Electric Transition Research Articles

Doping-mediated thermal control of phase transition for supersensitive ratiometric luminescence thermometry

Intelligent luminescent materials, characterized by optical switching in response to thermal stimulation, are highly attractive for cutting-edge temperature sensing technologies. However, the exploration of sensitive and reliable thermometric materials remains challenging. Herein, we establish a phase-transition-driven thermometric model that relies on the reversible transition between the monoclinic (β) and tetragonal (α) phase of LiYO2:Dy3+ crystals under controlled thermal stimulations. Accordingly, the ratiometric emissions from hypersensitive electric diploe transitions (4F9/2 → 6H13/2) drastically varied across the phase-transition temperature range, rendering remarkable thermal sensitivity and resolution (Sr-max = 35.24% K−1, δTmin = 0.009 K). We further demonstrate the extended control of phase-transition temperature and thermal hysteresis by a partial substitution approach. These findings highlight an endogenic approach to constructing customized luminescence thermometers via local crystal-field engineering, which raises new possibilities for practical sensing applications.

The influence of internet use on compensation standards for coal to electricity transition among Chinese residents based on the inverted U-shaped regulation effect of family life cycle

The factors that influence residents' willingness to accept long-term compensation are largely ignored, which leads to coal-to-electricity compensation failures. The core of Internet use is a viable solution to the inefficient coal-to-electricity transition for clean energy. This study employs the Heckman two-stage model to show that the compensation standard for coal-to-electricity transition should range from 25.61 to 174.07 yuan per person. Internet use has significantly promoted the compensation amount for the coal-to-electricity transition among residents. The conclusion is consistent with the theory of “information transmission”, indicating that netizens are particularly concerned about the positive information that interferes with the clean energy subsidy standards. The propensity score match method and replacement variables ensure the stability of the research conclusion. Secondly, a subdivision of the sample has shown a significant positive impact of internet use on women in rural areas with lower education levels in northern China. The paper also found that the increase in the importance of different Internet use promotes the amount of compensation for residents' coal-to-electricity transition. The driving mechanisms behind the increase include the learning effect, transaction cost effect and marketization effect, and the family life cycle was found to exhibit an inverted “U" regulation function in the relationship. Therefore, this study provides new policies for the determinants of compensation standards for the coal-to-electricity transition with Internet use.

Enabling large-scale integration of electric bus fleets in harsh environments: Possibilities, potentials, and challenges

This paper presents a comprehensive and detailed investigation of electric bus transit systems, focusing on their feasibility in harsh environmental areas. The aspects that combine economics, operation, long-term performance, and reliability are all addressed and discussed in both short and long-term horizons. This work covers most of the “important to consider” criteria, compares the strategies applied in E-bus energy management, and recommends the best practices to follow in the presence of many system variables. Due to the significant impact of the ambient temperature, characterizing the battery performance under hot ambient temperatures is performed considering the existing Li-ion battery technologies. Moreover, the grid impact of large-scale charging systems is identified and classified by identifying the factors affecting the grid hosting capacity and permissible interaction levels. This work includes developing a comprehensive picture of the state of the art, emphasizing the gaps found in the literature, and proposing new venues for future research that help address the identified issues to enable reliable E-transportation plans.

Numerical simulation of electric field-induced phase transition evolution and boiling characteristics in the evaporative cooling medium C6F12O

Phase change cooling technology offers high cooling efficiency, safety, and reliability, representing a novel approach to achieving efficient heat dissipation for high-power and large-capacity electrical equipment. The formulation of the cooling medium is pivotal to phase change cooling technology. However, current media exhibit compatibility, stability, economy, and environmental friendliness deficiencies. Consideration could be given to implementing the C6F12O medium due to its superior overall performance and ability to meet the latent heat requirements in phase change cooling equipment. This paper employs a numerical simulation approach that combines the phase field method based on the Cahn-Hilliard equation with the theory of electrohydrodynamics. It investigates the impact of temperature, electric field intensity, and electric field direction on the evolution of bubble motion and the boiling state of the C6F12O medium, considering the interaction of electric-fluid-heat-phase fields. Numerical results indicate that the system undergoes initial nucleate boiling, nucleate boiling, and film boiling stages at T = 330–335 K, T = 335–350 K, and T ⩾ 355 K, respectively. The introduction of an appropriate electric field can enhance the motion evolution of C6F12O bubbles. However, attention must be paid to the formation of bubble channels under high field strength to prevent potential decreases in insulation performance. An inhomogeneous electric field in the vertical direction proves more effective in improving the bubble release rate compared to a uniform electric field. To some extent, an inhomogeneous electric field in the horizontal direction can prevent the mass accumulation of bubbles in regions of high field intensity. This research has the potential to offer theoretical guidance for the engineering application of the C6F12O phase change cooling medium.

