)中的抗浸出性能相對較差,在中性和弱堿性環(huán)境中的化學穩(wěn)定性能相對較好。
[Abstract]:In this paper, the lanthanide praseodymium praseodymium (praseodymium) is used to simulate the trivalent subactinide neptunium neptunium, using Ce2OC2O3H2O3H2O Pr6O11 and NH4H2PO4 as raw materials.Praseodymium and cerium doped cerium monazite solid solution Ce1-xPrxPO4 + 0-1N was synthesized by solid state reaction. Cerium-doped cerium-doped monazite ceramic curable Ce0.5Pr0.5PO4 was prepared by hot pressing sintering. The X-ray diffraction (XRDDX), field emission scanning electron microscope (SEM), energy spectrum (EDS), etc., were obtained by means of weightlessness and differential scanning calorimetry (TG-DSCT), X-ray diffraction (XRD) and X-ray diffraction (XRDX) of cerium monazite doped with praseodymium and cerium-doped cerium-doped monazite.The solid solution law of cerium monazite (ce PO 4) and praseodymium monazite (pr PO 4) was studied. The better preparation process of ce 1-xPrxPO 4 O 4) monazite solid solution and its ceramic solidification were studied. The phase composition, density and microstructure of cerium monazite were analyzed.The results show that the optimum calcination process for the preparation of single-phase monazite solid solution Ce1-xPrxPO4OxO0-1) is calcined under 1200oC for 6h, and the unit cell parameter abcnc and unit cell volume V decrease linearly with the increase of pr content in monazite solid solution Ce1-xPrxPO4O4x0-1), and the results show that the single phase monazite solid solution Ce1-xPrxPO4O4xPO4x0-1) has a linear decrease with the increase of pr content.Cell parameters?The optimum technology for preparing Ce0.5Pr0.5PO4 monazite ceramic solidified by hot pressing sintering is 1150oC holding for 2 h or 30 MPA / L, the relative density of the solidified body can reach more than 99%, the phase is Ce0.5Pr0.5PO4 monazite solid solution, its grain size is tightly bound and the grain boundary is rather fuzzy.The chemical stability of hot press sintered Ce0.5Pr0.5PO4 ceramics was studied by means of MCC-1 static leaching experiment, the hydrothermal reactor was used to simulate the environment of deep geological treatment, and the inductively coupled plasma-mass spectrometry (ICP-MS) was used to study the chemical stability of the solidified Ce0.5Pr0.5PO4 ceramics.The results show that the chemical stability of ce and pr elements in Ce0.5Pr0.5PO4 ceramic cured by hot pressing sintering is good. The normalized leaching rate of ce element 鈮，

本文編號：1766236