Lattice modes in paraelectric La sub(1/2)Na sub(1/2)TiO sub(3) by infrared and Raman spectroscopy

The lattice dynamics of La sub(1/2)Na sub(1/2)TiO sub(3) single crystal have been investigated by far-infrared and Raman scattering spectroscopy. Far-IR reflectivity spectra revealed Slater, Last and Axe modes near 140, 190 and 555 cm super(-1), respectively. The frequency of the Slater mode decreas...

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Published inJournal of physics. Condensed matter Vol. 25; no. 8; pp. 1 - 4
Main Authors Borodavka, F, Simon, E, Gregora, I, Kamba, S, Haumont, R, Hlinka, J
Format Journal Article
LanguageEnglish
Published 27.02.2013
Subjects
Condensed matter
Cooling
Dynamic tests
Lattice vibration
Lattices
Phase transformations
Raman scattering
Spectra
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Summary:The lattice dynamics of La sub(1/2)Na sub(1/2)TiO sub(3) single crystal have been investigated by far-infrared and Raman scattering spectroscopy. Far-IR reflectivity spectra revealed Slater, Last and Axe modes near 140, 190 and 555 cm super(-1), respectively. The frequency of the Slater mode decreases by about 10% on cooling, which is enough to account for the observed increase of the low-frequency permittivity. The results allowed us to discuss the reasons for the suppressed ferroelectricity of the material. Temperature evolution of the Raman scattering intensity of an oxygen octahedra bending mode near 455 cm super(-1) suggests a second-order phase transition towards the perovskite aristotype phase near 870 K.
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ISSN:0953-8984
1361-648X
DOI:10.1088/0953-8984/25/8/085901