Temperature Stability Research Articles

A Melt-Processable Metal Halide Perovskite Ferroelectric.

Molecular ferroelectrics have increasingly garnered significant attention in both fundamental scientific research and technological applications due to their ease of processing, lightweight nature, and mechanical flexibility. Among these, metal halide perovskite ferroelectrics (MHP FEs), a subset of molecule-based ferroelectrics, exhibit diverse functionalities owing to their distinctive structures, thus emerging as a focal point of molecular ferroelectrics research. However, thin films, the predominant application form for MHP FEs, primarily rely on spin-coating, which presents considerable limitations. The development of melt-processable MHP FEs has been sparse, largely due to the challenge of integrating ferroelectricity with meltability. In this context, we propose a rational strategy for the successful synthesis of a melt-processable MHP FE, (MBPA)2PbBr4 (MBPA = N-methyl bromopropylammonium), featuring a notably low congruent melting temperature and excellent molten stability. The reversibility of solid and liquid states was demonstrated by X-ray diffraction and Raman and IR spectrum. Scanning electron microscopy examinations show a better quality of the melt-processed thin films compared to spin-coated ones. This study marks the successful implementation of integrating ferroelectricity and melt-processability into melt-processable MHP FEs, paving the way for a novel approach in processing MHP FEs and facilitating their future applications.

Superior energy storage performance in NaNbO3‐based lead‐free ceramics under low electric field

AbstractNaNbO3 (NN)‐based materials have attracted widespread attention due to their advanced energy storage performance and eco‐friendliness. However, achieving high recoverable energy storage densities (Wrec) and efficiency (η) typically requires ultrahigh electric fields (E > 300 kV/cm), which can limit practical use. In this work, we present a synergistic strategy that employs the ferroelectric material Bi0.5Na0.5TiO3 (BNT) to augment the Pmax and the linear material Bi0.2Sr0.7TiO3 (BST) to optimize the P–E loops. Furthermore, a two‐step sintering process is implemented to preserve high Pmax values under lower electric field. As a result, ternary (1−x)(0.90NN‐0.10BNT)‐xBST was successfully prepared, achieving a high Wrec of 5.1 J/cm3 and a η of 85% in x = 0.20 samples at a low electric field of 290 kV/cm. Moreover, the x = 0.20 samples showed good frequency stability (1–200 Hz) and temperature stability (27°C–100°C). These results provide guidance for the development of ceramics with high energy storage properties under low electric fields.

Minimally deformed regular Hayward black hole solutions in Rastall theory

Abstract We profit from the minimal geometric deformation technique of
gravitational decoupling and extend the regular Hayward black hole,
to derive new black hole solutions in the context of Rastall theory.
The field equations with an extended matter source are decoupled
into two subsystems. The first of these are specified by the metric
components of the regular Hayward black hole while the second set
which contains the effects of the added source is solved by
utilizing a constraint imposed via a linear equation of state. By a
linear combination of the solutions of these two subsystems, we
obtain two cases of the extended solutions. For specified values of
the Rastall and decoupling parameters, we investigate some
physical/thermodynamical properties of the obtained models. It turns
out that only the first model preserves asymptotic flatness. It is
found that the first and second models are described by exotic and
ordinary matter, respectively. Finally, we obtain an acceptable
behavior of the Hawking temperature and thermodynamic stability for
both models.

Study on high-temperature emission behaviors of crumb rubber modified asphalt: Experimental analysis and molecular simulation approach

The harmful emissions produced during the manufacturing and construction processes of crumb rubber modified asphalt (CRMA) significantly hinder its widespread application. Addressing this issue hinges on a thorough investigation into the mechanism governing its high-temperature emissions. This study employed microscale testing methods to analyze the microstructure and chemical property disparities between CRMA and base asphalt (BA). Subsequently, the impacts of varying crumb rubber (CR) content, experimental temperature, and sulfur stabilizer dosage on the high-temperature emissions of CRMA were investigated. Furthermore, comparative analyses of the molecular weight distribution, emission species, and CR crosslink density in asphalt after the fume experiment were conducted to further elucidate the high-temperature emission mechanisms. Finally, molecular simulation techniques were employed to analyze the interactions between CR and the four fraction molecules of asphalt at the microscale. The results indicated that the fume release volume of CRMA initially decreased and then increased with the addition of CR, while both the experimental temperature and sulfur stabilizer content exhibited a positive correlation with emission volume. CR reduced the volatilization of some small molecular hydrocarbons in the BA by absorbing light fractions. Meanwhile, excessive swelling caused the crosslinking density of CR to decrease by 77 %, which led to the release of toxic substances. At 20% CR content, the overall emissions of CRMA achieve their lowest level; however, the emission of toxic gases does not diminish. Molecular simulations have also confirmed the above results, showing that there is a strong interaction between CR and the light fractions. Compared with asphaltene molecules, rubber molecules had higher molecular polarity and stronger adsorption behavior for light fraction molecules.

