Ferroelectric/antiferroelectric thin/thick films with large electrocaloric (EC) effect in a broad operational temperature range are very attractive in solid-state cooling devices. We demonstrated that a large positive electrocaloric (EC) effect (maximum ΔT~20.7 K) in a broad temperature range (~110 K) was realized in Pb0.97La0.02(Zr0.65Sn0.3Ti0.05)O3 (PLZST) relaxor antiferroelectric (AFE) thin film prepared using a sol-gel method. The large positive EC effect may be ascribed to the in-plane residual thermal tensile stress during the layer-by-layer annealing process, and the high-quality film structure owing to the utilization of the LaNiO3/Pt composite bottom electrode. The broad EC temperature range may be ascribed to the great dielectric relaxor dispersion around the dielectric peak because of the coexistence of nanoscale multiple FE and AFE phases. Moreover, a large pyroelectric energy density (6.10 Jcm-3) was harvested by using an Olsen cycle, which is much larger than those (usually less than 10-4 Jcm-3) obtained by using direct thermal-electrical, Stirling and Carnot cycles, etc. These breakthroughs enable the PLZST thin film an attractive multifunctional material for applications in modern solid-state cooling and energy harvesting.

An ideal periosteum substitute should be able to mimic the periosteum microenvironment that continuously provides growth factors, recruits osteoblasts, and subsequent extracellular matrix (ECM) mineralization to accelerate bone regeneration. Here, a calcium‐binding peptide‐loaded poly(ε‐caprolactone) (PCL) electrospun membrane modified by the shish‐kebab structure that can mimic the periosteum microenvironment was developed as a bionic periosteum. The calcium‐binding peptide formed by the negatively charged heptaglutamate domain (E7) in the E7‐BMP‐2 with calcium ion in the tricalcium phosphate sol (TCP sol) through electrostatic chelation not only extended the release cycle of E7‐BMP‐2 but also promoted the biomineralization of the bionic periosteum. Cell experiments showed that the bionic periosteum could significantly improve the osteogenic differentiation of the rat‐bone marrow‐derived mesenchymal stem cells (rBMSCs) through both chemical composition and physical structure. The in vivo evaluation of the bionic periosteum confirmed the inherent osteogenesis of this periosteum microenvironment, which could promote the regeneration of vascularized bone tissue. Therefore, the hierarchical nanostructured electrospun membrane with periosteum‐mimic microenvironment is a promising periosteum substitute for the treatment of bone defects.

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Piezoelectric and ferroelectric ceramics with a high Curie temperature (Tc) have attracted much attention owing to their applications in severe environments. In this work, phase structure and dielectric, ferroelectric, and piezoelectric properties of (0.975 − x)BiScO3-xPbTiO3-0.025Pb(Cd1/3Nb2/3)O3 (BS-xPT-PCN) ceramics (x = 0.58–0.64) were studied. A composition-induced structural transformation occurs from the rhombohedral to tetragonal phase through an intermediate monoclinic phase with the increasing PT concentration. The relationship between the structure and electrical properties of the system was discussed. The BS-xPT-PCN system near the morphotropic phase boundary (MPB) (x = 0.62) exhibits excellent piezoelectric and ferroelectric performances with d33 = 508 pC/N, kp = 56%, and Pr = 40 μC/cm2. The high-temperature piezoelectricity of the sample with MPB (x = 0.62) was characterized by an in situ XRD. The excellent thermal stability of the crystal structure and the piezoelectric property indicate that the BS-xPT-PCN system is a promising candidate for high-temperature piezoelectric applications.

The periosteum plays a very important role in bone remodeling and regeneration due to its excellent osteogenic ability. However, in bone defects, the periosteum is inevitably damaged, has poor self-repair ability, and requires artificial materials as a substitute. This study is aimed to fabricate a highly bioactive poly­(ε-caprolactone)/tricalcium phosphate sol (PCL/TCP sol) hybrid membrane as an artificial periosteum covering the surface of the bone defect to enhance bone regeneration. Three kinds of PCL membranes with different TCP contents were prepared and marked as P20T1 (4.8 wt %), P10T1 (9.1 wt %), and P5T1 (16.7 wt %). The physicochemical properties’ evaluation confirmed that TCP sol was homogeneously dispersed in the PCL nanofibers. Compared with P5T1, samples P10T1 and P20T1 had enhanced the mechanical properties and a moderately hydrophilic surface (67.3 ± 2.4° for P20T1 and 48.9 ± 4.1° for P10T1). The biomineralization of hybrid membranes was significantly improved compared to the PCL membrane. Moreover, hybrid membranes significantly upregulated the rat bone marrow mesenchymal stem cells’ (rBMSCs) response (proliferation and osteogenic differentiation) to them, and P10T1 showed better surface properties (hydrophilicity, bioactivity, and biomineralization) than P20T1. Thus, sample P10T1 with the best properties in this study has great potential as an artificial periosteum to accelerate bone regeneration.