Domain size effects in a uniaxial ferroelectric relaxor system: The case of SrxBa1−xNb2O6

Abstract

We present investigations of the domain dynamics and of the evolution of the critical exponent β in a ferroelectric relaxor system, exemplarily in the up-to-date controversial strontium barium niobate (SBN). k-space spectroscopy at the phase-transition and when applying an electric field reveals a size-dependent response of the domains. This is supported by pyroelectric measurements that show, by analysis in terms of criticality, the critical exponent β is not only dependent on the level of poling but also on the manner in which the poling was achieved. It must be concluded that the crystals undergo a phase transition not—as commonly assumed—in a uniform way with homogeneous polarization throughout the crystal. Instead they behave as a set of more or less independent domains with size-dependent stability. Therefore, one should be very careful with critical exponents—especially those derived from experiments that explicitly or implicitly—assume a uniform polarization behavior.

Investigation of the electrocaloric effect in a PbMg2/3Nb1/3O3-PbTiO3 relaxor thin film

“…4 literally, as relaxors are never formally in thermal equilibrium. 22,26,27 However, the FH data suggests the intriguing possibility of a large ⌬T =9 K at 25°C when E = 723 kV cm −1 is applied. This is an interesting outcome because no dielectric material has shown or been predicted to show such a large ECE at room temperature.…”

“…1. Failure of the dielectric behavior above T m to collapse to a single frequency-independent curve could be simply due to sampling in a small temperature window, or due 21 to space charge associated with low crystallinity, or due [21][22][23] to inhomogeneity such that the transition is smeared out. The discrepancy in the absolute value of the calculated permittivity at 1 kHz ͑ϳ5%͒ ͑between Fig.…”

Domain-shape-based modulation of Čerenkov second-harmonic generation in multidomain strontium barium niobate

“…In preparation, the crystal was first heated up above the Curie temperature T c ≈ 70-80°C and then cooled down without applying an electric field to produce an unpoled sample. In order to influence the domain size and form, the sample was subsequently poled and repoled stepwise at room temperature [12,16]. For this, an electric field was applied along the polar axis and increased in steps of 10 V=cm every 2 s until finally 7:5 kV=cm are reached.…”

Sum-frequency generation in disordered quadratic nonlinear media

“…11 It has also been demonstrated that noncollinear second-harmonic generation in SBN can be used to characterize femtosecond laser pulses. [12][13][14] As the angular spectrum of planar SHG is directly related to the domain distribution this process can be used for k-spectroscopy 15,16 and to examine the switching behavior of ferroelectric domains. [17][18][19] Aside from noncollinear SHG the generation of the third harmonic via a cascaded χ (2) -process is also possible.…”