Showing papers by "Masaki Takata published in 2015"
TL;DR: A hydrogel actuator that operates by modulating its anisotropic electrostatics in response to changes of electrostatic permittivity associated with a lower critical solution temperature transition is shown.
Abstract: Electrostatic repulsion, long used for attenuating surface friction, is not typically employed for the design of bulk structural materials. We recently developed a hydrogel with a layered structure consisting of cofacially oriented electrolyte nanosheets. Because this unusual geometry imparts a large anisotropic electrostatic repulsion to the hydrogel interior, the hydrogel resisted compression orthogonal to the sheets but readily deformed along parallel shear. Building on this concept, here we show a hydrogel actuator that operates by modulating its anisotropic electrostatics in response to changes of electrostatic permittivity associated with a lower critical solution temperature transition. In the absence of substantial water uptake and release, the distance between the nanosheets rapidly expands and contracts on heating and cooling, respectively, so that the hydrogel lengthens and shortens significantly, even in air. An L-shaped hydrogel with an oblique nanosheet configuration can thus act as a unidirectionally proceeding actuator that operates without the need for external physical biases.
474 citations
TL;DR: A composite hydrogel with anisotropic mechanical properties dominated by electrostatic repulsion between negatively charged unilamellar titanate nanosheets embedded within it is described, anticipating that the concept of embedding an isotropic repulsive electrostatics within a composite material, inspired by articular cartilage, will open up new possibilities for developing soft materials with unusual functions.
Abstract: Machine technology frequently puts magnetic or electrostatic repulsive forces to practical use, as in maglev trains, vehicle suspensions or non-contact bearings. In contrast, materials design overwhelmingly focuses on attractive interactions, such as in the many advanced polymer-based composites, where inorganic fillers interact with a polymer matrix to improve mechanical properties. However, articular cartilage strikingly illustrates how electrostatic repulsion can be harnessed to achieve unparalleled functional efficiency: it permits virtually frictionless mechanical motion within joints, even under high compression. Here we describe a composite hydrogel with anisotropic mechanical properties dominated by electrostatic repulsion between negatively charged unilamellar titanate nanosheets embedded within it. Crucial to the behaviour of this hydrogel is the serendipitous discovery of cofacial nanosheet alignment in aqueous colloidal dispersions subjected to a strong magnetic field, which maximizes electrostatic repulsion and thereby induces a quasi-crystalline structural ordering over macroscopic length scales and with uniformly large face-to-face nanosheet separation. We fix this transiently induced structural order by transforming the dispersion into a hydrogel using light-triggered in situ vinyl polymerization. The resultant hydrogel, containing charged inorganic structures that align cofacially in a magnetic flux, deforms easily under shear forces applied parallel to the embedded nanosheets yet resists compressive forces applied orthogonally. We anticipate that the concept of embedding anisotropic repulsive electrostatics within a composite material, inspired by articular cartilage, will open up new possibilities for developing soft materials with unusual functions.
396 citations
TL;DR: The highly unique crystal structure of the metal-organic framework (MOF) zirconium 2-sulfoterephthalate is presented, which contains a large number of partially occupied ligand and metal cluster sites which directly affect the physical properties of the material.
Abstract: Understanding the role that crystal imperfections or defects play on the physical properties of a solid material is important for any application. In this report, the highly unique crystal structure of the metal-organic framework (MOF) zirconium 2-sulfoterephthalate is presented. This MOF contains a large number of partially occupied ligand and metal cluster sites which directly affect the physical properties of the material. The partially occupied ligand positions give rise to a continuum of pore sizes within this highly porous MOF, supported by N2 gas sorption and micropore analysis. Furthermore, this MOF is lined with sulfonic acid groups, implying a high proton concentration in the pore, but defective zirconium clusters are found to be effective proton trapping sites, which was investigated by a combination of AC impedance analysis to measure the proton conductivity and DFT calculations to determine the solvation energies of the protons in the pore. Based on the calculations, methods to control the pKa of the clusters and improve the conductivity by saturating the zirconium clusters with strong acids were utilized, and a 5-fold increase in proton conductivity was achieved using these methods. High proton conductivity of 5.62 × 10(-3) S cm(-1) at 95% relative humidity and 65 °C could be achieved, with little change down to 40% relative humidity at room temperature.
161 citations
TL;DR: It is shown that a space-filling design, relying on the two-dimensional nested hexagonal packing of a particular type of triptycene, enables the formation of large-area molecular films with long-range 2D structural integrity up to the centimeter length scale by vacuum evaporation, spin-coating, and cooling from the isotropic liquid of the triptyCene.