A Just Transition for Auto Workers? Negotiating the Electric Vehicle Transition in Germany and North America

Reducing human-made greenhouse gas emissions is crucially important for life on earth, but it requires restructuring industries in ways that could disrupt millions of workers’ lives globally. Whether this transition is “just” from the perspective of workers depends on the magnitude of job losses, the quality of new jobs, and the transitions workers experience from their current jobs to new ones. Using the example of the German automotive industry, where the shift to electric vehicle production has recently accelerated, the authors identify recommendations for unions and policymakers in North America and beyond. This article provides an overview of the tools for workers and trade unions in Germany to steer the transition and shows how analogous tools could be strengthened or created elsewhere.

Longitudinal Extension of Double π-Helix Enables Near-Infrared Amplified Dissymmetry and Chiroptical Response.

Near-infrared (NIR) circularly polarized light absorbing or emitting holds great promise for highly sensitive and precise bioimaging, biosensing, and photodetectors. Aiming at designing NIR chiral molecular systems with amplified dissymmetry and robust chiroptical response, herein, we present a series of double π-helical dimers with longitudinally extended π-entwined substructures via Ullmann or Yamamoto homocoupling reactions. Circular dichroism (CD) spectra revealed an approximate linear bathochromic shift with the rising number of naphthalene subunits, indicating a red to NIR chiroptical response. Particularly, the terrylene diimide-entwined dimers exhibited the strongest CD intensities, with the maximal |Δε| reaching up to 393 M-1 cm-1 at 666 nm for th-TDI[2]; and a record-high chiroptical response (|ΔΔε|) between the neutral and dianionic species of 520 M-1 cm-1 at 833 nm for th-TDI[2]Cl was achieved upon further reduction to its dianionic state. Time-dependent density functional theory (TDDFT) calculations suggested that the pronounced intensification of the CD spectra originated from a simultaneous enhancement of both electric (μ) and magnetic (m) transition dipole moments, ultimately leading to an overall increase in the rotatory strength (R). Notably, the circularly polarized luminescence (CPL) brightness (BCPL) reached 77 M-1 cm-1 for th-TDI[2]Cl, among the highest values reported for NIR-CPL emitters. Furthermore, all chiral dianions exhibited excellent air stability under ambient conditions with half-life times of up to 10 days in N-methylpyrrolidone (NMP), which is significant for future biological applications and chiroptic switches.

Controlling Chirogenic Effects in Porphyrin Based Supramolecular Systems: Theoretical Analysis Versus Experimental Observations.

Electronic circular dichroism (ECD) spectroscopy is a widely employed method for studying chiral analysis, requiring the presence of a chromophore close to a chiral centre. Porphyrinoids are found to be one of the best chromophoric systems serving for this purpose and enabling the application of ECD spectroscopy for chirality determination across diverse classes of organic compounds. Consequently, it is crucial to understand the induction mechanisms of ECD in the porphyrin-based complexes. The present study explores systematically the influence of secondary chromophores, bonded to an achiral zinc porphyrin or to chiral guest molecules, on the B-region of ECD spectra using the time-dependent density functional theory (TD-DFT) calculations. The study analyses the impact of change in both the conformation of achiral porphyrin (host) and change in position and conformation of chiral organic molecule (guest) on the B-band of ECD spectra (energy, intensity, sign of Cotton effect). Finally, conclusions made on model complexes are applied to published experimental data, contributing to a deeper understanding of various factors influencing ECD spectra in chiral systems. In addition, a computer program aimed to help rationalise ECD spectra by visualizing corresponding orbital energies, rotatory strengths, electric and magnetic transition moments, and angles between them, is presented.

