Abstract Metal halide perovskite light-emitting diodes (PeLEDs) have achieved remarkable progress in efficiency and spectral purity, yet their operational stability remains a critical challenge. A key factor determining device longevity is the interplay between microstructure, ionic dynamics, and defect states, which together govern charge injection, recombination, and degradation. Here, a multiscale dielectric and defect-state analysis of MAPbBr₃-based PeLEDs fabricated with controlled grain sizes is presented. Two groups of devices were fabricated through controlled annealing, resulting in emissive layer films with average grain sizes of ~25 nm (small-grained) and ~150 nm (large-grained). Devices with smaller grains delivered high peak brightness (~13,000 cd.m⁻²) and low turn-on voltage (~3.6 V), but exhibited reduced operational stability (T₅₀ ~ 175 min). On the other hand, devices with large grains achieved relatively longer lifetimes (T_50~ 252 min) with lower peak brightness (~4,500 cd.m⁻²) and higher turn-on voltages (~ 4.0 V). Temperature-dependent dielectric spectroscopy revealed correlated barrier hopping as the dominant conduction mechanism, with faster ion dynamics in small-grain PeLEDs and slower, higher-barrier ionic relaxation in large-grain devices (higher activation energy). Complementary deep-level transient spectroscopy (DLTS) identified the presence of a shallow trap level (~0.30 eV) consistent with bromide vacancies, linking defect energetics with grain-size-dependent dielectric response. By integrating the results of dielectric relaxation and DLTS measurements, this work establishes a unified framework that connects microstructure, ionic relaxation, and trap states, which can help in designing PeLEDs that balance brightness and stability for practical optoelectronic applications.

Correlating calcination conditions with microstructural features, dielectric response, and optical functionality in LaMnO3 nanoparticles

In this paper, we develop a new approach for analyzing collective quantum excitations in graphene, based on the quantum multistream model. We explore a range of phenomena, including the energy band structure of collective modes, linear and nonlinear excitations, statistical characteristics, and the linear dielectric response of quasiparticle excitations in graphene. A modified Wigner quasiprobability distribution is derived, enabling the study of phase-space dynamics for linear excitations. Our results reveal that quasiparticle excitations of massless Dirac fermions are governed by three distinct characteristic wavenumbers. Notably, we identify a broad energy bandgap associated with the collective effects, below which quasiparticle excitations become unstable. The thermodynamic analysis, encompassing internal pressure and heat capacity, uncovers several intriguing deviations from the behavior of a conventional Fermi electron gas. Furthermore, we demonstrate that massless Dirac fermions in graphene can sustain both large-amplitude cnoidal waves and solitary structures. By examining the dielectric response within the Lindhard framework, incorporating a quasiparticle energy dispersion that accounts for both single-particle and wave-like contributions, we gain new insights into the frequency-dependent response, loss-function spectrum, and static charge screening, highlighting key differences from the ordinary Fermi gas. This theory offers a unified approach to capturing both the particle-like and wave-like aspects of massless Dirac Fermion excitations, clearly distinguishing their individual contributions to various physical properties. It also extends beyond the conventional many-body theories incorporating the mean field approximations by appropriately linking the single-electron dynamics to collective behavior through the hybrid nature of quasiparticle matter-wave dispersion.

Synergistic effect of Ca - Zn substituted TiO2 composite: Dielectric response and antimicrobial efficacy

Enhanced dielectric and ferroelectric response of rGO incorporated K0.5Na0.5NbO3 hybrid system

Optimization of dielectric microwave response of MoS2 through human-machine interaction based on d-d orbital modulation phase engineering

To reveal the mechanisms governing the temperature-dependent electrical behavior of coal-bearing surrounding rocks, a multi-physics coupling model was established and combined with experimental data to systematically analyze the evolution of resistivity and dielectric properties with temperature. The results show that resistivity undergoes a three-stage transformation: it first increases due to microcrack development and pore-water evaporation, then decreases sharply as carriers are thermally activated, and further declines at higher temperatures. Dielectric properties are markedly enhanced beyond a critical threshold, accompanied by a relaxation peak that indicates interfacial and ionic polarization dominate under thermal activation. A pronounced frequency dispersion is also observed, with polarization processes being suppressed at higher frequencies. These findings demonstrate that temperature strongly regulates carrier mobility and polarization capacity, thereby exerting a fundamental influence on the resistivity and dielectric response of rocks. This work provides theoretical support and practical reference for temperature correction in deep resource geophysical exploration, real-time monitoring of thermal damage in mines, and stability assessment of rocks under high-temperature conditions.

