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Polycrystalline NiO-based thin films with Li or/and transition metal ions (V, Cr, Mn, Fe, Co, Cu, Zn) doping have been prepared by a sol-gel spin-coating method. Magnetization measurements reveal that V-, Fe-, and Mn-doped NiO thin films show obvious room-temperature ferromagnetic behaviors and ferromagnetic properties can be enhanced by the Li co-doping. Microstructure and X-ray core-level photoemission spectra analysis indicate that the ferromagnetism was not from the impurity TM metal cluster and may be ascribed to double exchange coupling effects via Li-induced holes. [ABSTRACT FROM AUTHOR]

Bi0.95A0.05FeO3 (A = Ba, Sr, Ca) thin films were deposited on (111) Pt/Ti/SiO2/Si substrates via chemical solution deposition. The magnetization of the doped specimens increases sharply as compared to that of pure BiFeO3, and it increases as the doped ionic radius gets larger. X-ray diffraction analysis reveals that the films are single phase, and no other extra magnetic phases are detected. X-ray photoelectron spectroscopy analysis suggests that the content of Fe3+ increases and that that of Fe2+ decreases. According to the x-ray diffraction and Raman analyses, there are corresponding changes in the lattice parameters and the Raman spectra as the doped ionic radius gets larger. These results indicate that neither the magnetic coupling of Fe2+ nor the parasitic magnetic phases could be the origin of the magnetization improvement, and we consider that the magnetization improvement mainly originates from the doped ionic radius size effect. [ABSTRACT FROM AUTHOR]

We prepared La doped of CaCu3Ti4O12 ceramics by a solid-state sintering process and observed nonlinear electrical varistor and high dielectric behaviors. Phase composition analyses show that the La can substitute on the Ca sites completely, and have no influence on the phase composition. The impedance spectroscopy at room temperature indicates that the La doping can maintain the dielectric permittivity of CaCu3Ti4O12 (∼104). The relationships between electrical current density versus applied electrical field show that these ceramic samples exhibit nonlinear varistor characteristics, which should be ascribed to the existing potential barrier height at the grain boundary. [ABSTRACT FROM AUTHOR]

Anatase titania-coated bismuth ferrite nanocomposites (BiFeO3/TiO2) have been fabricated via a hydrothermal approach combined with a hydrolysis precipitation processing. Analysis of the microstructure and phase composition reveals that a core-shell BiFeO3/TiO2 structure can be formed, which results in a significant redshift in the UV-vis absorption spectra as compared to a simple mechanical mixture of BiFeO3–TiO2 nanopowders. The core-shell structured BiFeO3/TiO2 nanocomposites exhibit higher photocatalytic activity for photodegradation of Congo red under visible-light (λ>400 nm) irradiation, which should be attributed to the enhancement of the quantum efficiency by separating the electrons and holes effectively. The obtained BiFeO3/TiO2 nanocomposites can be used as potential visible-light driven photocatalysts. [ABSTRACT FROM AUTHOR]

We prepared TiO2-rich CaCu3Ti4O12 (CCTO) ceramics by a solid-state sintering process and observed large nonlinear electrical and high dielectric behaviors. Microstructure and phase composition analyses show that CCTO grain-amorphous/TiO2 nanograin boundary-CCTO grain junction structures exist in these TiO2-rich CCTO ceramics, which leads to the nonlinear electrical and high dielectric properties. The temperature dependence of impedance spectroscopy and relationships between electrical current density versus applied electrical field indicate that the activation energy of the grain boundary for the TiO2-rich CCTO ceramics is almost the same as the potential barrier height and both of them are weakly independent of the doped concentration of TiO2, which supports the internal barrier layer capacitor model of Schottky barriers at the grain boundaries between semiconducting CCTO grains. [ABSTRACT FROM AUTHOR]

NaNbO3‐based antiferroelectric ceramics are promising candidates for high‐performance energy storage capacitors due to their environmental friendliness and low cost despite their current energy storage properties being inferior to those of their lead‐based and AgNbO3‐based counterparts. Typically, the antiferroelectric phase in NaNbO3 ceramics is not stable and the characteristic double hysteresis loops are seldom observed. In this work, the antiferroelectricity was improved by reducing the polarizability, resulting in well‐developed double hysteresis loops in 0.94NaNbO3–0.06(K0.5Bi0.5)SnO3 ceramics. To further improve the energy storage properties, defect engineering was performed for 0.94NaNbO3–0.06(K0.5Bi0.5)SnO3 by substituting Na+ with La3+ and introducing Nb vacancies. As a result, the stability of the field‐induced ferroelectric phase was reduced, and the energy storage properties were enhanced. The strategy of combining polarizability design and defect engineering can be a promising approach for optimizing NaNbO3‐based antiferroelectric ceramics. [ABSTRACT FROM AUTHOR]

