Amaechi Ifeanyichukwu C, Ruediger Andreas, Pignolet Alain
Institut National de la Recherche Scientifique, Centre Énergie, Matériaux & Télécommunications 1650 Boulevard Lionel-Boulet, Varennes Québec J3X 1P7 Canada
RSC Adv. 2023 Feb 8;13(8):4917-4923. doi: 10.1039/d2ra06297f. eCollection 2023 Feb 6.
We report the systematic measurements in bismuth titanate powders of Raman frequency shift, and full width at half maximum (FWHM), of optical phonons at = 0 obtained between ∼300 K and 673 K in air. Both the particle size and phonon confinement effects are reasonably satisfactory to explain the Raman peak shift and asymmetric broadening observed in the ferroelectric soft phonon mode at 42 cm. It is shown that the lattice parameter varies as particle size , and its contribution to size-dependent Raman shift and broadening of linewidth follows ∝ and ∝ law, respectively. Moreover, a single phonon coupling term corresponding to a three-phonon anharmonic process is sufficient to describe the phonon coupling decay culminating from the softening of this strongly overdamped phonon mode.
我们报告了在空气中约300 K至673 K温度范围内对钛酸铋粉末进行的系统测量，测量内容包括拉曼频移以及在波数为0时光学声子的半高宽（FWHM）。颗粒尺寸和声子限制效应对于解释在42 cm处铁电软声子模式中观察到的拉曼峰位移和不对称展宽都相当令人满意。结果表明，晶格参数随颗粒尺寸变化，并且其对尺寸依赖的拉曼位移和线宽展宽的贡献分别遵循∝ 和∝ 规律。此外，一个对应于三声子非谐过程的单声子耦合项足以描述由于这种强过阻尼声子模式软化而导致的声子耦合衰减。
