Understanding doped perovskite ferroelectrics with defective dipole model

Liu, J.; Jin, Li; Jiang, Zhijun; Liu, L.; Himanen, Lauri; Wei, Jie; Zhang, Nan; Wang, Dawei; Jia, Chun‐Lin

doi:10.1063/1.5051703

Cited by 21 publications

(20 citation statements)

References 63 publications

(110 reference statements)

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“…The distribution of iron at grain boundaries affects the electrical properties of the system as well, reducing mobility of the walls between polarization domains [29,30]. This is in agreement with the defective dipole model [31], according to which iron effectively immobilizes dipoles in its surroundings. Above the activation time of 180 min, increase in the content of incorporated iron reduces the value of the dielectric constant to a final value of 304.6 pF/m in the sample activated for 300 min.…”

Section: Resultssupporting

confidence: 80%

Evolution of structural and functional properties of the Fe/BaTiO3 system guided by mechanochemical and thermal treatment

et al. 2020

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Multiferroic systems are attractive to the researches worldwide due to diversity of existing applications, as well as possible novel ones. In order to contribute to understanding of the processes that take place within the structure of such a system, we subjected it to mechanochemical activation and thermal treatment. Powdery mixtures of iron and barium titanate in a mass ratio of 30% Fe and 70% BaTiO3 were activated in a planetary ball mill for time duration of 30 to 300 min and subsequently sintered at 1200?C in the atmosphere of air. During the activation the system undergoes structural phase transitions, whereby the content of iron and its oxides changes. The highest Fe content was observed in the sample activated for 270 min, with local maxima in crystallite size and microstrain values and a minimum in dislocation density. The complex dielectric permittivity changes in the applied radio frequency field, rangingfrom 176.9 pF/m in thesample activated for 90 min to 918.1 pF/m in the sample activated for 180 min. As the frequency of the field increases, an exponential decrease in the magnetic with a simultaneous increase in the electrical energy losses is noticeable. The system exhibits ferromagnetic resonance, whereby longer activation in the mill shifts the resonant frequency to higher values. Negative electrical resistance was observed in all analyzed samples. The activation time changes both the demagnetization temperature and the Curie temperature of the samples undergoing heating and cooling cycles in the external permanent magnetic field. Curie temperature is the highest in the sample activated for 240 min. Thermal treatment increases the initial magnetization of all samples, with the most pronounced increase of ~95% in the sample activated for 300 min. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. OI 172057]

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Section: Resultssupporting

confidence: 80%

Evolution of structural and functional properties of the Fe/BaTiO3 system guided by mechanochemical and thermal treatment

et al. 2020

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“…A direct analysis of the local dipoles gives additional evidence for the impact of Nb substitution compared to Zr substitution, as shown in Figure S9, Supporting Information and the corresponding discussion. Figure S9, Supporting Information is inspired by the visualization of dipoles in defected supercells presented by Liu et al, [42] even though it is important to note that we deal only with a static result obtained at 0 K, while Liu et al investigated the dynamical behavior of dipoles. Nevertheless, the analysis of local dipole changes also shows that Zr defects have a smaller impact on the neighboring dipole moments, and the impact is more isotropic, mostly changing the dipoles along the <100> directions.…”

Section: Origin Of Relaxor Behavior In Ba-based Perovskitesmentioning

confidence: 99%

Origin of Relaxor Behavior in Barium‐Titanate‐Based Lead‐Free Perovskites

Veerapandiyan

Popov

Mayer

et al. 2021

Adv Elect Materials

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perovskites, this is provided by the longrange correlation of B-site (Ti 4+ ) cation displacements. This correlation encompasses also strains up to the microscale, and is embodied by the appearance of ferroelectric domains. [3] Upon field cycling, as needed for charging-discharging the capacitor, ferroelectric domains switch in the direction of the applied field, thereby dissipating the associated elastic energy as heat. These losses are one of the main origins of the low recoverable energy density in this class of materials. [4] One often pursued strategy to increase the recoverable energy density of ceramic capacitors is thus to avoid elasticity-driven losses by disembodying electric charge from elastic strain through the disruption of the long-range correlation of Ti 4+ displacements. [2] When BTO is substituted at the perovskite B-site, in fact, the correlation of TiOTi chains is broken; [5] consequently, ferroelectric domains cease to permeate the whole lattice and are rather confined to nanoscale polar regions, whose size, correlation and distribution depends on substituent type and concentration. [6] The absence of longrange strain correlation limits the losses associated with elastic energy and slims down the polarization-electric field (P-E) hysteresis loop, thereby increasing the recoverable energy density, [2] provided that the achievable polarization at the maximum

