Rhombohedral superlattice structure and relaxor ferroelectric behavior of (Pb0.70Ba0.30)ZrO3 ceramics

Abstract

Superlattice reflections observed in the neutron powder-diffraction patterns of (Pb0.80Ba0.20)ZrO3 (PBZ20) and (Pb0.70Ba0.30)ZrO3 (PBZ30) are explained in terms of doubled rhombohedral cell (R3c). A Rietveld analysis of the neutron data reveals that the displacements of Pb2+/Ba2+ and Zr4+ decrease with increasing Ba2+ content while the thermal parameter for Pb2+/Ba2+ increases and becomes similar to ferroelectric relaxors. Dielectric studies indeed confirm relaxor behavior in PBZ30 with Vogel–Fulcher type relaxational freezing.

Effect ofBa2+substitution on the stability of the antiferroelectric and ferroelectric phases in(PbPokharel1, Pandey2 2002Phys. Rev. BSelf Cite281230View full textAdd to dashboardCite

“…Instead, Ba 2ϩ substitution modifies the strength of the already existing competing AFE and FE instabilities of the PZ matrix in such a way that when one of them dominates over the other, a pure AFE or FE phase results 12 whereas in the event of the two interactions being comparable, one gets glassy or relaxor FE behavior. 13 Thus the A O to F R to P C sequence of phase transition of PbZrO 3 is observed in PBZ also but only for a restricted composition range of 0рxр0.15. 12 But, for 0.20рxϽ0.30, the sequence of phase transition changes to F R to P C ͑Ref.…”

“…12͒ with the total absence of the A O phase. Further, for xϭ0.30, PBZ shows relaxor FE transition 12,13 whereas for xϾ0.30, it shows a reentrant relaxor ferroelectric behavior. 14 The difference in the ionic radii of Pb 2ϩ ͑1.17 Å͒ and Ba 2ϩ ͑1.29 Å͒ and the polarizabilities of the two ions seems to be playing the most important role in modifying the relative strengths of the AFE and FE instabilities.…”

High Energy Storage Density and Impedance Response of PLZT2/95/5 Antiferroelectric Ceramics

“…Microstructure and electrical properties of PLZT2/95/5 ceramics can be improved by powder processing or sintering. Generally, the AFE to FE phase transition in PZ occurs around 225 °C on heating [11]. The structure of the AFE phase is orthorhombic ( A O ) with eight formula units in the unit cell, whereas the FE phase has a rhombohedral structure ( F R ) possibly with two formula units [8].…”

“…The structure of the AFE phase is orthorhombic ( A O ) with eight formula units in the unit cell, whereas the FE phase has a rhombohedral structure ( F R ) possibly with two formula units [8]. The F R phase transforms into a cubic paraelectric ( P C ) phase (PE) on heating above 231 °C [11]. This phase transition of AFE to FE can be induced by varying the temperature [12], electric field [13] or hydrostatic pressure [14].…”

“…This phase transition of AFE to FE can be induced by varying the temperature [12], electric field [13] or hydrostatic pressure [14]. For example, the stabilization of the AFE and FE phases may be altered by chemical substitutions like substitution of La 3+ , Ba 2+ , Sr 2+ at Pb 2+ -site and Ti 4+ , Sn 4+ at Zr 4+ -site in PZ, such as in (Pb 1- x Ba x )ZrO 3 ceramics, Pb 0.95 Sr 0.05 (Zr 0.5 Ti 0.5 )O 3 ceramics, (Pb,La)(Zr,Sn,Ti)O 3 ceramics [8,9,10,11,12]. …”