Influence of electric field on local phase transformations in relaxor ferroelectrics PbSc0.5Ta0.5O3 and Pb0.78Ba0.22Sc0.5Ta0.5O3

Maier, Bernd; Steilmann, Thomas; Gospodinov, M.; Bismayer, U.; Mihailova, Boriana

doi:10.1063/1.4770479

Cited by 13 publications

(23 citation statements)

References 25 publications

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“…19,21,24,[28][29][30][31][32] The transition is close to tricritical but slightly first order in character, [16][17][18][19]28,30,33 such that the transition temperature, T trans , is only slightly different from the critical temperature, T c , and there is a small coexistence interval. T trans shifts to lower temperatures with increasing B-site disorder, [15][16][17][18]21,28 and, for example, is near 260 K in PST with 8% order (Q od = 0.08). 22 Even very low B-site order is not enough to prevent the macroscopic electric polarization from becoming established at low temperatures.…”

Section: Introductionmentioning

confidence: 99%

“…24 Reported values for the characteristic temperatures T * and T d in PST with low Q od are 450-500 K and ∼700 K, respectively. 9,15,21,23,35 We describe for the first time an experimental technique, resonant piezoelectric spectroscopy (RPS), which allows us to detect polar short range order over a large temperature interval in highly B-site ordered PST. RPS measurements were complemented by x-ray diffraction, dielectric constant, ferroelectric hysteresis, and resonant ultrasound spectroscopy (RUS) measurements.…”

Section: Introductionmentioning

confidence: 99%

“…This material was chosen because its dielectric anomaly shows relaxor behavior [15][16][17][18][19][21][22][23] when the degree of B-site order is low but becomes a classic ferroelectric when the degree of structural order is high. [16][17][18]24 Our sample shows the classic ferroelectric transition but maintains sufficient Sc/Ta disorder to allow the formation of tweed structures (for review of the tweed mechanisms and the role of structural disorder see Refs.…”

Section: Introductionmentioning

confidence: 99%

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Ferroelectric precursor behavior in PbSc0.5Ta0.5O3detected by fi

et al. 2013

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A novel experimental technique, resonant piezoelectric spectroscopy (RPS), has been applied to investigate polar precursor effects in highly (65%) B-site ordered PbSc 0.5 Ta 0.5 O 3 (PST), which undergoes a ferroelectric phase transition near 300 K. The cubic-rhombohedral transition is weakly first order, with a coexistence interval of ∼4 K, and is accompanied by a significant elastic anomaly over a wide temperature interval. Precursor polarity in the cubic phase was detected as elastic vibrations generated by local piezoelectric excitations in the frequency range 250-710 kHz. The RPS resonance frequencies follow exactly the frequencies of elastic resonances generated by conventional resonant ultrasound spectroscopy (RUS) but RPS signals disappear on heating beyond an onset temperature, T onset , of 425 K. Differences between the RPS and RUS responses can be understood if the PST structure in the precursor regime between T onset and the transition point, T trans = 300 K, has locally polar symmetry even while it remains macroscopically cubic. It is proposed that this precursor behavior could involve the development of a tweed microstructure arising by coupling between strain and multiple order parameters, which can be understood from the perspective of Landau theory. As a function of temperature the transition is driven by the polar displacement P and the order parameter for cation ordering on the crystallographic B site Q od . Results in the literature show that, as a function of pressure, there is a separate instability driven by octahedral tilting for which the assigned order parameter is Q. The two mainly displacive order parameters, P and Q, are unfavorably coupled via a biquadratic term Q 2 P 2 , and complex tweedlike fluctuations in the precursor regime would be expected to combine aspects of all the order parameters. This would be different from the development of polar nanoregions, which are more usually evoked to explain relaxor ferroelectric behavior, such as occurs in PST with a lower degree of B-site order.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Ferroelectric precursor behavior in PbSc0.5Ta0.5O3detected by fi

et al. 2013

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“…These XAS results support the recently proposed idea based on complementary Raman scattering and diffraction studies at nonambient conditions [5,23,24] that the polar nanoregions in relaxors are ferrielectric rather than ferroelectric in nature. Acoustic emission [25,26] and Raman spectroscopic studies under an external electric field [27,28] also revealed a coexistence of FE and AFE coupling within polar nanoregions, implying a resultant ferrielectric order on the mesoscopic scale.…”

Section: Introductionmentioning

confidence: 99%

X-ray absorption spectroscopy of Ru-doped relaxor ferroelectrics with a perovskite-type structure