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“…Following the defect‐engineered strategy, we present an efficient route to change the generally negative role of oxygen vacancies to be piezoelectrically/ferroelectrically friendly. Guided by the point‐defect mediated large piezoelectricity in ferroelectric crystals, defect‐dipoles formed by dopant–oxygen vacancy pairs are preferentially coupled with the strong spontaneous polarization from host according to general symmetry‐conforming property of point defects . Moreover, both experiments and theoretical calculations provide strong evidence that the dopant–oxygen vacancy combination can lead to heterogeneous polar regions and additional interfacial energies to flatten the free‐energy profile of the whole system especially at the morphotropic phase boundary (MPB), thus significantly enhancing the ferroelectricity and piezoelectricity …”

mentioning

confidence: 99%

Design for Highly Piezoelectric and Visible/Near‐Infrared Photoresponsive Perovskite Oxides

et al. 2018

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efficient/controllable photoexcited charge separation. [1,2] So far, the most commonly investigated SFPO is based on BiFeO 3 , [1,3] but its bandgap of ≈2.7 eV is not low enough to absorb the full spectrum of the visible light. The real potential of SFPO in photovoltaic applications significantly drives the exploring of new perovskite oxides with efficient visible light absorption. Recently, the realization of defect-driven-ferroelectricity and low bandgap states (even down to ≈1.1 eV) in perovskites (KNbO 3 ) 1−x (BaNi 1/2 Nb 1/2 O 3−δ ) x (KN-BNN) suggests that ferroelectricity and low bandgap can be simultaneously achieved by compositional modification. With two different transition-metal cations at the B-site in highly oxygen-vacancytolerable perovskite oxides, one cation (Nb 5+ ) provides off-center distortion and polarization, and the other (Ni 2+ ) decreases the difference in electronegativity within the perovskite BO bonds to create electronic states in the gap. The leaky conductivity associated with accommodation of Ni 2+ -oxygen vacancy combinations results in the loss of piezoelectricity especially at room temperature, which is generally the case for simple perovskite oxides. [4] Efforts have been taken to improve the tolerance of oxygen vacancies in order to keep the ferroelectricity, such as modifying the amount of BaNi 1/2 Nb 1/2 O 3−d (BNN) in the solid solution in order to decrease the concentration of oxygen vacancies, i.e., 0.98KN-0.02BNN, and 0.65PbTiO [5,6] or using more complex perovskite oxides with layered structure LaCoO 3 -mediated BiTiO 3 (E g = 2.65 eV). [7] However, an effective strategy to achieve an appropriate balance between the defect-induced low bandgap and defect-induced electrically leaky ferroelectricity is still currently lacking. Following the defect-engineered strategy, we present an efficient route to change the generally negative role of oxygen vacancies to be piezoelectrically/ferroelectrically friendly. Guided by the point-defect mediated large piezoelectricity in ferroelectric crystals, [8] defect-dipoles formed by dopant-oxygen vacancy pairs are preferentially coupled with the strong spontaneous polarization from host according to general symmetry-conforming property of point defects. [9][10][11] Moreover, both experiments and theoretical calculations provide strong evidence that the dopant-oxygen obtain low bandgap (i.e., 1.1-3.8 eV), the electrically leaky perovskite oxides generally lose piezoelectricity mainly due to oxygen vacancies. Therefore, the development of highly piezoelectric ferroelectric semiconductor remains challenging. Here, inspired by point-defect-mediated large piezoelectricity in ferroelectrics especially at the morphotropic phase boundary (MPB) region, an efficient strategy is proposed by judiciously introducing the gap states at the MPB where defect-induced local polar heterogeneities are thermodynamically coupled with the host polarization to simultaneously achieve high piezoelectricity and low bandgap. A concrete example, Ni 2+ -mediated (1...

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Understanding doped perovskite ferroelectrics with defective dipole model

Cited by 21 publications

References 63 publications

Evolution of structural and functional properties of the Fe/BaTiO3 system guided by mechanochemical and thermal treatment

Evolution of structural and functional properties of the Fe/BaTiO3 system guided by mechanochemical and thermal treatment

Origin of Relaxor Behavior in Barium‐Titanate‐Based Lead‐Free Perovskites

Design for Highly Piezoelectric and Visible/Near‐Infrared Photoresponsive Perovskite Oxides

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