Ferroelastic Domain Structure Research Articles

Ferroelastic structure AlNb1/2Ta1/2O4 ceramics with improved thermophysical and mechanical properties

AbstractEffect of B site doping on structural, thermophysical, and mechanical properties of AlNbxTa1‐xO4 ceramics obtained by solid‐phase sintering were investigated in this work. Ferroelastic domain structures derived from the reversible second‐order ferroelastic transformation between the tetragonal (t) and monoclinic (m) contribute to improving the high‐temperature fracture toughness of AlNbxTa1‐xO4 ceramics, and the room fracture toughness of AlNb1/2Ta1/2O4 ceramics is 3.4 MPa·m0.5. The brittleness index of AlNb1/2Ta1/2O4 (2.6 μm−0.5) is also lower than AlTaO4, which indicates that has better damage tolerance. Compared with single‐component AlTaO4 and AlNbO4, the AlNb1/2Ta1/2O4 has a lower thermal conductivity due to enhanced phonon scattering caused by mass disorder and lattice distortion effects. Additionally, AlNb1/2Ta1/2O4 has a good match with the coefficient of thermal expansion of ceramic matrix composites (CMCs), and hence, AlNb1/2Ta1/2O4 has a considerable potential to be the candidate material for thermal/environmental barrier coatings (T/EBCs).

Phenomenological phase field modeling of monolayer ferroelectrics FEβ-In2Se3

Recently, a number of two-dimensional van der Waals (vdW) ferroelectrics have been reported, showing the potential to develop various ultra-thin smart devices down to the atomic monolayer limit. In particular, they have been demonstrated to exhibit intriguing polar domain structures. However, phenomenological thermodynamic models of vdW ferroelectrics, which can capture their ferroic domain structure evolution, are still lacking, limiting our further exploration of domain-structure-related applications. In this work, combining first-principles calculations, we construct a phenomenological phase field model for monolayer ferroelectrics, FEβ-In2Se3. Based on the model, one can calculate the phase stability, ferroelectric hysteresis curves, and domain structures of FEβ-In2Se3 under different loading conditions, showing the feasibility of electromechanically driving the rotation of in-plane polarization and manipulation of the domain structures. By including the second-order partial derivative gradient energy term, the model further captures well the antiferroelectric–ferroelastic domain structures of β′-In2Se3 observed in previous experiments. The developed phase field model should help better understand the domain structure evolution behavior in low-dimensional materials and promote further exploration of domain-structure-related applications.

Light-Controlled Magnetoelastic Effects in Ni/BaTiO3 Heterostructures

Magnetoelastic and magnetoelectric coupling in the artificial multiferroic heterostructures facilitate valuable features for device applications such as magnetic field sensors and electric-write magnetic-read memory devices. In ferromagnetic/ferroelectric heterostructures, the intertwined physical properties can be manipulated by an external perturbation, such as an electric field, temperature, or a magnetic field. Here, we demonstrate the remote-controlled tunability of these effects under visible, coherent, and polarized light. The combined surface and bulk magnetic study of domain-correlated Ni/BaTiO3 heterostructures reveals that the system shows strong sensitivity to the light illumination via the combined effect of piezoelectricity, ferroelectric polarization, spin imbalance, magnetostriction, and magnetoelectric coupling. A well-defined ferroelastic domain structure is fully transferred from a ferroelectric substrate to the magnetostrictive layer via interface strain transfer. The visible light illumination is used to manipulate the original ferromagnetic microstructure by the light-induced domain wall motion in ferroelectric substrates and consequently the domain wall motion in the ferromagnetic layer. Our findings mimic the attractive remote-controlled ferroelectric random-access memory write and magnetic random-access memory read application scenarios, hence facilitating a perspective for room temperature spintronic device applications.

Facile Control of Ferroelastic Domain Patterns in Multiferroic Thin Films by a Scanning Tip Bias.