Abstract The ferromagnetic insulators (FMI) involving the phonon-magnon interaction in generation of spin currents are providing new opportunities to explore the thermal to electrical conversion efficiency in comparison to electron based themoelectrics. Here, we have investigated the magnetic damping behavior and spin Seebeck effect in crystalline, highly smooth surfaced, nano-meter thick FMI Ce 0.5 Y 2.5 Fe 5 O 12 (CeYIG) films, synthesized via pulsed laser deposition technique, for their application in spin caloritronics. The CeYIG films reveal an increase of saturation magnetization, strong magnetic anisotropy and a very low magnetic damping, optimum for investigation of pure spin currents generated via inverse spin Hall Effect. The room temperature longitudinal spin Seebeck effect (LSSE) was observed on sputtering of 8 nm thick Hall bar patterned rhodium (Rh) on CeYIG films. The magnitude of LSSE voltage obtained showed a characteristic increase and saturation of signal with the increase of film thickness, indicating the origin of spin current generation from the bulk of CeYIG film. The pure spin Hall magnetoresistance (SMR) was observed in temperature range of 5–300 K implying the LSSE observed in Rh layer is purely from the spin current generated within the FMI and free from parasitic magnetic proximity effect (MPE). The use of Rh as a normal metal for the detection of spin current can open a new window in the exploration of pure spin current related phenomena. Highlights • Crystalline nano-films of Ce doped Yttrium iron garnet deposited via pulsed laser deposition technique. • A very low magnetic damping is observed even on Ce doping. • The CeYIG films exhibit increase in saturation magnetization, strong magnetic anisotropy and enhanced Kerr rotation. • Observation of room temperature longitudinal spin Seebeck effect (LSSE) with a clear SMR signal down to 5 K. • A characteristic increase and saturation of LSSE signal with film thickness [ABSTRACT FROM AUTHOR]

Abstract Rhodium (Rh) is a 4d metal possessing a large spin orbit coupling strength and spin-Hall conductivity with a very small magnetic susceptibility, implying an insignificant magnetic proximity effect (MPE). We report here the observation of longitudinal spin Seebeck effect (LSSE) using Rh as a normal metal. A Rh film was sputtered on nanometer thick YIG films of highly crystalline nature and extremely low magnetic damping to obtain Rh/YIG hybrid structure. A clear thermal voltage V th (SSE voltage) was obtained when a temperature gradient was applied on the Rh/YIG hybrid. The Rh film showed a very weak anomalous Hall resistance and the magneto-resistive testing clearly ruled out the magnetization of the Rh films via MPE. The anisotropic magnetoresistance (AMR) revealed a clear spin hall magnetoresistance (SMR) signal in Rh film implying a purely intrinsic spin current generation, free from any parasitic magnetic effects. The work can open a new window in the study of pure and uncontaminated spin current, generated in ferromagnetic insulators, using Rh as spin current detector. Highlights • Synthesis of highly crystalline nanometer thick YIG films with very low magnetic damping. • Observation of room temperature longitudinal spin Seebeck effect using Rh as a spin detector. • Magneto-resistive measurements clearly ruling out the magnetization of Rh films via magnetic proximity effect. [ABSTRACT FROM AUTHOR]

Nanostructured BiFeO3 particles have been synthesized by a hydrothermal method, and the effects of particle size on photocatalytic activity and magnetic property of BiFeO3 were investigated. The optical absorption spectra indicate that the band-gap energy increases with decreasing crystalline size due to the quantum-size effect. The enhancement of room-temperature weak ferromagnetism can be observed in nanoscale BiFeO3 particles, which should be attributed to the size-confinement effect on the magnetic ordering. In addition, BiFeO3 nanoparticles with diameter about 5 nm show good photocatalytic performance by photodegradation of Congo red under visible-light (λ>400 nm) irradiation. [ABSTRACT FROM AUTHOR]

Mn-doped BaTiO3 nanoparticles have been synthesized using a hydrothermal method. Phase composition, microstructure, and Raman spectroscopy analysis indicate that a double-phase structure containing both cubic and tetragonal structures can be obtained. Electron paramagnetic resonance and x-ray photoelectron spectroscopy measurements prove that Mn ions exist as a form of Mn2+ in these nanoparticles. Magnetization measurements reveal that a ferromagnetic behavior can be observed in the Mn-doped BaTiO3 at low temperature, and the nominal ratio of Ba/Ti has a great influence on the ferromagnetic properties. This ferromagnetic mechanism can be ascribed to the exchange coupling interaction between the Mn2+ ions and the Ti4+ vacancy. [ABSTRACT FROM AUTHOR]

The Li-doped Ni–Si–O thin films (LixNi0.90-xSi0.10O, x=0.0–0.05) have been prepared by a sol-gel spin-coating method on silicon and quartz glass substrates. Analysis of phase composition and microstructure indicates that the films consist of cubic NiO phase and amorphous phase as annealed at 700 °C for 5 min. With the Li-doping concentration increasing, the core-level photoemission spectra show that a loss of the double-peak structure of the Ni 2p3/2 main line can be observed and current density of the films increases greatly, which should be ascribed to the increase of the hole carriers induced by the Li doping. Ultraviolet-visible absorption spectra indicate that the absorption edge of the films exhibits a redshift due to the related defects. [ABSTRACT FROM AUTHOR]

In this work, we have applied the first-principles calculations to investigate the structural stability, elastic properties and electronic structure of Mo2FeB2 with alloying elements Cr, Ni and Mn. The calculated cohesive energy shows that Cr, Ni and Mn prefer to occupy the Fe atom of Mo2FeB2. However, only when Mn is doped at the Mo atom of Mo2FeB2, it is converted from dynamic unstable state to stable state. The calculated elastic modulus shows that Mo2FeB2 will have better mechanical properties when alloying elements are at Fe site instead of Mo site. Moreover, Cr addition can improve the volume deformation resistance of Mo2FeB2, Mn addition can improve the shear deformation resistance for Mo2FeB2. The calculated B/ G ratio shows that Ni addition can improve the brittleness of borides. Furthermore, the hardness of Mo2FeB2 can be enhanced by adding Cr and Mn element. The calculated electronic structure indicates that the increasing of elastic modulus is attributed to the formation of Cr-B and Mn-B covalent bonds. [ABSTRACT FROM AUTHOR]