Peculiarities of Electrical Switching and Phase Transition Dynamics in Bismuth-Infused Se–Te Chalcogenide Glasses: From Bulk to Thin Film Devices

Peculiarities of Electrical Switching and Phase Transition Dynamics in Bismuth-Infused Se–Te Chalcogenide Glasses: From Bulk to Thin Film Devices

A multi-stage optimization of battery electric bus transit with battery degradation

Battery electric buses (BEBs) are appealing to transit operators for their elevated comfort, low noise, and zero tailpipe emissions. However, the degradation of BEB batteries over time challenges their performance and necessitates infrastructure adjustments. This study develops a generic multi-stage optimization model for BEB systems. The model addresses the dynamic influence of BEB battery degradation rates on the optimal BEB system configuration and operation, including component sizing, charging infrastructure allocation, BEB charging schedule, and battery replacement throughout the BEB usage lifecycle. A surrogate model-based space mapping (SMSM) algorithm is employed to address the inherent nonlinearity of incorporating battery degradation rates within the developed model. The model is tested on a real-world, multi-hub transit network, and the results highlight significant implications of battery degradation on the optimal spatiotemporal allocation of charging infrastructure, charging schedules, and battery replacement decisions throughout the 12-year BEB usage lifecycle. Sensitivity analysis highlights the influence of operational conditions on total system cost, indicating a 16.3 % increase in cost with a 50 % rise in both energy consumption rates and time-of-use (ToU) tariffs. Overall, the proposed model is a valuable decision-making tool for transit operators navigating BEB transit system planning.

Ultra-high strain in Bi0.5(Na0.41K0.09)TiO3 Pb-free piezoelectric ceramics modified by Sr(Hf0.5Sb0.4)O3

The lead-free piezoelectric ceramics used in piezoelectric actuators have attracted extensive attention owing to their substantial electric-field-induced strain. In this study, The (1-x)Bi0.5(Na0.41K0.09)TiO3-xSr(Hf0.5Sb0.4)O3 (BNKT-xSHS) piezoelectric ceramics were synthesized using the conventional solid-state reaction method. The impact of SHS substitution on the microstructure and electrical properties was systematically explored. Among them, the BNKT-0.015SHS sample, featuring ergodic relaxor states, demonstrates a high piezoelectric strain coefficient (d33*) of 785 p.m./V under a low electric field of 50 kV/cm(Strain = 0.392 %). It exhibits a repeatable strain value of 0.47 % under an 80 kV/cm electric field(d33* = 590 p.m./V). Moreover, the strain values remain around 0.4 % between room temperature and 100 °C, with variations within 90 %. The heightened repeatable strain response is considered to be linked to the electric field-induced reversible phase transition occurring within the ergodic relaxor state. The higher strain temperature stability is ascribed to the coexistence of quadrilateral polar nanoregions and rhombic polydomain nanoregions. This study provides an effective example for achieving significant strain responses, presenting a feasible candidate material for applications in piezoelectric actuators.

Achieving Strong Circularly Polarized Luminescence through Cascade Cationic Insertion in Lead-free Hybrid Metal Halides.

Generating circularly polarized luminescence (CPL) with simultaneous high photoluminescence quantum yield (PLQY) and dissymmetry factor (glum) is difficult due to usually unmatched electric transition dipole moment (μ) and magnetic transition dipole moment (m) of materials. Herein we tackle this issue by playing a "cascade cationic insertion" trick to achieve strong CPL (with PLQY of ~100 %) in lead-free metal halides with high glum values reaching -2.3×10-2 without using any chiral inducers. Achiral solvents of hydrochloric acid (HCl) and N, N-dimethylformamide (DMF) infiltrate the crystal lattice via asymmetric hydrogen bonding, distorting the perovskite structure to induce the "intrinsic" chirality. Surprisingly, additional insertion of Cs+ cation to substitute partial (CH3)2NH2 + transforms the chiral space group to achiral but the crystal maintains chiroptical activity. Further doping of Sb3+ stimulates strong photoluminescence as a result of self-trapped excitons (STEs) formation without disturbing the crystal framework. The chiral perovskites of indium-antimony chlorides embedded on LEDs chips demonstrate promising potential as CPL emitters. Our work presents rare cases of chiroptical activity of highly luminescent perovskites from only achiral building blocks via spontaneous resolution as a result of symmetry breaking.

