Enhancement Of Dipole Moment Research Articles

Rebuilding Peripheral F, Cl, Br Footprints on Acceptors Enables Binary Organic Photovoltaic Efficiency Exceeding 19.7 %

AbstractGiven homomorphic fluorine (F), chlorine (Cl) and bromine (Br) atoms are featured with gradually enlarged polarizability/atomic radius but decreased electronegativity, the rational screen of halogen species and locations on small molecular acceptors (SMAs) is quite essential for acquiring desirable molecular packing to boost efficiency of organic solar cells (OSCs). Herein, three isomeric SMAs (CH−F, CH−C and CH−B) are constructed by delicately rebuilding peripheral F, Cl, Br footprints on both central and end units. Such a re‐permutation of peripheral halogens could not only maintain the structural symmetry of SMAs to the maximum, but also acquire extra asymmetric benefits of enhanced dipole moment and intramolecular charge transfer, etc. Moreover, central brominating enhances molecular crystallinity of CH−B without introducing undesirable steric hindrance on end groups, thus rendering a better balance between high crystallization and domain size control in PM6:CH−B blend. Further benefitting from the large dielectric constant, small exciton binding energy, optimized molecular packing and great electron transfer integral, CH−B affords the first class binary OSC efficiency of 19.78 %, moreover, the highest efficiency of 18.35 % thus far when increasing active layer thickness to ~300 nm. Our successful screening in rebuilding peripheral halogen footprints provides the valuable insight into further rational design of SMAs for record‐breaking OSCs.

Rebuilding Peripheral F, Cl, Br Footprints on Acceptors Enables Binary Organic Photovoltaic Efficiency Exceeding 19.7 .

Given homomorphic fluorine (F), chlorine (Cl) and bromine (Br) atoms are featured with gradually enlarged polarizability/atomic radius but decreased electronegativity, the rational screen of halogen species and locations on small molecular acceptors (SMAs) is quite essential for acquiring desirable molecular packing to boost efficiency of organic solar cells (OSCs). Herein, three isomeric SMAs (CH-F, CH-C and CH-B) are constructed by delicately rebuilding peripheral F, Cl, Br footprints on both central and end units. Such a re-permutation of peripheral halogens could not only maintain the structural symmetry of SMAs to the maximum, but also acquire extra asymmetric benefits of enhanced dipole moment and intramolecular charge transfer, etc. Moreover, central brominating enhances molecular crystallinity of CH-B without introducing undesirable steric hindrance on end groups, thus rendering a better balance between high crystallization and domain size control in PM6:CH-B blend. Further benefitting from the large dielectric constant, small exciton binding energy, optimized molecular packing and great electron transfer integral, CH-B affords the first class binary OSC efficiency of 19.78 %, moreover, the highest efficiency of 18.35 % thus far when increasing active layer thickness to ~300 nm. Our successful screening in rebuilding peripheral halogen footprints provides the valuable insight into further rational design of SMAs for record-breaking OSCs.

Asymmetrified Benzothiadiazole‐Based Solid Additives Enable All‐Polymer Solar Cells with Efficiency Over 19 %

AbstractDisordered polymer chain entanglements within all‐polymer blends limit the formation of optimal donor‐acceptor phase separation. Therefore, developing effective methods to regulate morphology evolution is crucial for achieving optimal morphological features in all‐polymer organic solar cells (APSCs). In this study, two isomers, 4,5‐difluorobenzo‐c‐1,2,5‐thiadiazole (SF‐1) and 5,6‐difluorobenzo‐c‐1,2,5‐thiadiazole (SF‐2), were designed as solid additives based on the widely‐used electron‐deficient benzothiadiazole unit in nonfullerene acceptors. The incorporation of SF‐1 or SF‐2 into PM6 : PY‐DT blend induces stronger molecular packing via molecular interaction, leading to the formation of continuous interpenetrated networks with suitable phase‐separation and vertical distribution. Furthermore, after treatment with SF‐1 and SF‐2, the exciton diffusion lengths for PY‐DT films are extended to over 40 nm, favoring exciton diffusion and charge transport. The asymmetrical SF‐2, characterized by an enhanced dipole moment, increases the power conversion efficiency (PCE) of PM6 : PY‐DT‐based device to 18.83 % due to stronger electrostatic interactions. Moreover, a ternary device strategy boosts the PCE of SF‐2‐treated APSC to over 19 %. This work not only demonstrates one of the best performances of APSCs but also offers an effective approach to manipulate the morphology of all‐polymer blends using rational‐designed solid additives.

