Complex Domain Structure Research Articles

A ligand discovery toolbox for the WWE domain family of human E3 ligases

The WWE domain is a relatively under-researched domain found in twelve human proteins and characterized by a conserved tryptophan-tryptophan-glutamate (WWE) sequence motif. Six of these WWE domain-containing proteins also contain domains with E3 ubiquitin ligase activity. The general recognition of poly-ADP-ribosylated substrates by WWE domains suggests a potential avenue for development of Proteolysis-Targeting Chimeras (PROTACs). Here, we present novel crystal structures of the HUWE1, TRIP12, and DTX1 WWE domains in complex with PAR building blocks and their analogs, thus enabling a comprehensive analysis of the PAR binding site structural diversity. Furthermore, we introduce a versatile toolbox of biophysical and biochemical assays for the discovery and characterization of novel WWE domain binders, including fluorescence polarization-based PAR binding and displacement assays, 15N-NMR-based binding affinity assays and 19F-NMR-based competition assays. Through these assays, we have characterized the binding of monomeric iso-ADP-ribose (iso-ADPr) and its nucleotide analogs with the aforementioned WWE proteins. Finally, we have utilized the assay toolbox to screen a small molecule fragment library leading to the successful discovery of novel ligands targeting the HUWE1 WWE domain.

Identifying point defects and ordering in the high-entropy layered oxide Li1.5MO3-δ (M=Mn, Al, Fe, Co, Ni) for energy storage applications

High-entropy layered oxides (HELOs) represent a very promising class of next-generation battery cathodes, combining the well-studied properties of layered cathode materials such as LiCoO2 with the chemical tunability and stability of high-entropy materials. HELO materials often form particles with complex defects and domain structures, complicating accurate characterization of structure and cation mixing. Understanding disorder and order in HELO materials is necessary for understanding their performance and utility as cathodes. Here we demonstrate the characterization of the HELO Li1.5MO3-δ (M = Mn, Al, Fe, Co, Ni), wherein X-ray powder diffraction, transmission electron microscopy imaging, and electron diffraction patterns are analyzed to reveal the presence of ordering in the HELO, with imaging and diffraction simulation employed to compare experimental results to atomic modeling. Without rigorous characterization at the atomic scale, important features such as defect ordering can be easily overlooked and therefore remain unconsidered when interpreting experimental results.

The influence of thermo-electromechanical coupling on the performance of lead-free BNT-PDMS piezoelectric composites

In recent times, there have been notable advancements in haptic technology, particularly in screens found on mobile phones, laptops, light-emitting diode (LED) screens, and control panels. However, it is essential to note that the progress in high-temperature haptic applications is still in the developmental phase. Due to their complex phase and domain structures, lead-free piezoelectric materials such as Bi0.5Na0.5TiO3 (BNT)-based haptic technology behave differently at high temperatures than in ambient conditions. Therefore, it is essential to investigate the aspects of thermal management and thermal stability, as temperature plays a vital role in the phase and domain transition of BNT material. A two-dimensional thermo-electromechanical model has been proposed in this study to analyze the thermal stability of the BNT-PDMS composite by analyzing the impact of temperature on effective electromechanical properties and mechanical and electric field parameters. However, the thermo-electromechanical modelling of the BNT-PDMS composite examines the macroscopic effects of the applied thermal field on mechanical and electric field parameters, as phase change and microdomain dynamics are not considered in this model. This study analyzes the impact of thermo-electromechanical coupling on the performance of the BNT-PDMS composite compared to conventional electromechanical coupling. The results predicted a significant improvement in piezoelectric response compared to electromechanical coupling due to the increased thermoelectric effect in the absence of phase change and microdomain switching for temperature boundary conditions below depolarization temperature ( Td∼200∘ C for pure BNT material).

Theory of Moiré Magnetism in Twisted Bilayer α-RuCl3.

Motivated by the recent developments in moiré superlattices of van der Waals magnets and the desire to control the magnetic interactions of α-RuCl3, here we present a comprehensive theory of the long-range ordered magnetic phases of twisted bilayer α-RuCl3. Using a combination of first-principles calculations and atomistic simulations, we show that the stacking-dependent interlayer exchange gives rise to an array of magnetic phases that can be realized by controlling the twist angle. In particular, we discover a complex hexagonal domain structure in which multiple zigzag orders coexist. This multidomain order minimizes the interlayer energy while enduring the energy cost due to domain wall formation. Further, we show that quantum fluctuations can be enhanced across the phase transitions. Our results indicate that magnetic frustration due to stacking-dependent interlayer exchange in moiré superlattices can be exploited to tune quantum fluctuations and the magnetic ground state of α-RuCl3.

