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A fascinating aspect of nanoscale ferroelectric materials is the emergence of topological polar textures, which include various complex and stable polarization configurations. The manipulation of such topological textures through external stimuli like electric fields holds promise for advanced nanoelectronics applications. There are, however, several challenges to reach potential applications, among which reliably creating and controlling these textures at the nanoscale on silicon, and with lead-free compounds. We report the realization of epitaxial BaTiO3 nanoislands on silicon, with a lateral size as small as 30-60 nm, and demonstrate stable center down-convergent polarization domains that can be reversibly switched by an electric field to center up-divergent domains. Piezoresponse force microscopy data reconstruction and phase field modeling give insight into the 3D patterns. The trapezoidal-shape nanoislands give rise to center down-convergent lateral swirling polarization component with respect to the nanoisland axis, which prevents the formation of bound charges on the side walls, therefore minimizing depolarization fields. The texture resembles a swirling vortex of liquid flowing into a narrowing funnel. Chirality emerges from the whirling polarization configurations. The ability to create and electrically manipulate chiral whirling polar textures in BaTiO3 nanostructures grown monolithically on silicon holds promise for applications in future topological nanoelectronics. Epitaxial BaTiO3 ultra scaled nanoislands (30−60 nm) on Si exhibit an electrically switchable topological center down-convergent polar pattern. The peculiar island shape induces a lateral swirling component, which confers chirality to the polar domains. [ABSTRACT FROM AUTHOR]

Multiferroic CoFe2O4–Ba0.95Ca0.05Ti0.89Sn0.11O3 composite nanofibers (CFO–BCTSn NFs) were synthesized using a sol–gel electrospinning method. Scanning electron microscopy revealed the morphology of the composites, with fiber diameters ranging from 120 to 150 nm. Transmission electron microscopy confirmed the structure of the nanofibers, while X-ray diffraction, Raman spectroscopy, and high-resolution transmission electron microscopy verified the formation of the spinel structure of CFO and the perovskite structure of BCTSn, with no additional phases detected. The magnetic properties of the CFO–BCTSn NFs were demonstrated by magnetic hysteresis loops (M-H), and piezoresponse force microscopy confirmed their piezoelectricity. Magnetoelectric coupling was evidenced by comparing the M-H hysteresis loops of electrically poled and unpoled CFO–BCTSn NFs samples. These composite nanofibers have the potential to be utilized in innovative, lead-free magnetoelectric and magnetic field sensing technologies at the nanoscale. [ABSTRACT FROM AUTHOR]

Lead-free perovskite materials with high performance have high potential in clean energy storage applications and developments of electrocaloric devices. This work reports structural, dielectric, ferroelectric, energy storage, and electrocaloric properties near the ambient temperature in barium stannate titanate (BaTi0.89Sn0.11O3, BTS11) ceramic prepared by a sol–gel method. A single perovskite structure formation was confirmed using the X-ray diffraction analysis. Average grain size of 18.5 µm was found by the mean of the SEM micrograph with a density of 5.91 g/cm3. The multiphase coexistence at very near ambient temperature was proved using temperature-dependent micro-Raman measurements and differential scanning calorimetry. The BTS11 ceramic exhibits a high dielectric constant of 15,460 and a low dielectric loss (< 0.055) in a broad temperature range. Moreover, a high energy storage density of 122 mJ/cm3 was shown with an efficiency of 79%, a maximum value of electrocaloric temperature change (ΔT) of 0.86 K, and finally, an electrocaloric responsivity (ΔT/ΔE) of 0.24 K.mm/kV at the external electric field change of 35 kV/cm near ambient temperature. The enhanced dielectric, ferroelectric, and electrocaloric properties make BTS11 ceramics a great candidate for solid-state cooling technology and high energy storage applications near ambient temperature. [ABSTRACT FROM AUTHOR]

Structural, dielectric, ferroelectric, energy storage properties, and electrocaloric effect were studied in lead-free ceramic Ba0.95Ca0.05Ti0.89Sn0.11O3 (BCTSn) elaborated by the sol–gel method. Phase purity structure was confirmed from X-ray data using the Rietveld refinement analysis which revealed the coexistence of tetragonal (P4mm) and orthorhombic (Amm2) symmetries at room temperature. Phase transitions were detected by dielectric and differential scanning calorimetry measurements. The energy storage properties were determined from P-E hysteresis, and the electrocaloric properties were calculated indirectly via the Maxwell approach. The large value of electrocaloric temperature change of ΔT = 0.807 K obtained at a relatively small electric field of 30 kV cm−1, and the high energy storage efficiency can make BCTSn ceramic a promising candidate for environmentally friendly refrigeration and energy storage applications. [ABSTRACT FROM AUTHOR]

The crystal structure and lattice dynamics of quantum paraelectric BaxSr1−xTiO3 (x = 0, 0.01, 0.02) solid solutions are studied using X‐ray diffraction (XRD), Raman and terahertz‐infrared (THz‐IR) spectroscopies in a temperature range of 4–300 K. XRD and Raman spectroscopy reveal the cubic‐to‐tetragonal nonpolar structural phase transition at about 100 K. At the same time, Raman spectra manifest the presence of polar modes, TO2 and TO4, normally prohibited in paraelectric phase. Emergence of these modes indicates the appearance of the polar nanoregions in a broad temperature range. The modes become more intensive at low temperatures, and temperature dependence of their intensities on cooling reveals the kink‐like change of the slope from flat to steep, indicating on activation of polar nanoregions. The transmission THz‐IR spectra show that squared frequency of the polar TO1 soft mode, responsible for ferroelectric transition, follows Cochran's behavior at high temperatures. However, at low temperatures, it doesn't vanish at extrapolated Curie temperature but saturates, demonstrating the plateau feature below 20 K. This behavior, coherent with known saturation of the dielectric constant, indicates that transition to ferroelectric phase in BaxSr1−xTiO3 is suppressed by quantum fluctuations and the system stays in quantum paraelectric state at very low temperatures. [ABSTRACT FROM AUTHOR]