BiFeO3, known as the "holy grail of all multiferroics", provides an appealing platform for exploration of multifield coupling physics and design of functional devices. Many fantastic properties of BiFeO3 are regulated by its ferroelastic domain structure. However, a facile programable control on the ferroelastic domain structure in BiFeO3 remains challenging and our understanding on the existing control strategies is also far from complete. This work reports a facile control of ferroelastic domain patterns in BiFeO3 thin films under area scanning poling by exploiting the tip bias as the control parameter. Combining scanning probe microscopy experiments and simulations, we found that BiFeO3 thin films with pristine 71° rhombohedral-phase stripe domains exhibit at least four switching pathways solely by controlling the scanning tip bias. As a result, one can readily write mesoscopic topological defects into the films without the necessity to change the tip motion. The correlation between conductance of the scanned region and the switching pathway is further investigated. Our results extend the current understanding on the domain switching kinetics and the coupled electronic transport properties in BiFeO3 thin films. The facile voltage control of ferroelastic domains should facilitate the development of configurable electronic and spintronic devices.

Nanoscale ordering ferroelastic twins in ferromagnetic La2/3Sr1/3MnO3 heterostructures

To introduce coexistence of several ordering parameters in a material is a key but a very challenging goal in correlated materials, which can bring many novel phenomena and offer unprecedented opportunities for new device functions. Here, we demonstrate a general route to induce nanoscale periodic ferroelastic twins in otherwise weak- or non-ferroelastic perovskite oxides by coherently propagating ferroelastic twins in template materials into atop other films through unique structure coupling at perovskite oxide interfaces. Using the LaCoO3 thin film as a template and deliberately growing La2/3Sr1/3MnO3/LaCoO3 on the NdGaO3 (110) substrate, we were able to realize uniaxially and periodically ordering nanoscale ferroelastic twins in LaCoO3, and more importantly, such ferroelastic domain structure can be coherently transferred into La2/3Sr1/3MnO3. The uniaxial periodic ferroelastic twins in La2/3Sr1/3MnO3 can induce strong magnetic anisotropy which can compete with magneto-crystalline anisotropy, illustrating strong coupling between the ferromagnetism and ferroelasticity in La2/3Sr1/3MnO3. Our results provide a meaningful reference toward desired ferrelasticity for generating multiferrocity and developing novel oxide electronics.

Microstructural evolution and thermal-physical properties of YTaO4 coating after high-temperature exposure

YTaO4 is a promising candidate materials for next thermal barrier coatings (TBCs) due to low thermal conductivity, high thermal expansion coefficients, high melting point and low modulus. However, the current research on YTaO4 coating is relatively limited, there are obvious gaps of thermo-mechanical properties between bulks and coating. In this work, the YTaO4 coating was deposited on graphite substrate and TC4 substrate via atmospheric plasma spraying (APS). The phase transition temperature of M ↔ T phase is about 1426 ± 7 °C, which cause to the formation of ferroelastic domain structure. YTaO4 coating have an excellence anti-sintering performance due to a stable porosity during heat treatment, and the bonding strengths of YTaO4 coating on TC4 substrate has the maximum (35.12 ± 2.34 MPa) when the top coating thickness is ~250 μm. Compared with YTaO4 bulk, the thermal conductivity (0.53 W·m−1·K−1, 900 °C) of YTaO4 coating is reduced by 67–70 % in the entire temperature range. The low thermal conductivity for YTaO4 coating is the results of phonon scattering by porosity, domain boundaries and point defects. Moreover, the healing of intersplat pores with the increase of sintering temperature had significantly improved the hardness and elastic modulus of the coating.

Temperature symmetry breaking and properties of lead-free organic-inorganic hybrids: bismuth(III) iodide and antimony(III) iodide: (S(CH3)3)3[Bi2I9] and (S(CH3)3)3[Sb2I9

We have synthesized and characterized two novel lead-free organic-inorganic hybrid crystals: (S(CH3)3)3[Bi2I9] (TBI) and (S(CH3)3)3[Sb2I9] (TSI). Thermal DSC, TG, and DTA analyses indicate structural phase transitions (PTs) in both compounds; TBI undergoes two structural phase transitions at 314.2/314.8 K (cooling/heating) and at 181.5 K of first (I ↔ II) and second order (II ↔ III), respectively. The crystal structures of TBI are refined for phases I (325 K), II (200 K) and III (100 K). TBI exhibits ferroelastic properties since both PTs are accompanied by a change in the symmetry of crystals: P63/mmc → C2/c (I → II) and C2/c → P1̄ (II → III). The presence of a ferroelastic domain structure has been confirmed by optical observations. In turn, TSI also reveals two PTs: I ↔ II (at 303.9/304.1 K) and II ↔ III (212.9/221.4 K). To compare and obtain insight into the mechanism of the PTs of TBI, we have carried out temperature dependent single crystal X-ray diffraction studies. Additionally, to confirm the change in the dynamical states of molecules in PTs, dielectric measurements have been carried out between 100 K and 400 K in the frequency range of 200 Hz to 2 MHz. Moreover, the measurements of the 1H NMR spin-lattice relaxation time, T1, and a second moment, M2, of the 1H NMR line have been undertaken in the temperature range between 100 and 300 K.

