A Study of Raman Spectra and the Soft Mode Phase Transition under Hydrostatic Pressure in Ba2-xLaxTi4O11
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摘要: 本文测量了Ba1.8La0.2Ti4O11和Ba1.6La0.4Ti4O11在静高压下的拉曼振动谱，发现了软模的耦合模行为。通过比较Ba2Ti4O11的热力学理论计算值和实验数据，确认这种耦合是软模和一个声学模间的耦合，发生的相变是一个由具有Bg对称性的带中心软光学声子驱动的二级铁弹相变。Abstract: The Raman spectra of Ba2-xLaxTi4O11 under hydrostatic pressure have been completed. The behavior of the coupled soft mode is found. Through comparing the result of Ba2Ti4O11 obtained by termodynamics with the experimental data, it is believed that the coupling is one between q0 soft optical phonon with Bg symmetry and a acoustic phonon mode. The phase transition occurring in Ba2-xLaxTi4O11 is a secondary order one driven by the soft mode.
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Key words:
- hydrostatic pressure /
- free-energy /
- soft mode /
- coupling
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