Asymmetrified Benzothiadiazole-Based Solid Additives Enable All-Polymer Solar Cells with Efficiency Over 19 .

Disordered polymer chain entanglements within all-polymer blends limit the formation of optimal donor-acceptor phase separation. Therefore, developing effective methods to regulate morphology evolution is crucial for achieving optimal morphological features in all-polymer organic solar cells (APSCs). In this study, two isomers, 4,5-difluorobenzo-c-1,2,5-thiadiazole (SF-1) and 5,6-difluorobenzo-c-1,2,5-thiadiazole (SF-2), were designed as solid additives based on the widely-used electron-deficient benzothiadiazole unit in nonfullerene acceptors. The incorporation of SF-1 or SF-2 into PM6 : PY-DT blend induces stronger molecular packing via molecular interaction, leading to the formation of continuous interpenetrated networks with suitable phase-separation and vertical distribution. Furthermore, after treatment with SF-1 and SF-2, the exciton diffusion lengths for PY-DT films are extended to over 40 nm, favoring exciton diffusion and charge transport. The asymmetrical SF-2, characterized by an enhanced dipole moment, increases the power conversion efficiency (PCE) of PM6 : PY-DT-based device to 18.83 % due to stronger electrostatic interactions. Moreover, a ternary device strategy boosts the PCE of SF-2-treated APSC to over 19 %. This work not only demonstrates one of the best performances of APSCs but also offers an effective approach to manipulate the morphology of all-polymer blends using rational-designed solid additives.

One molecule to couple them all: Toward realistic numbers of molecules in multiscale molecular dynamics simulations of exciton-polaritons.

Collective strong coupling of many molecules to the confined light modes of an optical resonator can influence the photochemistry of these molecules, but the origin of this effect is not yet fully understood. To provide atomistic insights, several approaches have been developed based on quantum chemistry or molecular dynamics methods. However, most of these methods rely on coupling a few molecules (or sometimes only one) to a single cavity mode. To reach the strong coupling regime with such a small number of molecules, much larger vacuum field strengths are employed than in experiments. To keep the vacuum field realistic and avoid potential artefacts, the number of coupled molecules should be significantly increased instead, but that is not always possible due to restrictions on computational hardware and software. To overcome this barrier and model the dynamics of an arbitrarily large ensemble of molecules coupled to realistic cavity fields in atomistic molecular dynamics simulations, we propose to coarse-grain subsets of molecules into one or more effective supermolecules with an enhanced dipole moment and concerted dynamics. To verify the validity of the proposed multiscale model, we performed simulations in which we investigated how the number of molecules that are coupled to the cavity affects excited-state intra-molecular proton transfer, polariton relaxation, and exciton transport.

Effect of Ag2O nanoparticles on the excited state dipole moment of a novel BMNFC molecules through solvatochromic shift method