Achieving Strong Circularly Polarized Luminescence through Cascade Cationic Insertion in Lead‐free Hybrid Metal Halides

AbstractGenerating circularly polarized luminescence (CPL) with simultaneous high photoluminescence quantum yield (PLQY) and dissymmetry factor (glum) is difficult due to usually unmatched electric transition dipole moment (μ) and magnetic transition dipole moment (m) of materials. Herein we tackle this issue by playing a “cascade cationic insertion” trick to achieve strong CPL (with PLQY of ~100 %) in lead‐free metal halides with high glum values reaching −2.3×10−2 without using any chiral inducers. Achiral solvents of hydrochloric acid (HCl) and N, N‐dimethylformamide (DMF) infiltrate the crystal lattice via asymmetric hydrogen bonding, distorting the perovskite structure to induce the “intrinsic” chirality. Surprisingly, additional insertion of Cs+ cation to substitute partial (CH3)2NH2+ transforms the chiral space group to achiral but the crystal maintains chiroptical activity. Further doping of Sb3+ stimulates strong photoluminescence as a result of self‐trapped excitons (STEs) formation without disturbing the crystal framework. The chiral perovskites of indium‐antimony chlorides embedded on LEDs chips demonstrate promising potential as CPL emitters. Our work presents rare cases of chiroptical activity of highly luminescent perovskites from only achiral building blocks via spontaneous resolution as a result of symmetry breaking.

Theoretical study of low-lying electronic states spectra and transition properties of BeS molecule

There are only limited theoretical results published on the transition properties of the X1Σ+, A1Π, B1Σ+, C1Δ, D1Σ−, E1Δ, a3Π, b3Σ+, and c3Δ states of BeS, and even some of the states have no theoretical and experimental reports on the relevant aspects of these transitions. Therefore, we derived these transition properties in this study. The potential energy curves of X1Σ+, A1Π, B1Σ+, C1Δ, D1Σ−, E1Δ, a3Π, b3Σ+, c3Δ, d3Σ−, and e3Σ− states of the BeS molecule with their Ω states and the transition dipole moments between them were calculated by the complete active space self-consistent field method, followed by the internally contracted multireference configuration interaction method. For the accurate computation of the transition properties, scalar relativistic corrections and core–valence correlation were considered. The radiative lifetimes were approximately 10−6 s for the A1Π and b3Σ+ states, 10−7 s for the E1Δ state, 10−7–10−8 s for the C1Δ and D1Σ− states, and 10−8 s for the B1Σ+, c3Δ, and e3Σ− states. The transition properties of the seven Ω states generated by the X1Σ+, A1Π, B1Σ+, and a3Π electronic states, including several electric dipole-forbidden transitions were researched. In particular, the B1Σ+ 0+–X1Σ+ 0+, B1Σ+ 0+–A1Π1, and A1Π1–X1Σ+ 0+ systems have strong transitions. In this paper, the radiative lifetimes of A1Π1, B1Σ+ 0+, a3Π0−, a3Π0+, and a3Π1 electronic states were also computed. For the A1Π1, B1Σ+ 0+, and a3Π1 states, the distribution of the radiation lifetime with the rotational angular momentum quantum number J at 0 ≤ υ ≤ 15 and J ≤ 70 was evaluated. It is expected that the outcome of the calculations in this paper can contribute some meaningful guidelines for conducting further theoretical and experimental investigations.

