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A NiCo-LDH/Mn 3 O 4 composite is synthesized on nickel foam substrate though a two-step electrodepositon process. The growth of Mn 3 O 4 nanoneedles on NiCo-LDH nanosheets can greatly reduce the transport pathway of electrons and ions. Meanwhile, abundant active sites for redox reactions are generated and the structural endurance together with chemical stability of material is improved, thus strongly enhancing the electrochemical characteristics. When measured in a typical three-electrode cell, NiCo-LDH/Mn 3 O 4 demonstrates a high specific capacity of 1.86 C cm−2 (1034.33 C g−1) at the current density of 1 mA cm−2, a superior rate capability of maintaining 76.88% at 20 mA cm−2 and 17.98% capacity loss after 5000 cycles. In addition, an all-solid-state hybrid supercapacitor device (HSC) is fabricated with NiCo-LDH/Mn 3 O 4 as the cathode and commercially-used active carbon as the anode, which delivers a superior energy density of 57.03 Wh kg−1 at the power density of 765.8 W kg−1 and maintains 20.98 Wh kg−1 even when the power density increases to 9681.6 W kg−1. Therefore, the satisfactory electrochemical property enables NiCo-LDH/Mn 3 O 4 to become a prospective electrode material in energy storage field. • We first synthesize a 3D partially-cladding NiCo-LDH/Mn 3 O 4 composite. • The integration of nanosheets and nanoneedles improves the stability. • We first define and use the curve of accumulative contribution versus potential. • The NiCo-LDH/Mn 3 O 4 //AC HSC device shows high energy density and power density. [ABSTRACT FROM AUTHOR]

Ag modified g-C 3 N 4 /CdS (Ag@g-C 3 N 4 /CdS) S-scheme heterojunction with a distinctive charge transfer channel was prepared as a photocatalyst for photoreduction of H 2 O. The effect of nitrogen vacancies and photo-excited charge carriers in the water splitting on the Ag@g-C 3 N 4 /CdS was discussed. It was found that the charge carriers transport channel in Ag@g-C3N4/CdS S-scheme heterojunction was instrumental in the enhancement of H 2 production. The electrons in Ag nanospheres and in the conduction band (CB) of CdS can recombine with the holes in the valence band (VB) of g-C 3 N 4 , which prolonged the lifetime of electrons in the CB of g-C 3 N 4. Meanwhile, a unique charge transfer channel was produced in the Ag@g-C 3 N 4 /CdS. Compared with g-C 3 N 4 , Ag@g-C 3 N 4 /CdS photocatalyst demonstrated an enhanced performance which was assigned to the increased charge carrier lifetime. The supreme Ag@g-C 3 N 4 /CdS showed photocatalytic H 2 production activity up to 204.19 μmol for 4 h under illuminate (λ ≥ 420 nm), which was 11.74 times than that of g-C 3 N 4. [Display omitted] • Nitrogen vacancy and prolonged electron lifetime have improved H 2 production. • Surface π bond of coated g-C 3 N 4 enhances the Lewis acidity. • The results of XPS are consistent with the mechanism of S-scheme heterojunction. [ABSTRACT FROM AUTHOR]

Aurivillius Bi 5 Ti 3 FeO 15 (BTF) multiferroic (MF) nanofibers (NFs) of about 400 nm were fabricated by electrospinning and calcination. The BTF NFs exhibit an effective micro–piezoelectric coefficient of 35 pm/V and benign micro-ferroelectricity. Macro-ferroelectric and magnetoelectric coupling behavior were investigated in detail by non-sintering and pressing for the first time, which is smaller than that of the BTF ceramic or film due to the adverse effects of filled air. A magnetoelectric (ME) voltage coefficient as large as 14 mVcm −1 Oe −1 can be achieved. Weak ferromagnetism was also realized at RT. Although the sintering temperature was only 600 °C, MF BTF NFs as multiferroic materials were successfully obtained, which offers new insights into the design and application of promising lead-free MF materials for novel devices. [ABSTRACT FROM AUTHOR]

Magnesium titanate stannate - calcium strontium titanate (MgTi 0.95 Sn 0.05 O 3 - x Ca 0.8 Sr 0.2 TiO 3 ; abbreviated as MTS- x CST, x = 0.02, 0.04, 0.06, 0.08) microwave dielectric ceramics were synthesized via the conventional solid-state reaction. The optimum densities corresponded to higher sintering temperatures than the optimum quality factor, so the ceramics were classified as MTS- x CST-D and MTS- x CST-Q. All compositions exhibited a composite phase consisting of the rhombohedral structure MTS and the orthorhombic structure CST. As the sintering temperature rose, the relative densities of the ceramics increased significantly, while the formation of oxygen vacancies and titanium reduction were intensified. Finally, the x = 0.06 compositions sintered at 1425 °C (MTS-0.06CST-D) and 1375 °C (MTS-0.06CST-Q) had excellent temperature stability and low loss. At low frequency, the change of dielectric permittivity at 25–150 °C did not exceed 0.1, and the loss tangent was less than 0.003. In addition, microwave dielectric properties of MTS-0.06CST-D (ε r = 20.4, Qf = 63,770 GHz, τ f = −1.8 ppm/°C) and MTS-0.06CST-Q (ε r = 18.4, Qf = 74,740 GHz, τ f = −4.3 ppm/°C) compositions were obtained. These results suggest that MST-0.6CST ceramics could be a candidate material for 5 G microwave communication devices. • MgTi 0.95 Sn 0.05 O 3 - x Ca 0.8 Sr 0.2 TiO 3 were synthesized via the conventional solid-state reaction. • The sintered ceramics only kept MgTi 0.95 Sn 0.05 O 3 rhombohedral phase and Ca 0.8 Sr 0.2 TiO 3 orthorhombic phase. • Oxygen vacancies and titanium reduction after high temperatures sintering were investigated. • Excellent microwave dielectric properties of ε r = 20.4, Qf = 63,770 GHz, τ f = −1.8 ppm/°C and ε r = 18.4, Qf = 74,740 GHz, τ f = −4.3 ppm/°C were obtained. [ABSTRACT FROM AUTHOR]

Aurivillius Bi 3 TiNbO 9 has a very high Curie temperature (T c), but the piezoelectric coefficient (d 33) is very low, and the influence of ions with different radii on its performance is not clear. High temperature piezoelectric ceramics Bi 2.99 (Li 0.5 Ln 0.5) 0.01 TiNbO 9 (BTNO-1LiLn, Ln = La, Nd, Gd, and Er) were prepared by solid state reaction sintering, and its microstructure, piezoelectric properties and electrical conductivity were systematically studied. The T c of BTNO-1LiLn increases with the decrease of Ln3+ ions radii. BTNO-1LiEr obtains the highest d 33 of 10.6 pC/N. Considering the cation disorder of A-site and bismuth layer of calcium titanium layer in Aurivilius structure, the crystal structures of BTNO-1LiLa with special occupation and BTNO-1LiEr with the best performance are refined, and the source of spontaneous polarization (P s) is analyzed. It is proved that different occupation will have different effects on the high temperature piezoelectric properties and fatigue cycle properties of BTNO based ceramics. Finally, the band structure of BTNO pure ceramic based on the first principle is calculated. By comparing the activation energy and band gap width, it is indicated that (Li 0.5 Ln 0.5)2+ ions entering BTNO will form impurity energy levels and form p -type semiconductors. This study provides a theoretical basis for better performance of BTNO based high temperature piezoelectric ceramics. [Display omitted] • Discussing the effects of lanthanide ions entering into different sites on the high temperature piezoelectric properties of Bi3TiNbO9. • Analyzing the influence of lanthanide ions entering into different sites on the electrical characteristics of Bi 3 TiNbO 9. • The band structure of pure Bi 3 TiNbO 9 is calculated based on the first principle. [ABSTRACT FROM AUTHOR]