Porous fillers are considered as an effective way to improve the mechanical properties of dental composites through the interlocking with organic matrix. In this paper, mesoporous silica (mobil crystalline materials-41) of different particle sizes was synthesized, modified, and added in bisphenol-A glycidyl dimethacrylate/triethylene glycol dimethacrylate resins to obtain composites at different loading levels. The influence of mesoporous filler concentration, particle size, and surface modification on the mechanical properties (flexural strength, flexural modulus, and Vickers microhardness) of composites has been investigated in detail. Compared to nonporous silica, mesoporous silica significantly improved composites’ mechanical properties. Flexural strength and flexural modulus are increased by 44.5% and 33.4%, respectively, when filler mass fraction reaches 15 wt%. Samples filled with silane-modified mesoporous silica show a higher flexural strength with the particle size decreasing from around 470 to 35 nm. The results implied potential applications for dental composites filled with porous fillers. [ABSTRACT FROM AUTHOR]

The influence of poly(methylmethacrylate- co- N-vinyl-2-pyrrolidone), P(MMA- co-VP), on corrosion of carbon steels (J55, N80, P110SS and C110 steels) in 3.5 wt% NaCl solution saturated with CO was evaluated using static high pressure and high temperature (HPHT) autoclave. The surface was further evaluated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and contact angle measurements. Quantum chemical calculations have been used to evaluate the structural, electronic and reactivity parameters of the inhibitor on the steels surface. SEM, XRD and contact angle measurement studies reveal that the surface of metals are quite unaffected after use of inhibitor in 3.5% NaCl solution saturated with CO. [ABSTRACT FROM AUTHOR]

For an ideal electrostatic energy storage dielectric capacitor, the pursuit of simultaneously high energy density and efficiency presents a formidable challenge. Typically, under an applied electric field, an increase in energy density is usually accompanied with a deteriorated energy storage efficiency due to the escalated hysteretic loss, which is harmful to the reliability of the capacitor. Thus, a well‐balanced performance of improved energy density and maintained high efficiency is highly demanded. In this work, a structure with amorphous phases embedded in polycrystalline nanograins using the entropy tactic, leading to a higher transport barrier of carrier is constructed. Hence, the hysteretic loss is largely suppressed at a high electric field and the high polarization is still sustained in the high‐entropy film. Consequently, an ultrahigh energy density of 139.5 J cm−3 with a high efficiency of 87.9%, and a high figure of merit of 1153 are simultaneously achieved in the high‐entropy Ba2Bi4Ti5O18‐based relaxor ferroelectric. This work offers a promising avenue in materials structure design for advanced high‐power energy storage applications. [ABSTRACT FROM AUTHOR]

Abstract: Mn-doped CaCu3Ti4O12 (CCTO) polycrystalline ceramics have been prepared by the conventional solid state sintering. Our results indicate that 10% Mn doping can decrease the dielectric permittivity in CaCu3Ti4O12 by about 2 orders of magnitude (from 104 to 102). The grain and grain boundary activation energies show an obvious increase from 0.054eV to 0.256eV, and decrease from 0.724eV to 0.258eV with increasing the Mn doping concentration, respectively, which may be caused by the variation of Cu and Ti valence states in the CCTO samples evidenced by the X-ray absorption spectra. The similar grain and grain boundary activation energies result in invalidation of the internal boundary layer capacitance effect for the 10% Mn-doped CCTO sample, and thus result in the dramatic decrease of dielectric permittivity. [Copyright &y& Elsevier]

Nanostructured Zn and Ce co-doped In2 O3-based ceramics were fabricated using co-precipitation and Spark plasma sintering. It is shown that the nanograins in Zn and Ce co-doped In2 O3-based ceramics can lead to 50% reduction in the thermal conductivity of the sample with a 50 nm grain size and meanwhile keep good electric conductivity. As a result, a reported high ZT value of 0.4 at 1050 K was achieved for n-type oxide thermoelectrics. It is expected that the ZT value could reach 0.7 when the grain size is smaller than 20 nm. Our results indicate that nanosized grain is highly desired for reducing thermal conductivity and hence a higher ZT value in oxide thermoelectrics. [ABSTRACT FROM AUTHOR]

Using the spark plasma sintering process In2 −x Ce x O3 (0 ≤ x ≤ 0.10) fine grained ceramics have been synthesized. Our results indicate that all the In2 O3-based ceramic samples show good electrical conductivity and high thermoelectric power factor. In comparison with pure In2 O3 bulks or doped samples with grain size above 1 μm, the 100-300 nm fine grain In2 O3-based ceramics exhibit much lower thermal conductivities (1.9-2.5 W·(m·K)−1 at 1173 K), demonstrating a remarkable cooperative tuning effect imposed by grain size reduction and nano-clusters formation. The maximum figure of merit ZT value is optimized up to ~0.47 at 1223 K for In1.92 Ce0.08 O3 sample, which makes them promising candidates for thermoelectric applications. [ABSTRACT FROM AUTHOR]

As one of the most important energy storage devices, dielectric capacitors have attracted increasing attention because of their ultrahigh power density, which allows them to play a critical role in many high-power electrical systems. To date, four typical dielectric materials have been widely studied, including ferroelectrics, relaxor ferroelectrics, anti-ferroelectrics, and linear dielectrics. Among these materials, linear dielectric polymers are attractive due to their significant advantages in breakdown strength and efficiency. However, the practical application of linear dielectrics is usually severely hindered by their low energy density, which is caused by their relatively low dielectric constant. This review summarizes some typical studies on linear dielectric polymers and their nanocomposites, including linear dielectric polymer blends, ferroelectric/linear dielectric polymer blends, and linear polymer nanocomposites with various nanofillers. Moreover, through a detailed analysis of this research, we summarize several existing challenges and future perspectives in the research area of linear dielectric polymers, which may propel the development of linear dielectric polymers and realize their practical application. [ABSTRACT FROM AUTHOR]

