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Recently, NaNbO3-based ceramics with excellent energy storage performances (ESPs) and fast charge-discharge characteristics have attracted great attention. In this case, BaTiO3 modified 0.85NaNbO3-0.15Bi(Zn2/3Nb1/3)O3 (0.85NN-0.15BZN-yBT) ceramics were designed and successfully fabricated using solid state synthesis. The discharge storage density of the ceramics increases from 1.22 J/cm3 at y = 0–1.84 J/cm3 at y = 8%, which is 1.5 times higher than pure 0.85NN-0.15BZN ceramics. This ceramic reveals excellent temperature stability up to 150 °C, good discharge cycling after 105 cycles and high discharge speed of 2.0 μs, broadening the scope of NaNbO3-based ceramics for energy storage applications.

In this work, Mn modified 0.94Bi0.5Na0.5TiO3-0.06BaTiO3 thin films (abbreviation for BNT-BT-Mnx) are prepared on Pt/Ti/SiO2/Si substrate via sol-gel and spin-coating. The influences of Mn dopant on the microstructural characteristics, dielectric and energy storage performances are studied systematically. It is found that by incorporating the Mn into BNT-BT, the breakdown strength and maximum polarization are enhanced dramatically, leading to the giant energy storage density of 54 J/cm3, with high permittivity 355 at 1 kHz. Moreover, the dominant leakage conduction mechanisms of the thin films are studied by linear fitting method, revealing that the leakage current mechanism of BNT-BT-Mnx films transforms from space-charge-limited conduction (SCLC) to Schottky emission as the increasing of electric field. The excellent energy storage density as well as dielectric properties suggest that BNT-BT-Mn6 thin film might be an attractive lead-free material for energy storage devices.

The effects of sintering atmospheres (air, O2, and N2) and defect chemistry role of Mn in the structure, electrical properties, and conduction mechanism of Ca0.6Sr0.4TiO3 (CST) ceramics were extensively investigated in this study. O2 atmosphere sintering resulted in a decrease in the concentration of oxygen vacancies, as revealed by the expanded unit cell and increased Ti ions' valence state. The reverse was the case for samples sintered in N2. Interestingly, sintering in both of O2 and N2 resulted in deteriorated bulk resistivity, due to the transition of the conduction mechanism (n-type electronic→ionic→p-type electronic conduction) with increasing oxygen partial pressure (PO2). This was verified by subjecting the samples to annealing treatment in different atmospheres and measuring their high-temperature equilibrium conductivities. Additionally, Mn-doped CST ceramics demonstrated higher resistivity than that of the pure CST ceramics, regardless of the sintering atmospheres, which could be attributed to the self-changing of Mn ions’ valence state in different PO2.

There is a general observation that the Curie temperature and piezoelectric property of the ferroelectric ceramics can be enhanced only at the expense of each other, i.e., higher piezoelectricity, lower Curie temperature, thus, limits their applications over broad temperature range. In this research, Sm-modified 0.15 Pb(Mg1/3Nb2/3)O3-(0.85-x)PbZrO3-xPbTiO3 ceramics have been studied, where excellent piezoelectric coefficients d33 = 720 pC/N, d33∗ = 950 pm/V and high Curie temperature TC = 293 °C were simultaneously achieved for x = 0.42 composition by designing the morphotropic phase boundary (MPB) with local structural heterogeneity. Of particular significance is that a high thermal stability was observed with piezoelectric variation below 20% with temperature up to 280 °C, demonstrating that the x = 0.42 composition is a good candidate for piezoelectric application over broad temperature range where high temperature stability is required. This work provides a good paradigm for designing high-performance piezoelectric ceramics with high thermal stability via a combination of MPB and local structural heterogeneity.

Dielectric ceramic capacitors, with the advantages of high power density, fast charge-discharge capability, excellent fatigue endurance, and good high temperature stability, have been acknowledged to be promising candidates for solid-state pulse power systems. This review investigates the energy storage performances of linear dielectric, relaxor ferroelectric, and antiferroelectric from the viewpoint of chemical modification, macro/microstructural design, and electrical property optimization. Research progress of ceramic bulks and films for Pb-based and/or Pb-free systems is summarized. Finally, we propose the perspectives on the development of energy storage ceramics for pulse power capacitors in the future.

A core-shell structural nanoparticles preparative technique was applied to produce BaTiO3@NiO ceramics with excellent energy storage performance. Shell layers of NiO were coated onto BaTiO3 nanoparticles by sol-precipitation method. The structures, dielectric and energy storage properties of the BaTiO3@NiO ceramics were systematically investigated. Results show that, high-densification microstructures with fine-crystalline and uniform distribution are observed in all the ceramics, and excellent energy storage density of 2.72 J cm−3 with low remnant polarization is achieved at 230 kV cm-1 in BaTiO3@1 %NiO ceramics, which also possesses fast discharge features (τ0.9

Lone pair-π (LP-π) interactions between Lewis basic heteroatoms, such as oxygen and sulfur, and electron-deficient π systems, are an important type of non-covalent interactions. However, they have been seldomly used to control catalyst-substrate interactions in catalysis. We performed density functional theory calculations to investigate the strengths of LP-π interactions between different lone pair donors and cationic π systems, and at different complexation geometries. Energy decomposition analysis calculations indicated that the dominant stabilizing force in LP-π complexes is electrostatic interactions and the electrostatic potential surface of the π system predicts the most favorable site to form LP-π complexes. Benzotetramisole (BTM) is revealed as a privileged acyl transfer catalyst that promotes LP-π interactions because the positive charge of the acylated BTM is delocalized onto the dihydroimidazole ring, which binds strongly with a variety of oxygen and sulfur lone pair donors.

