INFRARED STUDIES OF PEROVSKITE TITANATES
INFRARED STUDIES OF PEROVSKITE TITANATES
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DOI：
10.1103/physrev.135.a408
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发表时间：
1964-01-01
期刊：
影响因子：
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通讯作者：
KHANNA, BN
中科院分区：
文献类型：
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作者：
PERRY, CH;RUPPRECHT, G;KHANNA, BN
在室温下，在 4000 至 30 cm− 1 范围内测量了 CaTi O 3 、SrTi O 3 和 PbTi O 3 的红外反射和透射光谱。反射数据已通过 Kramers-Kronig 方法进行了分析，从中得出了正常光学活性振动的频率，与从透射光谱获得的数据一致。根据群论的要求，观察到立方SrTi O 3 的三个红外主动振动。然而，在CaTi O 3 和PbTi O 3 的情况下，它们分别结晶为稍微扭曲的钙钛矿结构，变成斜方晶系和四方晶系，发现了以前未观察到的额外谱带。这些来自理想立方对称性的畸变会分裂简并模式，从而可能给出额外的频率。结果与其他工人的结果进行了比较。从所提供的数据中可以看出两个特征：(1) 对于这些钛酸盐来说，与阳离子无关的两个正常模式 ν 1 和 ν 2 基本上是恒定的。(2) 负责铁电行为的最低频率振动 ν 3 似乎随着阳离子质量的增加而减小。这表明了 Last 提出的模式分配。
The infrared reflection and transmission spectra of CaTi O 3, SrTi O 3, and PbTi O 3 have been measured from 4000 to 30 cm− 1 at room temperature. The reflection data have been analyzed by means of a Kramers-Kronig method, from which the frequencies of the normal optically active vibrations were derived in agreement with data obtained from transmission spectra. Three infrared active vibrations were observed for cubic SrTi O 3 as required by group theory. However, in the case of CaTi O 3 and PbTi O 3, which crystallize as slightly distorted perovskite structures to become orthorhombic and tetragonal, respectively, additional bands were found which had not been observed previously. These distortions from ideal cubic symmetry would split degenerate modes to possibly give additional frequencies. The results are compared with those of other workers. From the presented data two features emerge:(1) Two normal modes ν 1 and ν 2 are essentially constant for these titanates independent of the cation.(2) The vibration of lowest frequency, ν 3, which is responsible for the ferroelectric behavior, appears to decrease with increasing cation mass. This suggests a mode assignment as proposed by Last.