Abstract: Highly oriented, domain-boundary–free organic thin films could find use in various high-performance organic materials and devices. However, even with state-of-the-art supramolecular chemistry, it is difficult to construct organic thin films with structural integrity in a size regime beyond the micrometer length scale. We show that a space-filling design, relying on the two-dimensional (2D) nested hexagonal packing of a particular type of triptycene, enables the formation of large-area molecular films with long-range 2D structural integrity up to the centimeter length scale by vacuum evaporation, spin-coating, and cooling from the isotropic liquid of the triptycene. X-ray diffraction analysis and microscopic observations reveal that triptycene molecules form a completely oriented 2D (hexagonal triptycene array) + 1D (layer stacking) structure, which is key for the long-range propagation of structural order.
88 citations
TL;DR: A novel, simple synthetic method for metal (Ni) NPs in a MOF using the partial thermal decomposition of nickel(II) 2,5-dihydroxyterephthalate (Ni-MOF-74) is demonstrated.
63 citations
TL;DR: In this paper, a one-step hydrothermal treatment of pure phase vanadium oxide (VO2)(M/R) nanorods with superb metal-insulator transition properties was obtained in tungsten (W)-doped level ranges from 0.5 to 2.0 at% using a single-step treatment without additional annealing steps.
Abstract: Pure phase V1−xWxO2(M/R) nanorods with superb metal–insulator transition properties were obtained in tungsten (W)-doped level ranges from 0.5 to 2.0 at% using a one-step hydrothermal treatment without additional annealing steps. The assured level of W doping greatly promotes the grain growth of pure phase vanadium oxide (VO2)(M/R) and simultaneously the phase transition temperature (Tc) is depressed as much as 103 °C per at% W for the V1−xWxO2 nanorods when x = 1.0–2.0 at%. After mixing the pure phase VO2(M) (W-doped 0.5 at%, phase transition at 47 °C) nanorods with acrylic resin, the integrated visible transmission of the VO2 composite coating on glass is up to 60.6% and the integrated solar modulation efficiency is up to 10.3%. These results mean that the superior thermochromic property will greatly favor the practical application of VO2-based smart windows.
61 citations
TL;DR: The enhanced infrared intensity of soft phonon along with the resistivity reduction suggests the presence of unusual electron-phonon coupling, which may be responsible for the emergent ferroelectric structure compatible with metallic state.
Abstract: We report that a ferroelectric-like metallic state with reduced anisotropy of polarization is created by the doping of conduction electrons into BaTiO3, on the bases of x-ray/electron diffraction and infrared spectroscopic experiments. The crystal structure is heterogeneous in nanometer-scale, as enabled by the reduced polarization anisotropy. The enhanced infrared intensity of soft phonon along with the resistivity reduction suggests the presence of unusual electron-phonon coupling, which may be responsible for the emergent ferroelectric structure compatible with metallic state.
47 citations
TL;DR: The results of detailed spectroscopic studies indicate that in its double-decker aromatic arrays, FcNT possibly possesses propeller-chiral twists in addition to the helically chiral structure, where the former is considerably more dynamic than the latter.
Abstract: Coassembly of an achiral ferrocene-cored tetratopic pyridyl ligand (FcL) with AgBF4 in CH2Cl2/MeCN (7:3 v/v) containing chiral Bu4N(+) (+)- or (-)-menthylsulfate (MS*(-)) results in the formation of an "optically active" metal-organic nanotube (FcNT) composed of a C10-symmetric double-decker nanoring featuring 10 FcL units and 20 Ag(+) ions. The circular dichroism spectrum of FcNT along with its 2D X-ray diffraction (2D XRD) pattern indicates that the constituent metal-organic nanorings in FcNT stack one-handed helically on top of each other. A crystal structure of the dimeric double-decker model complex (Ag2(FcL')2) from a ditopic ferrocene ligand (FcL') and AgBF4 allowed for confirming the binding of MS*(-) onto the Ag(+) center of the complex. The results of detailed spectroscopic studies indicate that in its double-decker aromatic arrays, FcNT possibly possesses propeller-chiral twists in addition to the helically chiral structure, where the former is considerably more dynamic than the latter. Notably, both chiral structural motifs responded nonlinearly to an enantiomeric excess of MS*(-) (majority rule) though with no stereochemical influence on one another.
