微波介電材料La2/3TiO3-LaAlO3聲子計算:密度泛函微擾理論之研究

Phonon calculations on microwave dielectric material La2/3TiO3-LaAlO3: Density-Functional Perturbation Theory Study

林植南(Chi-Nan, Lin)

指導教授 ： 林諭男

淡江大學/理學院/物理學系碩士班/碩士(2009年)

https://doi.org/10.6846/TKU.2009.01105

摘要

近代固態物理的發展配合高速電腦的理論計算，已成為我們研究各式新穎樣品的重要途徑，本研究即以第一原理模擬計算微波介電材料(1-x)La2/3TiO3-xLaAlO3。首先我們從0.9La2/3TiO3 -0.1 LaAlO3的晶格結構中獲得純La2/3TiO3的原子位置，接著以密度泛函微擾理論來研究該材料在Γ點上之聲子行為。從聲子的計算結果輔以實驗量測獲得的拉曼光譜與紅外光光譜，藉此探討微觀下的聲子振動行為與介電機制的關係。

關鍵字

鑭鈦氧 ； 鋁酸鑭 ； 第一原理 ； 拉曼光譜 ； 紅外光光譜 ； 聲子

並列摘要

At the present, the combination of high performance computation and solid-state theory provides a promising methodology to elucidate the microscopic properties of versatile materials. We use the first-principles to start the simulation on the microwave dielectric material La2/3TiO3 - LaAlO3. At first, we get the La2/3TiO3 crystal structure from the atomic position of ceramic 0.9La2/3TiO3-0.1LaAlO3 , and then we use the Density - Functional Perturbation Theory to investigate the phonons at Γ point.
According to the phonon calculation, the calculated eigenvalues and the corresponding eigenvectors of each vibrational mode at Γ point provide a great help on our experimental observations. Comparing with Raman and FTIR spectrum, we can study the dielectric properties on the microwave dielectric material La2/3TiO3 - LaAlO3.

並列關鍵字

La2/3TiO3-LaAlO3 ； First Principles ； Raman ； FTIR ； Phonon

參考文獻

1. R.D. Richtmyer.; Dielectric Resonators, J. Appl. Phys. 10 (1039) 391-398

3. Kim, I. S., Jung, W. H., Inaguma, Y., Nakamura, T., and Itoh, M.; Dielectric Properties of A-site Deficient Perovskite-Type Lanthanum-Calcium-Titanium Oxide Solid Solution System [(1-x)La2/3TiO3-xCaTi03 (0.1≤x≤0.96)]. Materials Research Bulletin 30, 307-316 (1995)

4. Cho, S. Y., Kim, I. T., and Hong, K. S.; Microwave Dielectric Properties and Applications of Rare-earth Aluminates. Journal of Materials Research 14, 114-119 (1999)

6. Herbert, J. M.; Ceramic Dielectrics and Capacitors, Gordon and Breach, New York (1985)

7. P. Hohenbergand W. Kohn," Inhomogeneous Electron Gas ", Phys. Rev.B136, 864 (1964)