Advancing antimicrobial efficacy of Cucumis momordica seeds: Nanoemulsion application in Eurotium cristatum-mediated solid-state fermentation

This study explores the enhancement of Cucumis momordica seed powder's properties through Eurotium cristatum-mediated solid-state fermentation (SSF) and its application in nanoemulsions, emphasizing protein content, functional properties, stability, and antimicrobial activity. The protein content increased significantly from 23.28±0.23 % in the control to 29.83±0.12 % after 144 h of fermentation. The Cucumis momordica seed powder fermented for 96 h was further analyzed for its functional properties and characterization. The water absorption capacity was increased from 0.91 to 2.56 g/g, and oil absorption capacity from 0.79 to 1.16 g/g. SEM and FTIR analyses revealed morphological changes and chemical profile alterations, indicating enzymatic degradation and enhanced functional properties. Nanoemulsions from fermented powder showed reduced droplet sizes (148±0.34 nm to 126±0.37 nm) and more negative zeta potentials (-24.5±0.12 mV to −25.79±0.18 mV), suggesting improved stability. Temperature stability was superior in fermented seed powder nanoemulsions, demonstrating enhanced thermal resistance. Antimicrobial tests against E. coli and S. aureus showed significantly lower MIC and MBC values for fermented powder nanoemulsions (E. coli MIC: 1.089 mg/mL, MBC: 2.189 mg/mL; S. aureus MIC: 0.459 mg/mL, MBC: 1.196 mg/mL), indicating increased antimicrobial efficacy. These results highlight the potential of SSF and nanoemulsion technology in advancing the functionality and application of Cucumis Momordica seeds as natural antimicrobial agents.

Design and Construction of Monitoring and Control System in Swallow House Based on IoT

This study aims to design and build an Internet of Things (IoT) based monitoring and control system in a swiftlet building. Swiftlet nest farming is a rapidly growing industry in Indonesia, but still faces challenges in terms of monitoring and optimal environmental management for swiftlet productivity. The system developed integrates sensors to measure critical environmental parameters such as temperature. The research methodology includes hardware design using a microcontroller, sensors, and actuators connected to an IoT network. Software is developed to process sensor data, send it to blynk, and present information through a web interface that can be accessed remotely. This system is also equipped with an automatic control feature to keep environmental parameters within the optimal range. The results of the study show that the system is capable of real-time monitoring and providing notifications when an anomaly occurs. The automatic control feature successfully maintains temperature stability in the swiftlet building, where when the temperature read by the sensor is less than or equal to 25oC the lights will turn on and if the temperature is more than 29oC the lights will turn off. In conclusion, the implementation of this IoT-based monitoring and control system provides an effective solution to increase efficiency and productivity in swiftlet nest farming. This research opens up opportunities for further development in the application of IoT technology in the business sector, especially in swallow farming.

Effect of Inorganic Additive Strategy on the Stability of in Vanadium Redox Flow Battery Electrolyte by Molecular Dynamics.

Inorganic ions are considered to be effective additives to improve the temperature stability of all-vanadium redox flow batteries. In this study, molecular dynamics simulation has been performed to study the solvation structure and dynamic properties of VO2+ in the positive electrolyte by doping Na+, K+, and NH4+ in the presence of V2O5 precipitation. The results show that VO2+ ions aggregate into chainlike clusters in the electrolyte due to the induction of SO42-. The additives, which are stable in the solvation layers of VO2+, can work as protective shells to inhibit cluster growth. NH4+ is a superior dispersant compared with Na+ and K+ as it can stably exist in both the first solvation layer and the second solvation layer of VO2+. This work performed the molecular dynamics simulation of the electrolyte of vanadium redox flow batteries, and it gives some insights into the theoretical study of the modification of the cathode electrolyte.

Improving the Energy Storage Performance in Bi0.5Na0.5TiO3-Based Ceramics by Combining Relaxor and Antiferroelectric Properties.