We experimentally determined the ground and excited state dipole moments of BMNFC (5-bromo-N’-[(Z)-(4-methoxyphenyl)methylidene]naptho[2,1-b]furan-2-carbohydrazide) dye using the solvatochromic shift method and various solvatochromic correlations, including Lippert’s, Bakhshiev’s, Kawski-Chamma-Viallet’s, and solvent polarity equations. We employed the B3LYP/6-311G (d) level of theory to calculate the HOMO, LUMO, and MESP. In this study, we synthesized Ag2O nanoparticles using a quick and cost-effective chemical reduction method. Then, we used carboxymethylcellulose (CMC) as a capping agent. We studied the size, shape, and composition of these nanoparticles using a variety of analytical techniques. Transmission electron microscopy (TEM) analysis revealed a spherical morphology with an average diameter of 17 nm. The results show that adding Ag2O nanoparticles to BMNFC molecules changes their symmetric charge distribution, which in turn enhances their dipole moment. Molecules of enhanced dipole moment have attractive features in biomedical applications. Each molecule’s symmetry point group determines the extent to which nanoparticles affect the BMNFC molecule.

Surface-Enhanced Raman Scattering on Size-Classified Silver Nanoparticles Generated by Laser Ablation.

This study delved into the complex interplay between the nanostructural characteristics of nanoparticles and their efficacy in surface-enhanced Raman scattering (SERS) for sensitive detection of trace chemical substances. Silver nanoparticles were prepared for the SERS substrate by combining laser ablation, postannealing processes (up to 500 °C), and electrostatic mobility classification, allowing high-purity silver nanoparticles with controlling their sizes (40-100 nm) and aggregate structures. These nanoparticles were then inertially deposited on the substrates to create SERS-active surfaces, employing Rhodamine B as a probe to assess the impact of particle size, shape, and deposition density on SERS effectiveness. Our findings revealed that spherical nanoparticles, especially those approximately 50 nm in diameter, controlled to a spherical structure through gas-phase annealing at 500 °C and subsequent classification, yielded the most significant SERS enhancement. This optimal can be explained by the particle size response of the surface plasmon resonance, where the enhancement of the Raman signal for particles up to 50 nm (1/10 of the laser wavelength used in this study, 532 nm) arises from a balance between the enhancement of dipole moment and the number of "hot spot" regions (respectively proportional to the cube and inverse square of the diameters in theory, leading to a linear relationship between signal intensity and particle diameter); meanwhile, in larger size region than 50 nm, the Raman signal was decreased owing to the attribution of the phase difference between the electric field and dipole moment. Furthermore, we found that a deposition density of 2 μg resulted in nearly a single layer of particles, which is crucial for maximizing SERS hotspots and, consequently, the enhancement effect.

P-Phenylene bridge induced dual twisting and metameric impacts on molecular structure and dipole Moments: A computational study on pyridinium phenolate mesomeric betaines using linear response theory

In this contribution, molecular structures, and dipole moments (using self-consistent and linear response theories) were reported for two p-phenylene bridged mesomeric betaines, using AM1, HF, B3LYP, B3PW91, M06-2X, LC-ωPBE, CAM-B3LYP, MP2 and CASSCF methodologies. In this work (1) metameric influences on molecular conformations, and (2) molecular electric dipole moments, and then (3) impact of bridge by comparing with unbridged derivatives, are investigated. Metameric influence on conformational preference was observed and p-phenylene bridge was found to be acting like a facilitator. While most of the methodologies predicted only reasonable impacts of metamerism on molecular dipole moments; the CASSCF method predicted around 2-fold enhanced dipole moment for Reichardt’s type than Brooker’s type. p-phenylene bridge effectively enhanced the dipole moments (∼2-fold) than non-bridged zwitterions. Linear response theory-based (field-dependent) results were found to be similar to the static (field-independent) dipole moments. HF, MP2 and CASSCF exhibited similar behaviors, and DFT-based methodologies very different characteristics.