Film thickness dependence of in-plane ferroelastic domain structure in constrained tetragonal PbTiO3 films induced by isotropic tensile strain

In this study, the ferroelectric phase of PbTiO3 (PTO) thin films was grown on cubic single-crystal KTaO3 (KTO) substrates using metal–organic chemical vapor deposition. X-ray diffraction (XRD) was used to reveal an a1/a2 domain structure, which remained unchanged down to a film thickness of 2 nm. The a1 and a2 polydomains do not have a simple tetragonal symmetry because aa∥ and aa⊥ do not have the same values. The crystallographic tilt angle, α, is defined based on the rotation angle of the PTO lattice with respect to the cubic phase of KTO substrates. The in-plane tetragonal distortion (ca∥/aa∥) and α decreased with the decrease in the film thickness, following the in-plane tetragonal geometric equation: α=tan−1(ca∥aa∥)−45°. The isotropic tensile strains induced in-plane polarization directions along the [100] and [010] axes of the substrates. These axes are formed via the a1/a2 polydomain of the tetragonal-like phase. Moreover, synchrotron in-plane grazing incidence XRD and piezoelectric force microscopy were used to reveal the thickness dependency of the periodic domain width of the ferroelastic a1/a2 domain. The periodic domain width in the PTO films decreased, following Kittel's law, with the reduction in the film thickness.

Ferroelastic domain identification and toughening mechanism for yttrium tantalate–zirconium oxide

Yttrium tantalate (YTaO4) is the next generation of higher service temperature thermal barrier coatings (TBCs) materials due to its smaller volume effect in phase change, lower thermal conductivity and unique ferroelastic domain structure. However, the low fracture toughness limits its application. We first characterized the diffraction patterns of variants, and two variants (M1 and M2) observed in transmission electron microscopy (TEM) results were determined from four possible variants by mechanical derivation. The role of Zr4+ doping in ferroelastic toughening was explained in detail. With the increase of Zr4+ doping concentration, the monoclinic angle β and the domain rotation angle α decrease, respectively. The spontaneous strain component and the principal strain in the main space also have a similar decreasing trend. The decrease of the ferroelastic domain inversion energy barrier is beneficial to the improvement of fracture toughness. Combining the results of Vickers indentation, we found that Zr4+ could be enriched at the domain boundary to inhibit the generation of cracks. An appropriate amount of Zr4+ is conducive to the improvement of fracture toughness, and the excessive Zr4+ will reduce the fracture toughness due to the generation of by-product t-ZrO2. So, the optimal composition is Y0.44Ta0.44Zr0.12O2 and the best fracture toughness (2.9–3.8MPa m1/2) is equivalent to the commercial 8YSZ. This result will promote the application of a new generation of TBCs.

Self‐Assembled Epitaxial Ferroelectric Oxide Nanospring with Super‐Scalability (Adv. Mater. 13/2022)

Nanosprings In article number 2108419, Ziyao Zhou, Houbing Huang, Yong Peng, Ming Liu, and co-workers report freestanding, epitaxial, ferroelectric nanosprings with superscalability, which provide insights regarding mechanical behaviors and domain evolution of ferroelectric oxide springs. The excellent scalability originates from the continuous ferroelastic domain structures, resulting from twisting under coexisting axial and shear strains. The superstretchable, elastic, and recoverable oxide spring provides a novel platform to flexible electronics.

Self-Assembled Epitaxial Ferroelectric Oxide Nanospring with Super-Scalability.

