The contribution of 180° domain wall motion to dielectric properties quantified from in situ X-ray diffraction

Fancher, Chris M.; Brewer, Steven J.; Chung, Ching‐Chang; Röhrig, Sören; Rojac, Tadej; Esteves, Giovanni; Deluca, Marco; Bassiri‐Gharb, Nazanin; Jones, Jacob L.

doi:10.1016/j.actamat.2016.12.037

Cited by 40 publications

(15 citation statements)

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“…[44] Ferroelastic textures arise from non-180° domain wall motion that changes the fraction of dipole oriented along a stress direction (electrical or mechanical). [45] Recent work by Fancher et al [46] demonstrated that experimental pole figures can be used to estimate the macroscopic polarization of ferroelectric materials. The induced domain reorientation results in a preferred orientation of the 200 pole, even in materials with no preferred orientation for the 111 pole.…”

Section: Preferred Orientationmentioning

confidence: 99%

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On the Origin of the Large Remanent Polarization in La:HfO₂

Schenk

Fancher

Park

et al. 2019

Adv Elect Materials

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extraordinary result. [2][3][4][5][6][7] A physical explanation for these results has remained elusive. The dopant size has been speculated to be a key parameter and larger dopants seem in general favorable compared to dopants with a smaller ionic radius than Hf. [2,8] This trend has been confirmed theoretically by Batra et al., [5] who additionally conclude that trivalent dopants in general are a good choice to favor the polar phase in HfO 2 . Large trivalent dopants, as the lanthanoid series are therefore especially suitable to promote ferroelectricity. In comparison to Gd, as another lanthanoid, La lowers the total energy difference to the monoclinic ground state the most. Also, they derived general trends that a larger ionic radius and a lower electronegativity of a dopant are favorable for the FE phase. Batra et al. [5] did not firmly conclude that La is the most favorable dopant to promote ferroelectricty in hafnia because a clear identification of the relaxed structures was not always possible and assumptions required concerning the distribution of oxygen vacancies and dopants in the high-throughput computational approach. They rather focused on the aforementioned general chemical trends of dopant attributes that promote the FE Pca2 1 phase. Further clarification of this trend could be provided by Materlik et al., [6] who compared La with Al and Y (also trivalent, but different in atomic radius) andThe outstanding remanent polarization of 40 µC cm -2 reported for a 10 nm thin La:HfO 2 film in 2013 has attracted much attention. However, up to now, no explanation for this large remanent polarization has been presented. Density functional theory and X-ray diffraction are used to shine light onto three major aspects that impact the macroscopically observed remanent polarization: phase fraction, spontaneous polarization, and crystallographic texture. Density functional theory calculations show that the spontaneous polarization (P s ) of La:HfO 2 is indeed a bit larger than for other HfO 2 -or ZrO 2 -based compounds; however, the P s is not large enough to explain the observed differences in remanent polarization. While neither phase fractions nor spontaneous polarization nor strain are significantly different from those in other HfO 2 films, a prominent 020/002 texture distinguishes La doped from other HfO 2 -based ferroelectric films. Angulardependent diffraction data provide a pathway to calculate the theoretically expected remanent polarization, which is in agreement with the experimental observations. Finally, an interplay of the in-plane strain and texture is proposed to impact the formation of the ferroelectric phase during annealing. Further aspects of the special role of La as a dopant are collected and discussed to motivate future research.

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Section: Preferred Orientationmentioning

confidence: 99%

“…Recent work by Fancher et al demonstrated that experimental pole figures can be used to estimate the macroscopic polarization of ferroelectric materials. Their work built upon that of Jones by combining diffraction and electrical data to model the total dipole distribution.…”

Section: Preferred Orientationmentioning

confidence: 99%

On the Origin of the Large Remanent Polarization in La:HfO₂

Schenk

Fancher

Park

et al. 2019

Adv Elect Materials

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“…However, the permittivity does not show an enhanced response at these temperatures because non-180° domain walls do not contribute as substantially as 180° domain walls to the ε r ,33 of polycrystalline ferroelectrics 31 . Alternatively, it is likely that the coexistence of polymorphs in the Sm-doped PZT compositions enable these materials to have a larger extrinsic (e.g., domain wall) contribution to the properties due to better strain accommodation during deformation and/or interphase boundary motion.…”

Section: Discussionmentioning

confidence: 91%

“…The 180° domain walls can also contribute substantially to the ε r ,33 of polycrystalline ferroelectrics, as recently shown by Fancher et al . 31 . However, as mentioned previously and shown in Fig.…”

Section: Discussionmentioning

confidence: 99%

Unexpectedly high piezoelectricity of Sm-doped lead zirconate titanate in the Curie point region

Seshadri

Nolan

Tutuncu

et al. 2018

Sci Rep

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Large piezoelectric coefficients in polycrystalline lead zirconate titanate (PZT) are traditionally achieved through compositional design using a combination of chemical substitution with a donor dopant and adjustment of the zirconium to titanium compositional ratio to meet the morphotropic phase boundary (MPB). In this work, a different route to large piezoelectricity is demonstrated. Results reveal unexpectedly high piezoelectric coefficients at elevated temperatures and compositions far from the MPB. At temperatures near the Curie point, doping with 2 at% Sm results in exceptionally large piezoelectric coefficients of up to 915 pm/V. This value is approximately twice those of other donor dopants (e.g., 477 pm/V for Nb and 435 pm/V for La). Structural changes during the phase transitions of Sm-doped PZT show a pseudo-cubic phase forming ≈50 °C below the Curie temperature. Possible origins of these effects are discussed and the high piezoelectricity is posited to be due to extrinsic effects. The enhancement of the mechanism at elevated temperatures is attributed to the coexistence of tetragonal and pseudo-cubic phases, which enables strain accommodation during electromechanical deformation and interphase boundary motion. This work provides insight into possible routes for designing high performance piezoelectrics which are alternatives to traditional methods relying on MPB compositions.

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“…This observation agrees with recent work that modeled the evolution of the total dipole distribution function of BT with applied fields. 38 Evidence for both a single 180 and multiple 90 switching has been observed in single crystals of BT. 39,40 Li and Li hypothesized that interactions between neighboring domains could provide sufficient mechanical clamping to inhibit the nucleation of 90 domains.…”

mentioning

confidence: 99%

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

Fancher

Choe

Gorfman

et al. 2020

Applied Physics Letters

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The contribution of 180° domain wall motion to dielectric properties quantified from in situ X-ray diffraction

Cited by 40 publications

References 36 publications

On the Origin of the Large Remanent Polarization in La:HfO₂

On the Origin of the Large Remanent Polarization in La:HfO₂

Unexpectedly high piezoelectricity of Sm-doped lead zirconate titanate in the Curie point region

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

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The contribution of 180° domain wall motion to dielectric properties quantified from in situ X-ray diffraction

Cited by 40 publications

References 36 publications

On the Origin of the Large Remanent Polarization in La:HfO2

On the Origin of the Large Remanent Polarization in La:HfO2

Unexpectedly high piezoelectricity of Sm-doped lead zirconate titanate in the Curie point region

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

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On the Origin of the Large Remanent Polarization in La:HfO₂

On the Origin of the Large Remanent Polarization in La:HfO₂