Pb(Fe0.5Ta0.5)O3 magnetic and ferroelectric relaxor multiferroic crystals have been studied under both temperature and dc external electric field conditions by means of acoustic emission technique. All the characteristic relaxor points as Burns Td≈610K and intermediate T*≈500K temperatures, as well as both Curie ferroelectric cubic-tetragonal Tc1≈259K and tetragonal-monoclinic Tc2≈201K structural and Néel antiferromagnetic-paramagnetic TN≈187K phase transitions have been successfully detected. It is shown that, when an external dc electric field is applied, both Tc1 and Tc2 exhibit a nonlinear or V-shape behavior and attain the sharp minima at threshold temperatures Tth1≈247K and Tth2≈200K with the threshold field Eth≈0.1kVcm-1, as the field enhances, while their acoustic emission count rate monotonically increases. It is shown, too, that the TN behaves linearly in dependence on dc electric field with a negative slope of about -20KcmkV-1, while its acoustic emission count rate monotonically decreases. All these data are discussed from a viewpoint of presence of polar nanoregions and magnetoelectric coupling effect in Pb(Fe0.5Ta0.5)O3 crystals.
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- Acoustic emission
- Magnetoelectric properties
- Multiferroic properties
- Relaxor materials