Ultrafast Self‐Powered Ti–Zn–N Photodetector‐Based Optocoupler for Power Electronics Applications

This study presents an early exploration into the application of a self‐powered photodetector based on titanium zinc nitride (TiZnN) films in power electronics, aiming to overcome inherent limitations of conventional optocouplers such as low switching speed and specific operating voltage requirements. The fabricated device demonstrates excellent performance metrics, including photosensitivity of 136, the responsivity of 3.22 mA W−1at −8 V bias, and a peak detectivity of 1.76 × 108Jones at 0 V bias. Remarkably, ultrafast rise (τs) and decay times (τd) of 0.11 and 0.10 ms, respectively, are achieved, alongside broad‐band spectral absorption characteristics. Experimental validation showcases the efficacy of the TiZnN‐based optocoupler in practical applications, notably in power electronics triggerable relay systems and AC–AC converters. Leveraging the self‐powering capability inherent to the TiZnN photodetector, this optocoupler eliminates external power source dependencies, thereby enhancing its versatility and applicability in diverse electronic systems. The rapid response time of the device and broad spectral absorption further underscore its suitability for high‐speed signal transmission across varied operating conditions. This research paves a path for developing stable, cost‐effective, and self‐powered ultrafast optocouplers, eliminating concerns about compromising electrical signal transit. These advancements hold significant implications for enhancing electronic system performance, reliability, and functionality in critical applications.

An Application of Interacting Boson Fermion-Fermion Model (IBFFM) for <sup>134</sup>Cs Nucleus

This work concerns the calculations of interacting boson fermion-fermion model (IBFFM) for the odd-odd nucleus <sup>134</sup>Cs. The energy levels (positive and negative parity states), electric transition probability B(E2), magnetic transition probability B(M1), quadrupole and magnetic dipole moments have been studied in this work. The IBFFM results are compared with the available experimental data. In the present work, the IBFFM pattern of total and parametric dependent level densities for the odd-odd nucleus <sup>134</sup>Cs is investigated and compared to the pattern found in previous investigations in the framework of combinatorial and spectral distribution approaches. When comparing the theoretical values with the available experimental values, it was found that there is a good match between them. This is due to the values of the Hamiltonian parameters that were found accurately, so this IBFFM model is considered one of the effective models in studying the nuclear structure of odd-odd nuclei. The level density of the odd-odd nucleus <sup>196</sup>Au is investigated in the interacting boson-fermion-fermion model (IBFFM) which accounts for collectivity and complex interaction between quasiparticle and collective modes. The IBFFM spin-dependent level densities show high-spin reduction with respect to Bethe formula. This can be well accounted for by a modified spin-dependent level density formula.

An enhanced strain response in micrometer-thick BNT-ST thin films

Lead-free Bi0.5Na0.5TiO3-SrTiO3 (BNT-ST) thin films with various thicknesses were deposited on the Pt(111)/Ti/SiO2/Si(100) substrates employing a sol-gel technique with a two-step annealing process. Despite the variations in thickness, the films exhibited a consistent polycrystalline structure, evidenced by identical diffraction peaks, albeit with differences in intensity. An imprint became evident in micro-thick films, increasing with film thickness. Also, the emergence of self-polarization was observed in thicker films detected by piezoresponse force microscopy. Noteworthy is the pronounced influence of film thickness on strain response, with the 1.38 μm-thick films demonstrating a large strain of 1.18%. The outstanding strain response can be attributed to the notable contribution of electric field-induced phase transition and polarization dynamics. This work provides a promising potential application of micrometer-thick BNT-ST thin films in advanced actuator devices.

Optimizing Electric Vehicle Performance, Range and Parameter Estimation through NEDC Urban and Suburban Analysis using MATLAB

This research paper focuses on electric vehicle (EV) driving range and parameter estimation, with an emphasis on analyzing the New European Driving Cycle (NEDC) urban and suburban drive cycles. By examining these drive cycles, we obtain critical data on the moments when an electric vehicle transitions between constant velocity, acceleration, and deceleration phases, which significantly affect power consumption and driving range. We investigate various techniques for parameter estimation, including battery capacity, energy consumption rates, and powertrain efficiency, essential for improving EV performance and providing realistic range expectations. Empirical experiments in diverse driving conditions contribute valuable data to refine our understanding of EV driving range and performance in different scenarios. The research underscores the role of predictive modeling, data analytics, and advanced technologies in real-time parameter estimation, offering precise and convenient range predictions to enhance user confidence.