Energy storage dielectric ceramics play a more and more important role in power or electronics systems as a pulse power material, and the development of new technologies has put forward higher requirements for energy storage properties. Here, the sol-gel method was used to synthetize the 0.9BaTiO3-0.1Bi(Mg1/2Zr1/2)O3 (0.9BT–0.1BMZ) precursor powder and 0.9BT-0.1BMZ ceramics with pseudocubic phase was obtained. The 0.9BT-0.1BMZ dielectric ceramics possessed a strong relaxation behavior with 1.64 relaxation degree (g) and 0.15 eV relaxation activation energy (Ea) fitted by modified Curie–Weiss law and Vogel-Fulcher formulas, respectively. The most important was that by controlling the grain size to be reduced, the discharge energy storage density had been improved to 2.0 J/cm3 with high breakdown strength (325 kV/cm). In addition, the comprehensive analysis of electric field distributions, breakdown paths, and impedance spectra was illustrated the enhanced grain boundary effect can improve the energy storage performance obviously.

Poly (N-ethylaniline) (PNEA) composites with varying silicate content were fabricated on copper through a novel electropolymerized strategy in acidic solution. Thickness, compactness, conductivity and adhesive strength of the composite (PNEA-10Si) were optimized as silicate content reached 10 mM. Electrochemical, morphological and solution analyses were employed to evaluate the protective performance of PNEA and PNEA-10Si coatings for copper in 3.5 % NaCl solution. Results of electrochemical analyses indicated that as-prepared coatings retarded the oxygen reduction process efficiently for copper in 3.5 % NaCl solution, drained corrosion current density and elevated interfacial charge transfer resistance. Due to favorable barrier effect, compact structure and low porosity index, PNEA-10Si composite exhibited superior anti-corrosive performance, which was more tolerant than PNEA during long-time immersion. PNEA-10Si coated sample exhibited a stable topography after 144 h immersion with the minimum concentration of released ions revealing the improved protection capacity. Electronic/atomic-multiscale calculations were conducted to clarify the deposition and protection mechanism of as-prepared coatings. Outcomes of density functional theory corroborated that silicate is stabilized in the PNEA layer via electrostatic force; and immobile silicate positively contributed to the charge transfer barrier of the composite. Molecular dynamics simulations evidenced that the favorable compatibility between PNEA and silicate facilitated polymer deposition and confined in-situ ions diffusion.

Sodium niobate (NN)-based lead-free ceramic DyxNa1–x(Nb0.9Ta0.1)O3 denoted as (DNNT) x = 0, 0.05, 0.1, 0.2, and 0.3 was synthesized via a conventional solid-state method to achieve bulk lead-free d...

[(0.12BiAlO3-0.88BaTiO3)+0.5 wt%Nb2O5]+x wt.% B–Al–Si glass ceramics (x = 0, 1, 2, and 4) were prepared by solid-state method. The effects of B–Al–Si glass additive on microstructural and electrical properties were investigated. After the adding of B–Al–Si glass, quartz appeared as a new impurity phase and the average grain size of the samples decreased (from 540 nm to 330 nm). All the samples satisfy the EIA X8R specification, meanwhile, the breakdown strength (BDS) increased (from 17 kV/mm to 29 kV/mm) with the rising glass content. The ratios of relaxation time of grain boundary to grain (τgb/τg) of the ceramics at 460 °C were calculated according to the complex impedance data. It is found that decreased value of τgb/τg suggests a weakened interfacial polarization effect after B–Al–Si glass addition, which is beneficial to the BDS performance of ceramics.

Capacitor is an important part of many electronic devices, so the temperature stability as one key parameter of capacitor needs to be improved constantly for meeting the requirements of various application temperature. Here, combined with the X-ray diffraction (XRD), selected area electron diffraction (SAED) and Vienna Ab-initio Simulation Package (VASP) calculation, it was confirmed that Ca ion can substitute the Ti site in the BaTi1-xCaxO3-x [BTC100×] (0 ≤ x ≤ 0.05) ceramics synthesized by solid-phase method which greatly improved the low-temperature stability of dielectric constant. Moreover, introducing Bi3+ and Zn2+ into BTC4 to form (1-y)BaTi0·96Ca0·04O2.96-yBi(Zn0·5Ti0.5)O3 [(1-y)BTC4-yBZT] (0.1 ≤ y ≤ 0.2) ceramics can further improve the dielectric-temperature stability by means of diffused phase transition and core-shell structure. Most importantly, the 0.85BTC4-0.15BZT ceramics with a pseudocubic perovskite structure possessed a temperature coefficient of capacitance at 25 °C ( T C C 25 °C ) being less than ±15% over a wide temperature range of −55 °C–200 °C and a temperate dielectric constant (e = 1060) and low dielectric loss (tanδ = 1.5%), which measure up to the higher standard in the current capacitor industry such as X9R requirements.

The solid-state sintering route was employed for the production of (1-x)Bi2(Li0.5Ta1.5)O7-xTiO2 (x = 0, 0.02, 0.04, 0.06, 0.08) ceramics. The phase, microstructure and microwave dielectric properties of each ceramic composition were determined via X-ray diffraction, scanning electron microscopy and Haki Colmon resonator technique, respectively. The dielectric constant, tan δ and AC conductivity were also determined for the composition of x = 0.04. The TiO2 addition developed new phases of Bi3Ti4O12 and Bi3TaTiO9 for x = 0.04 along with Bi2(Li0.5Ta1.5)O7 phase which disappeared for x = 0.08. The τf of Bi2(Li0.5Ta1.5)O7 was tuned through zero by TiO2 addition and good microwave dielectric properties er~67.2, Qufo13,767 GHz and τf ~ −1.45 ppm/°C can be obtained for the composition of x = 0.04 sintered at 1050 °C for 2 h. This ceramic composition is a suitable candidate for 5G cellular base station resonator application.