High-performance ternary cobalt-based metal oxides, especially ZnCo 2 O 4 , have attracted increasing attention as promising electrode materials for supercapacitors. However, there are still great challenges for the as-reported ZnCo 2 O 4 materials, such as self-aggregation during repeated discharging-charging process and low packing density. To tackle the above issues, it is envisaged as an efficient strategy to combine the advantages of both hierarchical porous micro/nanostructures and self-supporting electrode to fabricate a free-standing hierarchical micro/nanostructured ZnCo 2 O 4 electrode. Herein we propose an efficient and simple synthetic strategy for the controllable synthesis of self-supporting hierarchical porous cactus-like ZnCo 2 O 4 material directly grown on Ni-foam using a facile hydrothermal method with post-calcination treatment. Furthermore, a growth mechanism is also proposed. The as-prepared cactus-like ZnCo 2 O 4 material possesses unique structural merits, such as hierarchical porous structures, large specific surface area, robust structural stability, and strong connections between the substrate and the ZnCo 2 O 4 active material. The unique cactus-like ZnCo 2 O 4 film electrode displayed excellent electrochemical performance, including a high specific capacity of 1115.7 F g−1 at 1 A g−1 and remarkable long cycle stability with 80.8% capacity retention after 30,000 cycles. A practical asymmetric supercapacitor (ASC) device was assembled using cactus-like ZnCo 2 O 4 and active carbon, which showed an excellent energy density of 35.4 Wh kg−1 at high power density of 160.1 W kg−1 and superior cycle stability (62.5% capacity retention after 30,000 cycles at 1 A g−1). All these results show that such hierarchical porous ZnCo 2 O 4 micro/nanostructured films are a promising candidate for high-performance supercapacitors for energy storage application. [Display omitted] • 3D hierarchical porous cactus-like ZnCo 2 O 4 film is grown on Ni foam. • A growth mechanism of the 3D cactus-like ZnCo 2 O 4 film is proposed. • The cactus-like ZnCo 2 O 4 electrode shows 80.8% capacitance retention after 30,000 cycles at 5 A g−1. • The ZnCo 2 O 4 @NF//AC asymmetric supercapacitor exhibits an excellent energy density and power density. [ABSTRACT FROM AUTHOR]

In order to hunt for the promising materials in energy-storage field, we prepared a series of compositions Bi 0.487 Na 0.427 K 0.06 Ba 0.026 TiO 3 - x CeO 2 (BNTC1000 x , x = 1.8, 2.2, 2.6, 3.0 wt%) by the solid–state reaction method. CeO 2 addition degraded the ferroelectricity of initial components and all these samples exhibited antiferroelectricity at room temperature. The optimum energy-storage density of 0.94 J/cm 3 was obtained at BNTC22 with the external electric field of 75 kV/cm. In addition, the energy-storage property not only possessed good temperature stability but also maintained high values over 0.81 J/cm 3 around 20–120 °C. These characteristics indicated that Bi 0.487 Na 0.427 K 0.06 Ba 0.026 TiO 3 - x CeO 2 system could be the promising lead-free materials for energy-storage capacitor application. The investigation on dielectric properties suggested that the dielectric relaxation behavior was involved in BNTC1000 x system and concerned with oxygen vacancy migration. [ABSTRACT FROM AUTHOR]

A hierarchical SnO 2 nanosheet structure was constructed by the hydrothermal method using hydrated stannous chloride and thiourea as raw materials. Then lysine was used as a coupling agent to load Pt nano quantum dots with different contents on the surface of the SnO 2 nanosheets. The composition, morphology and structure of Pt/SnO 2 were characterized by X-ray diffraction, transmission electron microscopy, scanning electron microscopy and energy dispersive spectroscopy. The gas sensitivity of the Pt/SnO 2 and SnO 2 nanostructures were also studied in detail. Compared with the pure SnO 2 nanosheets, the 3-dimensional structured nano 2.0% Pt/SnO 2 (Pt: SnO 2 = 2.0%, wt%) exhibits a higher gas sensitivity to ethanol gas at 240 °C. The gas sensitivity to 100 ppm ethanol of hierarchical nano 2.0% Pt/SnO is 2.5 times higher than pure SnO 2 nanosheet, and the response time and recovery time are 4 s and 5 s, showing excellent response and recovery behavior. Meanwhile, the sensor also exhibits a lower detection limit of 0.272 ppm, as well as the excellent temperature and time stability. The higher gas sensitivity is contributed from the "spillover" effect of Pt nano quantum dots and the Schottky barrier at the heterojunctions of hierarchical Pt/SnO 2 nanostructures. Schematic diagram of the gas sensing responses for ethanol of 3D hierarchical (a) nano SnO 2 (b) nano Pt/SnO 2 [Display omitted] • 3-diminsional (3D) hierarchical nano Pt/SnO 2 was prepared using a simple two-stage hydrothermal route. • Sensitivity and selectivity of 3D hierarchical Pt/SnO 2 to ethanol is significantly enhanced compared to pure nano SnO 2. • Sensor based on 3-diminsional hierarchical nano Pt/SnO 2 exhibits excellent humidity and time stability. [ABSTRACT FROM AUTHOR]

Sr x La (1− x ) Ti x Al (1− x ) O 3 (SLTA, x = 0.4–0.7) ceramics with additive of CaO–B 2 O 3 glass (1–10 wt%) were prepared by a solid-state reaction process, which led to a significant decrease in sintering temperature, from 1550 °C to 1100 °C. Dielectric properties of ceramics at low frequency were significantly improved by CaO–B 2 O 3 glass addition, especially the obtained dielectric loss ∼6 × 10 −4 at room temperature and 1 MHz. Superlattice reflection was detected in the prepared oxides by X-ray diffraction (XRD), selected area electron diffraction (SAED) and Raman spectra, indicating presence of cation ordering. Meanwhile, lattice images of high-resolution transmission electron microscopy (HRTEM) also certificated the presence of cations ordering. Notably, the detected superlattice reflection in perovskite structure associated with antiparallel A-site cation displacements and anti-phase octahedral tilting. This ordered structure as well as low temperature sintering both affected the microwave dielectric properties of Sr 0.7 La 0.3 Ti 0.7 Al 0.3 O 3 ceramics, which exhibited with ɛ r ∼ 43.3, Q × f ∼ 10,780 GHz and τ ƒ ∼ 20.8 ppm/°C. The smaller cations doped in A site, a larger difference in ionic radius or cation valence of B-site cations were considered to primarily facilitate the formation of cation ordering, which promoted microwave dielectric properties of the ceramics. [ABSTRACT FROM AUTHOR]

The electric and dielectric properties of (Bi 0.5− y Na 0.5 ) 0.94− x Ba 0.06 (Bi 0.2 Sr 0.7 □ 0.1 ) x TiO 3 (BNBT–BST) ceramics, derived from the morphotropic phase boundary (MPB) of the parent matrix 0.94(Bi 0.5 Na 0.5 )TiO 3 –0.06BaTiO 3 (BNT–BT), are studied. The pseudocubic structures are formed without apparent secondary phases for all the compositions. The Bi deficiency displays significant effect on the dielectric permittivity of BNBT–BST ceramics. A plateau of high permittivity ∼5000 in the temperature evolution is formed with small variation, indicating the potential use for the high-temperature dielectrics. The bulk conductivity, calculated from the complex impendence ( Z ′/ Z ″), is conducted to learn the influence of the oxygen vacancies on the dielectric response in different atmospheres. After the re-oxidation of the Bi deficient BNBT–BST ceramics, the operational temperature range is broadened with 10% variation in permittivity from 50 °C to 300 °C. [ABSTRACT FROM AUTHOR]