Progressive dielectric response of zirconium-doped CeO₂ for higher energy storage supercapacitor

Exploring the Impact of Silver Nanoparticles on the Structure, Optical Properties, and Dielectric Response of PVA–PVP Blends

The growing demand for faster and more reliable wireless communication has increased the need for microwave dielectric ceramics with high performance and thermal stability. In this paper, we synthesized Bi1-4x(LaxNdxSmxEux)VO4 ceramics (0.025 ≤ x ≤ 0.1) via a conventional solid-state method at a low firing temperature range of 740-860 °C. Structural analysis was conducted using X-ray diffraction, high-resolution transmission eleectron microscopy, and Raman spectroscopy and showed a composition-driven phase transition from monoclinic scheelite (space group: I2/a) to tetragonal zircon (space group: I41/amd) near x ≈ 0.075, with a mixed-phase region observed at relatively lower substitution levels. This structural change had a direct influence on the dielectric properties: the permittivity (εr) decreased from 66.98 at x = 0.025 to 19.85 at x = 0.1, while the quality factor (Qf) increased from 7904 to 16240 GHz. A nearly temperature-stable point was identified at x = 0.055, where τf reached +8.42 ppm/°C, which is attributed to a compensation effect arising from A-site cation rattling. Far-infrared analysis confirmed that phonon absorptions dominate the dielectric response in the microwave region. To validate practical applicability, a microstrip patch antenna fabricated from the x = 0.055 ceramic achieved a return loss of -22.5 dB at 2.46 GHz, along with 98.8% radiation efficiency and a peak gain of 5.22 dB. These results highlight that controlling the multi-ion substitution and their ratios provides an effective strategy for tuning the phase composition and dielectric performance in BiVO4-based ceramics, which has a strong potential for ISM-band communication devices and emerging wireless technologies.

Assessing the insulation condition of power transformers is crucial for maintaining the reliability of electrical power systems. This research aims to predict the remaining life of the transformer at PLTU Suralaya Unit 6 by integrating the measurement of the dissipation factor (tan δ) using Dielectric Frequency Response (DFR) testing at ultra-low frequency (1 mHz = 0.001 Hz) and estimating the Degree of Polymerization (DP) through empirical correlation. The DFR measurements were performed with the OMICRON DIRANA device (frequency range 0.1 mHz–1 kHz) and validated against tan δ measurements at 50 Hz using OMICRON CPTD equipment. The dissipation factor at 1 mHz was extracted and converted to an estimated DP value through a validated regression model. Results show a DP value of approximately 302, indicating advanced degradation of the cellulose insulation. This corresponds to an estimated remaining life percentage of 29.68%, equivalent to an operational lifespan of roughly 11.87 years before reaching the end-of-life threshold. The study confirms that ultra-low-frequency DFR testing combined with DP estimation provides a non-destructive and effective approach for transformer remaining life prediction. It is recommended to implement condition-based monitoring and supplement with oil chemical analysis (e.g., furan compounds) and other diagnostic methods to enhance prediction accuracy and support proactive asset management.

ABSTRACT This work explores the mechanism of stress‐induced dielectric response of graphene nanoplatelets loaded flexible polyurethane foam for potential sensing applications. The polyurethane foam composite is prepared by premixing graphene with polyether polyol and a blowing agent, followed by reaction with isocyanate. The mechanical properties show that the developed foam possesses admirable compressive strength. The bulk density is found to decrease with graphene loading. The wettability studies show the hydrophobic nature of the foam upon graphene loading. Cell morphology divulges information about the polymer matrix and dispersion of nanofillers in it. The thermal behavior of the foam is also noted at different levels of filler loading. The dielectric properties, such as capacitance and electrical conductivity, are studied under compression at varying frequencies and applied stresses, which show a gradient change in properties due to the formation of conductive pathways acting as charge carriers. The behavior of the nanofiller at the lower and higher frequencies reveals the charge transfer mechanism over this variation. The highest capacitance value of approximately 4.8 pF at 100 Hz under the highest applied strain (~80%) and the highest conductivity, 2.5 × 10 −3 μS/m at 80% strain with 5 kHz was recorded at 0.7 wt% graphene loading. Finally, the study gives insight into producing conductive polymeric foam that can be used as a stress sensor for novel applications such as in health care as a wearable sensor connected to the body, monitoring real‐time movement. As the emerging scenario requires a lightweight and heterogeneity, flexible polyurethane foam provides a good solution.