We present a rare-earth-doped ZnO ceramic with nonohmic electrical properties. Analysis of the microstructure and composition indicates that the ceramic is composed of the main phase of ZnO and the second phase of rare-earth oxides (e.g., Dy2O3, Pr6O11, Pr2O3). The average grain size is markedly increased from 3 to 18 μm, with an increase in the sintering temperature from 1150° to 1350°C. The corresponding varistor voltage and nonlinear coefficient decrease from 1014 to 578 V/mm, and from 15.8 to 6.8, respectively. The resistivity of grain and grain boundary evaluated by the complex impedance spectrum indicates that the resistivity of the grain is approximately constant (∼103Ω), and the resistivity of the grain boundary decreases. The relative dielectric permittivity of the sintered ceramic samples is much larger than that of pure ZnO ceramic, which should be ascribed to the internal boundary layer capacitance effect. [ABSTRACT FROM AUTHOR]

We present high-temperature electrical transport and thermoelectric power of K and/or La-doped Ca3Co4O9-based ceramics. Temperature and doping dependence of electrical transport properties indicate that both K and La substitutions can increase electrical conductivity at a high temperature, which are mainly related to an increase in carrier concentration and carrier mobility. A metallic-to-semiconducting transition temperature ( T*) can be observed and shifts to a lower temperature as the doping content increases. However, activation energy is almost independent of the doping. All of the samples show positive thermoelectric power, and the temperature dependence of the thermoelectric power exhibits a simple linear behavior at T> T*. Our experimental data indicate that all of the Ca3Co4O9-based ceramic samples exhibit large thermoelectric power (∼120 to 180 μV/K). [ABSTRACT FROM AUTHOR]

Dielectric materials featured with polarization at an applied electric field have been demonstrated with a wide range of applications such as energy storage and conversion, thus triggering tremendous efforts in scientific and industrial research. To date, numerous strategies have been explored to improve the performance of dielectric materials; especially, the recently reported high-entropy design enabling flexible composition configuration and tunable functional properties has attracted increasing attention. In this contribution, we review the very recent investigations and applications of high-entropy design for dielectric materials, including dielectric energy storage, electrocalorics, piezoelectrics, and ferroelectrics, and address the challenges and remaining concerns. Finally, we suggest future research directions for the preparation and in-depth structure characterization of high-entropy dielectric materials. This review will provide a holistic view of the most state-of-the-art high-entropy dielectric materials and envision prospects of high-entropy design for dielectrics. [ABSTRACT FROM AUTHOR]

LixNi0.97-xFe0.03 nanofibers with different Li doping concentration have been synthesized by electrospinning method. The phase composition and microstructure analysis show that Fe and Li doping has no influence on the phase structure and morphology of NiO nanofibers, which reveal that the doped Fe and Li have been incorporated into the NiO host lattice. All the Li and Fe co-doped NiO nanofiber samples show obvious room-temperature ferromagnetic properties. The saturation magnetization can be enhanced with increase of the Li doping concentration. This phenomenon can be ascribed to the fact that the hole doping makes ferromagnetic coupling interactions between the holes and localized Fe 3d states more efficient. [ABSTRACT FROM AUTHOR]

We present a remarkable effect of Mn doping on the dielectric and nonlinear electric properties of CaCu3Ti4O12 ceramics. The results indicate that only 2.5 at. % Mn doping can suppress the dielectric permitivity in CaCu3Ti4O12 by up to two orders of magnitude (from 104 to 102), and the nonlinear varistor characteristics disappear completely, which should be mainly ascribed to the decrease of potential barrier height at the grain boundary and charge compensation for the conduction electrons caused by the Mn doping. [ABSTRACT FROM AUTHOR]

Polycrystalline ZnO-based thin films with Li and/or Co doping have been prepared by a sol-gel spin-coating method on silicon substrates. Magnetization measurements reveal that Li-doped ZnO film shows paramagnetic behavior. However, the Co-doped ZnO thin films show obvious room-temperature ferromagnetic properties, and ferromagnetic properties can be enhanced by the Li codoping, which may be ascribed to indirect exchange via Li-related defects. All ZnO-based films exhibit ferroelectric behavior, and ferroelectric properties can be tuned by the dopants. [ABSTRACT FROM AUTHOR]

The authors present the structure transformation and magnetic properties of Bi1-xLaxFeO3 (x=0.0–0.15) ceramics prepared by a conventional solid-state reaction processing. Magnetic measurements reveal that remnant magnetization of 15% La-doped BiFeO3 has enhanced about 20 times as compared to pure BiFeO3. It is the structural phase transition (R3c–C222) near x=0.15 that destructs the spin cycloid, and thus enhances the ferromagnetic properties significantly. In these Bi1-xLaxFeO3 ceramic samples, besides the known antiferromagnetic Néel temperature TN1∼615 K, another Néel temperature TN2∼260 K can be observed due to the trace impurity phase of Bi2Fe4O9 in these ceramic samples. [ABSTRACT FROM AUTHOR]

Li and Fe codoped NiO thin films (LixNi0.98-xFe0.02O, x=0–0.05) were obtained by a sol-gel spin-coating method on silicon substrates. Phase composition and microstructure analysis indicated that the film samples contained 20–30 nm sized NiO particles. With increasing Li-doping concentration, the current density of the films increased due to the increase of hole carriers. Magnetization measurements revealed that all the thin films showed room-temperature ferromagnetic properties and could be enhanced by Li doping, which should be due to the fact that hole doping makes ferromagnetic coupling interactions between the hole carriers and localized Fe 3d spins more efficient. [ABSTRACT FROM AUTHOR]

Luminescence induced by mechanical stress has been observed in the SrAl2O4:Eu, Dy phosphors. The Dy3+ doping concentration and the loading pressure show strong influence on the intensity but the Eu2+ doped samples show little effect of mechanoluminescence (ML). The origin of the ML may be ascribed to the holes released due to the stress on the phosphors and then recombine with metastable Eu+1. [Copyright &y& Elsevier]

Corrections to the article "Ferromagnetism in antiferromagnetic NiO-based thin films" that was published in the 2011 issue are presented.

