E. Mojaev

Intermediate temperature scale T ∗ in lead-based relaxor systems

Via a combination of various experimental and theoretical techniques, a peculiar, identical temperature scale

Relaxor-like behavior of BaTiO3 crystals from acoustic emission study

{T}^{\ensuremath{\ast}}

Nature of thermally stimulated acoustic emission from PbMg1/3Nb2/3O3–PbTiO3 solid solutions

is found to exist in all complex lead-based relaxor ferroelectrics studied by us.

Burns, Néel, and structural phase transitions in multiferoic Pb(Fe2/3W1/3)O3-xPbTiO3 detected by an acoustic emission

{T}^{\ensuremath{\ast}}

Detection of phase transitions in sodium bismuth titanate–barium titanate single crystals by acoustic emission

corresponds to a nanoscale phase transition associated with random fields. Interestingly,

Evidence of local anisotropic strains in relaxor ferroelectrics below intermediate temperature T* detected by acoustic emission

{T}^{\ensuremath{\ast}}

Acoustic Emission Study of PZN-7%PT Crystals

also exists in other oxides with extraordinary properties, such as giant magnetoresistivity or superconductivity. By analogy with such latter systems, the giant piezoelectricity related to relaxors might originate from proximity competing states effect.

Acoustic emission and dielectric studies of phase transitions within the morphotropic phase boundary of xPb(Zr1/2Ti1/2)O3-(1−x)Pb(Ni1/3Nb2/3)O3 relaxor ferroelectrics

BaTiO3 crystals were studied by means of the acoustic emission during thermal cycling through 300–700 K range. In addition to pronounced acoustic emission at the ferroelectric phase transition temperature Tc≈400 K, also nucleation of nanoclusters was detected at somewhat smeared Burns temperature Td≈530–570 K and their local freezing at T∗≈506 K. Bias electric field shifts the T∗ and Tc linearly up, T∗ more steeply than Tc. Except for its much faster cluster dynamics than that of classical relaxor materials, BaTiO3 shows many relaxor-like features in its paraelectric phase.

Peculiar properties of phase transitions in Na0.5Bi0.5TiO3−0.06BaTiO3 lead-free relaxor ferroelectrics seen via acoustic emission

We discuss the nature of the thermally stimulated acoustic emission (AE) in single crystals of PbMg1/3Nb2/3O3–PbTiO3 (PMN-PT). In particular, we derive an expression describing the efficiency of AE and we discuss in this connection AE from pure PMN. We have carried out original experiments revealing the dependence of AE in PMN-PT on the electric bias fields, and we found that the AE efficiency of PMN-PT can be heavily enhanced in a certain temperature interval by applying an electric bias field.

Rolling-induced texturing in metal-clad MgB2 tapes and magnetoresistivity anisotropy

We investigated the ceramics samples of multiferoic solid solution of relaxor ferroelectric Pb(Fe2∕3W1∕3)O3 with ferroelectric PbTiO3 (abbreviated as PFW-xPT; x=0, 0.25, and 0.37) by means of acoustic emission (AE) method and simultaneously using the dielectric measurement below 700K. A distinct AE response has been detected at Burns temperature Td≈640–650K, where the dynamic polar clusters start to appear, at intermediate temperature of 510–520K, where the polar clusters become probably static, at ferroelectric phase transition temperatures Tc, and at Neel antiferromagnetic phase transitions. The Neel temperatures TN in ceramics were observed to be lower than in the crystals; the origin is discussed. Based on detected AE responses, we have corrected previously obtained phase diagram for PFW-xPT system.