0.5wt%MnO2-doped (1 − x)BaTiO3–xBiCoO3 ceramics short as (1 − x)BT–xBC–M sintered in air and reducing atmosphere via solid-state process were investigated. The X-ray diffraction results showed that solid solubility in (1 − x)BT–xBC ceramics sintered in the air was higher than that in reducing atmosphere. (1 − x)BT–xBC–M ceramics sintered in air transformed from tetragonal to pseudo-cubic phase when x ≥ 0.1. The scanning electron microscopy results indicated that the average grain size increased with the BC component increasing; however, opposite phenomena occurred in samples sintered in the reducing atmosphere. The dielectric temperature curves of samples sintered in reducing atmosphere were flatted with excellent insulation resistivity of an order of magnitude of 1013 Ω·cm, while anomalous dielectric constant and dielectric loss of samples sintered in the air with deteriorated insulation resistivity of an order of magnitude of 107 Ω·cm. The anti-reduction mechanism of (1 − x)BT–xBC–M system was explained by the “electron–hole” trapping effect and formation of defect dipoles $$\left[ {{\text{Mn}}_{{{\text{Ti}}}} ^{{\prime \prime }} - V_{{\text{O}}}^{{ \cdot \cdot }} } \right]$$ and $$\left[ {2{\text{Co}}_{{{\text{Ti}}}} ^{\prime } - V_{{\text{O}}}^{{ \cdot \cdot }} } \right]$$ .

Tunneling electroresistance (TER) is the change in tunneling resistance induced by ferroelectric polarization reversal in ferroelectric tunnel junctions (FTJs), and how to achieve a giant TER has always been a central topic in the study of FTJs. In this work, by considering the NaTiO3/BaTiO3/LaTiO3 junction with asymmetric polar interfaces as an example, we propose a novel scheme to realize a giant TER based on the reversible partial metallization of ferroelectric barrier upon the switching of ferroelectric polarization. Density functional theory calculations indicate that high on-state and low off-state conductances are obtained and the TER ratio is as high as 3.20 × 108% due to the reversible partial barrier metallization, which leads to a great difference in the effective tunneling barrier widths. The reversible partial barrier metallization, accompanied by the ferroelectric polarization reversal, is driven by the parallel or anti-parallel alignment of the depolarization electrical field of the ferroelectrical barrier and a strong built-in electrical field cooperatively contributed by the asymmetric polar interfaces and the difference in the work functions of the two leads. The findings suggest a feasible scheme for constructing promising high performance FTJ memory devices by combining both asymmetric polar interfaces and substantially different work functions.

G-quadruplex (G4) structures formed by guanine-rich nucleic acids are implicated in essential physiological and pathological processes and serve as important drug targets. The genome-wide detection of G4s in living cells is important for exploring the functional role of G4s but has not yet been achieved due to the lack of a suitable G4 probe. Here we report an artificial 6.7 kDa G4 probe (G4P) protein that binds G4s with high affinity and specificity. We used it to capture G4s in living human, mouse, and chicken cells with the ChIP-Seq technique, yielding genome-wide landscape as well as details on the positions, frequencies, and sequence identities of G4 formation in these cells. Our results indicate that transcription is accompanied by a robust formation of G4s in genes. In human cells, we detected up to >123 000 G4P peaks, of which >1/3 had a fold increase of ≥5 and were present in >60% promoters and ∼70% genes. Being much smaller than a scFv antibody (27 kDa) or even a nanobody (12–15 kDa), we expect that the G4P may find diverse applications in biology, medicine, and molecular devices as a G4 affinity agent.

The current work presents the designed series of compositions within pseudocubic regions based on (1–x)La0.03Na0.91NbO3–xBi(Li0.5Nb0.5)O3 ceramics abridged as (1–x)LNN–xBLN meant for energy storage...

Two new zinc coordination polymers, {[Zn(iPrIPA)(bpa)]⋅2H2O}n (1) and [Zn2(iPrIPA)2(bpp)]n (2) (iPrIPA = 5-i-propoxyisophthalate, bpa = 1,2-bis(4-pyridyl) ethane, bpp = 1,3-bis(4-pyridyl)propane), ...

Effects of different sintering atmospheres (O2 and air) on the energy storage properties and dielectric characteristics were systematically investigated for 2MgO–2Al2O3–5SiO2 (MAS)-coated Er0.02Sr0.97TiO3 (EST) ceramics. The core–shell structure was formed by the sol-precipitation method. The ceramic sintered in O2 features fine grain, excellent frequency stability, low leakage current, high dielectric breakdown strength (BDS), and high energy storage density (Wreco). Compared with air-sintered ceramics, the dielectric DC breakdown strength of ceramic sintered in oxygen atmosphere has been enhanced significantly from 375 to 590 kV/cm. Besides, the maximum Wreco of 2.01 J/cm3 and efficiency of 86.2% were obtained at 460 kV/cm, which demonstrated that the core–shell structure and atmosphere sintering provide an instructive strategy for the design of high energy storage materials.

Discovering new materials with high breakdown strength is of great significance for scientific research and industrial applications. Here, we combine experiments and density functional theory (DFT) calculations to report a systematic study of two titanosilicates - A2TiSi2O8 (A = Br, Sr) as a family of functional materials with wide band gaps, ultrahigh breakdown strength, and high thermal stability. The A2TiSi2O8 materials possess ultrahigh electric breakdown (Eb >200 kVmm−1, at 200 ℃), and good temperature stability (the variation of capacitance 3 %, from −100 to 200 ℃). DFT results show that electrons are likely localized in the Si O and Ti O polyhedrons. The electron difference density map and density of states (DOS) results elucidate the wide band gaps in titanosilicate family due to the strong Si O and Ti O bonds, indicating that the semiconductive behaviors are similar. The temperature-dependent structural evolution (from −100 to 500 ℃) is investigated via in-situ Raman spectroscopy.