et al. 2014

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X-ray absorption near-edge structure and extended x-ray absorption fine structure spectroscopy at the Ru K edge of Ru-doped PbSc 0.5 Ta 0.5 O 3 (PST-Ru), PbSc 0.5 Nb 0.5 O 3 (PSN-Ru), and 0.9PbZn 1/3 Nb 2/3 O 3 -0.1PbTiO 3 (PZN-0.1PT-Ru) as well as at the Ta L 3 edge of PST-Ru and the Nb K edge of PSN-Ru was applied to study the short-and intermediate-range atomic arrangements in perovskite-type (ABO 3 ) relaxor ferroelectrics. The compounds were also analyzed by complementary Raman scattering, visible/near-visible absorption spectroscopy, and synchrotron x-ray single-crystal diffraction. The results show that Ru is octahedrally coordinated in all three relaxor host matrices but the average oxidation state of Ru in PST-Ru and PSN-Ru is ß4.4, whereas it is ß3.8 in PZN-0.1PT-Ru. In PbSc 0.5 B 0.5 O 3 (B = Ta, Nb) Ru substitutes for the B cations in the form of isolated point defects, while in PZN-0.1PT-Ru Ru replaces adjacent A and B sites, forming a chainlike structural species of face-sharing elongated octahedra. Chemical 1:1 B-site order as well as dynamic BO 6 tilting is observed around both the Ru dopant and the major B cation in PST-Ru and PSN-Ru regardless of the fact that according to x-ray diffraction at ambient conditions, the average structure is cubic with weak or no long-range chemical order. Pb cations are off-center displaced from the prototypic cubic A site for all three compounds and in Ru-doped PbSc 0.5 B 0.5 O 3 the BO 6 tilt angle correlates with the degree of coherent B-Pb distances.

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“…[25][26][27][28][29] Similar behavior is found near the intermediate temperature T * . [12][13][14][15][16][17][18][19][20][21][30][31][32][33][34][35] On further cooling, a smeared frequency dependent temperature maximum of the dielectric response occurs near T m and, slightly below T m the freezing occurs at the freezing temperature T f , similar to polar-glass phases. [36][37][38][39] In contrast to these observations, one finds that AE studies [12][13][14][15][16][17][18][19]22,23,[25][26][27][28][29][30] show extremely sharp singularities at T d and T * , which is sometimes related to changes of the thermal expansion.…”

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confidence: 99%

Ferroelectric precursor behavior of highly cation-ordered PbSc0.5Ta0.5O3 detected by acoustic emission: Tweed and polar nanoregions

Dul’kin¹,

Salje²,

Aktas³

et al. 2014

Applied Physics Letters

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Highly cation-ordered, ferroelectric PbSc 0.5 Ta 0.5 O 3 (PST) crystals have been studied by acoustic emission over a wide temperature range. The high degree of order leads to a non-dispersive dielectric anomaly at T trans = 300 K of a weakly first order phase transition. Acoustic emission (AE) was found at three characteristic temperatures, 330 K, 409 K and ∼600 K, but none between these temperatures. These temperatures are close to those known from cation-disordered relaxor PST, containing polar nano regions (PNRs). The microstructure in our ferroelectric PST contains structural tweed rather than PNRs. The coincidence of the AE temperatures points towards a close structural relationship between PNRs and tweed. Furthermore, when electric fields are applied, we observe shifts of these temperatures which are similar to 'critical end point' behavior. The similarity of AE signals in relaxors and tweed ferroelectrics proves that AE detects signals in a wider parameter space than previously expected.Random fields and local phase transitions are commonly evoked when symmetry changes in heterogeneous systems. While some models predict a well-defined transition behavior, such as the spherical random-bondrandom-field (SRBRF), 1,2 where the system transforms at a well-defined temperature from a paraelectric phase to a spherical glass phase without long range order. Other approaches predict smeared cross-overs such as Vugmeister and Rabitz, 3 and the traditional composition fluctuations model, 4 and the super-paraelectric model by Cross. 5 In none of these cases would a classic criticality analysis in terms of Wilson exponents of single thermodynamic order parameters be applicable. Experimentally, smeared crossovers are indeed seen in relaxor ferroelectrics (RFEs). These are materials with wide frequency dispersions of the dielectric response in the transition region. In addition, the transition between a paraelectric and a ferroelectric phase is not only smeared but also split into a number of other singularities which are commonly ascribed to the existence and temperature evolution of polar nanosized regions (PNRs), 6,7 The structural properties of PNRs are still not fully understood with few studies focused on atomic-level correlation effects between PNRs. 8Smooth crossover near the Burns temperature T d at high temperature range is seen in RFEs by the temperature evolution of the refractive index, 9-11 dielectrics and Brillouin light scattering, 12-19 polarized Raman spectra, 20,21 thermal expansion, 22-24 and acoustic emission (AE). 25-29 Similar behavior is found near the intermediate temperature T * . 12-21,30-35 On further cooling, a smeared frequency dependent temperature maximum of the dielectric response occurs near T m and, slightly below T m the freezing occurs at the freezing temperature T f , similar to polar-glass phases. [36][37][38][39] In contrast to these observations, one finds that AE studies [12][13][14][15][16][17][18][19]22,23,[25][26][27][28][29][30] show extremely sharp singularities at T d and T...

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Influence of electric field on local phase transformations in relaxor ferroelectrics PbSc0.5Ta0.5O3 and Pb0.78Ba0.22Sc0.5Ta0.5O3

Cited by 13 publications

References 25 publications

Ferroelectric precursor behavior in PbSc0.5Ta0.5O3detected by fi

Ferroelectric precursor behavior in PbSc0.5Ta0.5O3detected by fi

X-ray absorption spectroscopy of Ru-doped relaxor ferroelectrics with a perovskite-type structure

Ferroelectric precursor behavior of highly cation-ordered PbSc0.5Ta0.5O3 detected by acoustic emission: Tweed and polar nanoregions

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