In-Plane Ferrielectric Order in van der Waals β'-In2Se3.

van der Waals ferroic materials exhibit rich potential for implementing future generation functional devices. Among these, layered β'-In2Se3 has fascinated researchers with its complex superlattice and domain structures. As opposed to ferroelectric α-In2Se3, the understanding of β'-In2Se3 ferroic properties remains unclear because ferroelectric, antiferroelectric, and ferroelastic characteristics have been separately reported in this material. To develop useful applications, it is necessary to understand the microscopic structural properties and their correlation with macroscopic device characteristics. Herein, using scanning transmission electron microscopy (STEM), we observed that the arrangement of dipoles deviates from the ideal double antiparallel antiferroelectric character due to competition between antiferroelectric and ferroelectric structural ordering. By virtue of second-harmonic generation, four-dimensional STEM, and in-plane piezoresponse force microscopy, the long-range inversion-breaking symmetry, uncompensated local polarization, and net polarization domains are unambiguously verified, revealing β'-In2Se3 as an in-plane ferrielectric layered material. Additionally, our device study reveals analogous resistive switching behaviors of different types owing to polarization switching, defect migration, and defect-induced charge trapping/detrapping processes.

A phase-field model for ferroelectric materials—Based on the multiphase-field method

A novel phase-field model is developed to investigate the domain structure in ferroelectric materials subjected to an external field. Differing from the time-dependent Ginzburg–Landau (TDGL) theory that describes domain structures based on the spatial and temporal evolution of polarization, our model utilizes the multiphase-field approach to calculate domain structures by minimizing the total energy functional with respect to the multiphase-field order parameter ϕ. The energy functional in the proposed model comprises the general multiphase interfacial energy and the phase-dependent bulk energy, accounting for the contributions from domain walls, and mechanical as well as electric fields. By considering the interplay between the different energy components, the model provides insights into the complex domain structure of ferroelectric materials and their response to external stimuli. This comprehensive approach is validated through simulations of both single-crystal and polycrystalline structures. The approach presented in this study simplifies the computational coefficients required to analyze the domain structure in ferroelectric materials, compared to the TDGL approach, by disregarding the Landau potential. This makes it possible to analyze the domain structure of materials without Landau coefficients. Furthermore, the proposed model serves as a reference for applying the multiphase-field concept to ferroelectric materials.

Effect of acceptor–donor co‐doping on the microstructure and electrical properties of BiScO3–PbTiO3‐based ceramics

AbstractDesigning BiScO3‐PbTiO3 (BS–PT) ceramics that merge high Curie temperature (TC) and large piezoelectric coefficient (d33) has always been a significant challenge for high‐temperature applications. Doping is a commonly used and effective method for enhancing the electrical performances of piezoelectric ceramics. In this study, the Li+/W6+ acceptor–donor co‐doping method was used to enhance the piezoelectric properties of 0.36BiSc1‐xLixO3–0.64PbTi1‐yWyO3 (0.36x = 0.64y) ceramics. The optimal electrical performance was observed at x = 0.01 near morphotropic phase boundaries, with a large d33 (505 pC/N), high TC (407°C), huge remnant polarization (Pr ∼ 40.9 μC/cm2), and inverse piezoelectric coefficient (d33* = 601 pm/V). Rietveld refinement and piezoelectric force microscopy results revealed that incorporating Li+/W6+ into the BS–PT ceramics decreased the T phase proportion and domain size and increased the domain wall density. The enhancement in piezoelectricity can be attributed to the lowered energy barrier resulting from the reduced T‐phase proportion and complex domain structure, which promotes polarization rotation and facilitates domain wall motion. This work demonstrates that acceptor–donor co‐doping is a promising strategy for optimizing the electrical performance of the BS–PT ceramics.

Unraveling the Role of Entropy in Thermoelectrics: Entropy-Stabilized Quintuple Rock Salt PbGeSnCdxTe3+x.