A comparison between poly(vinyl alcohol) (PVA)-formed (TYPE-I), Ba(OH)2/TiO2 [Ba/Ti] suspension-formed (TYPE-II), and cold isostatic pressed (CIP) pellets (TYPE-II+CIP) of 0.9BaTi1–xCaxO3-x–0.1BiAl...

Hydrogen peroxide (H2O2, 30%) dipping treatment was conducted on Mn-doped Ca0.6Sr0.4TiO3 (CST) in this research, to modify the concentration of oxygen vacancies in dielectric ceramics. Structure characterization, including XRD, SEM, IR, and XPS, indicated minimal effect of H2O2 dipping on phase structure and grain size, while revealed a chemical reaction between H2O2 and the surface of CST. Electrical properties of the grain region remained unchanged after treatment, while the grain boundary region was sensitive to H2O2 dipping, due to faster diffusion rate of oxygen vacancies in grain boundary region. In addition to that, the bulk insulating properties was found to be dominated by grain boundaries.

Nb-containing antiferroelectric materials have recently attracted great research interest as energy storage materials for pulsed power capacitors due to their extraordinary energy storage performances. In this case, the optimization of the energy storage performance is obtained by a compositional modulation of NaNbO3-Bi(Zn2/3Nb1/3)O3 bulk ceramics. An optimal energy performance can be obtained with a composition of 0.85NaNbO3-0.15Bi(Zn2/3Nb1/3)O3, which is accompanied by a stable charge energy density in temperatures up to 150 °C owing to its relaxor characteristics and excellent cycling stability after 105 cycles. This work further broadens the scope of NaNbO3-based ceramic applications in the area of pulsed power sources.

Bioinformatic analysis reveals an enrichment of putative DNA:RNA hybrid G-quadruplex-forming sequences (PHQS) on both sides of the transcription start sites (TSSs) in the genome of warm-blooded animals, suggesting a positive selection of PHQSs in evolution and functional role of DNA:RNA hybrid G-quadruplexes (HQs) in transcription. The formation of HQs downstream of TSS in transcribed DNA has been documented under in vitro conditions; however, it is still not known if such HQs can form at the upstream side of TSSs. In this study, we report that such HQs can form in transcription in DNA with two to three guanine tracts if RNA carrying the required number of G-tracts is supplied. We also show that the formation of such HQs is dependent on the negative supercoiling generated by RNA polymerases. These results suggest that HQs may also form at the upstream side of TSSs in vivo and play a role in transcription since the two requirements are satisfied in cells.

BaTiO3@xMgO (BT@xMg, x = 0–7 mol%) ceramics were prepared by MgO-coated BT powders, which were synthesized by a chemical precipitation method. The effects of MgO coating on the phase structure, microstructure and dielectric properties of BT@xMg ceramics were explored. The solid solubility of Mg2+ at B-site in BT was about 0.8 mol%, which was confirmed by the c/a ratio variation. When x

Due to advances in electronic device integration, miniaturization, and performance requirements, dielectric materials with a high energy storage density are required. Here, new BiMg0.5Ti0.5O3 lead-free energy storage thin films with excess Mg (i.e., nominal BiMgyTi0.5O3, with y = 0.50-0.62) were deposited on Pt/Ti/SiO2/Si substrates by sol-gel and spin-coating methods. The introduction of excess Mg can obviously increase the dielectric breakdown strength of thin films due to the appearance of an amorphous phase. The maximum recoverable energy storage density increased from 26 J/cm3 at y = 0.50 to 44.1 J/cm3 at y = 0.56. Furthermore, the dielectric films exhibited excellent thermal stability of the energy storage density from 30 °C to 100 °C, indicating that bismuth-magnesium-titanium films are promising candidates for next-generation lead-free energy storage capacitor applications.

Relaxor-ferroelectric ceramics capacitors have been in the front lines of investigations aimed at optimizing energy density due to their high Pmax, suppressed Pr, and high BDS levels, attributed to their highly dynamic polar nano-regions. A set of (1 − x)SrTiO3–x[0.88BaTiO3–0.12Bi(Li0.5Ta0.5)O3] ceramics (x = 0, 20, 40, 60 and 80 mol%), abbreviated as (1 − x)ST–x(BT–BLT), was designed and fabricated via a solid-state reaction route. A striking energy-storage density of 2.24 J cm−3, coupled with a high efficiency of η = 81% at 300 kV cm−1, was measured for these (1 − x)ST–x(BT–BLT) ceramics. The incorporation of BT–BLT ceramics was found to dramatically transform the paraelectric state of strontium titanate into the relaxor-ferroelectric state, by introducing broad relaxor behavior. The energy storage properties of the ceramic with x = 60 mol% showed outstanding stability in frequency (10–100 Hz) and temperature (20–120 °C), with minimal variation of (±≤0.5%), over the course of 105 cycles. Moreover, under various electric fields, rapid charge and discharge (≤1.5 μs) was also observed for this x = 60 mol% ceramic. Most significantly, the outcomes of this study are expected to provide a standard for other emerging lead-free dielectric ceramics displaying very good energy-storage properties and excellent electric field endurance, which are of pragmatic importance for cutting-edge pulsed power technology.