BiCuSeO is a promising oxygen‐containing thermoelectric material due to its intrinsically low lattice thermal conductivity and excellent service stability. However, the low electrical conductivity limits its thermoelectric performance. Aliovalent element doping can significantly improve their carrier concentration, but it may also impact carrier mobility and thermal transport properties. Considering the influence of graphene on carrier‐phonon decoupling, Bi0.88Pb0.06Ca0.06CuSeO (BPCCSO)‐graphene composites are designed. For further practical application, a rapid preparation method is employed, taking less than 1 h, which combines self‐propagating high‐temperature synthesis with spark plasma sintering. The incorporation of graphene simultaneously optimizes the electrical properties and thermal conductivity, yielding a high ratio of weighted mobility to lattice thermal conductivity (144 at 300 K and 95 at 923 K). Ultimately, BPCCSO‐graphene composites achieve exceptional thermoelectric performance with a ZT value of 1.6 at 923 K, bringing a ≈40% improvement over BPCCSO without graphene. This work further promotes the practical application of BiCuSeO‐based materials and this facile and effective strategy can also be extended to other thermoelectric systems. [ABSTRACT FROM AUTHOR]

To meet the miniaturization demands of next-generation electronics and electrical systems, energy storage capacitors with both high energy density and efficiency have become a research hotspot. Ferroelectric-based dielectrics are primary candidates due to the existence of spontaneous polarization and versatile domain structures. Since domains are fundamental structure units that respond to the external electric field, domain engineering is a general route to realizing high energy storage performance. In this perspective, we introduce a type of dielectrics, proposed recently and termed superparaelectrics, which has ultrasmall polar clusters (several unit cells) and exhibits nearly zero hysteresis and relatively high polarization due to the highly dynamical polar structure. Fundamental concepts of superparaelectricity are overviewed, and representative examples with state-of-the-art energy storage performance are reviewed to demonstrate the advantages of superparaelectrics. Finally, perspectives are provided about the future development of superparaelectric and electrostatic energy storage fields. [ABSTRACT FROM AUTHOR]

Future applications in power generation for wearable and portable electronics or active cooling for chips will benefit from near-room-temperature thermoelectric performance enhancement. Ga-doped ZnO (GZO) thin films are potential thermoelectric materials as they have the advantages of high cost-effectiveness, low toxicity, excellent stability, and high optical transparency. Inserting a ZnO buffer layer between the sapphire substrate and GZO thin films could contribute to optimizing carrier mobility and further improving electrical transport properties. However, thermoelectric performance at near-room-temperature ranges still needs to be promoted for practical applications. In this present study, ZnO single-crystal slices were directly selected as substrates for homogenously growing GZO thin films to further modify the substrate–film interface. The high Hall mobility of 47 cm2 V−1 s−1 and weighted mobility of 75 cm2 V−1 s−1 could be realized, resulting in better electrical transport performance. Consequently, the homogenously grown GZO thin films possessed competitively prominent power factor values of 333 μW m−1 K−2 at 300 K and 391 μW m−1 K−2 at 373 K. This work offers an effective avenue for optimizing the thermoelectric properties of oxide-based thin films via homogenous growth. [ABSTRACT FROM AUTHOR]

Thermoelectric oxide thin films are promising in chip cooling. The issues on the orientation of thin films are essential as they are related to the structures, morphologies, and thermoelectric properties. In this regard, the orientation modulation is conducted on La‐doped SrTiO3 thin films on (LaAlO3)0.3(Sr2TaAlO6)0.7 (LSAT) single crystal substrates. Layer‐by‐layer growth mode is found in (001)‐ and (110)‐ oriented thin films, resulting in few grain boundaries (GBs). In (111)‐oriented films, island growth mode leads to columnar grain boundaries that build up potential barriers for electrons to be strongly scattered and filtered, suppressing electron mobility and increasing effective mass. In addition, the GBs serve as oxygen vacancy diffusion paths when annealing, causing increased carrier concentration and lattice contraction. The weighted mobility of 71.9 cm2 V−1 s−1 and electrical conductivity of ≈600 S cm−1 are realized in the (001)‐oriented film at room temperature. Ultimately, outstanding power factor values of ≈569 µW m−1 K−2 (room temperature) and ≈791 µW m−1 K−2 (573 K) are successfully achieved, outperforming those in polycrystalline ceramics and (111)‐oriented films. This study systematically investigates the influence of grain boundaries and orientations on SrTiO3‐based thermoelectric films, which lays a solid foundation for improving thermoelectric performance in other oxide thin films. [ABSTRACT FROM AUTHOR]

