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Title: Pressure-induced ferroelectric to antiferroelectric phase transition in Pb0.99(Zr0.95Ti0.05)0.98Nb0.02O3
Authors: Avdeev, M
Jorgensen, JD
Short, S
Samara, GA
Venturini, EL
Yang, P
Morosin, B
Keywords: Neutron diffraction
Dielectric materials
Ferroelectric materials
Doped materials
Phase transformations
Orthorhombic lattices
Antiferroelectric materials
Issue Date: 9-Feb-2006
Publisher: American Physical Society
Citation: Avdeev, M., Jorgensen, J. D., Short, S., Samara, G. A., Venturini, E. L., Yang, P., & Morosin, B. (2006). Pressure-induced ferroelectric to antiferroelectric phase transition in Pb0.99(Zr0.95Ti0.05)0.98Nb0.02O3. Physics Review B, 73(6), 064105. doi:10.1103/PhysRevB.73.064105
Abstract: Zr-rich, Nb-doped lead zirconate titanate ceramic and powder samples with composition near Pb0.99(Zr0.95Ti0.05)0.98Nb0.02O3 [PZT95/5(2Nb)] have been studied in the range of hydrostatic pressure 0–6.2 kbar and temperature 12–295 K by time-of-flight neutron powder diffraction and dielectric measurements. The combination of the two techniques has led to further insights into the properties and pressure-induced ferroelectric rhombohedral R3c (FR(LT)) to antiferroelectric orthorhombic Pbam (AO) phase transition in this material, and the diffraction results have provided a detailed view of the ionic displacements induced by changes in pressure and temperature as well as the displacements accompanying the transition. At 295 K the diffraction results revealed a sharp transition at 2.1 kbar; at 200 K this transition occurs at 1.1 kbar. The transformation is incomplete: after the initial sharp drop in the FR(LT) content at the transition, 20 wt % of the sample remains in the low-pressure FR(LT) phase. Above the transition, the fraction of FR(LT), which exists as a minority phase in the high-pressure AO phase, continues to decrease, but even at our highest pressure of 6.2 kbar, ∼8wt% of the sample remains in the FR(LT) phase. The volume contraction at the FR(LT)-to-AO transition unexpectedly results in the retained minority FR(LT) being anisotropically ”clamped,” with its a axis slightly expanded and c axis contracted at the transition. On pressure release to 1 bar at 295 K, only 26% of the FR(LT) phase is recovered, and this remains in the clamped state because of the surrounding majority AO phase. Heating the sample above 350 K at 1 bar followed by cooling to room temperature results in full recovery of the FR(LT) phase. The spontaneous polarization (PS) of the FR(LT) phase and its pressure and temperature dependences were determined from the ionic displacements. At 295 K, PS=38μC/cm2—a value greater than the 31–32μC/cm2 commonly observed on ceramic PZT95/5(2Nb) samples. The difference is undoubtedly related to residual porosity in ceramic samples as well as the inability of the poling electric field to align all the polar domains. PS increases monotonically with decreasing temperature, reaching a value of ∼44μC/cm2 at 12 K. ©2006 American Physical Society
ISSN: 2469-9969
Appears in Collections:Journal Articles

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