Theoretical and experimental studies on sulfasalazine interactions with poly (lactic acid): Impact of hydrogen bonding and charge transfer interactions on molecular structure, electronic and optical properties

The interaction between sulfasalazine (SSZ) through different functional groups and poly (lactic acid) (PLA) in the chloroform phase was investigated in this study using density functional theory (DFT) and time-dependent density functional theory (TDDFT) methods. The binding energy and thermodynamic parameters show that the hydrogen double bond interaction between SSZ and PLA in state I (−0.71 eV) is stronger than in states II (−0.64 eV) and III (−0.51 eV). The SSZ and PLA interaction results in an enhanced dipole moment, greater solubility, and more negative values for Gibbs free energy (ΔGsolv) and energy gap (Eg). Considerable changes in absorption peaks of SSZ and PLA indicate surface adsorption of the drug (SSZ) into the carrier (PLA) in UV–Vis spectra. Theoretical UV–Vis analysis demonstrates SSZ interaction with PLA happens in the ultraviolet region with a maximum absorption peak at 380 nm, which is close to experimental UV–Vis analysis. The experimental spectra showed minimal variations in the maximum absorption wavelength, with respect to theoretical calculations. The presence of SSZ was found to cause a modification in the structure of PLA, as evidenced by both experimental and theoretical Infrared (IR) spectra.

Building-up relations between intra- and intermolecular interactions, miscibility, and performance for low-cost, efficient fully non-fused acceptor-based organic solar cells

Although the molecular electronic forces (e.g., intra- and intermolecular interactions) within active layers largely govern the device performance of organic solar cells (OSCs), they are complicated and less understood. In this study, we have synthesized two low-cost isomeric non-fused acceptors (TT-Naph1 and TT-Naph2) with 1-naphthyl and 2-naphthyl aromatic chains, respectively and quantified the molecular interaction−photovoltaic performance relationship. Benefiting from the enhanced dipole moment, TT-Naph2 possesses a strong dipole–dipole intermolecular interaction, while the improved backbone planarity endows TT-Naph1 with a strengthened intramolecular charge-transfer effect, which can regulate the desired blend morphology with the D18 donor polymer as a result of its low miscibility with D18. Less miscible nanostructures are more pronounced in the layer-by-layer (LBL) systems than bulk heterojunction (BHJ) ones, increasing the power conversion efficiencies (PCEs) in the sequence of TT-Naph2 BHJ < TT-Naph1 BHJ < TT-Naph2 LBL < TT-Naph1 LBL. Notably, a ternary LBL OSC based on TT-Naph1 achieved remarkable PCE of 18.41%, one of the top values for LBL-type OSCs. Our findings provide insights into the controlling effect of intra- and intermolecular interactions on the active layers for efficient non-fused acceptor-based OSCs.

Enhanced Photovoltaic Property and Panchromatic Photocatalytic by Forming D‐π‐A‐Bacteriochlorin Dyads: A Computational Investigation

The photovoltaic characteristics and panchromatic photocatalysis based on monomers and bithiophene‐chlorophyll dyads is investigated. The optical properties and the electron transport capacity of the titled dyes are explicated by investigating the geometry, electronic structure, electron injection, and recombination, intramolecular charge transfer, regeneration process, dye aggregation, and light‐harvesting. The results manifest that the original 3,3′‐dithioalkyl‐2,2′‐bithiophene (SBT)‐based molecule behaves better with photovoltaic performance and an enhanced JSC and VOC. For molecular design, the designed dyads not only show the enhanced absorption range and prolonged excited lifetimes but also noticeable electron transfer ability. Moreover, the strong interfacial interaction, fast electron transfer process, long recombination distance, inhibition in dye aggregate, enhanced regenerative interaction energy are elucidated, which is beneficial for a better photocurrent response. However, the slight shift of the conduction band edge in dyads significantly reduces the VOC, especially for SBT‐Chl. Among dyads, SBT‐BChl exhibits outstanding photovoltaic performance of 14%. Besides, photocatalysis analysis manifests that the dyad composites behave with red‐shifted spectra, enhanced dipole moments, better interfacial interaction to ensure electron transfer, which significantly improved the photocatalytic performance of TiO2. Our study is expected to offer theoretical guidelines for further screening the promising D‐π‐A‐bacteriochlorin dyads in photoelectric functional materials.

Precisely Orientating Atomic Array in One-Dimension Tellurium Microneedles Enhances Intrinsic Piezoelectricity for an Efficient Piezo-Catalytic Sterilization.