39 citations
TL;DR: Even though the magnetic domains are antiferromagnetic, it is shown that their distribution can be controlled using a magnetic field-cooling procedure.
Abstract: Long-range noncollinear all-in-all-out magnetic order has been directly observed for the first time in real space in the pyrochlore Cd_{2}Os_{2}O_{7} using resonant magnetic microdiffraction at the Os L_{3} edge. Two different antiferromagnetic domains related by time-reversal symmetry could be distinguished and have been mapped within the same single crystal. The two types of domains are akin to magnetic twins and were expected-yet unobserved so far-in the all-in-all-out model. Even though the magnetic domains are antiferromagnetic, we show that their distribution can be controlled using a magnetic field-cooling procedure.
36 citations
TL;DR: It is shown that the strong modulation mainly originates from lone-pair driven Pb(2+)-Bi(3+) ordering in the large pentagonal caves, which can suppress the local polarization in x-y plane in long ranges.
Abstract: Pb- or Bi-based perovskite oxides have been widely studied and used because of their large ferroelectric polarization features induced by stereochemically active 6s(2) lone pair electrons. It is intriguing whether this effect could exist in other related systems. Herein, we designed and synthesized a mixed Pb and Bi A site polar compound, PbBiNb5O15, with the TTB framework. The as-synthesized material turns out to be a relaxor with weak macroscopic ferroelectricity but adopts strong local polarizations. What's more, unusual five orders of incommensurate satellite reflections with strong intensities were observed under the electron diffraction, suggesting that the modulation is highly developed with large amplitudes. The structural modulation was solved with a (3 + 1)D superspace group using high-resolution synchrotron radiation combined with anomalous dispersion X-ray diffraction technique to distinguish Pb from Bi. We show that the strong modulation mainly originates from lone-pair driven Pb(2+)-Bi(3+) ordering in the large pentagonal caves, which can suppress the local polarization in x-y plane in long ranges. Moreover, the as-synthesized ceramics display strong relaxor ferroelectric feature with transition temperature near room temperature and moderate dielectric properties, which could be functionalized to be electromechanical device materials.
35 citations
TL;DR: Spectroscopic and X-ray diffraction analyses of a BY/TAC composite film in each alignment process revealed that brief humidification triggers restructuring of the BY assembly from 1D nematic-like order to anisotropic 2D columnar order, resulting in the dramatic increase in the order parameter.
Abstract: Single-layer thin alignment films of dye molecules are of growing importance, particularly for state-of-the-art LCD technology. Here we show that a sequential process involving the photoalignment and humidification of a chromonic liquid crystalline azobenzene (brilliant yellow; BY) dispersed in a triacetyl cellulose (TAC) matrix gives a thin alignment film with an exceptionally high order parameter (0.81). Spectroscopic and X-ray diffraction analyses of a BY/TAC composite film in each alignment process revealed that brief humidification triggers restructuring of the BY assembly from 1D nematic-like order to anisotropic 2D columnar order, resulting in the dramatic increase in the order parameter.
TL;DR: Structural analyses showed that the crystallisation of silks following extension deformation has a critical effect on their mechanical and optical properties.
Abstract: β-Sheet crystals play an important role in determining the stiffness, strength, and optical properties of silk and in the exhibition of silk-type-specific functions. It is important to elucidate the structural changes that occur during the stretching of silk fibres to understand the functions of different types of fibres. Herein, we elucidate the initial crystallisation behaviour of silk molecules during the stretching of three types of silk fibres using synchrotron radiation X-ray analysis. When spider dragline silk was stretched, it underwent crystallisation and the alignment of the β-sheet crystals became disordered initially but was later recovered. On the other hand, silkworm cocoon silk did not exhibit further crystallisation, whereas capture spiral silk was predominantly amorphous. Structural analyses showed that the crystallisation of silks following extension deformation has a critical effect on their mechanical and optical properties. These findings should aid the production of artificial silk fibres and facilitate the development of silk-inspired functional materials.
TL;DR: Enhanced piezoelectric properties, large polarizations, and high depolarization temperatures are observed in the wide morphotropic phase boundary region formed with a rhombohedral phase, with up to 92.5% Bi on the perovskite A site.
Abstract: Lead-free bismuth-based perovskite oxides with polarization directed along the [001](p) primitive perovskite unit cell edge, analogous to tetragonal PbTiO3, are synthesized at ambient pressure. Enhanced piezoelectric properties, large polarizations, and high depolarization temperatures are observed in the wide morphotropic phase boundary region formed with a rhombohedral phase, with up to 92.5% Bi on the perovskite A site.
