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Simultaneously enhanced d33 and Tc values were realized in BF–BT-based lead-free MPB piezoceramics through cooperatively regulating the lattice distortion and content of rhombohedral phase, domain heterogeneity and defect concentration.

With the development of energy-storage technology and power electronics industry, dielectric capacitors with high energy density are in high demand owing to their high power density. Especially for ferroic dielectrics (including ferroelectrics and antiferroelectrics) showing dipole moments in the perovskite unit cells, large dielectric response under electric fields makes them own outstanding potentials for achieving high energy-storage density. Particularly, destroying long-range ferroelectric/antiferroelectric ordering by enhancing compositional disorder is found to be effective for extremely improving energy-storage properties (both high recoverable energy-storage density and efficiency), because these macroscopic-nonpolar nanodomains are highly polarizable under strong external electric fields. Moreover, owing to the heterogeneous structure induced dielectric relaxation characteristics, excellent temperature stability can be achieved simultaneously. The recent developments of (anti)polar nanoregions with different possible local symmetries in various lead-free perovskite-structured dielectrics have been summarized in this review, together with the achieved energy-storage properties based on them. This review would provide a guidance for preparing high-performance energy-storage capacitors by local-structure engineering for next-generation pulse power applications.

While research on policy diffusion has attracted the attention of many scholars, little attention has been given to policy reinvention in diffusion. With the aim to explore the influencing factors and combination paths of policy reinvention in the Municipal Solid Waste Classification Policy (MSWCP), this study constructs a theoretical framework concerning internal factors, intergovernmental relations and external influence, and carries out an empirical analysis on the MSWCP of 31 large and medium-sized cities in China using the Qualitative Comparative Analysis. Based on the empirical results, this study identifies the different combination paths that induced local governments to reinvent policies and clarifies the various roles of financial resources, government attention, policy experience, peer competition, learning, and social demand in achieving policy reinvention, which is expected to provide new theoretical and practical enlightenment for policy reinvention research.

Antiferroelectric (AFE) materials exhibit outstanding advantages against linear or ferroelectric (FE) dielectrics in high-performance energy-storage capacitors. However, their energy-storage perfor...

Supercritical relaxor nanograined ferroelectrics are demonstrated for high-performance dielectric capacitors, showing record-high overall properties of energy density ≈13.1 J cm

The energy-storage performance of stable NaNbO3-based antiferroelectric (AFE) ceramics was for the first time reported in (0.94-x)NaNbO3-0.06BaZrO3-xCaZrO3 lead-free ceramics. A gradual evolution from an instable AFE phase (x≤0.01) to an orthorhombic AFE P phase (Pbma) (0.01 1.16 J/cm3 and an outstanding charge-discharge performance with fast discharge rate (t0.9

Perovskite-structured antiferroelectric (AFE) materials, which are dominated by PbZrO3 based solid solutions, are of particular importance owing to their excellent electromechanical properties. The driving force for new development of AFE materials is the result of environmental regulations which require the exclusion of lead components. However, currently reported lead-free AFE materials either show inferior stability or need extremely high driving fields (EA–F) for AFE–FE phase transition. Here we report a new NaNbO3-based solid solution with a room-temperature stable AFE phase and completely reversible field induced AFE–FE phase transition, possessing a relatively low EA–F of ∼8 kV mm−1, a large repeatable strain of ∼0.29%, and a large polarization difference (Pmax ∼ 24 μC cm−2, Pr ∼ 0 μC cm−2). The local and average structures were studied by transmission electron microscopy, in situ Raman spectrum and synchrotron X-ray diffraction, revealing that the solid solution with ≥16 mol% SrTiO3 belongs to the Pnma space group and exhibits nanoscale stripe domains of ∼55 nm, and reversibly responds to large external electric fields. This makes it a competitive lead-free AFE candidate for future applications of high-power energy-storage capacitors and large-displacement actuators.