Abstract Solid polymer electrolytes show great application potential in the next-generation all-solid-state Li-ion batteries due to its safety, electrochemical stability, and easy-processing feature. However, low ionic conductivity of solid polymer electrolytes hinders their commercialization. Currently, dispersing ceramic fillers in polymer electrolytes has been proved to be a promising approach to address this issue. Herein, we introduce Li 6.75 La 3 Zr 1.75 Ta 0.25 O 12 fillers into polyacrylonitrile-LiClO 4 matrix and study the effects of Li 6.75 La 3 Zr 1.75 Ta 0.25 O 12 on chemical and electrochemical properties of the polyacrylonitrile-based electrolytes. The addition of Li 6.75 La 3 Zr 1.75 Ta 0.25 O 12 triggers the cyclization and segmentation of polyacrylonitrile chains, which improves the mechanical strength and thermal stability of the electrolytes. The effects of Li 6.75 La 3 Zr 1.75 Ta 0.25 O 12 on the electrochemical properties of the electrolytes are thoroughly investigated. The polyacrylonitrile-based electrolyte with 20 wt% Li 6.75 La 3 Zr 1.75 Ta 0.25 O 12 fillers shows a high ionic conductivity of 2.2 × 10−4 S cm−1 at 40 °C, a wide electrochemical window of 4.9 V, and much improved Li+ transference number and cycling stability in a Li||Li symmetric cell. In addition, a solid-state LiFePO 4 ||Li full cell is assembled and tested at room temperature, demonstrating the applicability of polyacrylonitrile-based electrolytes in all-solid-state batteries. Highlights • LLZO induces cyclization and segmentation of polyacrylonitrile (PAN). • LLZO boosts the electrochemical performance of PAN-based electrolytes. • LLZO enhances mechanical strength and thermal stability of PAN-based electrolytes. • PAN-LiClO 4 -LLZO electrolytes deliver good full-cell performance. [ABSTRACT FROM AUTHOR]

The optic-electronic response is usually limited by poor electron–hole separation and phonon thermalization. Here, we show that natural superlattice materials with charged layers in BiOCuCh (Ch = S, Se, Te) can effectively suppress bulk carrier recombination and dissipation from phonon. The photogenerated hot carriers in BiOCuCh are separated by the intrinsic p–n junction naturally composed of the [Cu2Ch2]2− and [Bi2O2]2+ layers, and transport occurs with high speed within the two layers. Moreover, its dissipation can be substantially reduced because the interlayer coupling leads to low phonon thermalization. As a result, these materials both show prominent response to full-spectrum solar lights and resemble cocatalysts in their characteristics. Because of these merits, these oxychalcogenides provide a penetration point up-and-coming platform for the exploration of materials with an extraordinary optoelectric response. [ABSTRACT FROM AUTHOR]

A large-area laser-clad coating was realized by overlapping laser tracks and thus presents overlap and non-overlap zones on the surface. The microstructure and corrosion behaviors of the overlap and non-overlap zones of the multi-track laser-clad nickel-based alloy coating at various flow rates and impact angles were investigated. Results indicated that overlap zone presented coarse columnar dendrites rather than cellular structures. The primary phases were mainly composed of γ-Ni, and the precipitation at the grain boundary was Ni6Mo6C. At the impact angle of 60° and flow rate of 6 m/s, overlap zone showed 2.0 × 10–7 A/cm2 higher stable potentiostatic polarization current density at passivation film destruction and furrow formation than non-overlap zone. The increase content of Mox+ (Mo) in non-overlap zone was 4.38% more than that in overlap zone after corrosion indicating the better Cl− corrosion resistance. The current densities increased with the enhanced flow rate. At the impact angle of 60°, the flow rate increased from 1 to 6 m/s, and the potentiostatic current density increased by 3.0 × 10–7–3.7 × 10–7 A/cm2. With the increase of the impact angle, the stable current densities increased first and then decreased. And the surface morphology changed from long and shallow ravines to short deep gully. [ABSTRACT FROM AUTHOR]

Ceramic capacitors are ubiquitously used in high power and pulse power applications, but their low energy density, especially at high temperatures (>150 °C), limits their fields of application. One of the reasons is the low energy efficiency under high electric fields and/or at high temperatures. In this work, equimolar Sm3+ and Ti4+ cations were doped in NaNbO3 to increase relaxor characteristics and energy storage properties. The optimal recoverable energy density Wrec of 6.5 J/cm3 and energy efficiency η of 96% were attained in the ceramics with 10% (Sm, Ti) concentration (SmT10). Dense microstructure and low dielectric loss were attributed to the high energy storage performance. Impedance spectra analysis revealed that the grain boundary resistance dominates at low temperatures, while the grain resistance dominates at high temperatures. The ceramics show stable Wrec and η in a broad temperature range of −90 to 200 °C and repeated charge–discharge cycles up to 105. The comprehensive energy storage performance indicates SmT10 ceramics are among potential candidates for ceramic capacitors working at high temperatures. [ABSTRACT FROM AUTHOR]

Layered oxychalcogenides have received extensive attention in the fields of magnetism, superconductivity, lithium battery, and luminescence due to their unique electronic, magnetic properties, and layered structure, among which layered oxyselenides have excellent and promising thermoelectric performance, such as BiCuSeO and Bi2LnO4Cu2Se2. Here, we successfully synthesized Sr2MO2Cu2Se2 (M = Co, Ni, Zn) and Sr2FeO3CuSe and investigated the thermoelectric properties at a wide temperature range (298–923 K). They have a relatively high Seebeck coefficient (>300 μV K−1) in medium to high temperature range and possess a low thermal conductivity. The power factor and ZT reach 65 μW m−1 K−1 and 0.07 at 923 K for intrinsic Sr2NiO2Cu2Se2, and a higher performance is expected to be achieved by strategies like carrier concentration optimization and band structure engineering. [ABSTRACT FROM AUTHOR]

