Fabrication, structure, and frequency-dependent electrical and dielectric properties of Sr-doped BaTiO3 ceramics

Ultrahigh dielectric breakdown strength and excellent energy storage performance in lead-free barium titanate-based relaxor ferroelectric ceramics via a combined strategy of composition modification, viscous polymer processing, and liquid-phase sintering

With the problems of resource consumption and environmental harm, increasing attention has been paid to the conversion and storage of energy. The development of flexible nanodielectric materials with high energy density is one of the most active academic research directions in the field of functional materials and has important practical significance. Barium titanate/polyvinylidene fluoride- (BT/PVDF-) based nanocomposite film possesses excellent physicochemical properties and electrical properties, is a type of composite material with excellent energy density and has great application potential. In this paper, related studies on high energy density BT/PVDF-based nanocomposite films are classified and summarized. The possible mechanisms for the enhancement in energy density of BT/PVDF-based nanocomposite films under different strategies are discussed. This expected result of this paper is explaining the mechanisms of the increase in energy density of BT/PVDF-based nanocomposites and providing a new idea for the development of BT/PVDF-based nanocomposites with higher energy density. Finally, BT/PVDF-based nanocomposite for energy storage films are summarized, providing an outlook for future development and the problems to be solved. It is believed that future research may be directed toward optimizing raw materials, multiphase doping, three dimensional modulation, and optimization of process, of which three dimensional modulation will become the focus.

Design strategy of barium titanate/polyvinylidene fluoride-based nanocomposite films for high energy storage

Since the positive influences of defects on the performance of electroceramics were discovered, investigations concerning on defects and aliovalent doping routes have grown rapidly in the fields of inorganic chemistry and condensed matter physics. In this article, we summarized the types of defects in electroceramics as well as characterization tools of defects and highlighted the effects of intrinsic and extrinsic defects on the material performances with the emphasis on dielectric, ferroelectric, and piezoelectric properties. We mainly introduced defect related theoretical simulation and experimental results in several typical incipient ferroelectrics, ferroelectrics, and antiferroelectrics. Hence, the influences of defects on the crystal lattice were summed up, and then the main physical mechanisms were highlighted. Particularly, the performance enhancements of aliovalently doped electroceramics were also evaluated and reviewed. Finally, the outlook and challenges were discussed on the basis of their current developments. This article covers not only an overview of the state-of-the-art advances of defects and aliovalent doping routes in electroceramics but also the future prospects that may open another window to tune the electrical performance of electroceramics via intentionally introducing certain defects.

Defects and Aliovalent Doping Engineering in Electroceramics.

Significantly enhanced breakdown strength and energy density in sandwich-structured nanocomposites with low-level BaTiO3 nanowires

Grain size effect on the dielectric and non-ohmic properties of CaCu3Ti4O12 ceramics prepared by the sol-gel process

The electrocaloric effect and energy storage property are tuned in the Ba1-xCexTi0.99Mn0.01O3 ceramics prepared by the solid state reaction method. The ceramics with lower Ce content (x = 0.005, 0.015) show a better ΔT and ΔT/ΔE response. The ceramics with higher Ce content (x = 0.030, 0.040, 0.045) represent the broader ΔT peaks (50 K–60 K), and the higher energy storage density and efficiency. The largest electrocaloric response (ΔTmax = 1.22 K, ΔT/ΔE = 0.41 K mm/kV) is found in the Ba0.995Ce0.005Ti0.99Mn0.01O3 ceramics, which is comparable or even higher than that of the most isovalent substituting BaTiO3-based ceramics reported before. The maximum energy storage density 0.11 J/cm3 (E = 30 kV/cm) is obtained for the Ba0.970Ce0.030Ti0.99Mn0.01O3 ceramics, with high efficiency of 65–88% over a wide temperature range of 72 K. This work may open more opportunities to design high electrocalaric and energy storage performance lead-free systems from the viewpoint of the heterovalent and size mismatch substitution.

Tunable electrocaloric and energy storage behavior in the Ce, Mn hybrid doped BaTiO3 ceramics

Improved dielectric and nonlinear properties of CaCu3Ti4O12 ceramics with Cu-rich phase at grain boundary layers

Colossal dielectric response and relaxation behavior in novel system of Zr4+ and Nb5+ co-substituted CaCu3Ti4O12 ceramics

High-entropy alloys (HEAs) are promising as a new type of engineering material with extensive research value. Rare-earth elements are widely studied and used to prepare HEAs because of their unique properties. In this work, the MgMoNbFeTi2Yx (x = 0, 0.4%, 0.8% 1.2%) HEA coatings were manufactured by laser cladding technology. The effect of Y on the phase structure, microstructure, wear resistance, microhardness and corrosion resistance of the laser cladding coatings were investigated methodically. As a result, the coating samples exhibit brilliant bonding abilities between substrates and claddings layer with Y additives. When Y content is low, the phase composition consists of a face centered cubic (FCC; Mg, Ti-rich (Nb, Ti) C carbide) and biphasic body centered cubic (BCC) solid solution. With an increment in Y content (Y = 0.8%/1.2%), the phase composition is composed by one BCC phase along with FCC. In the simulated saturated saline cement solution, corrosion resistance of the HEA coating is enhanced by Y addition. In addition, the MgMoNbFeTi2Y0.8% HEA coating show an excellent corrosion resistance. The MgMoNbFeTi2Y1.2% HEA coating displays the highest average microhardness of about 1046 HV0.3, which is 2.7 times stronger than that of the coating without Y content (Y = 0) and more than 5 times higher than that of the average microhardness of the base material. More interesting, such HEA coating shows an excellent wear resistance. This work can provide a novel and effective approach to significantly improve the surface quality of the characteristics of HEAs, which will promote them further applications as a promising candidate material in advanced manufacturing fields.

Pu Mao

Papers

Grain size effect on the dielectric and non-ohmic properties of CaCu3Ti4O12 ceramics prepared by the sol-gel process

Tunable electrocaloric and energy storage behavior in the Ce, Mn hybrid doped BaTiO3 ceramics

Improved dielectric and nonlinear properties of CaCu3Ti4O12 ceramics with Cu-rich phase at grain boundary layers

Colossal dielectric response and relaxation behavior in novel system of Zr4+ and Nb5+ co-substituted CaCu3Ti4O12 ceramics

Microstructure and properties of MgMoNbFeTi2Yx high entropy alloy coatings by laser cladding