Correction: Thermally activated dielectric relaxation and impedance response in Sol–Gel synthesised Ni0.5Zn0.5Gd0.1Fe1.9O4 Nano-ferrite

Ultrafast control of light–matter interactions is a central theme in photonics, enabling access to non-equilibrium collective phenomena. Modulating the refractive index on sub-picosecond scales reveals fundamental limits of optical response, however conventional electro-optic and carrier-based schemes remain constrained by intrinsic speed limits. Ferroelectric hafnium oxide (HfO2) has recently attracted attention as a robust platform, maintaining polarization stability at nanometer dimensions while remaining compatible with modern material processing. Current directions focus on driving polarization dynamics with ultrafast optical fields, especially in the terahertz and mid-infrared regimes, to probe dielectric responses at the ultimate temporal and spatial limits. These approaches open pathways toward clarifying the intrinsic switching mechanisms of ferroelectrics and exploring novel routes for light–matter control in complex oxides.

The current research presents the synthesis, characterization, and application of a novel gas sensor based on polypyrrole/strontium titanate (PPy/STO) nanocomposites for the selective detection of CO2. Utilizing chemical oxidative polymerization, PPy and PPy/STO nanocomposites with varying STO (10–50) wt.% were synthesized and characterized. The structural and morphological analysis confirms the formation of spherical structure and well-dispersed PPy nanoparticles with increasing crystallinity and interaction of STO in PPy chain particle compactness as the STO content increases. The integration of perovskite STO within the conducting polymer matrix enhances the electronic structure, porosity, and surface area of the composite, promoting improved gas sensing performance. Electrical impedance spectroscopy reveals that the composites exhibit a frequency-dependent dielectric response and conduction attributed to charge carrier mobility and interfacial polarization effects. PPy/STO 20% exhibits highest conductivity and dielectric constants of 0.03604 Scm−1 and 1.074 × 104, respectively. Real-time CO2 sensing experiments conducted at 50 °C demonstrate good sensitivity, stability, and rapid response/recovery characteristics, particularly for the PPy/STO 10% and 40% composites. These findings highlight the potential of PPy/STO nanocomposites as flexible, lightweight, and efficient materials for portable CO2 gas sensors, addressing the growing needs for environmental and health monitoring.

This study presents a comprehensive first‐principles investigation of the structural, electronic, elastic, mechanical, optical, and thermoelectric properties of Tl 2 LiScX 6 (X = Cl, Br, I) double perovskites using density functional theory. The compounds crystallize in a stable cubic Fm3m phase, with Goldschmidt tolerance factors ranging from 0.93 to 0.97, and negative formation energies confirming their structural and thermodynamic stability. Halogen substitution (Cl → I) induces a systematic increase in lattice parameters (19.17–22.00 a.u.) and a reduction in direct bandgaps (3.85 eV → 1.99 eV), positioning Tl 2 LiScX 6 (X = Cl, Br, I) as promising candidates for ultraviolet‐to‐visible optoelectronic applications. Mechanical property analysis reveals ductile behavior and anisotropic elasticity, while optical properties demonstrate strong ultraviolet absorption and tunable dielectric responses, with Tl 2 LiScI 6 exhibiting the highest refractive index (2.18). Thermoelectric calculations predict high figures of merit (ZT > 0.8) across 100–1000 K, driven by favorable Seebeck coefficients and electrical conductivities (10 15 –10 18 (Ωm) −1 ). The synergistic optoelectronic performance of Tl 2 LiScX 6 (X = Cl, Br, I) underscores their potential for sustainable technologies, including ultraviolet optoelectronics and waste heat recovery systems. This work advances the design of perovskite materials by elucidating the structure–property relationships in this novel class of materials.