Comprehensively understanding the interdependency between the orientated atomic array and intrinsic piezoelectricity in one-dimension (1D) tellurium (Te) crystals will greatly benefit their practical piezo-catalytic applications. Herein, we successfully synthesized the various 1D Te microneedles by precisely orientating the atomic growth orientation by tuning (100)/(110) planes ratios (Te-0.6, Te-0.3, Te-0.4) to reveal the secrets of piezoelectricity. Explicitly, the theoretical simulations and experimental results have solidly validated that the Te-0.6 microneedle grown along the [110] orientation possesses a stronger asymmetric distribution of Te atoms array causing the enhanced dipole moment and in-plane polarization, which boosts a higher transfer and separation efficiency of the electron and hole pairs and a higher piezoelectric potential under the same stress. Additionally, the orientated atomic array along the [110] has p antibonding states with a higher energy level, resulting in a higher CB potential and a broadened band gap. Meanwhile, it also has a much lower barrier toward the valid adsorption of H2O and O2 molecules over other orientations, effectively conducive to the production of reactive oxygen species (ROS) for the efficient piezo-catalytic sterilization. Therefore, this study not only broadens the fundamental perspectives in understanding the intrinsic mechanism of piezoelectricity in 1D Te crystals but also provides a candidate 1D Te microneedle for practical piezo-catalytic applications.

Ni doping in unit cell of BiOBr to increase dipole moment and induce spin polarization for promoting CO2 photoreduction via enhanced build-in electric field

The weak bulit-in electric field of BiOBr material is difficult to promote electron-hole separation, resulting in low photocatalytic CO2 reduction performance. In this work, Ni has been successfully doped in unit cell of BiOBr and increase the unit cell dipole moment of BiOBr along the x, z directions from 0 to 0.04768 and 0.11293 eÅ, respectively. Enhancement of the unit cell dipole moment induces electron spin polarization near the Fermi energy level, which increases the surface potential from 18 mV to 36.2 mV. When the Ni doping ratio is 3 %, a higher carrier separation efficiency is achieved. 3 %Ni-BiOBr has the excellent CO2 photoreduction performance with CO yield of 378.7 μmolg−1h−1, which is 4.3 times higher than pure BiOBr (86.75 μmolg−1h−1). Briefly, this research work throws light on enhancing built-in electric field by increasing unit cell dipole moment and inducing spin polarization for improving the photocatalytic performance.

Unravelling the effect of donor-π-acceptor architecture in designing 1,3-indanedione based sensitizers for DSSC applications

• 1,3-indanedione-based electron-acceptor group has been employed in designing new sensitizers and theoretical calculations of the nine sensitizers, that are designed based on D-π-A architecture, were performed at DFT and TDDFT level. • HOMO-LUMO energy levels of the designed dyes are matching with the energy levels of titania and redox couples. • Frontier molecular orbital (FMO) analysis revealed intra-molecular charge transfer from the electron-donor to the 1,3-indanedione electron-acceptor. • Two-fold enhancement of dipole moment was observed in all sensitizers upon binding on (TiO 2 ) 9 nanocluster. • The simulated electronic spectra of free dyes and Dye@TiO 2 encompass the entire visible region. • Phenoxazine (POZ) and phenothiazine (PTZ) electron-donor moieties significantly improved the chemical reactivity and photophysical properties and therefore, corresponding RK4 and RK5 sensitizers are better than others. • The D-π-A architecture is found to be better than D-π-A-D architecture in the case of 1,3-indanedione-based sensitizers. Molecular engineering plays a vital role in the design of efficient organic sensitizers for DSSC applications. The study highlights the density functional theory calculations of nine organic sensitizers, designed based on a new 1,3-indanedione electron-acceptor cum anchoring group. The new sensitizers (RK1-9) have been designed by tailoring a modified 1,3-indanedione electron-acceptor with conventional electron-donors in the form of D-π-A architecture. Geometry optimization studies reveal that the RK7 & RK8 molecules have more twisted geometries. Similarly, the RK5 dye has the smallest energy gap of 2.34 eV compared to other dyes. LUMO energy levels of all the designed dyes are positive, found above the conduction band energy level, and the HOMO energy levels were more negative than the redox potentials. Calculated electrochemical parameters suggest that the dyes RK1-5 and RK9 inject the electrons efficiently into the conduction band of TiO 2 . Further, the Gibbs free energies of the dyes indicate that the RK4 and RK5 dyes regenerate much faster than the other dyes. The electronic absorption spectra of the RK dyes were steadily shifting towards the longer wavelength region with solvent polarity and further red-shifts upon adsorbing on the (TiO 2 ) 9 nanocluster. The LUMO and LUMO+1 wave functions of the RK dye@(TiO 2 ) 9 complexes are confined to the (TiO 2 ) 9 nanocluster, suggesting effective intramolecular charge transfer upon photo-excitation. Overall, the computational study demonstrates the significance of the 1,3-indanedione electron-acceptor and o the D-π-A architecture in the molecular design of new organic sensitizers for DSSC applications.

