Engineering Multiphase Phase Transitions for Exceptional Electrocaloric Performance and Ultraweak Electrostrictive Response in Ferroelectrics.

In the pursuit of eco-friendly alternatives for refrigeration technology, electrocaloric materials have emerged as promising candidates for efficient solid-state refrigeration due to their high efficiency and integrability. However, current advancements in electrocaloric effects (ECEs) are often constrained by high temperatures and elevated electric fields (-field), limiting practical applicability. Informed by phase-field simulation, this study introduces a (1-)Pb(YbNb)O-Pb(MgNb)O system, strategically engineered to incorporate highly ordered YN and disordered MN mixtures.

Innovative Design of BNKT-SLZT Ceramics: Maximizing the Polarization Difference for Enhanced Energy Storage.

Lead-free relaxor ferroelectric ceramics with outstanding energy-storage (ES) density () and high ES efficiency () are crucial for advanced pulse-power capacitors. This study introduces a strategic approach to maximizing the polarization difference (Δ) by inducing a transition from the ferroelectric phase to the ergodic relaxor (ER) phase. By employing this strategy, a series of ceramics, (1 - )(BiNaK)TiO-(SrLa)(ZrTi)O (BNKT-SLZT), with varying SLZT content ( = 0.

Moderate Fields, Maximum Potential: Achieving High Records with Temperature-Stable Energy Storage in Lead-Free BNT-Based Ceramics.

The increasing awareness of environmental concerns has prompted a surge in the exploration of lead-free, high-power ceramic capacitors. Ongoing efforts to develop lead-free dielectric ceramics with exceptional energy-storage performance (ESP) have predominantly relied on multi-component composite strategies, often accomplished under ultrahigh electric fields. However, this approach poses challenges in insulation and system downsizing due to the necessary working voltage under such conditions.

Defining ferroelectric characteristics with reversible piezoresponse: PUND switching spectroscopy PFM characterization.

Detecting ferroelectricity at micro- and nanoscales is crucial for advanced nanomaterials and materials with complicated topography. Switching spectroscopy piezoresponse force microscopy (SSPFM), which involves measuring piezoelectric hysteresis loops via a scanning probe microscopy tip, is a widely accepted approach to characterize polarization reversal at the local scale and confirm ferroelectricity. However, the local hysteresis loops acquired through this method often exhibit unpredictable shapes, a phenomenon often attributed to the influence of parasitic factors such as electrostatic forces and current flow.

Piezoactive Bioorganic Diphenylalanine Films: Mechanism of Phase Formation.

Self-organized peptides are unique materials with various applications in biology, medicine, and nanotechnology. Many of these applications require fabrication of homogeneous thin films having high piezoelectric effect and sufficiently low roughness. Recently, a facile method for the controlled deposition of flat solid films of the most studied peptide, diphenylalanine (FF), has been proposed, which is based on the crystallization of FF in the amorphous phase under the action of water vapor.

Ultrahigh Electrostrictive Effect in Lead-Free Ferroelectric Ceramics Via Texture Engineering.

The electrostrictive effect, which induces strain in ferroelectric ceramics, offers distinct advantages over its piezoelectric counterpart for high-precision actuator applications, including anhysteretic behavior even at high frequencies, rapid reaction times, and no requirement for poling. Historically, commercially available electrostrictive materials have been lead oxide-based. However, global restrictions on the use of lead in electronic components necessitate the exploration of lead-free electrostrictive ceramics with a high strain performance.

Efficient Broadband Light-Trapping Structures on Thin-Film Silicon Fabricated by Laser, Chemical and Hybrid Chemical/Laser Treatments.

Light-trapping structures formed on surfaces of various materials have attracted much attention in recent years due to their important role in many applications of science and technology. This article discusses various methods for manufacturing light-trapping "black" silicon, namely laser, chemical and hybrid chemical/laser ones. In addition to the widely explored laser texturing and chemical etching methods, we develop a hybrid chemical/laser texturing method, consisting in laser post-texturing of pyramidal structures obtained after chemical etching.

Enhanced Energy Storage Properties in Lead-Free (NaBi)SrTiO-Based Relaxor Ferroelectric Ceramics through a Cooperative Optimization Strategy.

Although relaxor ferroelectrics have been widely investigated owing to their various advantages, there are still impediments to boosting their energy-storage density () and energy-storage efficiency (). In this paper, we propose a cooperative optimization strategy for achieving comprehensive outstanding energy-storage performance in (NaBi)SrTiO (NBST)-based ceramics by triggering a nonergodic-to-ergodic transformation and optimizing the forming process. The first step of substituting NaNbO (NN) for NBST generated an ergodic state and induced polar nanoregions under the guidance of a phase-field simulation.