Ba 1 − x La x Ti 1 − x /4 O 3 (BLT, x = 0–0.08, abbreviated as BLT100x) ceramics were prepared by using a solid state reaction process. Their phase transition, surface morphology, dielectric properties, tunability and ferroelectric behaviors were examined. Substitution of La at A-site in BaTiO 3 leads to a downward shift of Curie temperature and diffused cubic–tetragonal (C–T) phase transition. BLT6 exhibits a high tunability (35.4 at 20 kV/cm), a low dielectric loss (0.002) and a high figure of merit (177 at 20 kV/cm) at 10 kHz and room temperature. The nonlinear dielectric behavior under the applied electric field is well described by the multipolarization model. And the temperature dependence of ferroelectric hysteresis loops proves that the field induced phase transition is restrained by substitution of La in BaTiO 3 , whereas polar nano-regions (PNRs) which are an extrinsic polarization contribution are present in BLT and play an important role to the high dielectric tunability of BLT. [ABSTRACT FROM AUTHOR]

Polycrystalline Bi 1− x La x FeO 3 (BLF, x = 0.05–0.2) were prepared by solid state reaction and followed by annealing in O 2 , air and N 2 . The electrical properties of BLF ceramics were investigated by impedance spectroscopy and it is found that the conduction is dominated by p -type conduction. The conductivity of samples varies by several orders of magnitude, depending on the oxygen partial pressure during the annealing process. Activation energy ( E a ) increases from ∼0.5 eV for O 2 /air-annealed samples to ∼0.9 eV for the N 2 -annealed samples, and E a shows a slightly increase with the increment of La doping amount. Besides, all the samples exhibit nonlinear current ( I )–voltage ( V ) characteristics, and the threshold field voltage is much higher for the N 2 -annealed samples than for the O 2 -annealed samples. The nonlinear coefficient increases with the increase of oxygen partial pressure and temperature as well as the decrease of the La doping amount. The intrinsic electrostatic barrier at the domain walls rather than grain boundaries is responsible for the nonlinear behavior. [ABSTRACT FROM AUTHOR]

Highlights: [•] High remnant polarization of 48.5μC/cm2 for BNTM25 ceramics was obtained. [•] No apparent fatigue was observed after switching over 106 cycles for BNTM25 ceramics. [•] Electromechanical quality factor (Q m) of BNTM50 ceramics reaches to 901. [ABSTRACT FROM AUTHOR]

Highlights: [•] K0.5Na0.5Nb0.99Mg0.01O2.985 crystallized in the orthorhombic space group Bmm2. [•] P–E loops of K0.5Na0.5Nb0.99Mg0.01O2.985 were studied after annealing and aging. [•] Defect dipoles and polarization were elaborated in K0.5Na0.5Nb1−xMg x O3−3x/2. [ABSTRACT FROM AUTHOR]

• Discussing the effects on the structures of (1- x)Ca 0.8 Sr 0.2 TiO 3 - x SmAlO 3 ceramics with the content of SmAlO 3. • Observing excellent temperature stability of dielectric permittivity and low dielectric loss at low frequencies. • Discovering a high-performance microwave dielectric ceramics with ε r = 42.0, Qf = 39,120 GHz, and τ f =-6.4 ppm/℃. (1- x)Ca 0.8 Sr 0.2 TiO 3 - x SmAlO 3 (abbreviated as (1- x)CST- x SA) perovskite ceramics were synthesized through the conventional solid-state reaction process. The effects of SmAlO 3 on the microstructure, low-frequency dielectric performances, and microwave dielectric properties for (1- x)CST- x SA ceramics were investigated systematically. All compositions exhibited an orthorhombic perovskite structure with dense surface morphology. With increasing the content of SmAlO 3 , the order of B-site cation revealed a trend of increase first and then slowly decreased. The presence of oxygen vacancies in the (1- x)CST- x SA ceramics was detected by using x-ray photoelectron spectroscopy. Excellent temperature stability of dielectric permittivity and low dielectric loss (tan δ lower than 0.005) were observed for (1- x)CST- x SA ceramics at low frequencies. For x = 0.35 composition, the temperature coefficient of the resonant frequency approached zero. In addition, the dielectric permittivity of 42.0, the quality factor of 39,120 GHz, and the temperature coefficient of resonant frequency of − 6.4 ppm/℃ were obtained for 0.65CST-0.35SA ceramics. It is suggested that (1- x)CST- x SA ceramics can be used as a candidate material for various microwave communication components. [ABSTRACT FROM AUTHOR]

Highlights: [•] (1−x)Ba(Zr0.25Ti0.75)O3–xMgO thick films were prepared by tape-casting. [•] Dielectric tenability was 92.54~30.56% at 42kV/cm, room temperature and 1kHz. [•] High figure-of-merit, 103.97~219.86, of these films was attained. [•] Dielectric dispersion of these films was described by the Lorentz-type relation. [•] (ɛ (0) / ɛ(E) )3 vs. (E2) was fitted by the Johnson’s equation according to Devonshire’s theory. [ABSTRACT FROM AUTHOR]

Abstract: Sr1− x (Bi, Na) x /2Bi2Nb2O9 (SBNBNO, x =0, 0.2, 0.4 and 0.6) ceramics were prepared by the conventional solid-state route. X-ray diffraction analyses (XRD) and Raman spectroscopy indicated that all specimens have a single phase with perovskite-type orthorhombic structure. The piezoelectric activity and Curie temperature of SrBi2Nb2O9 (SBN) ferroelectric ceramics are significantly improved by bismuth and sodium modification. The piezoelectric coefficient d 33 of the Sr0.6(Bi, Na)0.2Nb2O9 (SBNBN4) specimen was found to be 22pC/N, which is higher than the d 33 values (about 12pC/N) of SBN specimen. Moreover, the SBNBN4 specimen exhibited the excellent temperature stability of piezoelectric properties. In order to confirm the nature of the piezoelectric properties enhanced, the relationship between the structure and electrical properties was discussed. [Copyright &y& Elsevier]

Abstract: Pb[(Mg1/3Nb2/3)1− x Zr x ]O3 (x =0.03, 0.06, 0.09, 0.12) ceramics were prepared using a solid state reaction process. The phase structure and surface micrograph were analyzed by X-ray diffraction and scanning electron microscopy. The effects of Zr content on the dielectric and dielectric tunability properties were investigated systematically. The results showed that the high dielectric tunability (>75% at x =0.12), low dielectric loss (<0.15%) and high temperature stability of these relaxor ferroelectric ceramics were favorable and competitive to those of titanium-containing perovskite structure materials for tunable device applications. The high dielectric non-linear properties were further discussed in terms of the Landau–Ginsberg–Devonshire thermodynamic theory completed with a Langevin term. [Copyright &y& Elsevier]

Abstract: Zinc oxide nanosheet/zinc-covered carbon fiber composites (ZNSZCFs) were synthesized by annealing the zinc-covered carbon fibers with electroplating in air. The diameter of the ZNSZCFs was about 25μm. The strongest RL of ZNSZCFs was −32.98dB at 3.31GHz. The strong absorption of ZNSZCFs was less than −4dB (>65%) over the range of 7.54–18GHz (1.6mm in thickness) and 5.96–18GHz (2.0mm in thickness), respectively. The ZNSZCFs are believed to be ideal microwave absorbing materials. [Copyright &y& Elsevier]

