Morphotropic Phase Boundary in the Nanocrystalline PbZrxTi1-xO3 System

1996 ◽  
Vol 452 ◽  
Author(s):  
R. S. Katiyar ◽  
J. F. Meng
Keyword(s):  
Grain Size ◽  
Phase Transformation ◽  
Phase Boundary ◽  
Raman Spectra ◽  
Morphotropic Phase Boundary ◽  
Size Dependence ◽  
Phonon Mode ◽  
Ferroelectric Phase ◽  
Soft Mode ◽  
Bulk Materials

AbstractMicro Raman spectra for PbZrxTi1-xO3 (PZT) with a grain size of 60 nm have been recorded. The results show that the lowest E(TO) phonon mode of PbTiO3 (soft mode) displays a decrease in frequency and increase in linewidth with increasing Zr concentration. A discontinuous behavior of the phonon energy of the soft mode occurs at x=0.4 and it can be attributed to a phase transformation from the tetragonal ferroelectric to rhombohedral ferroelectric phase in PZT. The coupling between the soft mode and an additional impurity mode, has been observed, which plays an important role in the phase transformation. A lowest phonon mode at 10 cm−1 is detected and it is found to exhibit an increase in intensity for x above 0.2. The grain size dependence of the mode seems to be associated with the effect of grain size on the microstructure in PZT. The mechanism of grain size - induced new morphotropic phase boundary, which is lower than that of the corresponding bulk materials, is discussed.

Raman Studies of the Soft Phonon Modes in BaxSr1−x.TiO3 thin Films

2001 ◽  
Vol 688 ◽  
Author(s):  
D. A. Tenne ◽  
A. M. Clark ◽  
A. R. James ◽  
A. Soukiassian ◽  
K. Chen ◽  
...  
Keyword(s):  
Thin Films ◽  
Phase Transition ◽  
Raman Spectra ◽  
Ferroelectric Phase Transition ◽  
Ferroelectric Phase ◽  
Soft Mode ◽  
Buffer Layers ◽  
Laser Deposition ◽  
Phonon Modes ◽  
Barium Strontium

AbstractThe vibrational properties of barium strontium titanate thin films were studied by Raman spectroscopy in the temperature range from 5 to 300 K. The films were grown by pulsed laser deposition on SrTiO3 and LaAlO3 substrates with SrRuO3 buffer layers. Soft phonons are observed in Raman spectra of BaxSr1−xTiO3 films with Ba contents x = 0.05, 0.1, 0.2 and 0.5. The temperature dependence of the soft phonon frequencies and the splitting of the triply degenerated soft mode into two components of A and E symmetries indicate the ferroelectric phase transition. The E soft mode line is overdamped over a broad range of temperatures near the ferroelectric phase transition, while it is clearly seen in the spectra at temperatures away from the phase transition. The relative Raman intensity of the A soft mode and hard modes decreases gradually over a broad range of temperatures. This indicates a broad ferroelectric phase transition in the thin films. Comparison of Raman spectra for films grown on SrTiO3 and LaAlO3 substrates shows the influence of strain on the temperature of the ferroelectric phase transition.

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