Elastic and anelastic relaxation behaviour of perovskite multiferroics I: PbZr0.53Ti0.47O3 (PZT)–PbFe0.5Nb0.5O3 (PFN)

Abstract

Perovskites in the ternary system PbTiO 3 (PT)-PbZrO 3 (PZ)-Pb(Fe 0.5 Nb 0.5 )O 3 (PFN) have attracted close interest because they can display simultaneous ferroelectric, magnetic and ferroelastic properties. Those with the most sensitive response to external fields are likely to have compositions near the morphotropic phase boundary (MPB) which lies close to the binary join Pb(Zr 0.53 Ti 0.47 )O 3 (PZT)-PFN. In the present study, the strength and dynamics of strain coupling behaviour which accompanies the development of ferroelectricity and (anti)ferromagnetism in ceramic PZT-PFN samples have been investigated by resonant ultrasound spectroscopy. Elastic softening ahead of the cubic-tetragonal transition does not fit with models based on dispersion of the soft mode or relaxor characteristics but is attributed, instead, to coupling between acoustic modes and a central peak mode from correlated relaxations and/or microstructure dynamics. Softening of the shear modulus through the transition by up to *50 % fits with the expected pattern for linear/quadratic strain/order parameter coupling at an improper ferroelastic transition and close to tricritical evolution for the order parameter. Superattenuation of acoustic resonances in a temperature interval of *100 K below the transition point is indicative of mobile ferroelastic twin walls. By way of contrast, the first-order tetragonalmonoclinic transition involves only a small change in the shear modulus and is not accompanied by significant changes in acoustic dissipation. The dominant Address correspondence to E-mail: mc43@esc.cam.ac.uk DOI 10.1007/s10853-016-0280-2 J Mater Sci (2016) 51:10727-10760 feature of the elastic and anelastic properties at low temperatures is a concaveup variation of the shear modulus and relatively high loss down to the lowest temperature, which appears to be the signature of materials with substantial local strain heterogeneity and a spectrum of strain relaxation times. No evidence of magnetoelastic coupling has been found, in spite of the samples displaying ferromagnetism below *550 K and possible spin glass ordering below *50 K. For the important multiferroic perovskite ceramics with compositions close to the MPB of ternary PT-PZ-PFN, there must be some focus in future on the role of strain heterogeneity.

New trends in the nanophysics of ferroics, relaxors and multiferroics

“…In the recent years, considerable attention of scientists and engineers was paid to ferroelectric antiferromagnets PbFe 1/2 Ta 1/2 O 3 (PFT), 𝑇 𝑁 ≈ 130-180 K, and PbFe 1/2 Nb 1/2 O 3 (PFN), 𝑇 𝑁 ≈ 140 K [37,38] and their solid solutions with PbZr 0.53 Ti 0.47 O 3 [39][40][41][42][43][44][45][46]. Some of these solid solutions exhibit roomtemperature multiferroism and large enough ME coupling, which includes a mixture of linear and biquadratic contributions.…”

PZT-based Antiferroelectric Material Based on Building Roof Film Rolling Process and Preparation Method Thereof

“…It is found that the elasticity before moving the rectangular square axis is not suitable for models based on elastic position distribution or relaxation characteristics, but is determined by the correlation between the acoustic position and the midline of relevant relaxation and / or microstructure exercises. After modification, the elasticity of fatigue factor is about 50%, which corresponds to the expected position of linear / square pressure / parameter command, but the actual operation is more complex [5]. It is an important work to explore the stability of PZT materials.…”

Magnetoelastic coupling associated with vacancy ordering and ferrimagnetism in natural pyrrhotite, Fe7S8

“…The present study was initiated as part of a wider effort to characterise the strength and mechanisms of magnetoelastic phenomena in ferroic, multiferroic and superconducting phases through the in uence of strain coupling on elastic and anelastic properties [13][14][15][16][17]. Pyrrhotites provide an interesting example of magnetoelastic behaviour in which magnetic ordering is coupled with vacancy ordering either directly or indirectly via common strains.…”