A dual-functional peptide-PNA (peptide nucleic acid) conjugate consisting of a PNA G3-tract and an RHAU23 peptide is devised to target nucleic acids bearing three tandem guanine tracts (G-tracts). The PNA G3-tract joins the three G-tracts to form a stable bimolecular G-quadruplex (G4) and the resulting G4 is then bound by the RHAU23 moiety to form an extra stable G4-peptide complex. Owing to this synergistic dual structural enforcement, the conjugate accomplished extremely high selectivity and nM to sub-nM affinities towards its targets that are up to 1000 times greater than the small molecule G4 ligands. As a result, the conjugate impacts the tracking activity of motor proteins on DNA with superior selectivity and potency that are rarely seen in other G4-targeting approaches.

Defect engineering is applied to induce controllable changes in structures and dielectric behaviors in oxides. SrTiO3 ceramics modified by complex ions (Nb, Zn)x+ (x = 2, 3, 4 and 5) with variable valence states are prepared by standard solid state method. Phase structures, microstructures, defect structures and dielectric properties of the (Nb, Zn) co-doped SrTiO3 ceramics have been systematically investigated. In acceptor co-doping, M2 ceramics (x = 2) exhibits extremely low dielectric loss (≤0.001). M3 ceramics (x = 3) shows low conductivity and excellent thermal stability. In equivalent co-doping, M4 ceramics (x = 4) possesses giant permittivity and low dielectric loss. In donor co-doping, M5 ceramics (x = 5) presents improved permittivity while deteriorated dielectric loss. Further investigations reveal that oxygen vacancy is beneficial to the localization of charge carriers and then the low tangent loss, while excess electrons not only contribute to the improved permittivity but also result in high dielectric loss. Appropriate concentrations of oxygen vacancy and electron are significantly important for the formation of multiple defect dipoles or defect clusters, and therefore the greatly modified dielectric properties. The findings may facilitate the ability to engineer the advanced electronic materials.

Annealing temperature is a key element affecting the electrical properties and microstructure of dielectric thin films. In this case, BiAlO3 (BA) thin films were spin-coated on the Pt/Ti/SiO2/Si(100) substrates by sol-gel method and annealed at the temperature ranging from 450 °C to 550 °C. Then the influences of annealing temperatures on the microstructure, dielectric breakdown, and ferroelectric polarization of BiAlO3 thin films were studied. A optimal recoverable energy storage density (Wreco) of 31.1 J/cm3 and efficiency of 82.2% were achieved for the BA thin films annealed at 500 °C due to the ultrahigh dielectric breakdown strength (BDS) of 3535.7 kV/cm. This study offers a new paradigm for developing high-performance lead-free dielectric materials, which can largely extend the energy storage application of Bi-base perovskite materials.

Lead free dielectric ceramics of 0.65Bi0.51Na0.47Ti1-5x/4NbxO3- 0.35Ba(Ti0.7Zr0.3)O3 (BB35-100xNb, x = 0.00, 0.01, 0.02, 0.04 and 0.08) are fabricated by conventional solid-state sintering method for potential energy storage applications. Benefited from the coexistence of relaxor and antiferroelectric features, a high recoverable energy storage density of 3.2 J/cm3, together with high energy efficiency of 93%, is simultaneously achieved in bulk BB35-1Nb ceramic at the critical electric field of 280 kV/cm. The studied BB35-1Nb ceramic exhibits a wide temperature usage range of 20–160 °C with energy density variation below 3%, and excellent cycling reliability with both energy density and efficiency variations less than 4% over 106 cycles, together with its fast discharge time of ˜1.2 μs, making BB35-1Nb ceramic promising candidate for high-temperature, high power energy storage applications.

Amine-substituted cyclobutanes and cyclopropanes are important substructures in biologically active compounds. Moreover, many of the cycloalkane units bear multiple substituents and stereocenters. Therefore, synthetic methods that produce polysubstituted aminocyclobutanes and aminocyclopropanes in a highly diastereo- and enantioselective manner are of importance. Herein, we describe the diastereo- and enantioselective synthesis of various types of polysubstituted aminocyclobutanes and aminocyclopropanes through CuH-catalyzed hydroamination of 1-substituted cyclobutenes and cyclopropenes. These strained trisubstituted alkenes exhibit much higher reactivity compared to their unstrained analogues in the initial hydrocupration step of the reaction. Moreover, an interesting reversal of regioselectivity was observed in the hydroamination of 1-aryl-substituted cyclobutenes compared to the cyclopropene analogues. The origins of the enhanced reactivity of strained trisubstituted alkenes as well as the differences in the regio- and enantioselectivity between reactions with cyclobutenes and cyclopropenes were investigated computationally.

High-performance piezoelectric materials are pivotal to many electromechanical applications including piezoelectric actuators, sensors, and transducers. However, the general approach to achieve high piezoelectric properties by establishing morphotropic phase boundary (MPB) has limitation due to the weak anisotropy of the Gibbs free energy profile at the MPB region. Here, aliovalent Sm3+-doped 0.4Pb(Mg1/3Nb2/3)O3-(0.6-x)PbZrO3-xPbTiO3 piezoelectric ceramics were fabricated by a solid-state method, where the optimized piezoelectric coefficient d33 = 910 pC/N, dielectric constant er = 4090, and Curie temperature TC = 184 °C were obtained at x = 0.352, being attributed to the synergistic contributions from the MPB and enhanced local structural heterogeneity. Rayleigh analysis was adopted to study the intrinsic and extrinsic contributions in Sm-doped PMN-PZ-PT ceramics, where the extrinsic contribution was found to be on the order of 25-67% at 4 kV/cm. Of particular significance is that a large signal d33* = 820 pm/V (at 20 kV/cm) with a minimal strain variation of 5% was achieved for a composition of x = 0.372 over the temperature range of 20-160 °C, being superior to those previously reported piezoelectric ceramic materials. This work offers a good paradigm to simultaneously achieve high piezoelectric properties with good temperature stability in ferroelectric ceramics, which have great potential for piezoelectric application at elevated temperatures.