Ceramic capacitors have received great attention for use in pulse power systems owing to their ultra-fast charge-discharge rate, good temperature stability, and excellent fatigue resistance. However, the low energy storage density and low breakdown strength (BDS) of ceramic capacitors limit the practical applications of energy storage technologies. In this work, we present a series of relaxor ferroelectric ceramics (1-x) [0.94 Bi0.5Na0.5TiO3 -0.06BaTiO3]- x Sr0.7Bi0.2TiO3 (1-x BNT-BT- x SBT; x = 0, 0.20, 0.225, 0.25, 0.275 and 0.30) with improved energy storage performances by combining relaxor and antiferroelectric properties. XRD, Raman spectra, and SEM characterizations of BNT-BT-SBT ceramics revealed a rhombohedral-tetragonal phase, highly dynamic polar nanoregions, and a reduction in grain size with a homogeneous and dense microstructure, respectively. A high dielectric constant of 1654 at 1 kHz and low remnant polarization of 1.39 µC/cm2 were obtained with the addition of SBT for x = 0.275; these are beneficial for improving energy storage performance. The diffuse phase transition of these ceramics displays relaxor behavior, which is improved with SBT and confirmed by modified the Curie-Weiss law. The combining relaxor and antiferroelectric properties with fine grain size by the incorporation of SBT enables an enhanced maximum polarization of a minimized P-E loop, leading to an improved BDS. As a result, a high recoverable energy density Wrec of 1.02 J/cm3 and a high energy efficiency η of 75.98% at 89 kV/cm were achieved for an optimum composition of 0.725 [0.94BNT-0.06BT]-0.275 SBT. These results demonstrate that BNT-based relaxor ferroelectric ceramics are good candidates for next-generation ceramic capacitors and offer a potential strategy for exploiting novel high-performance ceramic materials.

Advancing Multi-Ion Sensing with Poly-Octylthiophene: 3D-Printed Milker-Implantable Microfluidic Device.

On-site rapid multi-ion sensing accelerates early identification of environmental pollution, water quality, and disease biomarkers in both livestock and humans. This study introduces a pocket-sized 3D-printed sensor, manufactured using additive manufacturing, specifically designed for detecting iron (Fe2+), nitrate (NO3 -), calcium (Ca2+), and phosphate (HPO4 2-). A unique feature of this device is its utilization of a universal ion-to-electron transducing layer made from highly redox-active poly-octylthiophene (POT), enabling an all-solid-state electrode tailored to each ion of interest. Manufactured with an extrusion-based 3D printer, the device features a periodic pattern of lateral layers (width = 80µm), including surface wrinkles. The superhydrophobic nature of the POT prevents the accumulation of nonspecific ions at the interface between the gold and POT layers, ensuring exceptional sensor selectivity. Lithography-free, 3D-printed sensors achieve sensitivity down to 1ppm of target ions in under a minute due to their 3D-wrinkled surface geometry. Integrated seamlessly with a microfluidic system for sample temperature stabilization, the printed sensor resides within a robust, pocket-sized 3D-printed device. This innovation integrates with milking parlors for real-time calcium detection, addressing diagnostic challenges in on-site livestock health monitoring, and has the capability to monitor water quality, soil nutrients, and human diseases.

Adhesion performance and enhancement mechanism of FA/GGBFS based geopolymer modified bitumen and acidic aggregate

The primary challenge in utilizing acidic aggregates in bitumen mixtures lies in enhancing the adhesive bond between the bitumen and the acidic aggregates. In this manuscript, to investigate the adhesion of different geopolymer modified bitumen with acidic aggregates, fly ash geopolymer (FG), fly ash- ground granulated blast furnace geopolymer (SFG), and ground granulated blast furnace (SG) were prepared by fly ash (FA), ground granulated blast furnace (GGBFS) with alkali activator. The different geopolymers were characterized with SEM, XRD, FTIR. Different geopolymer modified bitumen was prepared by adding geopolymers into virginal bitumen. The conventional properties, viscosity, and rheological properties of modified bitumen were measured and analysed. The adhesion of bitumen to acidic aggregates was tested by Zeta potential test, the improved boiling water test and pull-off test. The results showed that the electronegativity of bitumen and acidic aggregates were weakened significantly by Na+ in skeletal structure of fly ash geopolymer. The high temperature stability of fly ash geopolymer modified bitumen was improved and the bond strength of bitumen with acidic aggregates increased remarkably with the addition of 9 % fly ash geopolymer.

Low temperature machining advantages for sintered NdFeB magnets: A comparative experimental study of WAWJ with laser and WEDM

Sintered NdFeB magnets exhibit excellent magnetic properties and high reliability, making them widely used in fields such as new energy vehicles and electronic communications. However, NdFeB magnets have a low Curie temperature and poor thermal stability. