钙钛矿结构Pb、Te氧化物的合成与物性研究
发布时间：2018-08-21 13:20
【摘要】：钙钛矿氧化物具有优异的物理及化学性能,如铁电性、铁磁性、压电性等,成为现代材料领域的研究热点。另外,由于含Pb或者含Te原子的钙钛矿化合物中会产生结构畸变出现新的性能而被学者广泛研究,因此本文对钙钛矿结构的Pb、Te氧化物的合成与物性展开了探索性研究。本论文的工作主要包括三部分,第一部分采用熔融法合成出四方相、斜方相和立方相的PbTeO3,并对合成的样品进行物相分析,未得到纯相的样品;第二部分利用水热合成法制备出四方相PbTeO3单晶样品,对四方相PbTeO3单晶样品进行粉末X射线衍射、红外吸收光谱、常压拉曼光谱和高压拉曼光谱测量分析后得到以下结论:(1)四方相PbTe03的红外吸收光谱测量显示四个吸收峰分别位于634 cm-1、649 cm-1、670 cm-1和734 cm-1的位置,其中600 cm-1至700 cm-1处的吸收峰归属于Te-0键的伸缩振动。(2)结合理论计算的结果发现实验测量得到的常压拉曼谱中,位于600 cm-1至800 cm-1波数段的拉曼峰归属于Te032-酸根中Te-0键的对称伸缩振动模和反对称伸缩振动;位于178 cm-1至400 cm-1波数段的拉曼峰归属于TeO32-酸根整体的旋转、弯曲、摇摆等外振动模;而波数值小于144 cm-1的拉曼峰是由晶格振动模和Te032-酸根刚性多面体单元的外振动模共同引起的。(3)高压原位测量拉曼光谱研究发现,随着腔体压力增大至13.4 GPa时,四方相PbTe03的拉曼光谱在119 cm-1位置处的拉曼峰劈裂成两个拉曼峰,这可能是由TeO32-酸根刚性多面体的旋转所致,并不是PbTe03在压力的作用下发生相变;当压力升至18 GPa时,整个拉曼谱的拉曼峰出现峰形变宽,强度减弱的情况,说明此时拉曼振动模开始出现软化,四方相PbTe03的晶体结构开始出现不稳定的情形。第三部分采用水热合成法制备出纯相的正交结构的Pb2Te308晶体,对正交相的Pb2Te3O8进行红外吸收光谱、紫外可见吸收光谱以及拉曼光谱测量分析发现:(1)Pb2Te3O8 的红外吸收峰位置分别位于 404 cm-1、578 cm-1、658 cm-1、694 cm-1、739 cm-1位置处;(2)由Pb2Te3O8的紫外吸收光谱计算出了 Pb2Te3O8是带隙宽度为3.57ev的绝缘体;(3)正交相Pb2Te3O8单晶的常压拉曼光谱图,根据相关研究我们推测在Pb2Te3O8中,600 cm-1-800 cm-1波数范围内的 637 cm-1、657 cm-1、689 cm-1、723 cm-1、736 cm-1和761 cm-1六个拉曼峰是属于内部伸缩振动模,50 cm-1-400 cm-1频率范围的振动对应于晶格振动模式和Te3O84+基团的外振动模式;(4)高压原位测量拉曼光谱显示正交相的Pb2Te3O8晶体结构可稳定的保持至腔体压力达到21.8 GPa而不发生相变。
[Abstract]:Perovskite oxides with excellent physical and chemical properties, such as ferroelectricity, ferromagnetism, piezoelectric properties and so on, have become the research hotspot in the field of modern materials. In addition, due to the new properties of perovskite compounds containing Pb or Te atoms, the synthesis and physical properties of perovskite-based PbTE-Te oxides have been investigated. In the first part, tetragonal phase, oblique phase and cubic phase PbTeO _ 3 were synthesized by melting method. In the second part, tetragonal PbTeO3 single crystal samples were prepared by hydrothermal synthesis. The tetragonal PbTeO3 single crystal samples were characterized by powder X-ray diffraction and infrared absorption spectra. The results of atmospheric Raman spectroscopy and high pressure Raman spectroscopy are as follows: (1) the infrared absorption spectra of tetragonal PbTe03 show that the four peaks are located at 634 cm-1649 cm-1670 cm-1 and 734 cm-1, respectively. The absorption peaks from 600 cm-1 to 700 cm-1 belong to the stretching vibration of the Te-0 bond. (2) in combination with the theoretical results, it is found that the Raman spectra at atmospheric pressure are obtained from the experimental measurements. The Raman peaks located between 600 cm-1 and 800 cm-1 belong to the symmetric stretching mode and antisymmetric stretching mode of Te-0 bond in Te032- acid group, and the Raman peak from 178 cm-1 to 400 cm-1 belongs to the rotational, bending and swaying modes of TeO32- acid group. The Raman peak with wave value less than 144 cm-1 is caused by both the lattice vibration mode and the external vibration mode of the Te032-acid rigid polyhedron element. (3) the Raman spectra of high pressure in-situ measurements show that with the increase of cavity pressure to 13.4 GPa, The Raman spectra of tetragonal PbTe03 split into two Raman peaks at the position of 119 cm-1, which may be due to the rotation of the rigid polyhedron of TeO32-, not the phase transition of PbTe03 under pressure, when the pressure rises to 18 GPa. The Raman peak of the whole Raman spectrum is characterized by wide deformation and weak intensity, which indicates that the Raman vibration mode begins to soften and the crystal structure of tetragonal PbTe03 begins to be unstable. In the third part, pure phase Pb2Te308 crystal with orthogonal structure was prepared by hydrothermal synthesis method. Infrared absorption spectra of Pb2Te3O8 were obtained. The results of UV-Vis absorption spectra and Raman spectra show that: (1) the infrared absorption peak of Pb2Te3O8 is located at the position of 404 cm-1578 cm-1658 cm-1694 cm-1739 cm-1, and (2) from the UV absorption spectra of Pb2Te3O8, it is calculated that Pb2Te3O8 is an insulator with band gap width of 3.57ev. (3) the atmospheric pressure Raman spectra of orthotropic Pb2Te3O8 single crystals, Based on the relevant studies, we speculate that the six Raman peaks of 637 cm-1657 cm-1689 cm-1723 cm-1736 cm-1 and 761 cm-1 in the Pb2Te3O8 range of 600 cm-1-800 cm-1 are corresponding to the lattice vibration mode and Te3O84 group in the frequency range of 50 cm-1-400 cm-1. (4) the high pressure in-situ measurements show that the Pb2Te3O8 crystal structure can be kept stable until the cavity pressure reaches 21.8 GPa without phase transition.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O611.62