Abstract: Pure and chromium-doped CCTO (CaCu3Ti4O12) ceramics were prepared by a conventional solid-state reaction method, and the effects of chromium doping on the microstructures and electrical properties of these ceramics were investigated. Efficient crystalline phase formation accompanied by dopant-induced lattice constant expansion was confirmed through X-ray diffraction studies. Scanning electron microscopy (SEM) results show that doping effectively enhanced grain growth or densification, which should increase the complex permittivity. The dielectric constant reached a value as high as 20,000 (at 1kHz) at a chromium-doping concentration of 3%. The electrical relaxation and dc conductivity of the pure and chromium-doped CCTO ceramics were measured in the 300–500K temperature range, and the electrical data were analyzed in the framework of the dielectric as well as the electric modulus formalisms. The obtained activation energy associated with the electrical relaxation, determined from the electric modulus spectra, was 0.50–0.60eV, which was very close to the value of the activation energy for dc conductivity (0.50±0.05eV). These results suggest that the movement of oxygen vacancies at the grain boundaries is responsible for both the conduction and relaxation processes. The short-range hopping of oxygen vacancies as “polarons” is similar to the reorientation of the dipole and leads to dielectric relaxation. The proposed explanation of the electric properties of pure and chromium-doped CCTO ceramics is supported by the data from the impedance spectrum. [Copyright &y& Elsevier]

Abstract: Barium titanate–silver composites were prepared by using a solid state reaction process with silver contents ranging from 0mol% to 20mol%. XRD results and Raman spectra indicated that there was no phase other than BaTiO3 and Ag in the ceramics and tetragonality of barium titanate reduced with increasing Ag content. SEM images illustrated that Ag influenced densification and microstructure of BaTiO3 ceramics. Besides, addition of Ag led to increase in dielectric permittivity and broadening of ferroelectric–paraelectric phase transition peak. Also addition of Ag had effects on dielectric loss and dc conductivity. Dielectric and conductivity properties as a function of Ag volume fraction were explained by the percolation theory. [Copyright &y& Elsevier]

Abstract: The structural, electronic and optical properties of BiFeO3 (BFO) were investigated employing the first-principles within generalized gradient approximation (GGA). The magnetic moments were balanced out each other by the two irons spinning oppositely in a cell. The band gap of BFO was found to be 2.5eV by the electronic structure calculation. Analysis of the density of states indicated that the valence band was consisted with Fe-d and O-p states, and the conduction band was composed of Fe-d and Bi-p states. The dielectric function, absorption, refractive index, extinction coefficient, reflectivity and electron energy loss were calculated for radiation up to 31eV in order to understand optical properties of BFO. The reasons of the absorption were discussed. [ABSTRACT FROM AUTHOR]

Abstract: Ferroelectric ceramics BaBi4−x La x Ti4O15 (BBLT) were prepared with a solid-state reaction process. The obtained phases were confirmed as the Bi-layered perovskite phase with orthorhombic structure by the X-ray diffraction analysis (XRD). The dielectric relaxation was studied as a function of temperature and frequency. A dispersion of the maximum dielectric constant (ɛ max) appears around the temperature of T m , which shifts toward higher temperatures with the increase of frequency. The modified Curie–Weiss (CW) law was used to describe the relaxor behavior of BBLT ceramics. The relaxation indication coefficient (γ) was estimated with a quadratic fit of modified CW law. The coefficient firstly increases then decreases with the lanthanum increasing, which indicates that the BBT ceramics changes from relaxor-like ferroelectrics to relaxor ferroelectrics then to relaxor-like ferroelectrics with the lanthanum increasing. The relaxor nature of BBLT ceramics was attributed to the A site cationic disorder and the special relaxor behavior of BBLT ceramics was attributed to the high temperature phase transition by La3+ induced. [Copyright &y& Elsevier]

Abstract: TiN thin films were deposited on Si wafers using an unbalanced magnetron (UBM) sputtering technique and then annealed in vacuum at temperatures ranging from 300 to 900°C. The microstructure and surface morphology of the thin films at various processing parameters were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The variation of the hardness and surface roughness over the course of annealing treatment temperature was investigated. Annealing treatment was found to induce changes in the microstructure, crystallinity, texture, grain size, hardness and roughness of TiN films. The hardness of TiN films decreased after heat treatment in the vacuum, while surface roughness increased significantly. Moreover, the maximum values of hardness and roughness could be observed in films annealed at 450°C in comparison to those at other annealing temperatures. [Copyright &y& Elsevier]

Abstract: (1− x)[0.82Bi0.5Na0.5TiO3–0.18Bi0.5K0.5TiO3]–xBiFeO3 lead-free piezoelectric ceramics (abbreviated as BNKT–BFx with x varying from 0 to 0.10mol) were prepared by solid-state reaction process. Variation of the microstructure and piezoelectric properties of BNKT–BFx ceramics with BF content was investigated. The results indicated that the piezoelectric constant d 33, the planar electromechanical coupling factor k p and mechanical quality factor Q m varied with the BF amount. X-ray diffraction (XRD) analysis showed that the incorporated BF diffused into BNKT lattice to form a solid solution. Scanning electron microscope (SEM) also indicated that BF in high amount affected the microstructure. The morphotropic phase boundary (MPB) with rhombohedral and tetragonal coexistence for the ceramics lies in the range of x =0–0.06 in (1− x)BNKT–xBF system. The optimum values of d 33 and k p are 122pC/N and 0.317 at x =0.04. [Copyright &y& Elsevier]

Abstract: Lead-free ceramics (1− x)(K0.5Na0.5)0.95Li0.05NbO3–xBi0.5(K0.15Na0.85)0.5TiO3 [(1− x)KNLN–xBKNT] with x =0–0.04 were successfully synthesized by conventional solid-state sintering. Effects of Bi0.5(K0.15Na0.85)0.5TiO3 (BKNT) on the phase structure, microstructure and electrical properties of the (1− x)KNLN–xBKNT ceramics were investigated. BKNT strongly affected the sintering behavior, densification and microstructure of the ceramics. X-ray diffraction analysis revealed that all the (1− x)KNLN–xBKNT ceramics possessed pure perovskite structure, showing symmetries of orthorhombic at x <0.005, and tetragonal at x ≥0.015 at room temperature. Coexistence of orthorhombic and tetragonal phases was identified in the range of 0.005≤ x <0.015. The 0.99KNLN–0.01BKNT ceramics showed the optimum piezoelectric, ferroelectric properties and high Curie temperature, which were as follows: d 33 =240pC/N, k p =0.455, P r =20μC/cm2, E c =20.8kV/cm and T c =469°C. The mechanism of the enhanced piezoelectric properties was also discussed. These results indicate that this system looks a promising candidate for lead-free piezoelectric materials. [Copyright &y& Elsevier]

Abstract: Zinc oxide polycrystalline films were prepared by electrostatic spray deposition using the dispersions of zinc oxide nanocrystals as solution precursors for ultraviolet luminescence device applications. The structure and properties of the films were studied by X-ray diffraction, scanning electron microscope, energy dispersive X-ray spectroscopy and photoluminescence. Room temperature photoluminescence spectra of these films exhibit a strong near band-edge emission at 380nm and a negligible deep-level emission around 530nm, indicating the concentrations of the defects responsible for deep-level emissions are reduced on annealing. Moreover, temperature dependence of photoluminescence of ZnO film was investigated. [Copyright &y& Elsevier]