TL;DR: In this article, the reversibility of the device operation strongly depends on the substrate, suggesting that a governing mechanism might differ depending on substrates, and the importance of the film quality for future fundamental researches as well as for practical device applications based on electrolyte gated devices.
Abstract: Electrolyte gating on correlated VO2 thin films enables electrical control of the “bulk” electronic and structural phases over the electrostatic screening length. Although this unique functionality potentially provides novel electronic and optoelectronic device applications, there are intense discussions on the mechanism of the device operation both from electrostatic and electrochemical viewpoints. Here it is shown that the reversibility of the device operation strongly depends on substrates, suggesting that a governing mechanism might differ depending on substrates. Electrolyte gating on VO2 films grown on lattice-matched TiO2 substrates shows reversible gating effects, whereas that on hexagonal Al2O3 substrates become irreversible, although in both cases metallic states can be induced electrically. X-ray absorption spectroscopy measurements on irreversibly gated VO2/Al2O3 reveal permanent reduction of the valence state of vanadium upon gate-induced metallization, presumably originating from irreversible electrochemical doping under the presence of the extremely large electric field created at an electrolyte/VO2 interface. Our findings suggest essential importance of the film quality for future fundamental researches as well as for practical device applications based on electrolyte-gated devices.
TL;DR: The present results corroborate similar findings observed on different systems and confirm that o–p conversion can occur on non-magnetic solids and that electric field can induce the catalytic hydrogen o-p conversion.
Abstract: The ability to design and control properties of nano-sized space in porous coordination polymers (PCPs) would provide us with an ideal stage for fascinating physical and chemical phenomena. We found an interconversion of nuclear-spin isomers for hydrogen molecule H2 adsorbed in a Hofmann-type PCP, {Fe(pz)[Pd(CN)4]} (pz=pyrazine), by the temperature dependence of Raman spectra. The ortho (o)–para (p) conversion process of H2 is forbidden for an isolated molecule. The charge density study using synchrotron radiation X-ray diffraction reveals the electric field generated in coordination nano-space. The present results corroborate similar findings observed on different systems and confirm that o–p conversion can occur on non-magnetic solids and that electric field can induce the catalytic hydrogen o–p conversion.
TL;DR: In this article, the structure of polymeric chain-structured complexes were clarified by synchrotron X-ray powder diffraction measurements, and the derivation of the linker moiety (bdc to atpa or htpa) affects the inter-metal energy transfer from TbIII to EuIII.
Abstract: Polymeric chain-structured complexes were prepared with helical lanthanide complexes (LnL) and benzene-dicarboxylate derivatives (benzene-1,4-dicarboxylate (bdc), 2-aminoterephtalate (atpa) and 2-hydoloxyterephtalate (htpa)), which show some noteworthy physicochemical properties, photo-luminescence and thermal stabilities. The complex EuL-bdc shows bright luminescence originating from EuIII by UV excitation. The emission color can be tuned by the mixing of TbL. The structures of these chain complexes were clarified by synchrotron X-ray powder diffraction measurements. The derivation of the linker moiety (bdc to atpa or htpa) affects the inter-metal energy transfer from TbIII to EuIII.
TL;DR: The polymerized composite showed an aligned phase over a wide thermal range with excellent (2)H quadrupole splitting of the solvent signal, thus implying versatility as an alignment medium for NMR studies.
Abstract: In situ polymerization of a bicellar mixture composed of a phospholipid and polymerizable surfactants afforded unprecedented stable bicelles. The polymerized composite showed an aligned phase over a wide thermal range (25 to >90 °C) with excellent 2H quadrupole splitting of the solvent signal, thus implying versatility as an alignment medium for NMR studies. Crosslinking of the surfactants also brought favorable effects on the kinetic stability and alignment morphology of the bicelles. This system could thus offer a new class of scaffolds for biomembrane models.
TL;DR: In this paper, the double-perovskite type BaYMn2O5+δ was studied by high-temperature synchrotron X-ray diffraction (SXRD) under precisely controlled oxygen pressure to gain deeper understanding of the remarkable oxygen intake/release capability of this oxide.
