Effect of Ba incorporation on pressure-induced structural changes in the relaxor ferroelectric<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mtext>PbSc</mml:mtext></mml:mrow><mml:mrow><mml:mn>0.5</mml:mn></mml:mrow></mml:msub><mml:msub><mml:mrow><mml:mtext>Ta</mml:mtext></mml:mrow><mml:mrow><mml:mn>0.5</mml:mn></mml:mrow></mml:msub><mml:msub><mml:mtext>O</mml:mtext><mml:mn>3</mml:mn></mml:msub></mml:mrow></mml:math>

Welsch, Anna-Maria; Maier, Bernd; Engel, Jens; Mihailova, Boriana; Angel, R. J.; Paulmann, Carsten; Gospodinov, M.; Friedrich, Alexandra; Stosch, Rainer; Güttler, Bernd; Petrova, Dimitrina; Bismayer, U.

doi:10.1103/physrevb.80.104118

“…The substitution of Ba (having an isotropic outermost electron shell) for Pb (forming a stereochemically active lone pair) generates local elastic fields due to the larger ionic radius of Ba 2þ as compared to Pb 2þ as well as due to the violation of the system of lone-pair electrons. As a result, the development of ferroic LRO on both cooling and pressure increase is suppressed, leading to diffuse temperature-and pressure-induced transformation processes [31,33]. By contrast, the aliovalent substitution of Bi 3þ for Pb 2þ enhances the fraction of the ferroic phase developed below T c or above p c [34,36].…”

Section: Introductionmentioning

confidence: 87%

“…Figure 2 shows the parallel Z ZðXXÞ Z and cross Z ZðXYÞ Z polarized Raman spectra of PSTN and PSTS. Details of the peak assignments and types of vibrations giving rise to the Raman signals have previously been established [31,33,[45][46][47] and a brief summary is given in Table 1. As for other (Pb,A 00 )(B 0 ,B 00 )O 3 -type relaxors, the Raman spectra of PSTN and PSTS can only be interpreted in terms of Fm 3 3m symmetry, regardless of the degree of long-range CBO, because of the apparent presence of Raman peaks generated by the A 1g and the Pb-localized F 2g modes which are characteristic only of the double-perovskite structures.…”

Section: Temperature-induced Transformationsmentioning

confidence: 99%

“…Instead a new ferroic phase develops at high pressures [8,32]. Our recent investigations on pure and A-site doped PbSc 0.5 Ta 0.5 O 3 (PST) and PbSc 0.5 Nb 0.5 O 3 (PSN) clearly revealed the existence of a critical pressure p c in relaxors and demonstrated that the structure of the high-pressure phase has long-range order (LRO) of anti-phase octahedral tilts and locally ordered Pb shifts, while the B-cation polar shifts are suppressed [32][33][34][35]. The substitution of Ba (having an isotropic outermost electron shell) for Pb (forming a stereochemically active lone pair) generates local elastic fields due to the larger ionic radius of Ba 2þ as compared to Pb 2þ as well as due to the violation of the system of lone-pair electrons.…”

Section: Introductionmentioning

confidence: 98%

See 1 more Smart Citation

Transformation processes in relaxor ferroelectric PbSc_0.5Ta_0.5O₃heavily doped with Nb and Sn

