以密度泛函微擾理論研究微波介電材料Ba(Zn1/3,Nb2/3)O3之聲子特性

Phonon studys on microwave dielectric material Ba(Zn1/3Nb2/3)O3 form Density-Functional Perturbation Theory Study

周育祥(Yui-Hsiang Chou)

指導教授 ： 薛宏中

淡江大學/理學院/物理學系碩士班/碩士(2010年)

https://doi.org/10.6846/TKU.2010.00586

摘要

藉由第一原理去計算材料的介電性質。在此第一原理計算使用密度泛函微擾理論及線性響應的方法去簡化計算的過程。首先針對鑽石材料測試此一材料計算模式的準確性。
在証實此第一原理計算模式的可行性後，運用此模式計算BaTiO3和Ba(Zn1/3Nb2/3)O3材料在Γ點上聲子行為。經確認每一mode的振動特性，並輔以實驗上之Raman及FTIR光譜量測，去估計材料的介電特性。得到之結論為ABO3材料之介電常數與氧化物八面體緊密程度相關，而材料之品質因子則與氧化物八面體的扭曲變形程度有關。

關鍵字

密度泛函微擾理論 ； 線性響應 ； 聲子 ； 拉曼光譜 ； 紅外光光譜

並列摘要

We used the first principles theory to calculate the dielectric properties of the materials. In first principle calculation, we used” density-functional perturbation theory” and “linear response method” to simplify the simulation process. We first used diamond as model materials to test the accuracy of calculation.
After verifying the feasibility of first principle calculation, we then proceeded to calculate the phonon characteristics at Γ-point of BaTiO3 and Ba(Zn1/3Nb2/3)O3 materials. We identified the vibrational characteristics at each modes, compared these vibrational characteristics with the measured Raman and FTIR spectroscopy, estimated their dielectric properties. We concluded that the dielectric constant of ABO3 materials is closely related to the tightness of the octahedron, whereas the quality factor is intimately related to the distortion of the octahedron.

並列關鍵字

density-functional perturbation theory ； linear response ； phonon ； Raman ； FTIR

參考文獻

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