Abstract: Crystal structure of double-perovskite type BaYMn2O5+δ was studied by high-temperature synchrotron X-ray diffraction (SXRD) under precisely controlled oxygen pressure to gain deeper understanding of the remarkable oxygen intake/release capability of this oxide. The in situ SXRD analysis at 750 °C revealed that this oxide undergoes a distinct structural change upon lowering oxygen pressure, from a slightly oxygen-deficient “δ = 1” phase (BaYMn2O5.89; P(O2) = 103 Pa) to an oxygen-vacancy ordered “δ = 0.5” phase (BaYMn2O5.51; P(O2) = 10 Pa). The BaYMn2O5.89 structure (orthorhombic Cmmm) involves statistical distribution of oxygen vacancies within the yttrium plane. Meanwhile, the BaYMn2O5.51 structure (orthorhombic Icma) contains arrays of pyramidal MnO5 and octahedral MnO6 forming an alternate ordering, which is stabilized by a particular Mn3+ orbital ordering with collective displacements of Y3+ arrays. Thus, the discontinuous change in the oxygen content can be attributed to the structural reconstruction ...
TL;DR: In this article, the physical properties of hollandite titanates with double chains of edge-sharing octahedra with $d$ electrons in the 2g states were studied and it was shown that there is an electronic phase transition at $\ensuremath{\sim}220$ K at which various properties exhibit anomalies.
Abstract: We studied the physical properties of hollandite titanates, ${\mathrm{Ba}}_{x}{\mathrm{Ti}}_{8}{\mathrm{O}}_{16+\ensuremath{\delta}}$, which have double chains of edge-sharing ${\mathrm{TiO}}_{6}$ octahedra with $d$ electrons in the ${t}_{2g}$ states. We found that there is an electronic phase transition at $\ensuremath{\sim}220$ K, at which various properties exhibit anomalies. This phase transition is characterized by a modulation in the ${\mathrm{TiO}}_{6}$ chains and a spectral weight transfer of over 2 eV in the optical conductivity spectrum, which are presumably caused by charge and orbital ordering of the Ti ${t}_{2g}$ electrons.
TL;DR: The alloy structures with and without a reductive thermal treatment under a hydrogen atmosphere were examined, suggesting that highly crystalline spherical particles of ordered B2-type Fe-Co NAs form by the thermal treatment of the deposited grains.
Abstract: We succeeded in the efficient preparation of well-dispersed Fe-Co nanoalloys (NAs) using the arc plasma deposition method. Synchronous shots of dual arc plasma guns were applied to a carbon support to prepare the solid-solution type Fe-Co NAs having an approximately 1 : 1 atomic ratio. The alloy structures with and without a reductive thermal treatment under a hydrogen atmosphere were examined using X-ray powder diffraction, scanning transmission electron microscopy (STEM) combined with energy-dispersive X-ray analysis, high resolution STEM, and magnetic measurements, suggesting that highly crystalline spherical particles of ordered B2-type Fe-Co NAs form by the thermal treatment of the deposited grains.
TL;DR: The intrinsic charge carrier transporting properties of two isomeric linear- and bent-shaped 7-ring benzo-fused thieno[3,2-b] thiophenes and their octyl-substitution analogues were newly investigated using flash-photolysis and field-induced time-resolved microwave conductivity (TRMC) techniques.
Abstract: The intrinsic charge carrier transporting properties of two isomeric linear- and bent-shaped 7-ring benzo-fused thieno[3,2-b] thiophenes and their octyl-substituted analogues were newly investigated using flash-photolysis (FP-) and field-induced (FI-) time-resolved microwave conductivity (TRMC) techniques. FP-TRMC study in the solid state revealed that octyl-substitution potentially improved the photoconductivity due to the enhanced crystalline lamellar packing. After this screening process, local-scale hole mobilities at the thienoacene–poly(methylmethacrylate) insulator interfaces were precisely recorded using FI-TRMC, reaching up to 4.5 cm2 V−1 s−1 for the linear-shaped non-alkylated thienoacene. The combination of FP- and FI-TRMC measurements provides a rapid and quantitative evaluation scheme even for a variety of compounds with some issues in the processing conditions, leading to the optimized structure of the compounds used as active (interfacial) layers in practical electronic devices.
TL;DR: The structure of PGe was analyzed using X-ray diffraction and it was indicated to have labile polymer packing against RGe, which indicates its unique impact on physiological activity.
TL;DR: In this paper, the authors investigated the data-resolution dependence of the maximum entropy method (MEM) using the high resolution powder diffraction data measured at third-generation synchrotron radiation (SR) source, SPring-8.