Welsch

¹

,

Maier²,

Mihailova

³

et al. 2011

Zeitschrift für Kristallographie

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Alpha-U has been observed to undergo the following sequence of transformations at T 0 < 43K (lower limit of stability of the structure) a transition involving modes for which q CDW = < q x , q y , q z >; ortho.: Cmcm T 0 = 43K > mono.: C2/m11 (q x , q y , q z) T 1 = 37K > mono.: P211 (1/2, q y , q z). The phonon dispersion was measured by neutron inelastic scattering in the range (200, 43K) of existence of the high-temperature orthorhombic phase and in the range of the phase transformations at 43, 37 and 22K. Soft branches were associated with the normal-to-incommen-surate transitions in Brillouin zone: (201). The main component of the displacement pattern is consistent with the symmetry for a Σ 4 phonon mode. The static displacements associated with the displacive transition are produced by low-frequency and damped phonons at positions q s [(q x , q y , q z)] which on approaching the second-order phase transition (T 0) soften more than those with q c = [1/2, 0, 0], but not totally. Increasing the energy resolution by using cold neutrons on the three axis spectrometer IN14 near (101), we have seen in the range T-T 0 = 7K a small deviation from the linear law of Curie. The experimental phonon softening [1] which is accompanied by large changes in cell parameters at T 0 , is dependent on q y (T), q z (T) contrary to predictions of the Yamada theory. At T 0 = 43 K the modulation wave vector of the incommensurate low-temperature condensing soft mode is q min = [0.497 (1), 0.13 (1), 0.21 (1)] (q CDW. The electronic instability which causes Kohn anomaly also triggers the displacive (Peierls) transition. Relaxors are special class of ferroelectrics that exhibit a broad, diffuse phase transition over a temperature range and a strong frequency dependence of the dielectric constant as a function of temperature. Near room temperature they exhibit very high dielectric permittivity, electrostrictive and electrooptical coefficients , which determine relaxors as multi-functional materials, with a wide range of technological applications, including non-volatile memory devices. The global, average structure of relaxors, detectable by diffraction methods, remains pseudo-cubic even at liquid helium temperatures, whereas their nanoscale structure is rather complex. Near the Curie range and under zero-field conditions the ferroic clusters are sized only a few unit-cell parameters and they create and annihilate within 10-5-10-6 s. Thus, because of its length-and timescale sensitivity, inelastic light scattering is vital for gaining structural information. The mechanism of paraelectric-to-relaxor ferroelectric phase transition is still not clarified. To better understand the local structural phenomena occurring in relaxors we have applied Raman scattering and X-ray diffraction on single crystals of stoichiometric PbSc 0.5 Ta 0.5 O 3 (PST), solid solutions of type PbSc 0.5 Ta .5 O 3-PbSc 0.5 Nb .5 O 3 and PbSc 0.5 Ta .5 O 3-PbSnO 3 , A-site mixed (Pb 1-x A'' x)Sc 0.5 Ta 0.5 O 3 (A'' = Ba,), as well as Ru-doped PbSc 0.5 Ta 0.5 O 3. The ...

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“…2 Under pressure Pb-based relaxors undergo a continuous phase transition from a cubic to a rhombohedral structure, involving the development of long-range order of antiphase octahedral tilts, local ferroic order of the Pb atoms and a suppression of the offcentered displacements of the B-site cations. 10,11,12,13,14,15 The critical pressure at which the symmetry of the global structure is broken is preceded by a characteristic intermediate pressure p* at which the existing off-centered Pb and B-site cations dynamically decouple and anti-phase octahedral tilt order is detectible by neutron diffraction. 10,11,14,15 The reason for the appearance of PNRs at high temperatures and the suppression of ferroelectric order at low temperatures is still under discussion.…”

Section: Introductionmentioning

confidence: 99%

“…10,11,12,13,14,15 The critical pressure at which the symmetry of the global structure is broken is preceded by a characteristic intermediate pressure p* at which the existing off-centered Pb and B-site cations dynamically decouple and anti-phase octahedral tilt order is detectible by neutron diffraction. 10,11,14,15 The reason for the appearance of PNRs at high temperatures and the suppression of ferroelectric order at low temperatures is still under discussion. It is widely accepted that the relaxor state in perovskites is due to charge imbalance and corresponding local random electric fields associated with the compositional disorder on the cation sites.…”

Section: Introductionmentioning

confidence: 99%

Effect of La doping on the ferroic order in Pb-based perovskite-type relaxor ferroelectrics

