摘要
测量了七种非理想化学计量比的UO2＋ x （0＜ x＜0.66）及UO2和U3 O7等理想化学计量比氧化铀的拉曼和红外光谱，并进行了对比分析，其中U3 O7和U3 O8之间UO2＋ x的分子振动光谱为首次报道。拉曼光谱结果显示，随着UO2＋ x中x 值的增加，UO2特征峰中的578和1150 cm -1峰强度快速减弱，当 x＝0.19时，这两峰基本消失，可视为准完美萤石晶体结构U O2的标志。445 cm-1峰强度在减弱的同时变宽并偏移，当 x＝0.32时，该峰已偏移至459 cm-1处，同时在～630 cm-1出现一弱肩峰，这与四方相U3 O7的特征峰一致。当 x≥0.39时，459 cm -1峰发生分裂，在235和754 cm-1处出现新峰并增强，其特征逐渐与正交相的α-U3 O8接近。但直至 x＝0.60时，与α-U3 O8相比其333，397，483和805 cm -1峰仍不突出。红外光谱结果显示，随着U O2＋ x中x值的增加，U O2位于400～570 cm -1区间的强吸收特征谱带逐渐分裂为～421和～515 cm -1两峰并增强，同时U O2在～700 cm -1的弱吸收峰逐渐消失，～645 cm -1处的肩峰逐渐显现，出现的这三个峰正是U3 O7的特征红外吸收峰。当 x≥0.39时，在744 cm -1出现一强吸收峰并增强，该峰是α-U3 O8的最强特征峰。但即使 x＝0.60时，～645 cm-1峰仍然存在，同时～515 cm-1峰也未明显分裂成485和535 cm -1峰，这表明U O2.60仍处于四方相和正交相的过渡阶段。上述结果表明，随着 x值的增加，U O2＋ x的晶体结构发生变化，每次变化均在拉曼和红外光谱中得到体现。通过对比各特征峰相对强度和位置的变化情况，可很好区分和表征不同的氧化铀。
Both of Raman and infrared spectra of seven non-stoichiometry and threestoichiometry uranium oxides ,including UO2 ,U3O7 and UO2＋ x（0＆lt; x＆lt;0.66） ,are presented and discussed. The spectra of UO2＋ x in the stoichiometry range ,U3O7 to U3 O8 ,were first obtained and reported. Three typical peaks were observed at 445 ,578 and 1 150 cm-1 in the Raman spectrum of uranium dioxide. The intensities of the peaks at 578 and 1 151 cm-1 decrease quickly with increasing x value of UO2＋ x ,and while x=0.19 ,the two peaks disappear. Such peaks can therefore be considered as a fin-gerprint of the quasi-perfect UO2 fluo-rite structure. The peak at 445 cm -1 tends to weaken ,broaden and shift to higher wavenumber in more oxidised samples. When＆amp;nbsp;x=0.32 ,this peak is shifted to the 459 cm -1 and a weak peak at about 630 cm -1 appears. The two new peaks are typical of the tetragonal U3 O7. While x≥0.39 ,the peak at 459 cm -1 further splits into separate components. Two peaks at 235 and 754 cm -1 appear for UO2.39 and are visible with increased intensity as the oxygen-uranium ratio is increased. And the Raman spectra of UO2＋ x are gradually close to U3 O8 in theα-phase ,which has an orthorhombic unit cell. But several strongest features of theα-U3 O8 specturm at 333 ,397 ,483 and 805 cm-1 are still not outstanding even in UO2.60. The main feature of the UO2 infrared spectrum shows a very broad and strong adsorption band at 400~570 cm-1 and another feature is a weak adsorption peak at a-bout 700 cm -1. The 400~570 cm-1 band undergoes a progressive splitting into two new peaks at ~421 and ~515 cm -1 through increasing incorporation of oxygen into UO2. The weak peak at about 700 cm-1 disappears and a new weak peak appears at about 645 cm -1. The three new peaks are the infrared absorption features of U 3 O7. An absorption peak at 744 cm-1 which is the strongest feature ofα-U3 O8 infrared spectrum appears for UO2.39 and is visible with increased intensity in more oxidised samples.The peak at about 645 cm -1 still exists and 515 cm -1 peak has no further splitting into two new peaks at 485 and 535 cm -1 which also are the infrared absorption features of U3O8 in UO2.60. This indicates that UO2.60 is still in the transition period between tet-ragonal and orthorhombic phase of uranium oxide. A sequence of phase transitions occurs through increasing x value of UO 2＋ x with different Raman and infrared features.It is easy to identify different uranium oxides by comparing of relative intensities and locations of their characteristic peaks .
出处
《光谱学与光谱分析》
SCIE
EI
CAS
CSCD
北大核心
2014年第2期405-409,共5页
Spectroscopy and Spectral Analysis
基金
国防基础科研项目(B1520110010)资助
关键词
氧化铀
拉曼光谱
红外光谱
Uranium oxide
Raman spectroscopy
Infrared spectroscopy
作者简介
吕俊波，1981年生，中国工程物理研究院工程师e-mail：lvjunb0263@yahoo．com．cn
通讯联系人e-mail：gslwxy@21cn．com