Thermally-stable (0.75-x)BiFeO3-0.25PbTiO3-xBa(Zr0.25Ti0.75)O3 (0.1 ≤ x ≤ 0.27) piezoelectric ceramics were reported to have excellent dielectric and electromechanical properties of d33∼405 pC/N, kp∼46%, e33T/e0∼1810, tanδ∼3.1% and Tc∼421 °C close to tetragonal (T)-rhombohedral (R) morphotropic phase boundary. The dielectric measurement indicates that R ferroelectric phase is gradually transformed into relaxor ferroelectric across the phase boundary due to the substitution of BZT for BF. The transmission electron microscopy and convergent beam electron diffraction provide clear evidences that both the R-T phase coexistence and polar nanodomains contribute to enhanced piezoelectric properties at x = 0.19 through cooperatively facilitating polarization orientation. In combination with the macroscopic piezoelectric coefficient measurement, the quantitative analysis of synchrotron diffraction data under electric fields suggests that extremely large lattice strain contribution predominantly from R phases plus little extrinsic domain switching contribution should dominate the piezoelectric response of the x = 0.19 sample, mainly owing to both irreversible field-induced T to R phase transition and irreversible non-180° domain switching.

NaNbO3 (NN)-based lead-free antiferroelectric (AFE) ceramics with ultrahigh energy-storage density (Wrec) have attracted increasing attention for applications in high power electronic devices. However, large polarization hysteresis induced by the AFE-ferroelectric (FE) phase transition tends to cause high energy dissipation. In this work, a relaxor AFE orthorhombic R-phase ceramic in (1-x)NN-xCaTiO3 ((1-x)NN-xCT) solid solutions was found to show outstanding comprehensive energy-storage properties with giant Wrec = 6.6 J/cm3, high energy efficiency η = 80% and ultrahigh power density PD = 350 MW/cm3 as × ≥ 0.14. The results of Raman spectrum, Raman mapping and transmission electron microscopy demonstrate that introducing CT in NN will moderately enhance the local-structure inhomogeneity as compared with many other complex perovskites, thus benefiting the gradual transformation from AFE microdomains to AFE nanodomains with increasing CT content. This allows the polarization saturation to be reached at a relatively high electric field. Of particular importance is that the high band-gap in NN and CT, refined grain size and suppressed dielectric loss enable obviously enhanced dielectric breakdown strength. As a result, the proper balance between those different factors leads to an obvious improvement in the overall energy-storage performance of the AFE R-phase region. The above results demonstrate that the local structure engineering is expected to play a crucial role in the achievement of excellent energy-storage properties in NN-based lead-free relaxor AFE ceramics.

A composition-induced phase transition from a diffuse-type ferroelectric to a relaxor ferroelectric and then to a weak relaxor ferroelectric was observed in a new (0.68-x)Bi(Mg1/2Ti1/2)O3-0.32PbTiO3-xPb(Ni1/3Nb2/3)O3 (BMT-PT-xPNN) ternary system. Meanwhile, a gradual evolution process of nonergodic-ergodic-nonergodic realxor states was identified at room temperature from the BMT-rich side to the PNN-rich side. Two strain maxima of ∼0.42% and ∼0.29% under 7 kV/mm were obtained in the x = 0.2 and x = 0.65 samples, respectively. It is worthy to note that the high-field strain of the x = 0.2 composition was thermally stable but seriously hysteretic. By comparison, the x = 0.65 composition exhibited a weakly hysteretic strain and a relatively small threshold electric field. This phenomenon was attributed to larger sizes and slower dynamics of polar nanoregions (PNRs) in BMT-rich compositions than those in PNN-rich compositions. Moreover, it was believed that the strain hysteresis of BMT-PT-xPNN relaxor ferroelectrics would be dominated by the growth process of PNRs into ferroelectric microdomains during loading and their subsequent dissociation process during unloading.