Maier

¹

,

Welsch

²

,

Mihailova

³

et al. 2011

Self Cite

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The structural alteration induced by the substitution of three-valent cations with an isotropic electronic outermost shell for Pb 2+ in perovskite-type relaxors was investigated in the solid solutions Pb 1-x La x Sc (1+x)/2 Ta (1-x)/2 O 3 , x = 0.08 (PST-La) and Pb 1-. In order to distinguish the "charge" effects from "strain" effects associated with the incorporation of La 3+ in the structure, Srcontaining PbSc 0.5 Nb 0.5 O 3 was characterized as well. The structure of the compounds was analyzed by in-situ Raman spectroscopy, single-crystal x-ray diffraction and powder neutron diffraction at different temperatures or pressures. It is shown that the embedding of La 3+ strongly affects the ferroic structural species due to "strain" effects through a disturbance of the system of lone-pair electrons associated with Pb 2+ and a decrease in the tolerance factor. La doping suppresses the dynamical coupling between off-centered Pb and B-site cations and enhances anti-phase BO 6 octahedral tilting which, depending on the level of doping, may lead to long-range order of anti-phase BO 6 tilts at ambient conditions and frustrated anti-ferroelectric order of Pb ions at low temperatures.

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The high-pressure structure of (1-x)Na$$_{0.5}$$Bi$$_{0.5}$$TiO$$_3$$-xBaTiO$$_3$$ at the morphotropic phase boundary

Rösche,

Boffa Ballaran,

Malcherek

et al. 2024

Sci Rep

0

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The pressure-induced structural changes in the perovskite-type (ABO$$_3$$ 3 ) ferroelectric solid solution (1-x)Na$$_{0.5}$$ 0.5 Bi$$_{0.5}$$ 0.5 TiO$$_3$$ 3 -xBaTiO$$_3$$ 3 (NBT-xBT) at the morphotropic phase boundary (MPB) ($$x_{\text {MPB}}=0.048$$ x MPB = 0.048 ) have been analyzed up to 12.3 GPa by single-crystal x-ray diffraction with synchrotron radiation. A pressure-induced phase transition takes place between 4.4 and 5.0 GPa, where the pseudocubic low-pressure phase transforms into an orthorhombic high-pressure phase with space group Pnma. The high-pressure phase is comprised of mixed BO$$_6$$ 6 tilts and anti-polar A-cation displacements, without exhibiting coherent off-centered shifts of the B-site Ti$$^{4+}$$ 4 + cations that can be detected by synchrotron x-ray diffraction. Our results reveal that at ambient pressure and room temperature the NBT-$$x_\mathrm{{MPB}}$$ x MPB BT structure possesses anti-phase BO$$_6$$ 6 tilts with a relatively large correlation length and the same type of polar distortions as those present in pure NBT, but with strongly violated correlation length due to Ba$$^{2+}$$ 2 + -induced local elastic-stress fields. For $$x_{\text {MPB}}$$ x MPB the effect of Ba on the mesoscopic-scale structure is compensated by a mild external pressure of only 0.7 GPa, resulting in structural features resembling those of pure NBT at ambient conditions.

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Effect of Ba incorporation on pressure-induced structural changes in the relaxor ferroelectricPbSc0.5Ta0.5O3

Cited by 17 publications

References 35 publications

Transformation processes in relaxor ferroelectric PbSc_0.5Ta_0.5O₃heavily doped with Nb and Sn

Transformation processes in relaxor ferroelectric PbSc_0.5Ta_0.5O₃heavily doped with Nb and Sn

Effect of La doping on the ferroic order in Pb-based perovskite-type relaxor ferroelectrics

The high-pressure structure of (1-x)Na$$_{0.5}$$Bi$$_{0.5}$$TiO$$_3$$-xBaTiO$$_3$$ at the morphotropic phase boundary

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Effect of Ba incorporation on pressure-induced structural changes in the relaxor ferroelectricPbSc0.5Ta0.5O3

Cited by 17 publications

References 35 publications

Transformation processes in relaxor ferroelectric PbSc0.5Ta0.5O3heavily doped with Nb and Sn

Transformation processes in relaxor ferroelectric PbSc0.5Ta0.5O3heavily doped with Nb and Sn

Effect of La doping on the ferroic order in Pb-based perovskite-type relaxor ferroelectrics

The high-pressure structure of (1-x)Na$$_{0.5}$$Bi$$_{0.5}$$TiO$$_3$$-xBaTiO$$_3$$ at the morphotropic phase boundary

Contact Info

Product

Resources

About

Transformation processes in relaxor ferroelectric PbSc_0.5Ta_0.5O₃heavily doped with Nb and Sn

Transformation processes in relaxor ferroelectric PbSc_0.5Ta_0.5O₃heavily doped with Nb and Sn