Entropy-engineered materials are garnering considerable attention owing to their excellent mechanical and transport properties, such as their high thermoelectric performance. However, understanding the effect of entropy on thermoelectrics remains a challenge. In this study, we used the PbGeSnCdxTe3+x family as a model system to systematically investigate the impact of entropy engineering on its crystal structure, microstructure evolution, and transport behavior. We observed that PbGeSnTe3 crystallizes in a rhombohedral structure at room temperature with complex domain structures and transforms into a high-temperature cubic structure at ∼373 K. By alloying CdTe with PbGeSnTe3, the increased configurational entropy lowers the phase-transition temperature and stabilizes PbGeSnCdxTe3+x in the cubic structure at room temperature, and the domain structures vanish accordingly. The high-entropy effect results in increased atomic disorder and consequently a low lattice thermal conductivity of 0.76 W m-1 K-1 in the material owing to enhanced phonon scattering. Notably, the increased crystal symmetry is conducive to band convergence, which results in a high-power factor of 22.4 μW cm-1 K-1. As a collective consequence of these factors, a maximum ZT of 1.63 at 875 K and an average ZT of 1.02 in the temperature range of 300-875 K were obtained for PbGeSnCd0.08Te3.08. This study highlights that the high-entropy effect can induce a complex microstructure and band structure evolution in materials, which offers a new route for the search for high-performance thermoelectrics in entropy-engineered materials.

Structural analysis of human papillomavirus E6 interactions with Scribble PDZ domains.

The cell polarity regulator Scribble has been shown to be a critical regulator of the establishment and development of tissue architecture, and its dysregulation promotes or suppresses tumour development in a context-dependent manner. Scribble activity is subverted by numerous viruses. This includes human papillomaviruses (HPVs), who target Scribble via the E6 protein. Binding of E6 from high-risk HPV strains to Scribble via a C-terminal PDZ-binding motif leads to Scribble degradation in vivo. However, the precise molecular basis for Scribble-E6 interactions remains to be defined. We now show that Scribble PDZ1 and PDZ3 are the major interactors of HPV E6 from multiple high-risk strains, with each E6 protein displaying a unique interaction profile. We then determined crystal structures of Scribble PDZ1 and PDZ3 domains in complex with the PDZ-binding motif (PBM) motifs of E6 from HPV strains 16, 18 and 66. Our findings reveal distinct interaction patterns for each E6 PBM motif from a given HPV strain, suggesting that a complex molecular interplay exists that underpins the overt Scribble-HPV E6 interaction and controls E6 carcinogenic potential.

History dependence of avalanche dynamics of ferroelectric phase transition in BaTiO3 under external bias field

A ferroelectric phase transition under an external bias electric field after field cooling and zero field cooling in barium titanate single crystals shows scale invariant nucleation and growth of complex domain structures. The avalanche energy exponents vary with the external bias, depending on the cooling history of the sample under applied field or zero field cooling. After field cooling, resulting in a single domain sample, the energy exponent is near the integrated mean field value of 5/3, namely, 1.68 ± 0.022. The sample after field cooling shows the same exponent with an external bias electric field range of up to 4.5 kV/cm. The exponent of a multi-domain sample, after zero field cooling, decreases from ε = 1.85 to the fixed point of 1.66 under high fields. The different behavior is attributed to the greater complexity of domain patterns in the multi-domain sample, which reduces to a single domain state under strong applied fields. Compared with the single-domain state, the multi-domain state has more domain boundaries and the intersections formed by these domain boundaries. These domain boundaries and their intersections will hinder the movement of the phase boundary and act as a pinning effect on the front of the phase interface. The effect is to generate more small energy signals, making the critical exponent high. At the same time, the aftershock time distribution (Omori law) remains the same for all switching conditions with an Omori exponent near −1 and switching time correlations of −1 ± 0.05 for short times (<1 s) and −2 ± 0.10 for long times (>1 s).

