IET Nanodielectrics最新文献

Polypropylene (PP) insulation for HVDC cables faces critical challenges under combined high-temperature and high-field conditions, including elevated conductivity and electric field distortion. To elucidate the role of interfacial structure engineering in governing carrier confinement mechanisms, three PP composites were developed, incorporating bare CdSe quantum dots (QDs), silane-modified CdSe@KH570 QDs and CdSe@ZnS core–shell QDs, each at 0.10 wt% loading. At 90°C, PP/CdSe@ZnS achieves a characteristic breakdown strength of 284.9 kV/mm with 44.8% enhancement and exhibits an 87.5% reduction in conductivity, significantly outperforming other modifications. Thermally stimulated depolarisation current measurements reveal that core–shell quantum dots introduce deep trap levels at 1.06 eV compared to 1.02 eV for bare CdSe composites. Interfacial potential barrier and carrier probability distribution analysis demonstrate that the inorganic ZnS shell creates high-barrier double confinement for both electrons and holes with spatial separation that minimises recombination. In contrast, the valence band energy of the organic KH570 coating closely matches that of CdSe, resulting in hole wavefunction extension into the organic layer and substantial electron–hole overlap that increases recombination probability. These findings demonstrate that interfacial engineering through inorganic core–shell architectures provides optimal carrier confinement for next-generation HVDC cable insulation operating under demanding electrothermal conditions.

Dielectric elastomer (DE) can transfer electrical energy into mechanical energy, who demonstrates significant application potentiality in flexible actuation, sensing, and power generation. However, DE faces the technical bottleneck of high driving electric fields, limiting its practical applications. In this work, an advanced hybridised DE with silicone oil and acrylate was designed to reduce modulus and increase dielectric constant, and realize the characteristic of high driving strain under low electric field. The polysiloxane crosslinking agent with different molecular weight was prepared through the addition reaction between isocyanate and hydroxyl groups, in which dihydroxy-terminated silicone oil acted as the matrix, 4,4′-diphenylmethane diisocyanate acted as a chain extender and isocyanoethyl methacrylate acted as a capping agent. In combination with butyl acrylate (BA) to fabricate the new hybridised DE. As a result, the molecular weight of the crosslinker markedly impacts on the hybridised DE's modulus. The introduction of BA enhances the dielectric constant and reduces the modulus. The as-fabricated PM₂I-BA₁ achieves a high actuation sensitivity factor (β) of 34.2 and exhibits an actuation strain of 23% under an electric field of 22.5 kV/mm. The linear actuator obtains an output force of 96.3 mN (11 times its own weight) under 12.5 kV/mm.

The advancement of high-energy-density capacitors necessitates dielectric films with superior breakdown strength. Although enhancing crystallinity is a common strategy to improve dielectric breakdown performance, it is not the sole determinant of breakdown strength. This work systematically investigates the effect of annealing (60°C–140°C) on the microstructure and electrical breakdown behaviour of biaxially oriented polypropylene (BOPP) films. Annealing above 110°C is found to not only increase crystallinity and lamellar thickness but also promotes a rearrangement of the amorphous phase. A combination of in situ fourier transform infrared spectroscopy (FTIR), low-field solid-state nuclear magnetic resonance (LF-SSNMR), and Positron annihilation lifetime spectroscopy (PALS) reveals that annealing reduces free volume and significantly suppresses molecular chain mobility in the amorphous phase, as the annealing temperature raise to 140°C, the fractional free volume decreased from 0.15% to 0.09%, and the segment mobility was significantly suppressed. Consequently, the energy storage density has increased from 1.27 J/cm³ to 2.7 J/cm³, and the charge-discharge efficiency of the 140°C-annealed film still reached as high as 94.4%, meanwhile, the breakdown filed strength of the metallised 140°C-annealed film has also increased by 12.6% (≈67 MV/m). These findings demonstrate that amorphous phase mobility including mobility of functional groups, in addition to crystallinity, is a dominant factor governing breakdown behaviour. The constrained chain mobility impedes charge carrier transport and limits energy accumulation, thereby suppressing the initiation of electron avalanche breakdown. This study establishes a new structure–property relationship centred on the mobility of amorphous chains, identifying it as a key descriptor for design of high-performance dielectric polymers via annealing.

Dielectric materials are key elements in modern electronic applications such as sensors, actuators and communication systems. This review consolidates the importance of dielectric polarisation effects, dielectric parameters, synthesis methods, matrix–filler interactions and emerging applications based on dielectric composite materials. This study provides a structured overview by identifying critical aspects of dielectric research, with emphasis on polarisation behaviour, synthesis approaches and practical applications. The interaction of electronic materials produces different polarisation effects that help in evaluating the dielectric nature of composites. A major factor in dielectric materials is the influence of energy storage capability with minimal electric field loss. The Preferred Reporting Items for Systematic reviews and Meta-Analysis (PRISMA) flow has been used to identify keywords and consolidate the most influential parameters of dielectric systems. Metallic, ceramic and carbon-based fillers are highly promising for tailoring the properties of dielectric composites. Recent studies have focused on the effects of the matrix, filler type, frequency, dielectric permittivity and dielectric loss. Furthermore, different synthesis methods are discussed in a simplified manner, highlighting the potential of advanced approaches, such as printing technologies, for preparing dielectric composites. Some composite systems demonstrate property tailoring according to research needs, offering reduced dielectric losses and improved permittivity for enhanced energy storage. Overall, dielectric composites have emerged as highly promising candidates for future applications, potentially as replacements for conventional dielectric materials.

Bismuth ferrite (BiFeO₃, BFO) is a prominent lead-free multiferroic material, whereas strontium titanate (SrTiO₃, STO) is a high-permittivity perovskite oxide widely used to tailor dielectric performance. In this work, the solid-solution formation of (1 − x)BFO-xSTO (0.1 ≤ x ≤ 0.4) nano-ceramics was synthesised via a low-temperature molten salt method using NaCl as a flux. Rietveld refinement of X-ray diffraction patterns confirmed the formation of a single-phase perovskite structure without secondary phases. The FESEM micrographs indicated the uniform granular-shaped grain morphology of BFO. The XPS revealed the presence of mixed-valence Fe ions, indicating partial reduction within the BFO lattice. The incorporation of STO suppressed oxygen vacancies, enhancing the dielectric constant (∼151 at 100 kHz for x = 0.4) and reducing the dielectric loss with increasing STO content. M-H loops exhibited weak ferromagnetic behaviour, attributed to enhanced spin canting and lattice distortion. These results highlight the effective tuning of dielectric and magnetic properties through STO substitution, demonstrating the potential of BFO-STO ceramics for multifunctional electronic device applications such as spintronics and dielectric storage components.