Abstract: Lead magnesium niobate–lead titanate (0.80Pb(Mg1/3Nb2/3)O3–0.20PbTiO3, PMN–PT) thick films on platinum metallic foils were successfully fabricated by electrophoretic deposition (EPD). The room temperature relative dielectric constant and the maximum relative dielectric constant were 4645 and 25,640 at 1kHz, respectively. The relaxor nature of PMN–PT thick films was studied in terms of diffused phase transition along with frequency dispersion of temperature of dielectric maximum (T m). Deviation from Curie–Weiss behavior and temperature evolution of the local order parameter were found in the films. The degree of relaxation obtained from the modified Curie–Weiss law strongly suggests the relaxor behavior. Vögel–Fulcher relationship was used to analyze the frequency dependence of temperature of dielectric maximum (T m). [Copyright &y& Elsevier]

Abstract: The influence of the microstructure on dielectric properties of Sr0.8(K,Na)0.2Bi2Nb2O9 (SKNBNO) prepared by the solid-state route is reported. The formation of Bi-layer structure was obviously restrained owing to the K and Na ions substituting Sr ions by the X-ray diffraction analysis (XRD) and scanning electron micrograph (SEM). At the same time, some slight secondary phase of bismuth oxide was detected but the structure was not changed. The dielectric constant was restrained by K and Na ions substituting Sr ions, which is mainly attributed to the slight change of lattice constants resulting in a decreased “rattling space” for the cations inside the distorted Nb(V)O6 oxygen octahedron of the perovskite block. A clear enhancement in the stability of frequency and temperature was noticed for SKNBNO sample compared to Sr2Bi2Nb2O9 (SBN) samples. [Copyright &y& Elsevier]

Abstract: High aspect ratio platelike sodium niobate (NaNbO3) was successfully synthesized from precursor Bi2.5Na3.5Nb5O18 by the topochemical microcrystal conversion process. Platelike bismuth layered-perovskite Bi2.5Na3.5Nb5O18 precursor was first synthesized by the molten-salt synthesis process, and then reacted with the complementary reactant Na2CO3 in NaCl flux, the platelike Bi2.5Na3.5Nb5O18 particles were transformed into the perovskite NaNbO3 particles that preserved the morphology of Bi2.5Na3.5Nb5O18 precursor at 950°C for 4h with the weight ratio of oxide to salt 1:1.5. The length of NaNbO3 seed crystals was in the range of 15–30μm, and the thickness range was 0.6–1μm. The aspect ratio of length to thickness varied from 15:1 to 50:1. Furthermore, by surveying the variations of the crystal micrographs and X-ray diffraction patterns, formation mechanisms were proposed from changing soaking temperature, salt amount and soaking time in the process. [Copyright &y& Elsevier]

Abstract: Perovskite Pb(Mg1/3Nb2/3)O3 (PMN) crystallites were synthesized via a single-step process, namely a hydrothermal process, at low temperature, by using PbO, MgO and Nb2O5 as precursors. PMN were obtained when the precursors were heated to 150°C for 24h with KOH concentration of 11M. Effects of the initial KOH concentration, temperature and reaction time on the phase evolution and morphologies of PMN crystallites were systematically investigated. The optimum KOH concentration was found to be 11M, which led to the stabilization of the perovskite powder against the pyrochlore phase, and to the growth of high-quality PMN crystallites suitable for subsequent characterization. According to morphological evolution during the reaction, a possible growth mechanism was proposed based on the dissolution–crystallization process. [Copyright &y& Elsevier]

Abstract: The influence of copper on the microstructure, electrical properties, resistances of grain and grain boundary of nonstoichiometric CaCu3x Ti4O12 ceramics, with x =0.8, 0.9, 1.0, 1.1 and 1.2) prepared by solid state reaction were investigated. The second phase TiO2 and CaTiO3 are found in copper deficiency samples while CuO appears in the other samples. The grain size changes dramatically with the increase of copper. Frequency dependence dielectric permittivity exhibits that the deficient and excess of copper promote to a decrease of dielectric permittivity. Impedance complex plane shows both copper deficient and copper excess result in the increases of resistances of grain, grain boundary and contact resistance between electrode and ceramics. [Copyright &y& Elsevier]

Abstract: Phase structure, microstructure, dielectric and piezoelectric properties of 0.4wt% CeO2 doped 0.94(Bi0.5Na0.5)TiO3–0.06BaTiO3 (Ce-BNT6BT) ceramics sintered in the temperature range from 1120 to 1200°C have been investigated as a candidate for lead-free piezoelectric ceramics. Tetragonal phase played an important role in improvement of electrical properties and the density of the ceramics. Dielectric constant decreased slightly with the increase of sintering temperature in ferroelectric region but a reverse phenomenon occurred in antiferroelectric and paraelectric regions, suggesting that interfacial polarizations were improved with the increase of sintering temperature and domain walls of ferroelectricity became active after depolarization. At room temperature, Ce-BNT6BT ceramics sintered at 1180°C showed good performances: dielectric constant was 914 at 1kHz, thick coupling factor k t was 0.52, and the ratio of k t /k p was 2.3. The ceramics were suitable for narrowband filters and ultrasonic transducers in commercial applications. [Copyright &y& Elsevier]

Due to its excellent ionic conductivity and electronic insulation, β/β″-alumina is widely used as a solid electrolyte in molten salt electrochemical cell and alkali metal thermoelectric convertor (AMTEC). In this article, nano-3mol% Yttrium partial stabilized zirconia (3YSZ) toughened β″-alumina solid electrolytes (BASEs) were fabricated by surface modification of β/β"-alumina precursor particles with ethylenediaminetetraacetic acid (EDTA) - Zirconium (IV)/Yttrium (III) complex. The performance of BASEs with 0-10 wt% amount of nano-3YSZ addition (Zr-BASE) was systematically investigated on their phase composition, density, microstructure, bending strength, and conductivity. It was found that nano-3YSZ grains were intergranular and uniformly distributed in BASE matrix even at as low as 3 wt% amount of addition, which resulted in higher density, more homogeneous microstructure, higher Weibull modulus, higher characteristic strength and increased grain boundary resistance of Zr-BASE than those of BASE without 3YSZ addition. Zr-BASE with 5 wt% amount of nano-3YSZ addition demonstrated good conductivity (0.071 S•cm−1 at 300 °C, 0.33 S cm−1 at 600 °C) and higher characteristic strength (283 MPa). The obtained results indicated that surface modification by EDTA-Zr(IV)/Y(III) complex advantaged in the preparation of better performance BASEs with a small amount of nano-3YSZ addition. Image 1 • EDTA complex surface modification was used to uniformly adding nano-3YSZ to BASE. • Zr-BASE was obtained with higher mechanical strength and medium ion conductivity. • BASE with 5 wt% 3YSZ addition showed better ion conductivity and mechanical strength. • EDTA complex was good at preparing better performance BASE with low 3YSZ addition. [ABSTRACT FROM AUTHOR]

With the rapid development of portable, foldable, and wearable intelligent electronic systems, there is an increasing demand for energy storage devices with enhanced flexibility, reduced weight, and high performance. Therefore, the configurations of modern electronics have developed from three-dimensional bulks or two-dimensional thin films to superflexible one-dimensional fibers. Fiber-shaped supercapacitors (FSCs) are widely favored by scholars because of their advantages including quick charge/discharge, high power density, excellent cycle stability, portability, light weight, outstanding flexibility, weavability and favourable compatibility with human body. The energy storage performance of FSCs heavily relies on the fiber electrode materials. Among various electrode materials, metal oxides are widely researched by virtue of earth abundance, low cost, ease of preparation, environmental benignity, tunable nanostructures, and more importantly, ultrahigh theoretical specific capacitance. This article firstly comprehensively reviews the main research progress in the current development and application of high-performance metal oxides based FSCs from the design of active materials, configuration of devices, and the investigation of energy storage properties investigation. Meanwhile, the main issues severely restricting the performance improvement of metal oxides based FSCs are discussed, and the corresponding ideas and the specific methods to address these issues are discussed. Secondly, the influences of different types of fiber-shaped substrates, electrolytes as well as assembly methods on the performance of metal oxides based FSCs are also discussed. Ultimately, a brief conclusion is made, accompanied by comments on the future technological development directions in the field of metal oxides based FSCs. [ABSTRACT FROM AUTHOR]