Brown’s equation for the simulation of complex domain structures in ferroelectrics

<sec>Ferroelectric material possesses spontaneous polarization at room temperature, which can be switched by an external electric field. The diverse domain structures within ferroelectric materials, consisting of polarizations in various directions, often significantly affect their physical properties and practical applications. Numerical simulations can aid in comprehending and validating the complex domains observed in experiments. They can also provide guidance for controlling such structures. One popular method for finding dipole configurations is to create an energy model and employ it in Monte-Carlo simulations to find dipole configuration. However, since these simulations usually reaches the ground state of the system (the state with the lowest global energy), they often miss the dipole configurations of interest, such as topological domain structures, which are usually metastable.</sec><sec>Here, in order to simulate complex domain, we introduce Brown's equation, which is originally used for micromagnetic simulation, into the large-scale simulation of ferroelectric materials. Using the effective Hamiltonian as the energy model, we derive the Brown's equations with respect to the electric dipoles in ferroelectric materials, and invesitgate perovskites such as<inline-formula><tex-math id="M6">\begin{document}${\rm{BaTiO_3}}$\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="5-20222150_M6.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="5-20222150_M6.png"/></alternatives></inline-formula> bulk, <inline-formula><tex-math id="M7">\begin{document}${\rm{PbTiO_3}}$\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="5-20222150_M7.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="5-20222150_M7.png"/></alternatives></inline-formula> bulk, and <inline-formula><tex-math id="M8">\begin{document}${\rm{SrTiO_3}}$\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="5-20222150_M8.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="5-20222150_M8.png"/></alternatives></inline-formula>/<inline-formula><tex-math id="M9">\begin{document}${\rm{PbTiO_3}}$\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="5-20222150_M9.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="5-20222150_M9.png"/></alternatives></inline-formula>/<inline-formula><tex-math id="M10">\begin{document}${\rm{SrTiO_3}}$\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="5-20222150_M10.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="5-20222150_M10.png"/></alternatives></inline-formula> sandwiched structures. We demonstrate the reliability and feasibility of Brown's equation in ferroelectrics through the simulation of <inline-formula><tex-math id="M11">\begin{document}${\rm{BaTiO_3}}$\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="5-20222150_M11.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="5-20222150_M11.png"/></alternatives></inline-formula> bulk and <inline-formula><tex-math id="M12">\begin{document}${\rm{PbTiO_3}}$\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="5-20222150_M12.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="5-20222150_M12.png"/></alternatives></inline-formula> bulk, which are consistent with experiments. Then, using Brown's equation derived in our work, we obtain various domain structures in <inline-formula><tex-math id="M13">\begin{document}${\rm{SrTiO_3}}$\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="5-20222150_M13.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="5-20222150_M13.png"/></alternatives></inline-formula>/<inline-formula><tex-math id="M14">\begin{document}${\rm{PbTiO_3}}$\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="5-20222150_M14.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="5-20222150_M14.png"/></alternatives></inline-formula>/<inline-formula><tex-math id="M15">\begin{document}${\rm{SrTiO_3}}$\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="5-20222150_M15.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="5-20222150_M15.png"/></alternatives></inline-formula> sandwiched structures, including periodic stripe domains and vortex domains. The simulation results are compared with related exprimental results.</sec>

Automatic Ferroelectric Domain Pattern Recognition Based on the Analysis of Localized Nonlinear Optical Responses Assisted by Machine Learning

AbstractSecond‐harmonic generation (SHG) is a nonlinear optical method allowing the study of the local structure, symmetry, and ferroic order in noncentrosymmetric materials such as ferroelectrics. The combination of SHG microscopy with local polarization analysis is particularly efficient for deriving the local polarization orientation. This, however, entails the use of tedious and time‐consuming modeling methods of nonlinear optical emission. Moreover, extracting the complex domain structures often observed in thin films requires a pixel‐by‐pixel analysis and the fitting of numerous polar plots to ascribe a polarization angle to each pixel. Here, the domain structure of GeTe films is studied using SHG polarimetry assisted by machine learning. The method is applied to two film thicknesses: A thick film containing large domains visible in SHG images, and a thin film in which the domains' size is below the SHG resolution limit. Machine learning‐assisted methods show that both samples exhibit four domain variants of the same type. This result is confirmed in the case of the thick film, both by the manual pixel‐by‐pixel analysis and by using piezoresponse force microscopy. The proposed approach foreshows new prospects for optical studies by enabling enhanced sensitivity and high throughput analysis.