本文编号：2195864
[Abstract]:Perovskite oxides with excellent physical and chemical properties, such as ferroelectricity, ferromagnetism, piezoelectric properties and so on, have become the research hotspot in the field of modern materials. In addition, due to the new properties of perovskite compounds containing Pb or Te atoms, the synthesis and physical properties of perovskite-based PbTE-Te oxides have been investigated. In the first part, tetragonal phase, oblique phase and cubic phase PbTeO _ 3 were synthesized by melting method. In the second part, tetragonal PbTeO3 single crystal samples were prepared by hydrothermal synthesis. The tetragonal PbTeO3 single crystal samples were characterized by powder X-ray diffraction and infrared absorption spectra. The results of atmospheric Raman spectroscopy and high pressure Raman spectroscopy are as follows: (1) the infrared absorption spectra of tetragonal PbTe03 show that the four peaks are located at 634 cm-1649 cm-1670 cm-1 and 734 cm-1, respectively. The absorption peaks from 600 cm-1 to 700 cm-1 belong to the stretching vibration of the Te-0 bond. (2) in combination with the theoretical results, it is found that the Raman spectra at atmospheric pressure are obtained from the experimental measurements. The Raman peaks located between 600 cm-1 and 800 cm-1 belong to the symmetric stretching mode and antisymmetric stretching mode of Te-0 bond in Te032- acid group, and the Raman peak from 178 cm-1 to 400 cm-1 belongs to the rotational, bending and swaying modes of TeO32- acid group. The Raman peak with wave value less than 144 cm-1 is caused by both the lattice vibration mode and the external vibration mode of the Te032-acid rigid polyhedron element. (3) the Raman spectra of high pressure in-situ measurements show that with the increase of cavity pressure to 13.4 GPa, The Raman spectra of tetragonal PbTe03 split into two Raman peaks at the position of 119 cm-1, which may be due to the rotation of the rigid polyhedron of TeO32-, not the phase transition of PbTe03 under pressure, when the pressure rises to 18 GPa. The Raman peak of the whole Raman spectrum is characterized by wide deformation and weak intensity, which indicates that the Raman vibration mode begins to soften and the crystal structure of tetragonal PbTe03 begins to be unstable. In the third part, pure phase Pb2Te308 crystal with orthogonal structure was prepared by hydrothermal synthesis method. Infrared absorption spectra of Pb2Te3O8 were obtained. The results of UV-Vis absorption spectra and Raman spectra show that: (1) the infrared absorption peak of Pb2Te3O8 is located at the position of 404 cm-1578 cm-1658 cm-1694 cm-1739 cm-1, and (2) from the UV absorption spectra of Pb2Te3O8, it is calculated that Pb2Te3O8 is an insulator with band gap width of 3.57ev. (3) the atmospheric pressure Raman spectra of orthotropic Pb2Te3O8 single crystals, Based on the relevant studies, we speculate that the six Raman peaks of 637 cm-1657 cm-1689 cm-1723 cm-1736 cm-1 and 761 cm-1 in the Pb2Te3O8 range of 600 cm-1-800 cm-1 are corresponding to the lattice vibration mode and Te3O84 group in the frequency range of 50 cm-1-400 cm-1. (4) the high pressure in-situ measurements show that the Pb2Te3O8 crystal structure can be kept stable until the cavity pressure reaches 21.8 GPa without phase transition.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O611.62
【参考文献】
相关期刊论文 前2条
1 李大光;章弘毅;张鹤丰;郭清泉;曹明澈;;钙钛矿型复合氧化物的研究与应用进展[J];材料导报;2006年S1期
2 牛新书;曹志民;;钙钛矿型复合氧化物光催化研究进展[J];化学研究与应用;2006年07期
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