Lead-free Ba0.85Ca0.15Zr0.10Ti0.90O3 (BCZT) ceramic exhibits excellent dielectric, ferroelectric and piezoelectric properties at the morphotropic phase boundary (MPB). Previously, we demonstrated that the use of the anionic surfactant sodium dodecyl sulfate (SDS, NaC12H25SO4) could enhance the dielectric properties of BCZT ceramic using surfactant-assisted solvothermal processing [1]. In the present study, structural, dielectric, ferroelectric properties, as well as electrocaloric effect and energy storage performances of this BCZT ceramic were thoroughly investigated. X-ray diffraction (XRD) measurements revealed the presence of single perovskite phase at room temperature with the coexistence of orthorhombic and tetragonal symmetries. In-situ Raman spectroscopy results confirmed the existence of all phase transitions from rhombohedral through orthorhombic and tetragonal to cubic symmetries when the temperature varies as reported in undoped-BaTiO3. Evolution of energy storage performances with temperature have been investigated. BCZT ceramic exhibits a high energy storage efficiency of ~ 80% at 120 °C. In addition, the electrocaloric responsivity was found to be 0.164 × 10−6 K·m/V at 363 K. [ABSTRACT FROM AUTHOR]

Polarized Raman spectra of the epitaxial Ba0.4Sr0.6TiO3 film grown on MgO substrate with thickness of 600 nm were studied in a broad temperature range of 80-600 K and the phase transition from paraelectric to tetragonal ferroelectric phase was observed at about 500 K. This critical temperature is substantially higher than that calculated from the lattice-mismatch strain theory. In addition, the predicted from the theory low-temperature orthorhombic and rhombohedral phases were not observed. We ascribe the strengthening of the tetragonal ferroelectric phase to the effect of the interface-induced build-in electric field resulted from the interface-accumulated charges. [ABSTRACT FROM AUTHOR]

An essay is presented in which the author argues against the English translations of the Russian poem "Eugene Onegin" written by Aleksandr Pushkin. Particular focus is given to Vladimir Nabokov's approach of translation. She also looks and compares translations from Stanley Mitchell and Charles Johnston. Each translation received several criticisms from Michael Wachtel and writers Rachel Polonsky and Edmund Wilson.

It is well known that the ferroelectric layers in dielectric/ferroelectric/dielectric heterostructures harbor polarization domains resulting in the negative capacitance crucial for manufacturing energy-efficient field-effect transistors. However, the temperature behavior of the characteristic dielectric properties, and, hence, the corresponding behavior of the negative capacitance, are still poorly understood, restraining the technological progress thereof. Here we investigate the temperature-dependent properties of domain structures in the SrTiO3/PbTiO3/SrTiO3 heterostructures and demonstrate that the temperature–thickness phase diagram of the system includes the ferroelectric and paraelectric regions, which exhibit different responses to the applied electric field. Using phase-field modeling and analytical calculations we find the temperature dependence of the dielectric constant of ferroelectric layers and identify the regions of the phase diagram wherein the system demonstrates negative capacitance. We further discuss the optimal routes for implementing negative capacitance in energy-efficient ferroelectric field-effect transistors. [ABSTRACT FROM AUTHOR]

The field-induced polarization reversal in the c-oriented ferroelectric phase of strained perovskite film has been studied. We show that in addition to the conventional longitudinal switching mechanism, when the c-oriented polarization vector changes its modulus, the longitudinal-transversal and transversal mechanisms when the perpendicular component of polarization is dynamically admixed are possible. The latter process can occur either via the straight-abrupt or initially continues polarization turnover scenario. We specified the obtained results for the case of PbTiO3 and BaTiO3 ferroelectrics and propose the experimental methods for their investigation. [ABSTRACT FROM AUTHOR]

Sm-doped Pb(Mg 1/3 Nb 2/3 )O 3 -PbTiO 3 (Sm-PMN-PT) bulk materials have revealed outstanding ferroelectric and piezoelectric properties due to enhanced local structural heterogeneity. In this study, we further explore the potential of Sm-PMN-PT by fabricating epitaxial thin films by pulsed laser deposition, revealing that Sm doping significantly improves the capacitive energy-storage, piezoelectric, electrocaloric, and pyroelectric properties of PMN-PT thin films. These Sm-PMN-PT thin films exhibit fatigue-free performance up to 10 9 charge-discharge cycles and maintain thermal stability across a wide temperature range from -40 to 200 °C. Notably, the films demonstrate a colossal electrocaloric effect with a temperature change of 59.4 K and a remarkable pyroelectric energy density reaching 40 J cm -3 . By using scanning transmission electron microscopy and phase-field modeling, we revealed that these exceptional properties arise from the increased local structural heterogeneity and strong local electric fields along spontaneous polarization directions, facilitating the nucleation of polymorphic nanodomains characterized by a slush-like polar structure. These findings highlight the enormous potential of Sm-PMN-PT films in capacitive energy storage and solid-state electrothermal energy interconversion. Furthermore, this approach holds broad potential for other relaxor ferroelectrics by enabling the manipulation of nanodomain structures, paving the way for developing robust multifunctional materials.