第一性原理计算钛酸铅A位掺杂对其负热膨胀性的影响

近年来，实验发现钛酸铅基材料具有负热膨胀性，且其热膨胀程度会受到掺杂元素的影响．目前所研究的A位掺杂体系中，仅Cd原子掺杂能使钛酸铅负热膨胀性增强．所以研究A位掺杂钛酸铅，比较Cd原子与其他原子在掺杂钛酸铅时化学键的异同，有助于深刻理解钛酸铅负热膨胀的本质．本文利用第一性原理，分别优化了Sr、Ba、Cd掺杂钛酸铅的晶格常数，计算了它们的态密度和电荷密度．结果表明Cd一O键的共价性强于Pb—O键，而Ba—O键和Sr—O键几乎呈离子性，Ba／Sr对Pb的替代削弱了化合物的共价性，降低了自发极化强度．与实验测量的热膨胀系数对比可以发现，月位原子与氧原子之间的共价性增强，化合物负热膨胀程度升高；若A位...

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Bibliographic Details
Published in物理化学学报 Vol. 30; no. 8; pp. 1432 - 1436
Main Author 王方方 曹战民 陈骏 邢献然
Format Journal Article
LanguageChinese
Published 北京科技大学冶金与生态工程学院，物理化学系，北京100083%北京科技大学冶金与生态工程学院，有色金属冶金系，北京100083 2014
Subjects
密度泛函理论
态密度
结构计算
负热膨胀
钛酸铅
Structure calculation
态密度
Density of states
密度泛函理论
负热膨胀
钛酸铅
结构计算
PbTiO3
Negative thermal expansion
Density function theory
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ISSN1000-6818
DOI10.3866/PKU.WHXB201405281

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Summary:近年来，实验发现钛酸铅基材料具有负热膨胀性，且其热膨胀程度会受到掺杂元素的影响．目前所研究的A位掺杂体系中，仅Cd原子掺杂能使钛酸铅负热膨胀性增强．所以研究A位掺杂钛酸铅，比较Cd原子与其他原子在掺杂钛酸铅时化学键的异同，有助于深刻理解钛酸铅负热膨胀的本质．本文利用第一性原理，分别优化了Sr、Ba、Cd掺杂钛酸铅的晶格常数，计算了它们的态密度和电荷密度．结果表明Cd一O键的共价性强于Pb—O键，而Ba—O键和Sr—O键几乎呈离子性，Ba／Sr对Pb的替代削弱了化合物的共价性，降低了自发极化强度．与实验测量的热膨胀系数对比可以发现，月位原子与氧原子之间的共价性增强，化合物负热膨胀程度升高；若A位原子与氧原子之间的共价性削弱，负热膨胀程度降低．可见A位原子与氧原子之间的共价性影响了钛酸铅基化合物负热膨胀性．
Bibliography:11-1892/06
Density function theory; Negative thermal expansion; PbTiO3; Density of states;Structure calculation
Recent experimental results have indicated that the negative thermal expansion is a common phenomenon in PbTiO3-based materials, and that this expansion is affected by various substitutions. Interestingly, Cd substitution in PbTiO3 has a unique effect compared with other A-site substitutions, in that it enhances negative thermal expansion. Therefore, studying A-site substitution in PbTiO3, the role of which still remains unclear, would provide a deeper understanding of the nature of the negative thermal expansion of PbTiO3-based materials. Herein we report the results of structural calculations, densities of states and the minimum electron densities of Pb1-xSrxTiO3, Pb1-xBaxTiO3, and Pb1-xCdxTiO3 supercells on the basis of chemical bond first-principles calculations. The results demonstrate that the hybridization between Cd—O orbitals is more pronounced than that between Pb—Oorbitals, while the bondin
ISSN:1000-6818
DOI:10.3866/PKU.WHXB201405281