Challenges for density functional theory in simulating metal-metal singlet bonding: A case study of dimerized VO2.

VO2 is renowned for its electric transition from an insulating monoclinic (M1) phase, characterized by V-V dimerized structures, to a metallic rutile (R) phase above 340K. This transition is accompanied by a magnetic change: the M1 phase exhibits a non-magnetic spin-singlet state, while the R phase exhibits a state with local magnetic moments. Simultaneous simulation of the structural, electric, and magnetic properties of this compound is of fundamental importance, but the M1 phase alone has posed a significant challenge to the density functional theory (DFT). In this study, we show none of the commonly used DFT functionals, including those combined with on-site Hubbard U to treat 3d electrons better, can accurately predict the V-V dimer length. The spin-restricted method tends to overestimate the strength of the V-V bonds, resulting in a small V-V bond length. Conversely, the spin-symmetry-breaking method exhibits the opposite trends. Each of these two bond-calculation methods underscores one of the two contentious mechanisms, i.e., Peierls lattice distortion or Mott localization due to electron-electron repulsion, involved in the metal-insulator transition in VO2. To elucidate the challenges encountered in DFT, we also employ an effective Hamiltonian that integrates one-dimensional magnetic sites, thereby revealing the inherent difficulties linked with the DFT computations.

Enhancing Chiroptical Responses in Helical Nanographenes via Geometric Engineering of Double [7]Helicenes.

Helical nanographenes with high quantum yields and strong chiroptical responses are pivotal for developing circularly polarized luminescence (CPL) materials. Here, we present the successful synthesis of novel π-extended double [7]helicenes (ED7Hs) where two helicene units are fused at the meta- or para-position of the middle benzene ring, respectively, as the structural isomers of the reported ortho-fused ED7H. The structural geometry of these ED7Hs is clearly characterized by single-crystal X-ray analysis. Notably, this class of ED7Hs exhibits bright luminescence with high quantum yields exceeding 40 %. Through geometric regulation of two embedded [7]helicene units from ortho-, meta- to para-position, these ED7Hs display exceptional amplification in chiroptical responses. This enhancement is evident in a remarkable approximate fivefold increase in the absorbance and luminescence dissymmetry factors (gabs and glum), respectively, along with a boosted CPL brightness up to 176 M-1 cm-1, surpassing the performance of most helicene-based chiral NGs. Furthermore, DFT calculations elucidate that the geometric adjustment of two [7]helicene units allows the precise alignment of electric and magnetic transition dipole moments, leading to the observed enhancement of their chiroptical responses. This study offers an effective strategy for magnifying the CPL performance in chiral NGs, promoting their expanded application as CPL emitters.

Policy legacies and energy transitions: Greening policies under sectoral reforms in Argentina and Chile

Under what conditions do greening policies lead to a fast deployment of solar and wind energies? Environmental economics assume that market factors and technological innovations are the main drivers of energy transitions. While these assumptions sometimes hold for well-functioning markets; in emerging economies, the combination of scarce capital, weak institutions, and market distortions creates specific challenges that make their paths to clean energies different from those of developed states. I analyze greening reforms of the electricity sector in Argentina and Chile, exploring instances of success and failure. Using archive data and interviews to stakeholders, I explain how previous sector structures created different market distortions that hindered an effective electricity transition even in the context of significant cost-savings from investment in new technologies. Successful greening policies entailed broader electricity-sector reforms that removed previous binding constraints and restructured incentives for key private-sector stakeholders. I corroborate this argument by employing synthetic control methods to evaluate policies’ impact. I show that broad greening policies led to a significant penetration of renewable energies: by 2020 the share of solar and wind energies in Argentina and Chile were about 7.3% and 13.6% higher than in the counterfactual scenarios in which the greening reforms had not occurred.