Compared with traditional tetragonal (T) P4mm - rhombohedral (R) R3m morphotropic phase boundary (MPB) system, the structure-property relationship of MPB systems with octahedral tilt is still unclear. In this work, the phase structure evolution under composition and electric field modulations in lead-free (0.9-x)NaNbO3-0.1BaTiO3-xCaZrO3 (NN-BT-xCZ) close to the untilt P4mm-tilt R3c MPB was investigated in details by means of the ex- and in-situ x-ray diffraction and various electrical property measurements. Both P4 mm and R3c phases can irreversibly transform into a Cc phase under electric field loading, which should be considered as a result of the cooperative coupling between ferroelectric and antiferrodistortive instabilities. Quantitative analysis indicates that little composition dependent lattice strain and domain switching of P4 mm phase can be observed, and the variation of piezoelectric coefficient is closely related to Cc phase, which exhibits an enhancement of both lattice strain and domain switching within MPB. This suggests that lattice strain and domain switching of Cc phase are coupled. On the contrary, both of them are competed in P4 mm phase because the P4 mm phase is dominated by irreversible domain switching. The experimental results would benefit for deeply understanding the origin of piezoelectric response for many octahedral-tilt MPB piezoelectric systems.

Relaxor ferroelectric (FE) ceramic capacitors have attracted increasing attention for their excellent energy-storage performance. However, it is extremely difficult to achieve desirable comprehensive energy-storage features required for industrial applications. In this work, very high recoverable energy density W-rec approximate to 8.73 J cm(-3), high efficiency eta approximate to 80.1%, ultrafast discharge rate of

Environmentally-benign antiferroelectrics (AFEs) have attracted a great deal of attention in recent years owing to their special structure and polarization/strain-electric field response, exhibiting giant application advantages in multifunctional devices. In this work, a detailed phase diagram in a binary lead-free system between AFE NaNbO3 (NN) and ferroelectric (FE) (Bi0.5Na0.5)TiO3 (BNT) was established according to the measurement of dielectric and ferroelectric properties in combination with the multiscale structure analysis such as Raman spectra, synchrotron x-ray diffraction and transmission electron microscopy. Multiple AFE phases of different stability, crystal symmetry and domain morphology were stabilized near room temperature, involving AFE orthorhombic P (Pbma) and R (Pnma) phases in NN-rich compositions and AFE tetragonal phase (P4bm) in BNT-rich compositions, as well as field induced metastable AFE monoclinic phase (P21). Owing to the electric field induced AFE-FE phase transformation especially for relaxor AFEs with antipolar nanoregions, tunable and excellent electrical properties of temperature-stable dielectric permittivity, ultrahigh energy-storage density and efficiency and low-hysteresis high strain can be generated in the proximity of these AFEs, showing outstanding potentials in thermally-stable capacitors, dielectric energy storage and large-strain ceramic actuators for NN-BNT solid solutions.

Light-frame wood building construction dominates the single-family residential home market in the United States. Such buildings are susceptible to damage from extreme winds due to hurricanes in coastal areas and tornados in the Midwest. The consequences of extreme winds on the built environment and on social and economic institutions within the community can be severe and are likely to increase in the coming decades as a result of increases in urbanization and economic development and the potential impacts of changing climate in hazard prone areas. Current building practices provide minimum standards for occupant safety and health, including structural integrity, water and sanitation, lighting, ventilation, means of egress and fire protection. However, they generally do not consider building resilience, which includes robustness and an ability to recover following extreme natural hazard events. Nor do they address sustainability, the notion that building design, construction and rehabilitation should not adversely impact the environment. In this paper, we establish a generalized cost and carbon footprint life-cycle analysis methodology for examining the benefits of different building practices for residential light-frame wood construction subjected to tornado hazards. A multi-objective approach is used to reveal tradeoffs between resilient and sustainable practices for typical residential construction. We show that when the life cycle of a typical residence is considered, a balance between resilience, sustainability and cost might be achieved in design and rehabilitation of residential building construction for tornado hazards.

Dielectric materials with both high recoverable energy-storage density Wrec and efficiency η have attracted a lot of attention in recent years. Permittivity plays a crucial role in simultaneously achieving high polarization strength and large applied electric fields for any kinds of dielectric materials, among which antiferroelectric ceramics exhibit giant potentials in energy storage. Adjustment of permittivity has seemed to be more in linear dielectrics, but much less cared about in polar dielectrics so far for high-power energy-storage applications. In this work, a novel lead-free solid solution of (1-x)(Bi0.5Na0.5)TiO3-xKNbO3 was reported to show excellent comprehensive energy-storage performances of Wrec of ~5.2 J/cm3, large η of ~88%, fast discharge rate of t0.9