We report doping at B-Site in TmFeO 3 with In3+ ion of varying concentration (x = 0.02, 0.05, 0.07, 0.1) to explore the effect of In3+ ion substitution on structural, magnetic and vibrational properties. XRD study revealed that all the synthesized samples exhibit distorted perovskite orthorhombic (Pbnm) crystal symmetry. The immediate observable effect was an increase in lattice parameters with increasing doping up from x = 0.0 to 0.1 as evidenced by diffraction peaks shifted towards lower angle. Spin reorientation transition (Γ 4 →Γ 2) in all prepared samples occurs at temperature (∼85–92 K) to be a process involving the continuous rotation of Fe3+ spins. M-H curves display the coexistence of weak ferromagnetism and antiferromagnetic ordering at all the measured temperatures with reduction in coercive field and remanence values. Varied magnetic behaviors were observed in this series of compounds, which are believed to be associated with the different interactions of Fe and rare earth ions. The occurrence of two-magnon and two-phonon modes in Raman spectra at temperature around 100 K attributed to spin-reorientation transition exhibited by TmFe 1-x In x O 3. This might be unambiguous evidence for spin-phonon coupling in the prepared compounds. The coupling and possible presence of two phonon and magnon pair scattering and other energy carriers have been used to explain several recently discovered thermally driven spin transport phenomena. • XRD data reveals that samples TmFe 1-x In x O 3 possess the orthorhombic structure (Pbnm). • Spin reorientation transition (Γ 4 → Γ 2) arises at temperature between 85 and 92 K. • M-H curves display the coexistence of weak ferromagnetism and antiferromagnetic ordering • Evidences for spin-phonon coupling are also comes from Raman spectra of In-doped TmFeO 3. • Orthoferrites are very attractive option to fulfill the demand of miniaturization data storage and spintronics devices. [ABSTRACT FROM AUTHOR]

Abstract: Lead magnesium niobate–lead titanate (0.80Pb(Mg1/3Nb2/3)O3–0.20PbTiO3, PMN–PT) 16-μm thick films on platinum metallic foils were successfully fabricated by electrophoretic deposition (EPD). The EPD process was conducted in ethanol medium with pH 6.0. The effects of deposition parameters, such as deposition voltage and deposition time were evaluated. Single-phase PMN–PT thick-film structures without any pyrochlore phase were obtained after the sintering at 1100°C for 1h. Relaxor-like behaviour was clearly demonstrated in PMN–PT thick films. The room temperature relative dielectric constant and the maximum relative dielectric constant were 4800 and 26100 (at 1kHz), respectively, which are comparable to the reported values for bulk samples. [Copyright &y& Elsevier]

Crystal structures and electrical properties of (Na 0.5 K 0.5 ) 1− x Li x NbO 3 ( x = 0, 0.055, 0.06, 0.065, 0.07; KNN- x Li) ceramics were investigated systematically. Rietveld refinements confirmed that the ceramic with x = 0.06 modification had a typical morphtropic phase boundary (MPB) structure, where the proportions of orthorhombic ( Amm 2) and tetragonal ( P 4 mm ) phases were 58.37% and 41.63%, respectively. However, tetragonal phase structure was predominant in the x = 0.07 ceramic with 75.57% P 4 mm phase. Piezoelectric ceramics KNN- x Li were post-annealed in nitrogen (N 2 ) and oxygen (O 2 ), and atmosphere had a strong impact on the electrical properties of them. O 2 treatment resulted in improvements in ferroelectric polarization, electrostriction characteristic and piezoelectric property, due to the decrease in oxygen vacancy concentration. On the contrary, a deteriorated performance was found in the N 2 -treated samples. Impedance data of KNN- x Li ceramics were largely dominated by the sample bulk, and variable-atmosphere experiments suggested that the KNN-0.06Li ceramic was mainly n -type material. The O 2 -treated KNN-0.06Li ceramic with a T c of 473 °C had a remnant polarization ( P r ) of 29.2 μC/cm 2 , a field-induced strain ( S 33 ) of 0.152%, a piezoelectric coefficient ( d 33 ) of 218 pC/N and an electromechanical coupling factor ( k p ) of 43%. [ABSTRACT FROM AUTHOR]

Defect engineering and heterojunction formation are essential for modifying photocatalysts to improve the separation efficiency of photogenerated carriers. In this work, an all-organic π-π interaction-based novel heterojunction (NVCN/TCPP), that combines nitrogen vacancies enriched-g-C 3 N 4 and tetra (4-carboxylphenyl) porphyrin (TCPP) was synthesized. Scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR/TEM), X-ray diffraction (XRD), Fourier Transform-Infrared (FT-IR) spectroscopy, Brunauer-Emmett-Teller (BET) test, and X-ray photoelectron spectroscopy (XPS) were used to investigate the surface morphology, micromorphology, crystal structure, and functional groups in the samples. Both NVCN and TCPP had a two-dimensional nanosheet morphology. The electron paramagnetic resonance (EPR) results confirmed the existence of nitrogen vacancies in graphitic carbon nitride (g-C 3 N 4). The photocatalytic performance of the composites was evaluated by the degradation of Rhodamine B (RhB) under visible light. NVCN/TCPP-1 showed the best photocatalytic performance, which was attributed to the synergistic effect of nitrogen vacancies and TCPP present in the composite that facilitated the separation and transfer of photogenerated carriers. We conducted a thorough investigation into the mechanism for enhanced photocatalysis and presented a Z-scheme heterojunction mechanism to explain our findings. This study could serve as a valuable reference for the construction of organic heterojunctions. [Display omitted] • The all-organic NVCN/TCPP with nitrogen vacancies were fabricated sucessfully. • The nitrogen vacancies enriched-g-C 3 N 4 and TCPP are connected by the π-π interaction. • The EPR results confirmed the existence of nitrogen vacancies in the g-C 3 N 4. • The NVCN/TCPP-1 showed excellent photocatalysis and separation efficiency of the carriers. • The enehanced photocatalysis of the NVCN/TCPP-1 attributed to a Z-scheme mechanism. [ABSTRACT FROM AUTHOR]

Co 3 O 4 has been extensively studied for its ultra-high theoretical specific capacitance (3560 F g−1) and cost-effectiveness. However, its poor conductivity originating from the relatively wide band gap, results in a low specific capacitance, a low energy density and a poor rate performance. In order to improve the rate performance of Co 3 O 4 , an in situ formed Co@Co 3 O 4 structure was assembled with a post-heat treatment. Therein, Co nanosheet arrays (NSAs) were deposited on the activated carbon cloth (ACC) with a simple electrodeposition method. The Co@Co 3 O 4 core-shell structure was characterized with XRD, HRTEM and XPS after argon ion etching. In addition, the kinetic analysis of redox reaction was introduced to quantify the contribution of redox pseudocapacitance and intercalated pseudocapacitance ("battery-type" materials). The Co@Co 3 O 4 nanosheets show a high specific capacitance of 1520 F g−1 at 1 A g−1 and the specific capacitance retention at 10 A g−1 takes 80.3% of the value at 1 A g−1. The assembled hybrid supercapacitors (HSCs) show a superb energy density (60 Wh kg−1) as well as a long lifespan (82.6% of the initial value after 10000 cycles). The eminent performance stems from the synergistic effect of Co@Co 3 O 4 core-shell nanostructure, ensuring the structural stability and the rapid transmission of electrons. In situ synthesis of 3D Co@Co 3 O 4 nanosheet arrays possessed high specific capacitance of 1520 F g−1 at 1 A g−1 as well as outstanding rate performance Moreover, the contribution of various pseudocapacitive was quantified. Image 1 • A simple in-situ synthesis method of Co@Co 3 O 4 was proposed. • The framework of Co conductive array combined with Co 3 O 4 shell formed a collective network for ultrafast electron transport. • The contribution of different pseudocapacitive were quantified. • Hybrid supercapacitors exhibited a superior high-rate performance and energy density. [ABSTRACT FROM AUTHOR]