As a transparent thermoelectric oxide, gallium‐doped zinc oxide (GZO) has the potential to power wearable or portable electronics and may be used in the integrated circuits industry for chip cooling. Constructing ZnO–GZO interfaces has been proposed as an effective strategy for improving thermoelectric performance of GZO thin films. However, without the aid of band structure calculation for multilayered films, it is hard to directly elucidate the underlying mechanisms of carrier transport. Weighted mobility is an indicator that reveals the inherent electronic transport properties like carrier scattering, electronic band structure, and so on. Thus, to further investigate the effects of ZnO–GZO interfaces on electrical properties of GZO thin films, the structures containing different numbers of ZnO–GZO interfaces were designed and the correlations among numbers of ZnO–GZO interfaces, weighted mobility, and electrical properties were explored. It was found that with more ZnO–GZO interfaces, the weighted mobility increased, and the power factor values also improved as well. Consequently, an enhanced power factor value reached 439 μW m−1 K−2 at 623 K. This work demonstrated the beneficial effects of multiple interfaces on the improvements of electrical transport performance through analyzing weighted mobility, which laid a foundation for further optimization of thermoelectric performance. [ABSTRACT FROM AUTHOR]

Dielectric ceramics with high polarization and low sintering temperature are important for high-performance and low-cost multilayer ceramic capacitors (MLCCs). Herein, BiFeO3 was added to a lead-free composition 0.48BaTiO3-0.4Bi(Mg0.5Hf0.5)O3-0.12SrTiO3 to lower the sintering temperature and increase the polarization simultaneously. As a result, a low sintering temperature of 950 °C and high comprehensive energy storage properties with a recoverable energy density Wrec of 5.7 J/cm3 and an energy efficiency η of 92% at 450 kV/cm were achieved. Together with the good temperature stability and cycling stability of Wrec and η, the ceramics exhibit great potential in the energy storage MLCCs with low-cost Ag-Pd electrodes with a high Ag content. [ABSTRACT FROM AUTHOR]

Polymer composite dielectrics capable of high energy density, high efficiency, and high‐temperature stability are in high demand for application in various electronic vehicles and power systems. A major challenge, however, is the reasonable design of high‐performance nanofillers that are beneficial to the polarization and breakdown strength simultaneously. Here, high‐entropy‐induced ceramic nanofibers with a stable Bi2Ti2O7‐type pyrochlore phase are developed as effective nanofillers to enhance the energy storage performance of polyetherimide (PEI) composites. Benefiting from the linear pyrochlore phase, refined grain size, and increased amorphous fraction of the high‐entropy nanofillers, the resultant PEI composites exhibit significantly improved energy storage performance over a wide temperature range of 25–150 °C. Notably, a high energy density of 6.46 J cm−3 under an electric field of 590 MV m−1 is achieved at 150 °C, which outperforms most of the reported PEI composites. This study provides a guideline for the development of dielectric fillers with tunable dielectric properties and microstructures, thus promoting the development of high‐performance polymer composites. [ABSTRACT FROM AUTHOR]

The anomalous Hall effect (AHE) is a quantum coherent transport phenomenon that conventionally vanishes at elevated temperatures because ofthermal dephasing. Therefore, it is puzzling that the AHE can survive in heavy metal (HM)/antiferromagnetic (AFM) insulator (AFMI) heterostructures at high temperatures yet disappears at low temperatures. In this paper, an unconventional high-temperature AHE in HM/AFMI is observed only around the Néel temperature of AFM, with large anomalous Hall resistivity up to 40 nQ cm is reported. This mechanism is attributed to the emergence of a noncollinear AFM spin texture with a non-zero net topological charge. Atomistic spin dynamics simulation shows that such a unique spin texture can be stabilized by the subtle interplay among the collinear AFM exchange coupling, interfacial Dyzaloshinski-Moriya interaction, thermal fluctuation, and bias magnetic field. [ABSTRACT FROM AUTHOR]

Objective To evaluate the microstructure and mechanical behavior of polymer-infiltrated zirconia ceramics as a function of Fe 2 O 3 concentration (0–0.3 mol%). Methods Polymer-infiltrated zirconia ceramics with different concentrations of Fe 2 O 3 were prepared by infiltration and polymerization. XRD was employed to determine phase structure. The microstructure and fracture mechanism was observed by SEM. Flexural strength and fracture toughness were measured by three-point bending method and single-edge-notched beam method, respectively. Data were analyzed by Weibull distribution. A nanoindentation system was employed to determine elastic modulus and hardness. Results With increasing content of Fe 2 O 3 , the flexural strength, fracture toughness, elastic modulus and hardness are all greatly enhanced and the chromatic behavior also improves significantly. As a tradeoff made between strength and elastic modulus, specimen containing 0.2 mol% Fe 2 O 3 is found to be the better one, with flexural strength and fracture toughness values being 336.8 MPa and 3.91 MPa m 1/2 , respectively. Moreover, it maintains a relatively low elastic modulus of 88.2 GPa and a moderate hardness of 4.8 GPa, close to those of natural enamel. Significance This polymer-infiltrated zirconia ceramic material is a dental material of biomimetic chromatic and mechanical properties. [ABSTRACT FROM AUTHOR]

