Soft mode in PMN–PSN ceramics

Abstract

Various ordered and disordered (1–x)Pb(Mg1/3Nb2/3)O3 –x Pb(Sc1/2Nb1/2)O3 (PMN–PSN) ceramics were studied by THz transmission spectroscopy in the temperature range of 10–300 K. It is found that the dielectric relaxation dominates in the spectra in higher temperatures, T > 170 K. In contrast, below 150 K, the strength of relaxation becomes so weak that the phonon contribution can be separated. The phonon contributribution in the investigated frequency range (200 GHz–2 THz) is presumably caused by the E component of the Last mode. The component exhibits hardening on cooling in all investigated ceramics and its critical temperature in ferroelectric PMN–PSN ceramics (x = 1, 0.95) is lower than the critical temperature in PMN–PSN relaxors (x = 0.2). (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Classical ferroelectriclike behavior of highly orderedPb(Sc1/2Nb1/2Sivasubramanian1, Subramanian2, Kojima3 2016Phys. Rev. B7150View full textAdd to dashboardCite

“…The linear decrease in the square of the frequency of this mode in the ferroelectric phase is consistent with the behavior of the ferroelectric soft mode [59]. However, it is not the soft mode but the dynamics of the PNRs that dominate the low frequency dielectric response of the PSN [59]. Therefore, in terms of the observed similarities in the dielectric anomalies at T c , the first order nature of the phase transition, and the relaxation dynamics of PNRs in the relaxor phase and along with the existence of the soft mode, it appears that the phase transition behavior of the highly ordered PSN is very similar to that of BT.…”

“…The anomalous softening of a localized Pb vibrational mode takes place in the temperature range of 800-500 K and levels off in the temperature range of 500-300 K. Once again, the same mode exhibits a softening behavior towards T c upon heating from 100 K [60]. The linear decrease in the square of the frequency of this mode in the ferroelectric phase is consistent with the behavior of the ferroelectric soft mode [59]. However, it is not the soft mode but the dynamics of the PNRs that dominate the low frequency dielectric response of the PSN [59].…”

“…As in the case of BT, a soft mode-like behavior of the low frequency optical phonon mode is observed in PSN both above and below T c [59,60]. The anomalous softening of a localized Pb vibrational mode takes place in the temperature range of 800-500 K and levels off in the temperature range of 500-300 K. Once again, the same mode exhibits a softening behavior towards T c upon heating from 100 K [60].…”

Terahertz Emission from Tubular Pb(Zr,Ti)O3Nanostructures

“…Ferroelectricity exists in the PZT nanotubes, as revealed by hysteretic switching, and it is supported by the observation of terahertz radiation generated by the nanotubes at femtosecond laser illumination. It is noted that, compared to extensive terahertz studies on single crystal and superlattice films of electro-optic semiconductors (ZnTe, GaAs-based and GaN-based), as well as ferroelectric relaxors, − there are relatively few works on nanostructures of these materials. Parkinson et al investigated the time-resolved conductivity of isolated GaAs nanowires by optical-pump terahertz-probe time-domain spectroscopy.…”

Broadband dielectric spectroscopy of PbMg1/3Nb2/3O3–PbSc1/2Nb1/2O3 ceramics

“…However, the evidence for resonant soft mode existence in PMN-PSN was already presented in Ref. [18]. Therefore, the nature of ferroelectric transitions in ordered PMN-PSN ceram- ics is mixed between displacive and order-disorder types.…”