2005/04/28 by S. Kamba, M. Berta, Milan Berta +6
Chemistry · Engineering · Materials Science · Physics and Astronomy · #Acoustic Wave Resonator Technologies #Analytical Chemistry (journal) #Atmospheric temperature range #Chemistry #Condensed matter physics #Dielectric #Far infrared #Ferroelectric and Piezoelectric Materials #Ferroelectricity #Infrared #Infrared spectroscopy #Laser #Materials science #Molecular physics #Nuclear magnetic resonance #Optics #Optoelectronics #Phonon #Photorefractive and Nonlinear Optics #Physics #Polar #Raman spectroscopy #Sapphire #Soft modes #Thermodynamics #cond-mat.mtrl-sci
paper · pdf · doi:10.1063/1.2061895
published as J. Appl. Phys. 98, 074103 (2005) · 6 pages, 5 figures
arxiv created 2005/04/28 · openalex publication_date 2005/10/01 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
Temperature dependences of the optic phonons in PbSc1∕2Ta1∕2O3 (PST) sol-gel films deposited on sapphire substrates were studied by means of Fourier transform far-infrared transmission spectroscopy in the temperature range of 20–900K. Four films displaying different B-site order with both ferroelectric and relaxor behavior were studied. In all cases the TO mode near 80cm−1 at 10K softens on heating to ≈45cm−1 following the Cochran law with extrapolated critical temperature near 700K which is 400K above the temperature of dielectric maximum, Tm. Above 600K the TO1 mode remains stabile. This mode can be assigned to the A1 component of the ferroelectric soft-mode inside polar clusters which form below the Burns temperature near 700K. In the ordered PST film another mode activates below Tm in the infrared spectra near 60cm−1, also exhibiting an anomalous temperature dependence due to its coupling with the former mode. It is assigned to the A1 component of the F2g Raman active mode. The central mode, which appears below the Burns temperature in the terahertz range, is assigned to the dynamics of polar clusters. It slows down on cooling and vanishes from our spectral range below Tm. Another overdamped excitation assigned to the E component of the soft mode appears near 30cm−1 at low temperature.