Heterogeneities and defects in powder compacts and sintered alumina bodies visualized by using the synchrotron X-ray CT

The uniaxial die compaction and sintering is an important industrial production method for metal and ceramic components. While submicron- and nano-sized powders are finding increasing use for making dense materials with finest grain sizes, the uniformity of microstructure, and then, the reliability of the products depend on the heterogeneity in powder packing structure. Here we applied the synchrotron X-ray multiscale-CT to characterize the complex domain structures, i.e., agglomerates, in powder compacts, and revealed how heterogeneous distribution of fine residual pores is formed by the differential sintering of agglomerates by using a submicron alumina powder as a model. A crack-like defect was identified as the largest defect. This defect was formed along the boundary between a plate-shaped agglomerate and its surroundings. A technique was also proposed to visualize the heterogeneous distribution of residual pores by using SEM. These characterization methods will open up new possibilities for the optimization of ceramic processing.

Delineating complex ferroelectric domain structures via second harmonic generation spectral imaging

Understanding the mechanisms and spatial correlations of crystallographic symmetry breaking in ferroelectric materials is essential to tuning their functional properties. While optical second harmonic generation (SHG) has long been utilized in ferroelectric studies, its capability for probing complex polar materials has yet to be fully realized. Here, we develop a SHG spectral imaging method implemented on a home-designed laser-scanning SHG microscope, and demonstrate its application for a model system of (K,Na)NbO3 single crystals. Supervised model fitting analysis produces comprehensive information about the polarization vector orientations and relative fractions of constituent domain variants as well as their thermal evolution across the polymorphic phase transitions. Multiple domains and phases are clearly delineated at different temperatures, suggesting the phase competitions in (K,Na)NbO3. Besides, we show that unsupervised matrix decomposition analysis can quickly and faithfully reveal domain configurations without a priori knowledge about specific material systems. The SHG spectral imaging method can be readily extended to other ferroelectric materials with potentials to be further enhanced.

Investigation of wavelength-induced uncertainties in full-wave radar tomography of high contrast domain: An application to small solar system bodies

This paper aims to reconstruct the internal structure of a two-dimensional test object via numerically simulated full-wave time domain radar tomography with the presence of wavelength-induced (WI) uncertainties, following from a complex domain structure, and domain diameters 21 or 64 times the wavelength of the signal propagating inside the target. In particular, we consider an application in planetary scientific studies of reconstructing the interior structure of an arbitrary high contrast small Solar System Body (SSSB), i.e., an asteroid, with a probing signal wavelength limited by the instrument and mission payload requirements. Our uncertainty reduction model finds the reconstruction via averaging multiple inverse solutions assuming that the WI deviations in the solutions correspond to random deviations, which we assume to be independent and identically distributed (IID). It incorporates error marginalisation via a randomised signal configuration, spatial-averaging of candidate solutions, frequency-based error marginalisation, and the truncated singular value decomposition (TSVD) filtering technique, based on our assumptions of the phase discrepancy of the signal, domain parameters, and the full-wave forward model. The numerical experiments are performed for 20 and 60 MHz centre frequencies proposed for CubeSat-based radars, the latter being the centre frequency of the Juventas Radar which will be aboard Hera mission to investigate the interior structure of asteroid Dimorphos. A benchmark reconstruction of the target was obtained with the spatial averaging, sparse point density and frequency randomised configuration for both 20 and 60 MHz frequency systems.

Long-Term Isothermal Phase Transformation in Lead Zirconate.

Lead zirconate PbZrO3 has been the subject of research interest for several dozen years. Recently, even its antiferroelectric properties have started to be questioned, and many researchers still deal with the so-called intermediate phase below Curie temperature (TC), whose existence is not fully understood. It turns out that PbZrO3 doped with Nb exhibits below TC phases with complex domain structures. One of them undergoes self-organization taking place at a constant temperature, and transforms, after several minutes, into a lower phase. This isothermal transition was investigated through dielectric, pyroelectric current and Raman scattering measurements. Discontinuities accompanied it in the permittivity and pyroelectric current. The obtained Raman spectra proved that those discontinuities are strictly linked with the isothermal transition between two intermediate phases. The ordering process in lead sublattice stimulated by thermal fluctuations is discussed as a driving force for this peculiar phenomenon.