Nanoscale Vacancy-Mediated Aggregation, Dissociation, and Splitting of Nitrogen Centers in Natural Diamond Excited by Visible-Range Femtosecond Laser Pulses.

Natural IaA+B diamonds were exposed in their bulk by multiple 0.3 ps, 515 nm laser pulses focused by a 0.25 NA micro-objective, producing in the prefocal region (depth of 20-50 μm) a bulk array of photoluminescent nanostructured microtracks at variable laser exposures and pulse energies.

Spatially-Resolved Study of the Electronic Transport and Resistive Switching in Polycrystalline Bismuth Ferrite.

Ferroelectric materials attract much attention for applications in resistive memory devices due to the large current difference between insulating and conductive states and the ability of carefully controlling electronic transport via the polarization set-up. Bismuth ferrite films are of special interest due to the combination of high spontaneous polarization and antiferromagnetism, implying the possibility to provide multiple physical mechanisms for data storage and operations. Macroscopic conductivity measurements are often hampered to unambiguously characterize the electric transport, because of the strong influence of the diverse material microstructure.

Hierarchical Multi-Scale Coupled Periodical Photonic and Plasmonic Nanopatterns Inscribed by Femtosecond Laser Pulses in Lithium Niobate.

The ultrafast interaction of tightly focused femtosecond laser pulses with bulk dielectric media in direct laser writing (inscription) regimes is known to proceed via complex multi-scale light, plasma and material modification nanopatterns, which are challenging for exploration owing to their mesoscopic, transient and buried character. In this study, we report on the first experimental demonstration, analysis and modeling of hierarchical multi-period coupled longitudinal and transverse nanogratings in bulk lithium niobate inscribed in the focal region by 1030 nm, 300 fs laser pulses in the recently proposed sub-filamentary laser inscription regime. The longitudinal Bragg-like topography nanogratings, possessing the laser-intensity-dependent periods ≈ 400 nm, consist of transverse birefringent nanogratings, which are perpendicular to the laser polarization and exhibit much smaller periods ≈ 160 nm.

Ferroelectric Nanodomain Engineering in Bulk Lithium Niobate Crystals in Ultrashort-Pulse Laser Nanopatterning Regime.

Ferroelectric nanodomains were formed in bulk lithium niobate single crystals near nanostructured microtracks laser-inscribed by 1030-nm 0.3-ps ultrashort laser pulses at variable pulse energies in sub- and weakly filamentary laser nanopatterning regimes. The microtracks and related nanodomains were characterized by optical, scanning probe and confocal second-harmonic generation microscopy methods.

Competition between Ferroelectric and Ferroelastic Domain Wall Dynamics during Local Switching in Rhombohedral PMN-PT Single Crystals.

The possibility to control the charge, type, and density of domain walls allows properties of ferroelectric materials to be selectively enhanced or reduced. In ferroelectric-ferroelastic materials, two types of domain walls are possible: pure ferroelectric and ferroelastic-ferroelectric. In this paper, we demonstrated a strategy to control the selective ferroelectric or ferroelastic domain wall formation in the (111) single-domain rhombohedral PMN-PT single crystals at the nanoscale by varying the relative humidity level in a scanning probe microscopy chamber.

Nanohydrodynamic Local Compaction and Nanoplasmonic Form-Birefringence Inscription by Ultrashort Laser Pulses in Nanoporous Fused Silica.

The inscription regimes and formation mechanisms of form-birefringent microstructures inside nano-porous fused silica by tightly focused 1030- and 515-nm ultrashort laser pulses of variable energy levels and pulsewidths in the sub-filamentary regime were explored. Energy-dispersion X-ray micro-spectroscopy and 3D scanning confocal Raman micro-spectroscopy revealed the micro-tracks compacted by the multi-shot laser exposure with the nanopores hydrodynamically driven on a microscale to their periphery. Nearly homogeneous polarimetrically acquired subwavelength-scale form-birefringence (refractive index modulation ~10) was simultaneously produced as birefringent nanogratings inside the microtracks of wavelength-, energy- and pulsewidth-dependent lengths, enabling the scaling of their total retardance for perspective phase-modulation nanophotonic applications.

Engineering of Pyroelectric Crystals Decoupled from Piezoelectricity as Illustrated by Doped α-Glycine.

Design of pyroelectric crystals decoupled from piezoelectricity is not only a topic of scientific curiosity but also demonstrates effects in principle that have the potential to be technologically advantageous. Here we report a new method for the design of such materials. Thus, the co-doping of centrosymmetric crystals with tailor-made guest molecules, as illustrated by the doping of α-glycine with different amino acids (Threonine, Alanine and Serine).

Exploring Charged Defects in Ferroelectrics by the Switching Spectroscopy Piezoresponse Force Microscopy.

