(1-x)BaTiO₃-xZnNb₂O₆ (x=0.5mol%, 1mol%, 1.5mol%, 2mol%, 3mol%, 4mol%) (BTZN) ceramics were synthesized by solid state method. The sintering temperature, structure, dielectric property and ferroelectric property of BTZN ceramics were systematically investigated. The sintering temperature of BTZN ceramics decreased with increasing ZnNb₂O₆ content. XRD results show that the second phase Ba₂Ti₅O₁₂ was observed when the content of ZnNb₂O₆ reached 3mol%. The dielectric measurements result showed that with increasing ZnNb₂O₆ content, the dielectric constant of BTZN ceramics decreased gradually, while the frequency stability of dielectric constant increased gradually. The temperature dependence of dielectric constant results showed that all BTZN ceramics met the characteristics of X8R capacitors. Polarization values of BTZN ceramics decreased with increasing ZnNb₂O₆ content. The dielectric breakdown strength of 240 kV/cm and a recoverable energy density of 1.22 J/cm ³ were achieved in the sample of x=4mol%.

Yb:YAG transparent ceramics with high optical quality were fabricated by solid-state reaction and vacuum sintering method (1750 ℃×30 h) using high-purity Y₂O₃, α-Al₂O₃ and Yb₂O₃ powders as raw materials. The measured concentration of Yb ³⁺in 5.0at% Yb:YAG ceramics is 6.41×10 ²⁰ cm ^-3, and the cell density is 4.65 g/cm ³. The microstructures, spectral characteristics and laser performance parameters of Yb:YAG ceramics were studied in this work. FESEM results show that Yb:YAG ceramics have uniform and compact structure, clean and straight grain boundaries, and the average grain size is about (19±3) μm. The in-line transmittance of Yb:YAG ceramics with thickness of 4.0 mm reaches 82.5% at 400 nm and 85.2% at 1100 nm. The minimum pump saturation light intensity occurs at 940 nm, and the pump threshold power at 1030 nm is the lowest. The quality factor of 1030 nm laser pumped at 940 nm is 1.02×10 ^-22 cm·s. By calculating the gain cross section, it is indicated that Yb:YAG ceramics can be tuned broadband, and are ideal laser gain media.

Being a typical Kondo topological insulator, samarium hexaboride (SmB₆) attracts much interest in condensed physics and material sciences in recent years. In comparison with their bulk counterparts, SmB₆ nanostructures have more abundant surface electron states due to larger specific surface area, which are believed as idea platforms for studying surface quantum properties and physic mechanism. Through chemical vapor deposition (CVD), SmB₆ nanobelt and nanowire films were respectively prepared on Si substrate. Both SmB₆ nanowires and nanobelts are proven as the cubic single crystals, and their growth directions are, along [100] and [110], respectively. Field emission (FE) results show that SmB₆ nanobelts have a turn-on field of 3.24 V/μm and their maximum current density arrives at 466.16 μA/cm ², which are better than SmB₆ nanowires. Considering that SmB₆ nanostructures have lower electron affinity, higher electron conductivity and more abundant surface states, they are regarded as excellent cold cathode nanomaterials if their FE performances can be further improved.

Electromagnetic interference (EMI) shielding films with excellent mechanical properties are highly promising for applications in flexible devices, automotive electronics and aerospace. Inspired by the excellent mechanical properties of nacre derived from its micro/nanoscale structure, high-performance MXene/Cellulose nanocrystals (CNC) composite films were prepared by simple solution blending and followed vacuum-assisted filtration process. The presence of CNC significantly improves the mechanical properties with tensile strength increasing from 18 MPa to 57 MPa and toughness improving from 70 kJ/m ³ to 313 kJ/m ³. Meanwhile, the composite film still exhibits high electrical conductivity (up to 10 ⁴ S/m) and excellent EMI shielding efficiency (over 40 dB) with a small thickness of 8 μm.

With the development of wearable flexible electronic technology, the demand for flexible sensor with high sensitivity and wide sensing range is gradually increasing. The application of suitable conductive materials with high electrical conductivity and high flexibility as sensitive materials for sensors is the key to obtain high performance sensors. In recent years, MXene materials have become very promising sensitive materials due to their good conductivity, high flexibility, good hydrophilicity, and controllable synthesis. The types of MXene-based flexible force sensors, microstructure design of sensitive materials, sensing performance, and sensing mechanism analysis have been expound and summarized in this paper.

Solid-state cooling technology based on the electrocaloric (EC) effect is attracting increasing attention as an important alternative for traditional cooling systems because of its advantages of high efficiency, environmental friendliness, light weight, low cost, and easy miniaturization. Ferroelectric materials are suitable candidates for EC refrigeration due to their large polarization and entropy change through applying or removing an external electric field. Recently, study on the EC effect of lead-free bulk ceramics has become one of hot topics on ferroelectric community due to the requirements of sustainable development. In this review, we firstly introduce the significant history events in EC research and the basic principles of EC refrigeration. Then, design strategy for achieving a large EC temperature change near room temperature and a wide using range is summarized. Subsequently, we systematically review the research status of EC effect in BaTiO₃-based, Bi_0.5Na_0.5TiO₃-based and K_0.5Na_0.5NbO₃-based lead-free bulk ceramics and discuss their advantages as well as challenges. Finally, we propose some prospects for the future work on EC effect in lead-free bulk ceramics.