Polarization-sensitive UVA photodetector based on heterojunction of ITO and rare-earth doped bismuth ferrite ceramics

Ferroelectric photovoltaic materials have been subjected to intensive research in view of their applications for high-performance self-biased UV photodetectors. This work reports the ferroelectric polarization-enhanced near-UV (λ = 405 nm) and UVA (λ = 360 nm) photoresponse of the indium-tin-oxide (ITO)/(Bi0.93Sm0.07)FeO3/Pt and ITO/(Bi0.93Gd0.07)FeO3/Pt heterostructures. A superior photoresponse was observed in the ITO/(Bi0.93Gd0.07)FeO3/Pt device with photoresponsivity of ∼7.3×10−2A/W, specific detectivity of ∼2.5×1011Jones, and response times of τr ∼1 ms and τd ∼1 s under 360-nm light illumination. The photocurrent generation is facilitated by the interfacial E fields and ferroelectric polarization-induced E field. The improved photosensing ability is ascribed to the collective effect of the electric field-enhanced interaction between oxygen 2p and Fe 3d orbitals and the interconnection of grain boundaries and domain walls that plays roles of charge transport paths. (Bi0.93Gd0.07)FeO3 exhibited a more superior photoresponse than (Bi0.93Sm0.07)FeO3 due to its more complex domain structure, smaller bandgap, and stronger orbital hybridization. These results demonstrate the feasibility of utilizing the ferroelectric polarization and domain structure in (Bi0.93Gd0.07)FeO3 to enhance photodetection, thus providing a route for the realization of a highly sensitive and self-biased visible-UVA photodetector.

Computer-aided characterization of ferroelectric phase transitions and domain structures using polarizing light microscopy

Optical microscopy is an essential characterization technique that is used as an initial step in the study of domain structures and phase transitions of ferroelectric materials. Image analysis aided by advanced computer algorithms is urgently required to enable an improved accuracy and higher efficiency of data processing. In this study, an automatic full-angle light intensity detection algorithm is developed to study polarizing light microscopy images of domain structures and the phase evolution process is decoded using the scale invariant feature transform method. This data processing algorithm is then used to characterize the phase transition process in relaxor ferroelectric PMN-0.29PT single crystals with complex domain structures. An emerging in-plane tetragonal phase is tracked during the rhombohedral (R) to tetragonal (T) phase transition, which is associated with peaks present in the temperature-dependent dielectric curve. Compared to the traditional polarizing light microscopy characterization method, this computer-aided algorithm enables a quicker and more informative analysis of domain evolutions in ferroelectric single crystals.

High Curie temperature bismuth-based piezo-/ferroelectric single crystals of complex perovskite structure: recent progress and perspectives

The recent progress in high TC bismuth-based piezo-/ferroelectric single crystals is reviewed in terms of materials design, crystal growth, physical properties, crystal chemistry, and complex domain structures, and the future perspectives are discussed.

Calorimetric Investigation of Hydrogen-Atom Sublattice Transitions in the Ice VI/XV/XIX Trio.

Ice XIX represents the latest discovery of ice polymorphs and exists in the medium pressure range near 1–2 GPa. Ice XIX is a partially hydrogen-ordered phase, by contrast to its disordered mother phase ice VI, which shares the same oxygen-atom network with ice XIX. Ice XIX differs in terms of the ordering of the hydrogen-atom sublattice, and hence the space group, from its hydrogen-ordered sibling ice XV, which also features the same type of oxygen network. Together, ice VI, XV, and XIX form the only known trio of ice polymorphs, where polymorphic transformations from order to order, order to disorder, and disorder to order are possible, which also compete with each other depending on the thermodynamic path taken and the cooling/heating rates employed. These transitions in the H-sublattice have barely been investigated, so we study here the unique triangular relation in the ice VI/XV/XIX trio based on calorimetry experiments. We reveal the following key features for H-sublattice transitions: (i) upon cooling ice VI, domains of ice XV and XIX develop simultaneously, where pure ice XV forms at ≤0.85 GPa and pure ice XIX forms at ≥1.60 GPa, (ii) ice XIX transforms into ice XV via a transient disordered state, (iii) ice XV recooled at ambient pressure features a complex domain structure, possibly containing an unknown H-ordered polymorph, (iv) recooled ice XV partly transforms back into ice XIX at 1.80 GPa, and (v) partial deuteration slows down domain reordering strongly. These findings not only are of interest in understanding possible hydrogen-ordering and -disordering processes in the interior of icy moons and planets but, more importantly, also provide a challenging benchmark for our understanding and parameterizing many-body interactions in H-bonded networks.