TL;DR: A nitronyl nitroxide-appended hexabenzocoronene (HBC(NN), when allowed to coassemble with bis(hexafluoroacetylacetonato)cobalt(II), forms a coaxial nanotubular architecture featuring NN-Co(II) coordinated copolymer chains immobilised on the outer and inner nanotube surfaces.
TL;DR: In this paper, the combined power of the maximum entropy method (MEM) and synchrotron powder X-ray diffraction (SPXRD) is exerted to accurately reconstruct the electron density distribution (EDD) of the hydrogen storage material, KBH4.
TL;DR: In this paper, images of the spatial distribution of nanostructures in thin films were successfully reconstructed by grazing-incidence small-angle X-ray scattering (GISAXS) coupled with computed tomography (CT) measurements.
Abstract: Images of the spatial distribution of nanostructures in thin films were successfully reconstructed by grazing-incidence small-angle X-ray scattering (GISAXS) coupled with computed tomography (CT) measurements. As a model sample of inhomogeneous thin films, a thin film was patterned with four characters (F, B, S and L) consisting of nanoparticles of gold (Au), platinum (Pt), Au/Pt and Pt/Au, respectively, on a silicon substrate. The characters each produced respective two-dimensional GISAXS images which reflect the nanoparticle structures and their correlations in the thin film. The application of the GISAXS-CT technique to the characteristic scattering GISAXS intensity of each component enables one to reconstruct the images of each character independently. Moreover, it was found that the patterned images could be reconstructed even from very weak scattered intensities at higher q positions and the diffuse intensities. These results indicate that the GISAXS-CT method is a powerful tool to obtain distinct reconstruction images detailing the particle size, shape and surface roughness.
TL;DR: Layer-by-layer films composed of redox-active ruthenium dimer and Zr(IV) ions were fabricated on an indium tin oxide electrode and it has been clarified that this film has a crystalline structure.
Abstract: Layer-by-layer films composed of redox-active ruthenium dimer and Zr(IV) ions were fabricated on an indium tin oxide electrode. The fabricating behavior was monitored by cyclic voltammetry and UV–vis absorption spectral measurements. The orientation of the film was also monitored by grazing-incidence small-angle and wide-angle X-ray scattering (GISAXS) measurements, and it has been clarified that this film has a crystalline structure. The peaks obtained by GISAXS were changed upon oxidation reaction, which indicates that a change in the orientation of the ruthenium dimer occurred in the film.
TL;DR: In this article, a representati e -conjugated motif, perylenediimide (PDI), was functionalized with taper-shaped semi-fluoroalkyl chains at one of its imide positions, self-assembled into various ordered phase structures depending on the type of side chains at the other imide position.
Abstract: A representati e -conjugated motif, perylenediimide (PDI), when functionalized with taper-shaped semi-fluoroalkyl chains at one of its imide positions, self-assembled into various ordered phase structures depending on the type of side chains at the other imide position. Asymmetrical substitution by semi-fluoroalkyl/alkyl chains allowed the PDI molecule to form a rectangular columnar liquid crystalline mesophase while semi-fluoroalkyl/ triethyleneglycol-substitution resulted in a lamellar-packed crystalline mesophase. In both mesophases, the immiscible nature of superhydrophobic/hydrophobic or superhydrophobic/hydrophilic segments works as the major droving force to lead semi-fluoroalkyl/alkyl or semi-fluoroalkyl/oxyethyleneglycol nano-domains, resulting in high stability of the mesophases with the wide temperature range over 100oC. The compound decorated with tapered semi-fluoroalkyl chains at the both imide positions exhibited complicated crystalline ordered phases with high thermal stability.
TL;DR: In this paper, a collaboration of researchers from Japan discovered that exposure of Gd${}{0.5}$Tb${}_{0.6}$MnO{}_{3}$ to x-ray irradiation induces a reversible transition into a new hidden state, which is also characterized by cycloidal order, but with a different modulation wave vector.
Abstract: Gd${}_{1-x}$Tb${}_{x}$MnO${}_{3}$ oxides are characterized by two main competing states that exhibit both ferroelectric and multiferroic ordering. Both states involve cycloidal magnetic order that drives ferroelectricity. In their new article, a collaboration of researchers from Japan discovered that exposure of Gd${}_{0.5}$Tb${}_{0.5}$MnO${}_{3}$ to x-ray irradiation induces a reversible transition into a new hidden state, which is also characterized by cycloidal order, but with a different modulation wave vector. The ability to manipulate the state with x-rays suggests a novel route for photocontrol of multiferroic materials.