Multiple Softening of Low-Frequency Raman Modes of Tungsten-Bronze Lead Barium Niobate Relaxor Ferroelectric Single Crystals

• Published in: Journal of the Korean Physical Society Vol. 76; no. 10; pp. 935 - 939
• Main Authors: Naqvi, Furqan Ul Hassan, Ko, Jae-Hyeon, Lim, Ki-Soo
• Format: Journal Article
• Language: English
• Published: Seoul The Korean Physical Society 01-05-2020; Springer Nature B.V; 한국물리학회
• Subjects: Barium; Crystals; Ferroelectric materials; Ferroelectricity; Lattice vibration; Lead; Mathematical and Computational Physics; Niobates; Particle and Nuclear Physics; Phase transitions; Physics; Physics and Astronomy; Raman spectroscopy; Relaxors; Room temperature; Single crystals; Softening; Temperature; Theoretical; Transition temperature; Tungsten bronze; 물리학; 77.80.−Jk; Vibrational property; Raman scattering; Mode Softening; 78.30.−j; Lead barium niobate; 77.80.−e
• ISSN: 0374-4884; 1976-8524
• DOI: 10.3938/jkps.76.935

The vibrational properties of tetragonal tungsten-bronze lead barium niobate, Pb
(1−x)
BaxNb
2
O
6
, with
x
= 0.5 were investigated by using Raman spectroscopy over a wide temperature range from room temperature to 550 °C. The Raman modes in the measured spectrum were divided into three spectral ranges, internal symmetric and antisymmetric vibrational modes of the oxygen octahedra and low-frequency external lattice modes. The temperature dependences of the Raman shifts showed anomalous changes at the ferroelectric phase transition temperature of ~350 °C. Especially, lowfrequency modes below ~300 cm
−1
commonly exhibited multiple softening upon heating toward the transition temperature, indicating that the lattice becomes softer on approaching the ferroelectric phase transition temperature.