Monitoring the charged defect concentration at the nanoscale is of critical importance for both the fundamental science and applications of ferroelectrics. However, up-to-date, high-resolution study methods for the investigation of structural defects, such as transmission electron microscopy, X-ray tomography, etc., are expensive and demand complicated sample preparation.

New Data on Variously Directed Dose-Response Relationships and the Combined Action Types for Different Outcomes of Nanoparticle Cytotoxicity.

Spherical selenium-oxide and copper-oxide nanoparticles (SeO-NP with mean diameter 51 ± 14 nm and CuO-NP with mean diameter 21 ± 4 nm) were found to be cytotoxic for human fibroblast-like cells as judged by decreased ATP-dependent luminescence. Compared with SeO-NP, CuO-NP produced a somewhat stronger effect of this kind. Along with cell hypertrophy developing in response to certain doses of SeO-NP and CuO-NP, our experiment also revealed doses causing a decrease in cell and cell-nucleus sizes.

Local Piezoelectric Properties of Doped Biomolecular Crystals.

Piezoelectricity is the ability of certain crystals to generate mechanical strain proportional to an external electric field. Though many biomolecular crystals contain polar molecules, they are frequently centrosymmetric, signifying that the dipole moments of constituent molecules cancel each other. However, piezoelectricity can be induced by stereospecific doping leading to symmetry reduction.

Advanced Large-Scale Nanofabrication Route for Ultrasensitive SERS Platforms Based on Precisely Shaped Gold Nanostructures.

One of the key issues for SERS-based trace applications is engineering structurally uniform substrates with ultrasensitivity, stability, and good reproducibility. A label-free, cost-effective, and reproducible fabrication strategy of ultrasensitive SERS sensors was reported in this work. Herein, we present recent progress in self-assembly-based synthesis to elaborate precisely shaped and abundant gold nanoparticles in a large area.

Local Polarization Reversal by Ion Beam Irradiation in SBN Single Crystals Covered by Dielectric Layer.

Formation of the domain structure by ion beam irradiation was studied in thermally depolarized Ce-doped strontium barium niobate single crystals covered by a dielectric layer. Three types of irradiation regimes were used: dot exposure, stripe exposure, and line exposure. The dependences of the domain size and depth on the irradiated dose were measured.

Cardioinotropic Effects in Subchronic Intoxication of Rats with Lead and/or Cadmium Oxide Nanoparticles.

Subchronic intoxication was induced in outbred male rats by repeated intraperitoneal injections with lead oxide (PbO) and/or cadmium oxide (CdO) nanoparticles (NPs) 3 times a week during 6 weeks for the purpose of examining its effects on the contractile characteristics of isolated right ventricle trabeculae and papillary muscles in isometric and afterload contractions. Isolated and combined intoxication with these NPs was observed to reduce the mechanical work produced by both types of myocardial preparation. Using the in vitro motility assay, we showed that the sliding velocity of regulated thin filaments drops under both isolated and combined intoxication with CdO-NP and PbO-NP.

Comparative and Combined Vasotoxicity of Nanoparticles Containing Lead and Cadmium.

toxicological experiments were performed on an endothelial cell line exposed to different doses of spherical nanoparticles of cadmium and/or of lead sulfides with mean diameter 37 ± 5 nm and 24 ± 4 nm, respectively. Toxic effects were estimated by Luminescent Cell Viability Assay, endothelin-1 concentration and cell size determination. Some dose-response relationships were typically monotonic (well approximated with hyperbolic function) while others were bi- or even 3-phasic and could be described within the expanded hormesis paradigm.

Some data on the comparative and combined toxic activity of nanoparticles containing lead and cadmium with special attention to their vasotoxicity.

Moderate subchronic intoxication was induced in rats by repeated intraperitoneal injections of PbO (49.6 ± 16.0 nm) and/or CdO (57.

Local electronic transport across probe/ionic conductor interface in scanning probe microscopy.

Charge carrier transport through the probe-sample junction can have substantial consequences for outcomes of electrical and electromechanical atomic-force-microscopy (AFM) measurements. For understanding physical processes under the probe, we carried out conductive-AFM (C-AFM) measurements of local current-voltage (I-V) curves as well as their derivatives on samples of a mixed ionic-electronic conductor LiMnO and developed an analytical framework for the data analysis. The implemented approach discriminates between contributions the highly resistive sample surface layer and the bulk with the account of ion redistribution in the field of the probe.

Surface Piezoelectricity and Pyroelectricity in Centrosymmetric Materials: A Case of α-Glycine.

Surface pyroelectricity and piezoelectricity induced by water incorporation during growth in α-glycine were investigated. Using the periodic temperature change technique, we have determined the thickness (~280 µm) of the near surface layer (NSL) and its pyroelectric coefficient (160 pC/(K × cm) at 23 °C) independently. The thickness of NSL remains nearly constant till 60 °C and the pyroelectric effect vanishes abruptly by 70 °C.