External Electric Field Induces a Mechanistic Crossover in the Reactivity of 1,3-Dienes with Sulfur Dioxide: Sulfolene Versus Sultine

1,3-Dienes (1) react with SO2 to produce sulfolenes (2) and sultines (3). Previous experiments and computational studies have shown that hetero-Diels-Alder (HDA) reaction producing the sultine is kinetically favorable compared to the chelotropic (CE) reaction producing the sulfolene. In this article, DFT calculations for a series of substituted 1,3-dienes show that under the influence of a moderate oriented external electric field (OEEF) of 2.0-4.0 V nm-1 along the reaction axis, the chelotropic reaction becomes the kinetically favorable reaction. In the absence of the OEEF, the destabilizing distortion involved in bringing the 1,3-diene and SO2 to the CE transition-state (TS) exceeds than for the HDA TS. However, under the influence of the OEEF, the strongly stabilizing electrostatic interactions in the CE TS effectively overcome the structural distortion energy. The enhanced dipole moment of the CE TS vis-à-vis the HDA TS under the OEEF accounts for the stabilization of the former.

A New Platform of B/N‐Doped Cyclophanes: Access to a π‐Conjugated Block‐Type B3N3 Macrocycle with Strong Dipole Moment and Unique Optoelectronic Properties

AbstractWe herein describe a new design principle to achieve B/N‐doped cyclophane where an electron‐donor block of three triarylamines (Ar3N) and an acceptor block of three triarylboranes (Ar3B) are spatially separated on opposite sides of the π‐extended ring system. DFT computations revealed the distinct electronic structure of the block‐type macrocycle MC‐b‐B3N3 with a greatly enhanced dipole moment and reduced HOMO–LUMO energy gap in comparison to its analogue with alternating B and N sites, MC‐alt‐B3N3. The unique arrangement of borane acceptor Ar3B and amine donor Ar3N components in MC‐b‐B3N3 induces exceptionally strong intramolecular charge transfer in the excited state, which is reflected in a largely red‐shifted luminescence at 612 nm in solution. The respective linear open‐chain oligomer L‐b‐B3N3 was also synthesized for comparison. Our new approach to donor–acceptor macrocycles offers important fundamental insights and opens up a new avenue to unique optoelectronic materials.

A New Platform of B/N-Doped Cyclophanes: Access to a π-Conjugated Block-Type B3 N3 Macrocycle with Strong Dipole Moment and Unique Optoelectronic Properties.

