The Raman and infrared (IR) wavenumbers were computed for the Aurivillius structure ABi4Ti4O15 (ABT) (ACa, Sr, Ba) in an orthorhombic space group (A21am, No. 36, C122v) using normal coordinate analysis. This study aimed to investigate the impact of A‐site cations on vibrational phonons. The analysis of zone center phonons primarily involved numerous stretching and bending bonds, serving as force constants. These force constants were utilized to assign the calculated wavenumbers in the examined phase for the first time. The theoretical findings in this paper exhibited a favorable correlation with the wavenumbers reported in the literature. Comparisons of force constants, bond lengths, and wavenumbers were conducted to elucidate A‐site cation disordering in these intricate compounds. The outcomes indicated that, in the studied complexes, the Sr atom exhibited an ideal radius for fitting into the structure. The mass of the A‐site cations was identified as a factor contributing to tilts in the octahedra. An additional analysis was carried out to assess the impact of A‐cations on both the affected equatorial and axial bonds, providing a clearer understanding of the structure. Outer octahedra displayed greater sensitivity to A‐site cations compared with inner octahedra. A study of potential energy distribution was also conducted in this work to determine the significance of each force constant in all calculated wavenumbers. It was observed that higher wavenumbers were predominantly influenced by vibrations in oxygen atoms, while lower wavenumbers were mainly affected by A‐site cations. Notably, overdamping was observed in the lowest frequency of the BBT compound.

中文翻译：

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振动研究分析四层 Aurivillius 氧化物 ABi4Ti4O15 (A-Ca, Sr, Ba) 中 A 位阳离子无序

计算了 Aurivilius 结构 ABi 的拉曼波数和红外 (IR) 波数4钛4氧15(ABT) 斜方空间群中的 (ACa, Sr, Ba) (A21am, No. 36, C122v）使用正常坐标分析。本研究旨在研究 A 位阳离子对振动声子的影响。区域中心声子的分析主要涉及大量拉伸和弯曲键，作为力常数。这些力常数首次用于分配所检查相中的计算波数。本文的理论研究结果与文献报道的波数具有良好的相关性。通过比较力常数、键长和波数来阐明这些复杂化合物中 A 位阳离子的无序性。结果表明，在所研究的配合物中，Sr 原子表现出适合结构的理想半径。A 位阳离子的质量被确定为导致八面体倾斜的一个因素。我们还进行了一项额外的分析，以评估 A-阳离子对受影响的赤道键和轴键的影响，从而更清楚地了解结构。与内八面体相比，外八面体对 A 位阳离子表现出更高的敏感性。这项工作还进行了势能分布的研究，以确定所有计算的波数中每个力常数的重要性。据观察，较高的波数主要受氧原子振动的影响，而较低的波数主要受 A 位阳离子的影响。值得注意的是，在 BBT 化合物的最低频率中观察到过阻尼。