Time-Resolved X-Ray Diffraction Reveals the Hidden Mechanism of High Piezoelectric Activity in a Uniaxial Ferroelectric

Abstract

High piezoelectric activity of many ferroelectrics has been the focus of numerous recent studies. The structural origin of this activity remains poorly understood due to a lack of appropriate experimental techniques and mixing of different mechanisms related to ferroelectricity and ferroelasticity. Our work reports on the study of a uniaxial Sr 0.5 Ba 0.5 Nb 2 O 6 ferroelectric where the formation of regions with different spontaneous strains is ruled out for the symmetry reason and where the interrelation between piezoelectricity and ferroelectricity can be inspected in the isolated fashion. We performed X-ray diffraction experiment on a single crystalline sample under alternating electric field and observed unknown hidden-in-the-bulk mechanism, which suggests that the highest piezoelectric activity is realized in the volumes where nucleation of small ferroelectric domains takes place. This new mechanism creates a novel roadmap for designing materials with enhanced piezoelectric properties.Electromechanical coupling is the ability of some solids to convert mechanical energy into electrical and vice versa. Solids exhibiting linear electromechanical coupling are called piezoelectrics: they may become electrically polarized under a mechanical stress or mechanically deformed under an electric field. Piezoelectricity closely co-exists with ferroelectricity -the ability to switch spontaneous polarization states under an electric field. This letter reports on the observation of a new piezoelectric activity mechanism, suggesting that it may appear in a purely uniaxial ferroelectric in the form of correlation between lattice parameter and domains size. We observed this mechanism by time-resolved synchrotron Xray diffraction on SBN50 single crystals under alternating electric field. We have chosen SBN50 as a model uniaxial ferroelectric whose para-and ferroelectric phases are tetragonal The time-resolved X-ray diffraction experiment was performed using a custom-built stroboscopic data-acquisition system, which operates on the principle of a multi-channel analyser and qualifies for the investigation of repetitive processes down to the nanosecond time scale. The details of this technique are described elsewhere [4], [33][34][35] and briefly summarized in the supplemental materials. It has already been applied to the determination of small (~10 -4 Å) electric field induced bond distortions [36][37][38][39][40][41][42], the determination of

Simultaneous resonant x-ray diffraction measurement of polarization inversion and lattice strain in polycrystalline ferroelectrics

“…The time-resolved X-ray diffraction data were acquired using a bespoke stroboscopic data acquisition system operating on the principle of a multi-channel analyser, and providing an ideal platform for the investigation of repetitive processes down to the nanosecond time scale 19 21 33 . Similar stroboscopic approaches have previously been applied to the determination of small (~10 −4 Å) electric field induced bond distortions 18 19 20 , the determination of piezoelectric coefficients 34 , the study of ferroelectric ceramics 11 12 35 and single crystals 22 . In the configuration used here, the system used 10000 time channels of width 2 μs, later binned by a factor of 20 to improve the counting statistics at a temporal resolution (i.e.…”

“…Time-resolved X-ray diffraction is also a powerful tool for measuring structural dynamics (e.g. 21 22 ).…”

Intrinsic Ferroelectricity in Charge-Ordered Magnetite

“…There are some transient effects close to the times of the pulses themselves, which are asymmetric for the positive and negative pulse (c.f. the anisotropy visible in the switching in Figure 3 and in in-situ diffraction experiments on other compounds [40,44]), and which depend on the movements of the atoms switching mechanism [40]. However, the main effect is that, in between the pulses, the intensity is clearly above average in the interval after the application of the negative pulse and below average in the interval after the application of the positive field pulse.…”

“…The measurements then have to be conducted and time-resolved, with electronic coordination between voltage pulses, detector read-out and diffractometer movements. To this extent, we adapted a setup for time-resolved diffraction, which had been previously used primarily for studying piezoelectric samples, for the synchrotron beamline P09 [41] of PETRAIII [40,[42][43][44][45]. We chose a photon energy of 8.55 keV, sufficiently far above the Fe K edge to suppress resonant scattering effects and EXAFS (extended x-ray absorption fine structure) , but close enough to provide for a significant imaginary part of the Fe scattering factor.…”

Effect of alloying BaTiO3 with BiZn1/2Ti1/2O3 on polarization reversal

“…Time-resolved x-ray diffraction data were acquired using a bespoke stroboscopic multi-channel analyzer data acquisition system (10 000 data channels). [20][21][22][23][24][25][26] Measured data were later binned by a factor of 20 to improve the counting statistics, resulting in a final time resolution of 40 ls. The electric current was monitored using an active probe measuring the voltage drop across a 1 kX active resistor with a resolution of 6 ls using a Rohde and Schwarz oscilloscope (HMO3044, Hameg, Germany).…”