We herein describe a new design principle to achieve B/N-doped cyclophane where an electron-donor block of three triarylamines (Ar3 N) and an acceptor block of three triarylboranes (Ar3 B) are spatially separated on opposite sides of the π-extended ring system. DFT computations revealed the distinct electronic structure of the block-type macrocycle MC-b-B3N3 with a greatly enhanced dipole moment and reduced HOMO-LUMO energy gap in comparison to its analogue with alternating B and N sites, MC-alt-B3N3. The unique arrangement of borane acceptor Ar3 B and amine donor Ar3 N components in MC-b-B3N3 induces exceptionally strong intramolecular charge transfer in the excited state, which is reflected in a largely red-shifted luminescence at 612 nm in solution. The respective linear open-chain oligomer L-b-B3N3 was also synthesized for comparison. Our new approach to donor-acceptor macrocycles offers important fundamental insights and opens up a new avenue to unique optoelectronic materials.

On the surface interaction of C60 with superalkalis: a computational approach

We study the surface interaction of C60 with superalkali (SA) clusters for SA = FLi2, OLi3 and NLi4 using a density functional approach and compare it with exohedral LiC60 complex. The interaction takes place via two or more Li–C bonds and leads to SAC60 complexes, which are stabilised by electron transfer from SA to C60 moieties. Thus, SAC60 complexes can be represented as (SA)+C60 − having enhanced dipole moment and the energy gap, unlike endohedral SA@C60 complexes with negligible dipole moment and lower energy gap. These findings suggest that C60 fullerene can be activated by the surface interaction with SA clusters.

Ferromagnetic, ferroelectric, and magnetoelectric properties in individual nanotube-based magnetoelectric films of CoFe2O4/BaTiO3 using electrically resistive core-shell magnetostrictive nanoparticles

Since 2010, two-phase magnetoelectric (ME) films consisting of magnetostrictive and piezoelectric phases have been continuously developed with regard to their promising ME responses, for potential applications such as ultra-sensitive magnetic sensing, magnetic-field induced energy harvesting, and nano-transduction. Generally, one-dimensional piezoelectric nanowires, nanorods, and nanotubes are used to enlarge the active area for strain transfer between the piezoelectric and magnetostrictive phases of ME films. In this study, we developed 1–2 type individual nanotube-based ME films of CoFe2O4/BaTiO3 with main considerations in the optimization of magnetostrictive phase, piezoelectric phase, and interface between the phases, respectively. First, core-shell magnetostrictive nanoparticles were improved with a high resistivity of 3.89 MΩ·cm and saturation magnetization of 20.8 emu/g via a sufficient TiO2 coating on the CoFe2O4 nanoparticles. Then, individually free-standing TiOx nanotubes were prepared with an optimal structure exhibiting a large pore size of 220 nm and high interspace distance of 80 nm. Final 1–2 type ME films of CoFe2O4/BaTiO3 were successfully prepared by magnetostrictive particle electrodeposition and perovskite conversion in sequence. Enhanced dipole moments through high amounts of BaTiO3 phase were achieved with a maximal remnant polarization (Pr) of 0.192 µC/cm2 from the AC-electrodeposited (AC-) ME films exhibiting a dense film structure. Maximal ME coefficient of the AC-ME films was achieved with magnitude of 27.39 mV/cm∙Oe at Hbias = 1000 Oe. As a result, considering the investigations, the 1–2 type ME films could be expected for possible applications such as high-sensitive magnetic sensors or low-power energy harvesters.

Nanoclusters and amorphous ice flakes built from water dimers

The water-solid interaction is fundamentally important for understanding and controlling the structures of interfacial water. Here we study the initial stage of water adsorption and nucleation on a Cd(0001) surface, through a combination of low temperature scanning tunnelling microscopy (STM) experiments and first-principles density-functional theory (DFT) calculation. Water is found to aggregate into various clusters with the dominant of water dimers. Particularly, the amorphous ice nanoflakes are built exclusively from water dimers. Driven by the electric field from a STM tip, the water dimers can hop across the surface, detach from a cluster with subsequent attaching to another, or rotate or diffuse within the amorphous ice nanoflakes. DFT calculations demonstrate that the ultrahigh stability of water dimers results from the adsorption-induced enhancement of dipole moment of water.