A series of Bi 0.48 (Na 0.84 K 0.16) 0.48 Sr 0.04 (Ti 1- x Ta x)O 3 (abbreviated as NKS-100 x Ta) lead-free piezoelectric ceramics were fabricated using a traditional solid-state method. The structure and electrical properties of NKS-100 x Ta were investigated in detail. The composition for x = 0.01 presented an enhanced electric field induced bipolar strain of ∼0.53%, as well as the giant unipolar strain of ∼0.478% corresponding to S max / E max ∼682 p.m./V at 70 kV/cm. It is found that the ferroelectric-relaxor transition temperature (T F-R) shifted down to ambient temperature and the remnant polarization (P r) decreased with the Ta doping. It destroyed the long-range ferroelectric ordering and increased the relaxor characteristic. Therefore, the origin of giant strain was ascribed to the transformation from the ferroelectric phase to relaxor phase under the applied electric field. In addition, the well fatigue properties within 104 cycles indicated that the prepared ceramics offered extendable availability for sensors and actuators. Fig. 5. (a) Unipolar strain curves of the NKS-100 x Ta measured at 70 kV/cm with 1 Hz frequency. (b) P r , P m and d * 33 as a function of Ta content. Image 1 • A ferroelectric-to-relaxor transition is obtained by chemical modification. • The giant unipolar strain of 0.478% corresponding to S max / E max ∼ 682 pm/V at 70 kV/cm obtained at ambient temperature. • The giant strain derives from the combination of interior and extrinsic effects. [ABSTRACT FROM AUTHOR]

Abstract Leed-free ferroelectric (1-x)(0.72Bi 0.5 Na 0.5 TiO 3 -0.28Bi 0.2 Sr 0.7□0.1 TiO 3)-xLa (NBST-xLa; x = 0, 0.5%, 1.5%, 2%) ceramics were synthesized using a conventional solid-state reaction method and the effect of La-doping on the microstructure and electrical properties was investigated. The introduction of La could reduce the grain size and improve the porosity of NBST ceramics. Temperature-dependent dielectric permittivity illustrated that the relaxation properties of NBST-xLa ceramics changed parabolically with the increase of La content. The introduction of La gave rise to a large dielectric breakdown strength and maximum polarization when x = 0.5%, which was attributed to the variation of the microstructure and the relaxation properties of NBST-xLa ceramics, respectively. The optimum effective energy storage density of 1.2 J/cm3 at 90 kV/cm was achieved when x = 0.5%. These results indicated that NBST-0.5%La ceramic may provide a practical perspective for energy storage ceramics research. Highlights • La-doped ceramics were synthesized using a solid-state reaction method. • The introduction of La gave rise to a large DBS and P max. • NBST-0.5%La possessed the optimum effective energy storage density. [ABSTRACT FROM AUTHOR]

The high theoretical capacity of silicon (Si) makes it an attractive anode for lithium-ion batteries (LIBs). However, the poor cycle performance due to the volumetric expansion of Si during the charging-discharging process hinders its practical applications. A composite of graphene and silicon can buffer effectively the volumetric expansion of Si during the charging and discharging process of the battery. Herewith we describe a honeycomb structure constructed with Si nanoparticles (NPs), acetylene black (ACET), and reduced graphene (rGO). In this 3D structure, ACET and Si formed a Si/C composite by mechanical ball milling and it was then encapsulated in a graphene oxide (GO) suspension. After reduction with hydrazine hydrate (N 2 H 4 ·H 2 O) to create rGO, a stable composite Si/C/rGO was obtained. As an anode for LIB, the Si/C/rGO composite exhibited excellent cycle and rate performance. Firstly, the initial coulombic efficiency (ICE) of the battery is very high, exceeding 85%. Secondly, the reversible capacity was retained at 1004 mAh/g after 270 cycles at a current density of 1 A/g. The composite maintained good cycling stability even at current densities of 2 and 3 A/g. Finally, in the rate cycle test, the reversible capacity was up to 450 mAh/g at 5 A/g. [Display omitted] • Forming N-C, C-O-N chemical bonds in Si/C/rGO composite. • Initial coulombic efficiency exceeded 85%. • Specific capacity remained 1004 mAh/g at 1 A/g after 270 cycles. • Rate performance was excellent with capacity of 460 mAh/g at 5 A/g. [ABSTRACT FROM AUTHOR]

The development of lead-free ceramics with high energy storage density is critical due to the human health and environmental hazards of lead and the demand to miniaturize and integrate electronic devices. Nevertheless, the high applied electric field limits their use in integrated circuits. In this work, (1- x) Bi 0.5 (Na 0.82 K 0.18) 0.5 Ti 0.99 (Y 0.5 Nb 0.5) 0.01 O 3 - x NaNbO 3 (BNKTYN-100 x NN) ceramics were prepared, and excellent energy storage properties were obtained. It has revealed that NaNbO 3 dopant reduces remanent polarization and increases relaxor degree. BNKTYN-9NN ceramics has high energy storage density (W rec =1.6 J/cm3) and responsivity (ξ = W rec / E = 145.5 J/(kV•m2)) under 110 kV/cm. Meanwhile, good temperature stability (20–120 °C) and fatigue resistance (105 cycles) were also obtained in BNKTYN-9NN ceramics. In addition, doping NaNbO 3 suppresses the dielectric anomaly peak, and BNKTYN-9NN ceramics has excellent temperature-stable dielectric permittivity from 53° to 447°C. These results suggest that BNKTYN-100 x NN ceramics are promising for energy storage equipment. • Using antiferroelectric NaNbO 3 to improve the energy storage performance of Bi 0.5 (Na 0.82 K 0.18) 0.5 TiO 3 -based ceramics. • A high W rec of 1.6 J/cm3 and η of 73.1 % at a lower electric field of 110 kV/cm were obtained in the x = 0.09 composition. • BNKTYN-9NN ceramics has outstanding dielectric temperature stability from 53 °C to 447 °C. [ABSTRACT FROM AUTHOR]