Oxide nanosprings have attracted many research interests because of their anticorrosion, high-temperature tolerance, oxidation resistance, and enhanced-mechanic-response from unique helix structures, enabling various applications like nanomanipulators, nanomotors, nanoswitches, sensors, and energy harvesters. However, preparing oxide nanosprings is a challenge for their intrinsic lack of elasticity. Here, an approach for preparing self-assembled, epitaxial, ferroelectric nanosprings with built-in strain due to the lattice mismatch in freestanding La0.7 Sr0.3 MnO3 /BaTiO3 (LSMO/BTO) bilayer heterostructures is developed. It is found that these LSMO/BTO nanosprings can be extensively pulled or pushed up to their geometrical limits back and forth without breaking, exhibiting super-scalability with full recovery capability. The phase-field simulations reveal that the excellent scalability originates from the continuous ferroelastic domain structures, resulting from twisting under co-existing axial and shear strains. In addition, the oxide heterostructural springs exhibit strong resilience due to the limited plastic deformation nature and the built-in strain between the bilayers. This discovery provides an alternative way for preparing and operating functional oxide nanosprings that can be applied to various technologies.

Influence of cooling rate on ferroelastic domain structure for epitaxial (100)/(001)-oriented Pb(Zr, Ti)O3 thin films under tensile strain

Epitaxial (100)/(001)-oriented Pb(Zr x Ti1−x )O3 [PZT] films were grown at 700 °C on (100)KTaO3 single crystal substrates by pulsed metalorganic chemical vapor deposition. We investigated the influence of the cooling condition on the ferroelastic domain structure for PZT films under compressive and tensile strains. Under compressive strain, the c-domain fraction (V c ) was not strongly influenced by the cooling rate. On the other hand, changing the cooling rate caused a significant change in V c in the PZT films grown under tensile strain. In addition, a post-annealing step at a certain temperature below the Curie temperature promoted the formation of a c-domain in the a 1/a 2-domain. These results indicate the need to effectively time the formation of the c-domain in the a 1/a 2-domain, which is governed by the growth kinetics. The ferroelastic domain structure under tensile stress is determined by the growth kinetics, while a slow cooling rate leads to a thermodynamically stable domain structure.

Enhanced mechanical and thermal properties of ferroelastic high-entropy rare-earth-niobates

A novel class of high-entropy rare-earth-niobates (RENbO4) was synthesized via solid-state reaction method. The XRD Rietveld refinement, Raman, and SEM-EDS results implied that the uniform doped element distribution. Unique ferroelastic domain structure formed by t-m phase transition brings the excellent ductility for RENbO4 ceramics (Poisson's ratios > 0.3), where 7RENbO4 exhibits enhanced mechanical properties (Hv = 4.96±0.08 GPa, KⅠc = 2.05±0.14 MPa•m0.5). Moreover, due to the lattice distortion derived from high-entropy effects, high-entropy rare-earth-niobates present lower thermal conductivity (6RENbO4, 2.30-1.40 W m−1 K−1, 100-1000°C) and higher thermal expansion coefficients (5RENbO4, 9.03 × 10−6 K−1, 719°C). These moderate properties indicate a potential materials design for TBCs application.

Observation of Ferroelastic and Ferroelectric Domains in AgNbO3 Single CrystalSupported by the National Natural Science Foundation of China (Grant Nos. 11572040, 11604011 and 51972028), the National Key Research and Development Program of China (Grant No. 2019YFA0307900), Beijing Natural Science Foundation (Grant No. Z190011), and the Technological Innovation Project of Beijing Institute of technology.

Compared to AgNbO3 based ceramics, the experimental investigations on the single crystalline AgNbO3, especially the ground state and ferroic domain structures, are not on the same level. Here, based on successfully synthesized AgNbO3 single crystal using a flux method, we observed the coexistence of ferroelastic and ferroelectric domain structures by a combination study of polarized light microscopy and piezoresponse force microscopy. This finding may provide a new aspect for studying AgNbO3. The result also suggests a weak electromechanical response from the ferroelectric phase of AgNbO3, which is also supported by the transmission electron microscope characterization. Our results reveal that the AgNbO3 single crystal is in a polar ferroelectric phase at room temperature, clarifying its ground state which is controversial from the AgNbO3 ceramic materials.

Ferroelastic domain hierarchy in the intermediate state of PbZr0.98Ti0.02O3 single crystal

PbZrO3-based antiferroelectric crystals are of great interest in both fundamental and applied research, not only because of the antiferroelectric feature at room temperature but also because of the existence of a peculiar intermediate state at elevated temperatures. Here, we report a detailed description of domain structure change at the temperature-induced antiferroelectric-to-ferroelectric phase transition. A complex process of different types of domains is revealed to appear at different stages of the phase transition. A hierarchical ferroelastic domain structure forms in the stabilized intermediate state, where the dense domain walls show potential impact on the physical properties of the crystal.