Isomaltulose is becoming a focus as a functional sweetener for sucrose substitutes; however, isomaltulose production using sucrose as the substrate is not economical. Low-cost feedstocks are needed for their production. In this study, beet molasses (BM) was introduced as the substrate to produce isomaltulose for the first time. Immobilized sucrose isomerase (SIase) was proved as the most efficient biocatalyst for isomaltulose synthesis from sulfuric acid (H2SO4) pretreated BM followed by centrifugation for the removal of insoluble matters and reducing viscosity. The effect of different factors on isomaltulose production is investigated. The isomaltulose still achieved a high concentration of 446.4 ± 5.5 g/L (purity of 85.8%) with a yield of 0.94 ± 0.02 g/g under the best conditions (800 g/L pretreated BM, 15 U immobilized SIase/g dosage, 40°C, pH of 5.5, and 10 h) in the eighth batch. Immobilized SIase used in repeated batch reaction showed good reusability to convert pretreated BM into isomaltulose since the sucrose conversion rate remained 97.5% in the same batch and even above 94% after 11 batches. Significant cost reduction of feedstock costs was also confirmed by economic analysis. The findings indicated that this two-step process to produce isomaltulose using low-cost BM and immobilized SIase is feasible. This process has the potential to be effective and promising for industrial production and application of isomaltulose as a functional sweetener for sucrose substitute.

G-quadruplexes (G4s) formed by guanine-rich nucleic acids play a role in essential biological processes such as transcription and replication. Besides the >1.5 million putative G-4–forming sequences (PQSs), the human genome features >640 million single-nucleotide variations (SNVs), the most common type of genetic variation among people or populations. An SNV may alter a G4 structure when it falls within a PQS motif. To date, genome-wide PQS–SNV interactions and their impact have not been investigated. Herein, we present a study on the PQS–SNV interactions and the impact they can bring to G4 structures and, subsequently, gene expressions. Based on build 154 of the Single Nucleotide Polymorphism Database (dbSNP), we identified 5 million gains/losses or structural conversions of G4s that can be caused by the SNVs. Of these G4 variations (G4Vs), 3.4 million are within genes, resulting in an average load of >120 G4Vs per gene, preferentially enriched near the transcription start site. Moreover, >80% of the G4Vs overlap with transcription factor–binding sites and >14% with enhancers, giving an average load of 3 and 7.5 for the two regulatory elements, respectively. Our experiments show that such G4Vs can significantly influence the expression of their host genes. These results reveal genome-wide G4Vs and their impact on gene activity, emphasizing an understanding of genetic variation, from a structural perspective, of their physiological function and pathological implications. The G4Vs may also provide a unique category of drug targets for individualized therapeutics, health risk assessment, and drug development.

This letter replies to the comments by Tkach et al. on our previous publication about the issues of ZnO volatilization, Ti3+ content and lattice constant etc. In this reply, we present a detailed discussion and rebuttal on the issues concerned in the comments.

Effects of sintering and annealing atmosphere on the defect structures and the dielectric behaviors of (Nb + Zn) co-doped SrTiO3 ceramics are systematically investigated. Giant permittivity (~50,100), low dielectric loss (~0.04) and wide temperature (25–330 °C)/frequency (20–105 Hz) stabilities are achieved in the N2 sintering ceramics. Further investigations indicate massive defects and defect clusters are involved, contributing to the giant permittivity. The associated defects not only restrain the ionization of oxygen vacancy, but also localize the motions of oxygen vacancy and electron, resulting in the low dielectric loss and the suppressed relaxation peaks.

Dielectric ceramics with high energy storage density and energy efficiency play an important role in high power energy storage applications. In this work, lead free relaxor ferroelectric ceramics in (1-x)Bi0.51Na0.47TiO3- xBa(Zr0.3Ti0.7)O3 (BNT-BZT100x: x = 0.20, 0.30, 0.40 and 0.50) system are fabricated by conventional solid-state sintering method. The BNT-BZT100x ceramics are sintered dense with minimal pores, exhibiting pseudocubic symmetry and strong relaxor characteristic. A high energy storage density of 3.1 J/cm3 and high energy efficiency of 91% are simultaneously achieved in BNT-BZT40 ceramic with 0.1 mm in thickness, at the applied electric field of 280 kV/cm. The temperature stability of the energy density is studied over temperature range of 20–160 °C, showing minimal variation below 1.5%, together with the excellent cycling reliability (the variations of both energy density and efficiency are below 3% up to 106 cycles), making BNT-BZT40 ceramic promising candidate for high-temperature dielectric and energy storage applications. Keywords: Energy storage, Lead free ceramic, Relaxor characteristic

0.5Bi 0·5 Na 0·5 TiO 3 -0.5SrTiO 3 -x wt% MgO (x = 0, 0.5, 1.0, 1.5, 2.0, 3.0) ceramics were fabricated via solid-state method. The effect of MgO doped on energy storage properties, dielectric performance, phase structure and microstructures of 0.5Bi 0·5 Na 0·5 TiO 3 -0.5SrTiO 3 (BNST) ceramics were studied systemically. The Mg 2+ substituted Ti 4+ site in BNST, which was confirmed by X-ray diffraction (XRD) result. The scanning electron microscope (SEM) images show that all the ceramic samples exhibit uniform and compact morphologies. The temperature dependent permittivity exhibits frequency dispersion, indicating that the ceramic samples are typical relaxor ferroelectrics. It was found that MgO doped BNST can significant improve the breakdown strength (E b ) of samples from 109 kV/cm to 227 kV/cm, which results in a great enhancement on energy storage density. The sample of x = 3.0 has the largest energy storage density (2.17 J/cm 3 ), which is twice as much as the BNST. Consequently, we consider that MgO-doped BNST ceramics are able to be a promising candidate in the field of pulsed-power devices.