Oxygen-vacancy-induced one-dimensional (1D) CeO 2 nanotubes (CeNT) has successfully loaded on two-dimensional (2D) graphitic carbon nitride (g-C 3 N 4) by simple methods for investigating the performance of photocatalytic degradation of sewage. The results of characterization analyses have proved that the CeNT are uniformly dispersed on the surface of the g-C 3 N 4 nanosheets. The electron paramagnetic resonance (EPR) spectra signal exhibited the existence of oxygen vacancies in CeNT. Photoluminescence spectra (PL), UV–vis diffuse reflectance spectra (UV–vis DRS) and photoelectrochemical measurements demonstrated that the appropriate amount of CeNT (28 mg) can effectively improve the separation efficiency of photogenerated charge carriers and the photoresponse property of the samples. The rhodamine B (RhB) degradation experiments verify the same results that the photocatalytic degradation efficiency of the samples for RhB increased initially, followed by a decreased, meanwhile the degradation activity didn't decrease prominently after four circles. Also, the reactive species trapping experiment indicated that the holes (h+) and superoxide radicals (∙O 2 -) played major role in the photocatalytic reaction. Finally, the enhanced photocatalytic performance can be attributed to the synergistic effects of the oxygen vacancies in CeNT and a new charge transfer mechanisms of Step-scheme heterojunction for electron separation, which could provide a new green solution for photocatalytic sewage treatment. [Display omitted] A sustainable approach for the interfacial optimization of one-dimensional CeO 2 nanotubes loaded two-dimensional graphite carbon nitride with synergistic enhancement of visible-light-driven photoelectric and photocatalytic pollutant degradation is reported. • A series of CeNT/g-C 3 N 4 composites were prepared by a suitable and reliable possess. • The EPR spectra indicated the presence of oxygen vacancies over CeNT. • Appropriate CeNT modification can enhance the separation efficiency of the carriers. • The active species trapping experiment indicated that h+ and·O 2 - played major role. • The enhanced photocatalysis ascribed to optimization of S-scheme heterojunction. [ABSTRACT FROM AUTHOR]

Graphitic carbon nitride (g-C 3 N 4) shows a graphite-like layered structure, which provides a high theoretical value for solar-to-hydrogen evolution especially for a 2D nanostructure. However, conventional polycondensation induces a strong agglomeration and collapse of nanostructure, resulting in a relatively poor photocatalytic performance. To overcome this problem, we develop a gas bubbling exfoliation strategy with NH 4 Cl assistant to make ultrathin 2D g-C 3 N 4 nanosheets self-assembled into a 3D macroporous network on a large scale. The hierarchical structure significantly improves the specific surface area to 176.4 m2 g−1 (11.6 times higher than the reference g-C 3 N 4), which allows a large water/g-C 3 N 4 interface for photocatalytic water reduction reaction. The ultrathin 2D g-C 3 N 4 nanosheets show a thickness of about 1.4 nm, which greatly suppress photoinduced carriers recombination and enhance charge transfer at the interface. Furthermore, the doping of N and Cl is achieved during synthesis. As a result, the resulting g-C 3 N 4 demonstrates a remarkable improvement in H 2 production of 12.89 mmol g-1 h−1, which is 21 times higher than the g-C 3 N 4 obtained from the conventional condensation method. These explorations provide a facile guidance for the quasi 3D g-C 3 N 4 hierarchical architecture engineering even for various energy-related applications. [Display omitted] • Ultrathin 2D g-C 3 N 4 nanosheets self-assembled into a 3D macroporous network. • Enhanced H 2 production of 12.89 mmol g-1 h−1 is achieved, which is 21 times higher. • The hierarchical structure improves the specific surface area to 176.4 m2 g−1. • The ultrathin 2D g-C 3 N 4 nanosheets show a thickness of about 1.4 nm. [ABSTRACT FROM AUTHOR]

Lead-free (1- x)[(Bi 0.5 Na 0.5) 0.94 Ba 0.06 TiO 3 ]- x AgNbO 3 (abbreviated as BNTBT-100 x AN) ceramics were fabricated using a conventional solid-phase reaction technique. The effect of the antiferroelectric AgNbO 3 dopants for fatigue resistance, energy-storage density, temperature-stable permittivity, and conductivity mechanism was systematically investigated. The addition of AgNbO 3 led to the decrease of remnant polarization and the increase of dielectric breakdown strength, a large effective energy-storage density of ~1.27 J/cm3 corresponding to the conversion efficiency of ~ 77.5% for BNTBT-5AN ceramic were attained under applied 105 kV/cm field. Meanwhile, it exhibited an outstanding fatigue-resistant performance at 70 kV/cm fixed field up to 105 cycles accompanied with excellent temperature-stable properties in the temperature range of 30 °C ~ 120 °C. Besides, BNTBT-5AN sample has also obtained outstanding temperature-stable permittivity, which was associated with the enhancement of the ergodic relaxor domain structure. A little variance of dielectric content (Δ ε' / ε' 150 °C ≤ ± 15%) was acquired from 40 °C to 387 °C with a small tangent loss (tan δ ≤ 0.05) between 50 °C and 461 °C. Hence, it revealed that the high energy storage properties and excellent dielectric temperature stability for BNTBT-5AN ceramic were conducive to its better applications in electronic equipment. • A large effective energy-storage density of ~ 1.27 J/cm3 corresponding to the conversion efficiency of ~ 77.5% for x = 0.05 composition were attained under applied 105 kV/cm field. • BNTBT-5AN ceramic has also obtained outstanding temperature-stable permittivity, which was associated with the enhancement of the ergodic relaxor domain structure. • A little variance of dielectric content (Δ ε' / ε' 150 °C ≤ ± 15%) was acquired from 40 to 387 °C with a small tangent less (tan δ ≤ 0.05) between 50 °C and 461 °C for BNTBT-5AN ceramic. [ABSTRACT FROM AUTHOR]

Nanostructured SnO 2 /TiO 2 hybrid materials can be promising anode materials for lithium ion batteries (LIBs). We herein report a novel and energy-saving photodeposition approach to fabricate SnO 2 /TiO 2 composite nanotubes. In the photodeposition process, Sn 2+ ions are oxidized to SnO 2 by the photogenerated holes, thus SnO 2 nanoparticles are deposited onto both the inner and outer walls of TiO 2 nanotubes. This results in the formation of the SnO 2 /TiO 2 composite nanotubes with a hierarchically porous architecture. The existence of the positive bias can enhance the photooxidation of Sn 2+ ions by decreasing the hole–electron recombination, leading to the deposition of more SnO 2 nanoparticles on the walls of TiO 2 nanotubes. The SnO 2 /TiO 2 composite film electrode fabricated by the photodeposition at the positive bias shows much higher lithium storage capacity than the corresponding controllable electrodes during the electrochemical cycling at a current density of 100 μA cm −2 . The specific capacity of SnO 2 in the composite film electrode photodeposited at the positive bias is estimated to be 766 mAh g −1 after 100 cycles at a current density of 100 μA cm −2 , demonstrating its prominent lithium storage performance. The as-constructed facile and energy-saving photodeposition method can be used as an efficient route to prepare other composite materials with controlled morphologies and dimensions. [ABSTRACT FROM AUTHOR]

Oxygen defects have been considered to play an important role on the gas sensing properties of the sensor. In this work, oxygen vacancies are produced by quenching the commercial SnO 2 and characterized by the X-ray photoelectron spectroscopy (XPS), adsorption and impedance spectra. Impedance spectra indicate that the quenched samples have a significant increase in conductivities, as well as a large reduction in activation energy from 1.14(1) to 0.20(1) eV, with the quenching temperature increasing. Furthermore, the gas sensors based on quenched SnO 2 are prepared and gas sensing experiments give strong evidence that the oxygen vacancies enhance the sensor performances. By increasing the concentration of oxygen vacancies, the sensor displays a higher response toward ethanol (100 ppm) at 300 °C. [ABSTRACT FROM AUTHOR]

The 0.94Bi 0.5 Na 0.5 TiO 3 –0.06BaTiO 3 (BNBT6) introduced by CaZrO 3 (CZ) lead-free ferroelectric ceramics are successfully fabricated by conventional solid state reaction. The influence of CZ substitution on the phase transition, microstructure, dielectric, ferroelectric, and energy storage properties of (1 − x)BNBT6-xCZ ceramics are systematically investigated. The energy-storage density 0.7 J/cm 3 under the electric field 70 kV/cm is obtained in the 0.97BNBT6-0.03CZ. In addition, its energy-storage property exhibits thermal stability at the temperature range of 30–130 °C. [ABSTRACT FROM AUTHOR]