Raman Spectrum of Gadolinium Molybdate above and below the Ferroelectric Transition
Raman Spectrum of Gadolinium Molybdate above and below the Ferroelectric Transition
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铁电转变上方和下方钼酸钆的拉曼光谱
DOI：
10.1103/physrevb.8.2991
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发表时间：
1973
影响因子：
3.7
通讯作者：
J. Hardy
中科院分区：
文献类型：
--
作者：
F. G. Ullman;B. Holden;B. Ganguly;J. Hardy
在室温和159 ℃以上的铁电转变温度下，获得了单畴钆氧化物在几种晶向上的90 °散射拉曼谱。在0-200 cm-1范围内的线都可以与拉曼活性声子相关联，并通过对称性考虑、散射效率计算和不同晶体取向的光谱比较来识别。在200-1000-cm-1范围内的谱线可以用四面体离子的耦合振动来识别。频率高于1000 cm-1的光谱来源于杂质荧光。确定了多畴的存在对光谱的影响;观察到的单畴和多畴晶体之间的差异是由于相邻畴的孪晶引起的B1-B2对称性混合。没有新的软模式，除了已知的软模式在约43 cm-1，观察。一些只存在于低温相中的谱线不能从对称性分析中识别，并且可能来自高温相的区域边界模式。
90 deg scattered Raman spectra of single-domain gadolinium molybdate have been obtained at room temperature and above the 159 deg C ferroelectric transition on several crystal orientations. Lines in the 0-200-cm-1 range can all be associated with Raman-active phonons and are identified by symmetry considerations, scattering-efficiency calculations, and comparison of spectra for different crystal orientations. Lines in the 200-1000-cm-1range can be identified with coupled vibrations of tetrahedral molybdate ions. Spectra for frequencies above 1000 cm-1 originate from impurity flourescence. The effect of the presence of multiple domains on the spectra was detemined; the observed differences between single-domain and multiple-domain crystals result from B1-B2 symmetry mixing from the twinning of adjacent domains. No new soft modes, in addition to the known soft mode at about 43 cm-1, were observed. A few of the lines that are present in only the low-temperature phase cannot be identified from symmetry analysis and are probably derived from zone- boundary modes of the high-temperature phase.