Temperature dependence on the domain structure of epitaxial PbTiO3 films grown on single crystal substrates with different lattice parameters

Epitaxial PbTiO3 (PTO) thin films were deposited on different single crystal (100)KTaO3 [KTO], (110)DyScO3 [DSO], (110) GdScO3 [GSO] and (001)SrTiO3 [STO] substrates. Temperature dependence of the lattice parameters and the domain structure showed a systematic change with misfit strains (Sm) of PTO films, explored by high-resolution X-ray diffraction measurements. Fully (001)-orientation films on STO and fully (100)-orientation films on KTO substrates were confirmed, and the elevated phase transition temperature (Tc) was confirmed in PTO films induced by both large compressive (STO) and tensile strains (KTO). While, for PTO films grown on GSO substrates with small tensile strains, Tc is similar to the powder data. And, ferroelastic domain structure changed from (100)-orientation to (100)/(001)-orientations was observed during decreased temperature. The temperature dependence of domain structures PTO films with the different Sm are in good agreement with thermodynamic calculation for the temperature–Sm diagram of ferroelastic domain structure.

Thermal stability, cation dynamics, and ferroelastic domain walls in the α→β→γ phase transitions of perovskite (C2H5NH3)2MnCl4 crystals

Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) confirmed that the (C2H5NH3)2MnCl4 crystal undergoes α-β-γ phase transitions at approximately TC2 = 225 K and TC1 = 424 K, remains stable until 470 K, and displays a weight loss of 25.24% at around 579 K due to partial thermal decomposition. Cation dynamics near these temperatures was investigated by MAS 1H NMR and MAS 13C NMR experiments. The small changes in the 1H chemical shift for C2H5 near TC2 are consistent with the transition from the orthorhombic γ-phase to the orthorhombic β-phase. Also, the abrupt changes in NMR signals near TC1 correspond to structural change from the orthorhombic β-phase to the tetragonal α-phase. The 13C spin-lattice relaxation time in the rotating frame (T1ρ) below TC2 is shorter for CH3 than that for CH2, due to the greater mobility at the free end of the alkyl chain. In addition, the temperature-dependent ferroelastic domain structure was studied near the α-β phase transition. There was no noticeable temperature dependence in 1H and 13C T1ρ values at TC1 and TC2, whereas the change in the domain wall was prominent near TC1.

Large Electromechanical Responses Driven by Electrically Induced Dense Ferroelastic Domains: Beyond Morphotropic Phase Boundaries

Piezoelectric materials based on ferroelectrics with a perovskite structure are among the most useful materials because they can convert electrical energy into mechanical energy and vice versa. Although piezoelectricity strongly depends on ferroelastic domain density, there are no general methods to controllably fabricate dense domain structures in ferroelectric films. Here, we report a mechanism to achieve a large piezoresponse based on an electrically induced dense ferroelastic domain structure in ferroelectric films. We demonstrate a large piezoelectric coefficient of 310 pm/V under both bipolar and unipolar electric fields, which is about 3 times larger than that in epitaxial single-crystalline thin films of tetragonal PbZr0.4Ti0.6O3 grown on silicon substrates. Analysis by a combination of in situ Raman and piezoresponse force microscopy suggests that the large piezoelectric response can be explained by the motion of dense ferroelastic domain walls. This mechanism provides a general method to enhance the piezoelectric properties of ferroelectric materials.

Ferroelasticity, domain structures and phase symmetries in organic–inorganic hybrid perovskite methylammonium lead chloride

Polarized light microscopic images of CH3NH3PbCl3 crystals revealing the cubic – orthorhombic (OS) – orthorhombic (OP) phase sequence on cooling, the ferroelastic domain structures and the absence of ferroelectricity.

Growth and characterization of ternary BiScO3–Pb(Cd1/3Nb2/3)O3–PbTiO3 ferroelectric single crystals with high Curie temperature

BiScO3–Pb(Cd1/3Nb2/3)O3–PbTiO3 single crystals with high quality have been successfully grown by the top-seeded solution growth method and the single ferroelastic domain structures and ferroelectric behaviors have also been reviewed.