Energy storage capacitors have gained much attention for their potential energy storage applications in pulse power system. In this paper, Ba0.3Sr0.7TiO3 (BST) crystallite thin films were prepared on Pt/Ti/SiO2/Si(100) substrates using a sol-gel method at different annealing temperatures from 650 to 850 °C. The films have a crystallite structure, in which amorphous phase forms a three-dimensional network structure and BST tiny grains are wrapped in it. The effects of annealing temperature on the phase structure, morphology, energy storage and dielectric properties of BST microcrystalline films were investigated. The grain size and the crystallinity increased with the increase of annealing temperature, and both pores and defects were produced on the surface when temperature reaches up to 750 °C. When annealing temperature increases, the breakdown strength and energy storage density increased initially, followed by an decrease. The optimal energy storage performance was achieved in the sample with the energy storage density of 31.6 J/cm3 at 3.0 M V/cm, while annealing at 700 °C. Moreover, the sample also exhibited a moderate dielectric constant (60) and a low dielectric loss (0.001).

In this work, nominal composition (1-x)BaTiO3-xBi(Zn0.5Y0.5)O2.75 [abbreviated as (1-x)BT-xBZY, (x = 0.05, 0.1, 0.15, 0.2, 0.25)] ceramics were prepared by solid-state reaction method, and sintered in reducing atmosphere. Effect of introducing BZY on the structure, dielectric and insulating properties of BT was investigated. XRD results demonstrated that the unit cell volume of (1-x)BT-xBZY ceramics expanded with the addition of BZY, accompanied with the transformation from tetragonal to pseudo-cubic phase when x ≥ 0.05. Electrical properties measurement showed that the dielectric-temperature stability and insulating properties of (1-x)BT-xBZY ceramics were effectively improved by BZY addition, where the optimum performances were achieved at x = 0.15, with the dielectric constant of 1362 and dielectric loss of 1.4%, and resistivity of 5.5 × 1012 Ω cm at room temperature, meeting the standard of X8R specification for MLCC application. The feasible mechanism of improved anti-reduction properties for (1-x)BT-xBZY ceramics was investigated by employing X-ray photoelectron spectra (XPS) and thermally stimulated depolarization current (TSDC) testing techniques, where the formation of defect dipoles [2YTiˈ- V O .. ] and the deoxidation of Bi ion were revealed and considered to be responsible for the anti-reduction behavior.

In this paper, x mol% Mn-doped SrTiO3 (STMx, x = 0, 0.5, 1, 3 and 5) thin films were synthesized by a sol-gel method. The effect of Mn doping on the microstructure and electrical performance was investigated. STMx (x ≤ 1) thin films shows a single cubic perovskite phase while impurity phase appears for STM3 and STM5 thin films confirmed by X-ray diffraction. X-ray photoelectron spectra reveals that STM1 thin film has the lowest concentration of oxygen vacancy. The dielectric constant and loss of STMx (x ≤ 1) films display good frequency stability, while decrease with the frequency for STM3 and STM5 thin films. And all samples display excellent bias stability of dielectric constant; this is advantageous for applications in a high electric field. The ferroelectric test demonstrates that the electrical breakdown strength increases and leakage current decreases for Mn doped SrTiO3 films. A great recoverable energy storage density of 23.8 J/cm3 with an efficiency of 69.8% at 2.286 MV/cm is obtained in STM1 thin film. Furthermore, STM1 thin film shows good frequency stability of energy storage properties. It indicates that Mn doping is a simple and effective method to improve the energy storage properties of dielectric capacitors.

The site-selective functionalization of carbohydrates is an active area of research. Reported here is the surprising observation that the sterically encumbered adamantyl group directed site-selective acylation at the C2 position of S-glycosides through dispersion interactions between the adamantyl C-H bonds and the π system of the cationic acylated catalyst, which may have broad implications in many other chemical reactions. Because of their stability, chemical orthogonality, and ease of activation for glycosylation, the site-selective acylation of S-glycosides streamlines oligosaccharide synthesis and will have wide applications in complex carbohydrate synthesis.

The projected increase in world energy consumption within the next 50 years, coupled with low emission requirements, has inspired an enormous effort towards the development of efficient, clean, and renewable energy sources. Efficient electrical energy storage solutions are keys to effective implementation of the electricity generated from these renewable sources. In step with the development of energy storage technology and the power electronics industry, dielectric materials with high energy density are in high demand. The dielectrics with a medium dielectric constant, high breakdown strength, and low polarization hysteresis are the most promising candidates for high-power energy storage applications. Inspiring energy densities have been achieved in current dielectrics, but challenges exist for practical applications, where the underlying mechanisms need to be understood for further enhancing their properties to meet future energy requirements. In this review, we summarize the principles of dielectric energy-storage applications, and recent developments on different types of dielectrics, namely linear dielectrics, paraelectrics, ferroelectrics, and antiferroelectrics, are surveyed, focusing on perovskite lead-free dielectrics. The new achievements of polymer-ceramic composites in energy-storage applications are also reviewed. The pros and cons of each type of dielectric, the existing challenges, and future perspectives are presented and discussed with respect to specific applications.