Polar topologies in ferroelectric/paraelectric superlattices have been an important substance to explore exotic physical properties. Although enormous efforts have been paid to this field, the universality of the formation of polar topologies in various superlattices and their electric field dynamics is still unknown. Herein, we employ a phase-field model to construct three types of ferroelectric/paraelectric superlattices with tetragonal, rhombohedral, and orthorhombic symmetries and investigate their static structures and dynamic responses as a function of epitaxial strain. It is found that all superlattices undergo a similar vortex–spiral–in-plane topology transition, which corresponds to peaked dielectric permittivity curves and ferroelectric-, antiferroelectric-, and paraelectric-like hysteresis loops. Such polarization behaviors are attributed to the triple-well free energy landscape. The flexibility of hysteresis loops generates high energy density and efficiency of ferroelectric/paraelectric superlattices. This study offers a systematic view of the generality of polar topologies in multilayered ferroelectrics. [ABSTRACT FROM AUTHOR]

Capacitors with high energy storage performances are highly desired for the miniaturization, lightweight, and integration of high-end pulse systems. However, the trade-off between dielectric constant and breakdown strength restricts further performance optimization. To improve energy storage properties, a new tactic with rising attention, the high-entropy concept, has been demonstrated to suppress leakage current and enlarge the breakdown strength. However, the mechanisms connecting the insulation properties and entropy are still unclear. Herein, we successfully fabricated a series of entropy-modulated Cd 2 Nb 2 O 7 -based pyrochlore ceramics via the doping of multiple elements, and high-entropy pure pyrochlore was obtained due to the entropy-stabilization effect. Our results revealed that the insulation properties are distinctly enhanced via the enlarged carrier transport barriers and reduced carrier concentration, which should be attributed to entropy-induced large lattice distortion, grain-refining, and fewer defects. The optimized insulation properties significantly enhance breakdown strength from 148 kV cm−1 to 457 kV cm−1. A high energy density of 2.29 J cm−3 with a high energy efficiency of 88% is thus achieved in the high-entropy ceramic, which is 150% higher than the pristine material. This work indicates the effectiveness of high-entropy design in the improvement of energy storage performance, which could be applied to other insulation-related functionalities. [Display omitted] [ABSTRACT FROM AUTHOR]

Polycrystalline SmBaCuFeO5+δ/Ag composite ceramics have been synthesized by a traditional ceramic processing method. Phase composition and microstructural analyses indicate that with the introduction of Ag additives, the second phases of copper oxides and Ag appear in these composite ceramic samples. The hole concentration and molibility can be enhanced greatly by the addition of Ag particles, which results in a large increase in the electrical conductivity. The thermal conductivity behaviors show that phonons can be scattered effectively by point defects and mesoscale grain boundaries, which remain a slight change in thermal conductivity. A maximum ZT value 0.047 has been achieved at 1023 K in the SmBaCuFeO5+δ/20 vol% Ag composite ceramic, and is about 16 times than the pure SmBaCuFeO5+δ sample. Our results reveal that Ag addition is an effective way to enhance the thermoelectric properties. [ABSTRACT FROM AUTHOR]

We report remarkably the enhanced thermoelectric performance of Sn-Zn co-doped In2O3 that were synthesized by a solid-state reaction followed by spark plasma sintering in the mid-temperature range. The X-ray diffraction study indicates that Sn and Zn were successfully co-substituted at the In site without forming any additional phase even at 8% doping concentration. The co-substitution shows a significant increase in the electrical conductivity by band structure modification resulting in a significantly enhanced power factor. The point defect engineering combined with nanostructuring using a high energy ball milling suppressed the lattice thermal conductivity, which eventually resulted in an increased ZT value of 0.32 at 973 K, that is, about 7 times higher than that of pure In2O3. Thus, this study demonstrates the important role of co-substitution in improving the thermoelectric properties of n-type oxides. [ABSTRACT FROM AUTHOR]

Nanostructured transition-metal oxides exhibit excellent properties, such as ferromagnetic, ferroelectric, photoluminescence and semiconductive behaviors, etc. The band gap and electronic structure of these oxides can be controlled by size and dimensions; they can also be used in a wide range of applications including microelectronics, energy storage, sensors, and biomedicine due to their tunable chemical and physical properties. Here, we give a comprehensive review of the controllable growth of some typical transition-metal oxide nanostructures (e.g., WOx, FeOx, ZnO, TiO2, VO2, etc.), which can be used to effectively understand the fabrication methods as well as the growth mechanism and inspire their potential applications. [ABSTRACT FROM AUTHOR]

Layered oxyselenides have been widely investigated as promising thermoelectric materials due to their unique merits such as super‐lattice structural features and intrinsic complexity, which contributes to low thermal conductivity and easily controllable electrical properties. Newly developed Bi2LnO4Cu2Se2 (Ln stands for lanthanide) oxyselenides are found to be potential thermoelectric systems since they have excellent electrical conductivity over 103 S cm−1. In this work, unique energy and time‐saving method combined self‐propagating high‐temperature synthesis (SHS) with spark plasma sintering (SPS) is adopted to successfully prepare a highly pure Bi2LnO4Cu2Se2 instead of a traditional solid‐state reaction. To explore the most suitable lanthanide for Bi2LnO4Cu2Se2, thermoelectric performance in a wide temperature range (300 to 923 K) of Bi2LnO4Cu2Se2 (Ln = Nd, Sm, Eu, Gd, Tb, Dy, Ho, and Er) is deeply evaluated and studied. Ultimately, with a relatively high electrical conductivity, moderate Seebeck coefficient, and extremely low thermal conductivity, a maximum ZT value of ≈0.27 at 923K is achieved in Bi2DyO4Cu2Se2, which is 4 times larger than that of the ever‐reported Bi2YO4Cu2Se2 and proves a potential thermoelectric system for further investigation. This work may provide some enlightenment and broaden the horizon in finding new thermoelectric materials, especially for complex layered compounds. [ABSTRACT FROM AUTHOR]