The electrical conductivity and dielectric characteristics were investigated across a frequency range of 200–5 MHz and a temperature range of 318 K to 433K for MgTi 2 O 5 nanoparticles (NPs). The electrical conductivity data displayed two dominant conduction mechanisms: a quantum mechanical tunneling model (QMT) and the correlated barrier hopping model (CBH). The activation energy values derived from the Direct Current (DC) Conductivity were 0.15 and 0.27 eV. In addition, the activation energy values derived from the Alternating Current (AC) Conductivity decreased as frequency increased from 0.13 to 0.014 eV due to the improvement of electronic jumps among localized states. Additionally, dielectric investigation of MgTi 2 O 5 NPs within the frequency range from (200 – 5 MHz) and the temperature range from (318K–433K) revealed that both real (ε 1 ) and imaginary (ε 2 ) components of a dielectric permittivity decrease as the frequency increased and increased as a temperature increased due to thermal motion of electrons, which is related to the polarization mechanism.

In this study, borate-based glass and glass–ceramics doped with varying concentrations of ZrO2 were synthesized, followed by controlled heat treatment for crystallization. X-ray diffraction, density, Fourier-transform infrared spectroscopy, field emission scanning electron microscope, and dielectric relaxation spectroscopy were employed to characterize the prepared samples. XRD analysis confirmed the formation of the nanocrystalline ZrO2 phase within the glass–ceramic matrix. The average crystallite size, determined by the Scherrer formula, fell within the nanometric range. DRS investigated the dielectric response of all samples over a wide frequency range (0.1 Hz–1 MHz) at 30 °C. It showed enhanced dielectric properties with increasing ZrO2 content. Significantly increased permittivity while decreased loss tangent for glass and glass ceramics with higher ZrO2 content. Furthermore, glass ceramic exhibited better dielectric properties than glass samples. For electrical properties, the optimal mol% suggested for Zr4+ is 2 since it exhibited the highest permittivity (~ 23 at 1 MHz) and lowest loss tangent (~ 0.005) for glass and glass ceramics. The substitution of CaO by ZrO2 increases both permittivity and AC conductivity while reducing the dielectric losses, confirming the enhancement of dielectric properties. Furthermore, the antimicrobial activity of the prepared samples was tested. The antimicrobial activity of the glass–ceramic results from the presence of ZrO2 nanocrystals, which act in a similar manner to ZrO2 nanoparticles. Cytotoxicity and long-term stability assays were carried out. The results display the effect of ZrO2 on structure, crystallinity, and the noticed electrical and biological responses, making them promising materials for use in applications that require electrical functionality and biocompatibility.

Potassium niobate borate K3Nb3B2O12 exhibits uniaxial antiferroelectricity, where polarization flipping occurs along only one crystallographic direction, while a linear dielectric response is observed in perpendicular directions. The present study investigates the temperature dependence of dielectric permittivity and electric-field-induced polarization of K3Nb3B2O12 polycrystalline ceramics to clarify its potential for high-voltage applications. The results demonstrated a high relative permittivity of approximately 130 at room temperature and its enhancement under an applied electric field. Notably, the onset electric field for permittivity boosting was found to be markedly smaller than that observed in typical uniaxial antiferroelectrics. This study paves the way for the development of next-generation capacitors for power electronics with uniaxial antiferroelectricity.

High dielectric materials are essential in a wide array of applications, particularly in electronics, energy storage, and electrochemistry. Their significance arises from their ability to influence the performance and efficiency of devices and systems. While Density Functional Perturbation Theory (DFPT) is a popular computational method for predicting dielectric constants, it is computationally expensive and not scalable for large systems. Recently, artificial intelligence (AI) has advanced rapidly, but the intrinsic challenges of predicting dielectric constants, such as the broad range of data, have hindered the development of AI models for this task.To address these challenges, we propose a deep learning model that efficiently predicts dielectric properties by leveraging the interactions between fundamental chemical fingerprints and a convolutional neural network (CNN). Our model demonstrates superior accuracy in predicting both isotropic and anisotropic dielectric properties compared to state-of-the-art graph-based models. It outperforms existing approaches in terms of various error metrics, including mean absolute error and mean squared error. We believe that this model offers a powerful and efficient alternative to traditional methods, effectively capturing the complex relationships between material composition and dielectric response.