【作者】 薛理辉；

【导师】 袁润章；

【作者基本信息】 武汉理工大学 ， 材料学， 2003， 博士

【摘要】 稀土光谱复杂多变，对稀土光谱的研究不仅能丰富稀土知识，而且能为稀土材料的研究奠定理论基础。本工作研究稀土氧化物和若干典型的稀土矿物的光谱，目的是确定它们的特征和机理，并进而弄清各种稀土光谱之间的关系。论文共分两部分：（1）对振动拉曼光谱和振动红外光谱的研究；（2）对电子光谱，包括光致发光谱、可见光吸收谱、电子拉曼光谱和电子红外光谱的研究。 1．利用三种显微拉曼光谱仪和不同的激发光，包括325.0nm、457.9nm、488.0nm、514.5nm、632.8nm和785.0nm等六种波长的激光，获取样品的拉曼光谱。用拉曼光谱和红外光谱系统分析了样品的振动特征，主要结果如下： （1）第一次完整报道了九种C型（立方型）稀土氧化物在400～800cm^-1红外谱区和80～800cm^-1拉曼谱区的振动光谱。这些数据表明振动频率取决于晶体结构并揭示了镧系收缩效应对振动频率的规律性影响。作者发现，C型Yb₂O₃的拉曼光谱具有异常现象，不仅其谱图形状不同于其它C型氧化物，而且谱峰位置也不满足镧系收缩规律。作者认为，Yb₂O₃特殊的拉曼光谱可能反映的是Yb³⁺的电子拉曼光谱与Yb₂O₃的振动拉曼光谱的混合谱或耦合谱，Yb₂O₃特殊的拉曼光谱效应，可能涉及电子拉曼光谱理论的关键问题。 （2）轻稀土RE₂O₃（RE=La，Pr，Nd，Sm）在空气中极易水化和碳酸化。通过拉曼光谱、红外光谱和X射线衍射法确定了其水化和碳酸化产物为RE（OH）₃、六方RE₂O₂CO₃、四方RE₂O₂CO₃和RE₂O（CO₃）₂。精确测定了Pr₆O₁₁标样中所出现的水化相Pr（OH）₃的结晶学参数，结果为：六方晶系，空间群P6₃／m，a=0.6465，c=0.3759，Z=2，D_x=4.684g／cm³。补充了Pr（OH）₃的JCPDS衍射卡（45-86）中遗漏的数据，纠正了其中两个衍射峰的指标化错误。 （3）变生态矿物拉曼光谱的强度很弱、谱线宽而弥散，而退火晶态矿物的拉曼谱峰强而尖锐。确定了褐钇铌矿族矿物、易解石族矿物、独居石和氟碳酸盐矿物的特征拉曼和红外振动频率，并对振动谱峰进行了归属。讨论了矿物的成分、结构对振动光谱的影响。 2．在电子光谱的研究上，主要结果如下： （1）设计了一种利用拉曼光谱仪获取可见光吸收谱的新方法，利用这种方法所获得的高分辨可见光吸收谱可建立起稀土化合物的拉曼光谱、光致发光谱和红外光谱之间的重要联系，它对识别各种复杂的稀土光谱、探讨发光和吸收机理有重要的作用。薛理辉武汉理工大学博士学位论文摘要 （2）发现在常温下，由于Boltzm^分布律的作用，在RE3+的基态电子态和激发态间跃迁所产生的发光谱带和吸收谱带中的精细谱峰的位置一一相同，解释了产生这种关系的原因，并弄清了Er203中Er3+的基态电子态4lts.12和激发态电子态2凡/2、4凡/2的stark能级分裂情况，确定了常温下ErZO3中Er3+的4了15/2一2凡/2和‘I，5/2一‘凡/2精细能级间的跃迁形式。 （3）提出了电子红外光谱的概念，与普通的红外光谱即振动红外光谱不同的是，电子红外光谱来源于电子能级间的吸收跃迁。发现EuZq在400一4o00cm一’谱区的绝大部分红外谱峰以及NdZ氏、氟碳钟钡矿、氟碳钙钟矿、黄河矿、氟碳钟矿在1650一32O0cm一‘谱区中的红外谱峰出自E矿+和Nd3+电子能级的吸收跃迁，确定了常温下EuZ伪中Eu3+的’F0一;电子态的stark能级分裂情况和’D。一一7F0一;精细能级间的跃迁形式。 （4）发现在可见光区不发光的LaZO3、 YZ仇和LuZO3，其光谱纯样品在可见激光激发下有较强的发光现象，确定了这三个样品的发光谱分别来源于样品中痕量的sm3+、Er，+和Eu，+。 （5）变生态稀土矿物的发光谱带和吸收谱带宽而弥散，加热后谱带明显变得尖锐。晶态稀土矿物具有类线性的发光和吸收谱带，而且谱带的形状和位置与矿物的化学组分、晶体结构和激发方式紧密相关。呈示并研究了褐忆妮矿族矿物、易解石族矿物、独居石和稀土氟碳酸盐矿物在488.OIun和514.5tun激光激发下的光致发光谱，确定了光致发光中心的性质。另外，发现这些矿物对可见光的吸收主要表现为Nd3+的吸收，Nd3+可能是矿物光致发光的重要敏化剂。更多还原

