Repository logo
 

Elastic and anelastic relaxation behaviour of perovskite multiferroics II: PbZr$_{0.53}$Ti$_{0.47}$O$_3$ (PZT)–PbFe$_{0.5}$Ta$_{0.5}$O$_3$ (PFT)

Published version
Peer-reviewed

Change log

Authors

Schiemer, JA 
Lascu, I 
Harrison, RJ 
Kumar, A 
Katiyar, RS 

Abstract

Elastic and anelastic properties of ceramic samples of multiferroic perovskites with nominal compositions across the binary join PbZr0.53Ti0.47O3–PbFe0.5Ta0.5O3 (PZT–PFT) have been assembled to create a binary phase diagram and to address the role of strain relaxation associated with their phase transitions. Structural relationships are similar to those observed previously for PbZr0.53Ti0.47O3–PbFe0.5Nb0.5O3 (PZT–PFN), but the magnitude of the tetragonal shear strain associated with the ferroelectric order parameter appears to be much smaller. This leads to relaxor character for the development of ferroelectric properties in the end member PbFe0.5Ta0.5O3. As for PZT–PFN, there appear to be two discrete instabilities rather than simply a reorientation of the electric dipole in the transition sequence cubic–tetragonal–monoclinic, and the second transition has characteristics typical of an improper ferroelastic. At intermediate compositions, the ferroelastic microstructure has strain heterogeneities on a mesoscopic length scale and, probably, also on a microscopic scale. This results in a wide anelastic freezing interval for strain-related defects rather than the freezing of discrete twin walls that would occur in a conventional ferroelastic material. In PFT, however, the acoustic loss behaviour more nearly resembles that due to freezing of conventional ferroelastic twin walls. Precursor softening of the shear modulus in both PFT and PFN does not fit with a Vogel–Fulcher description, but in PFT there is a temperature interval where the softening conforms to a power law suggestive of the role of fluctuations of the order parameter with dispersion along one branch of the Brillouin zone. Magnetic ordering appears to be coupled only weakly with a volume strain and not with shear strain but, as with multiferroic PZT–PFN perovskites, takes place within crystals which have significant strain heterogeneities on different length scales.

Description

Keywords

40 Engineering, 3403 Macromolecular and Materials Chemistry, 4016 Materials Engineering, 34 Chemical Sciences

Journal Title

Journal of Materials Science

Conference Name

Journal ISSN

0022-2461
1573-4803

Volume Title

52

Publisher

Springer
Sponsorship
NERC (NE/B505738/1)
Natural Environment Research Council (NE/F017081/1)
Engineering and Physical Sciences Research Council (EP/I036079/1)
European Research Council (320750)
Engineering and Physical Sciences Research Council (EP/M000524/1)
RUS facilities in Cambridge were established with funding from the Natural Environment Research Council (Grants NE/B505738/1, NE/F017081/1). The present work was supported by Grant No. EP/ I036079/1 from the Engineering and Physical Sciences Research Council. We thank Dr. Sam Crossley for his assistance with dielectric analysis and the use of his software to run those measurements. JAS gratefully acknowledges the hospitality of the Max Planck Institute for Chemical Physics of Solids. The Nanopaleomagnetism lab has received funding from the European Research Council under the European Union’s Seventh Framework Programme (FP/2007– 2013)/ERC Grant Agreement 320750. SED and HS acknowledge support from the Winton Programme for the physics of sustainability. HS also acknowledges support from the Funai Foundation for Information Technology and the British Council Japan Association. Part of the work was carried out at the University of Puerto Rico, supported by the DOEEBSCoR project DEG02-ER46526.