SrTi1-x(Zn1/3Nb2/3)xO3 ceramics with various defect concentration were designed and prepared via solid state reaction method, the close relationships between defect structure and dielectric behavior of were investigated in detail. High permittivity (∼9100) and low dielectric loss (∼0.03) are achieved at an optimum doping concentration (x = 0.015) due to the enhanced local polarization, while the dielectric properties deteriorate because of the increasing self-compensation as the impurity concentration continuously increases. Further investigation shows that, the giant permittivity is owing to the defect polarization, including off-center Zn2+/Ti3+, combination center ( N b T i · − e ′ ∙ T i 4 + ) and defect dipoles ( T i 3 + − V O · · − T i 3 + ) as well as the contribution from interface polarization, low dielectric loss results from the localization of electron by the defect dipoles/clusters. These findings provide the requisite data and idea for defect design in complex perovskite materials.

The effect of sintering atmosphere on the microstructure and dielectric properties of Sr0.985Ce0.01TiO3 were investigated in this article. The sample sintered in nitrogen achieves a colossal permittivity (∼12655) and ultralow dielectric loss (0.006) at room temperature and 1k Hz. XRD results reveal that all the samples belong to P m 3 ¯ m space group and no secondary phase is detected. It can be verified by XPS measurement that the nitrogen sintered sample has the highest Ti3+ content. Five dielectric relaxations can be observed in the dielectric spectroscopy in the test temperature range from −130–500 °C, which can be attributed to the existence of Ti3+ ions, oxygen vacancies and the other associated defect clusters. Moreover, the off-center Ti3+ ions make a certain contribution to the high permittivity. The ultralow dielectric loss at room temperature could be ascribed to the formation of defect clusters in the samples sintered in air and nitrogen. These defect clusters which associated with the oxygen vacancy, such as T i 3 + − V O .. − T i 3 + and V S r " − V O ¨ are able to localize charge carriers and restrain the motion and ionization of oxygen vacancies.

In this work, the phase structure of BaTiO3 nanopowders produced by the alkoxide-hydroxide and the hydrothermal method, respectively, was systemically investigated. BaTiO3 nanopowders with cubic phase produced by the alkoxide-hydroxide method could transform to tetragonal phase when heated to about 1100 °C. Cubic to tetragonal phase transformation behavior of BaTiO3 nanopowders coated with 0.3BZT-0.7BT or 0.03Nb2O5-0.01Co2O3 was studied. The internal stress within core-shell structure was proposed to explain the BaTiO3 phase transformation behaviors. The mismatch of thermal expansion coefficient between core and shell plays a crucial role in cubic to tetragonal phase transformation of BaTiO3. By tuning the composition of shell and the ratio of the shell to the core, the cubic BaTiO3 core can transform to tetragonal phase successfully after sintering at 1100 °C in BaTiO3 based ceramics with core-shell structure and it is mainly resulted by the reduced internal stress between the shell and core.

Lead-free (1-x)BaTiO3-xBi(Mg1/2Zr1/2)O3 ((1-x)BT-xBMZ) ceramics with perovskite structure were synthesized by solid-state reaction methods. (1-x)BT-xBMZ solid solution transforms from tetragonal (x≤0.04) to pseudocubic (x≥0.08) and exhibits a dispersive dielectric behavior with respect to frequency, showing typical relaxor characteristics with BMZ increasing. The optimal energy storage density of 1.25 J cm−3 and energy efficiency of >95% are obtained at x = 0.15, with maximum dielectric breakdown strength of 185 kV cm-1 at 200 μm thickness., The energy storage density and energy efficiency of 0.85BT-0.15BMZ ceramics maintain at about 0.8 J cm−3 and 89% at 150 kV cm-1 over temperature range of 25 °C∼150 °C, exhibiting good thermal stability. The pulse discharge capability of 0.85BT-0.15BMZ ceramics were measured under different electric fields, showing a short charge-discharge time of 1.3 μs. Therefore (1-x)BT-xBMZ solid solution with high energy density and efficiency, good temperature stability and fast discharge speed, is promising candidate for high power applications.

Sandwich-structured SrTiO3/BiFeO3/SrTiO3 (ST/BF) thin films were prepared via a sol-gel method for energy storage applications. The thin films demonstrated good frequency stability of the dielectric constant within the measured frequency range, low dielectric loss and broad capacitance-temperature variation (25oC-200 °C, ΔC/C25oC≤±6.0%). Through BF layer insertion modulation, the crystallization quality and energy storage density of ST/BF thin films significantly increased in comparison to ST films. In addition, with the increase thickness of BF layers, the breakdown strength and energy storage density decreased. The maximum recoverable energy storage density (Urec of 40.69 J/cm3) with an efficiency of 44.7% at 2.06 MV/cm was obtained within this system. Moreover, compared to simple tri-layered thin films, the Urec value of the thin films with more interfaces was enhanced to 80%. The results indicate that sandwich-structured ST/BF thin films are a cost-effective, potential more efficient option for energy storage fields.

Solid-state sintering method was used for the synthesis of Mg1−xCoxSiO3 (x = 0–0.25) ceramics. Phase, microstructure and microwave dielectric properties of the ceramics were investigated. With increase in Co2+ content, the increase was observed in the lattice parameters. The Qufo value of MgSiO3 was enhanced from 103,453 to 145,846 GHz with increasing the value of x content from 0 to 0.15. The Co2+ substitution also led to an obvious decrease in the sintering temperature by ~ 100 °C. Clino-enstatite phase formed for the composition with x = 0 while Proto-enstatite formed as the major along with minor clino-enstatite phase for the compositions with x > 0. Good dielectric properties at microwave frequencies i.e. er ~ 8.11, Qufo ~ 145,846 GHz and τf ~ − 12 ppm/°C were obtained for the composition with x = 0.15 sintered at 1350 °C for 9 h. This is suggested to be a very favorable dielectric material for millimeterwave applications.