【Abstract】 The spectra of the rare earth are complicated, confused and variable. The study on spectra of the rare earth can not only enrich the knowledge of the rare earth, but also provide the theoretical basis for researching the rare earth materials. This work is to study the spectra of the rare earth oxides and some typical rare earth minerals found in China. The aim is to determine their characteristics and mechanisms, and further to clarify the relationship among various spectra. This PhD thesis is divided into two parts: (1) the study on vibrational Raman and infrared spectra, (2) the study on electronic spectra, including the photoluminescence, visible absorption, electronic Raman spectra and the electronic infrared spectroscopy.1. Three kinds of laser Raman spectrometers and six wavelengths of exciting source, including 325.0nm, 457.9nm, 488.0nm, 514.5nm, 632.8nm and 785.0nm laser lines, are used to obtain the Raman spectra. The vibrational characteristics of the specimens have been analyzed systematically by Raman and infrared spectra. The main results are as follows:(1) The infrared spectra from 400~800cm-1 and Raman spectra from 80~ 800cm-1 of nine cubic rare earth oxides are first reported completely. It is evident from these data that the crystal structure determines the frequency position, and clearly shows the effect of the lanthanide contraction in this series of compounds. An abnormal phenomenon in the Raman spectrum of Yb2O3 is found. It is supposed that the special Raman spectrum may be the mixed or coupled spectra of the electronic Raman spectrum of Yb3+ and the vibrational Raman spectra of Yb2O3. The special Raman effect of Yb2O3 may be related to some key questions about the theory of the electronic Raman spectra.(2) The light rare earth sesquioxides are easy to be hydrated and carbonated in air. It is determined from the Raman and infrared spectra and X-ray diffraction patterns of RE2O3(RE=La,Pr,Nd,Sm) specimens that the major hydrated and carbonated products are RE(OH)3, hexagonal RE2O2CO3, tetragonal RE2O2CO3 and RE2O(CO3)2. The crystal structure of Pr(OH)3 has been measured in detail. Pr(OH)3 is hexagonal with 2 molecules per unit cell (a=0.6465, c=0.3759), spacegroup P63/m, and density Dx=4.684g/cm3. Some omitted data of Pr(OH)3 in the JCPDS file 45-86 are supplemented and the two errors of indices have been corrected.(3) The Raman spectra of the metamict minerals are very weak, but strong and sharp notably after heating. The characteristic frequencies of the Raman and infrared spectra of the fergusonite and aeschynite group minerals, monazites and the rare earth fluoro-carbonate minerals have been determined and assigned. The influence of the minerals’ compositions and crystal structures on vibrational peaks has been discussed.2. As to the study on the electronic spectra of the rare earth, the main results are as follows.(1) Based on a reconstructed Raman microprobe, a new method of obtaining high-resolution visible region absorption spectra is designed. The method makes it possible to establish a relationship among four kinds of spectra of the rare earth specimen, including visible region absorption spectra, photoluminescence spectra, infrared spectra and Raman spectra. The method plays an important role in distinguishing and studying the complicated and confused spectral characteristics and mechanisms of the rare earth.(2) It is found and explained that due to the Boltzmann distribution law at room temperature, the positions of the fine peaks of the photoluminescence band stemming from the transitions between an excited state and the ground state of a RE3+, match these of the absorption bands from the transitions between the ground state and the excited state. The Stark split energy levels of the ground state 4I15/2 and two excited states 2S3/2 and 4F9/2 of the Er3+ in Er203 have been determined. And the transmitting form of the Stark split energy levels between the ground state and the two excited states has been clarified.(3) A concept of the electronic infr更多还原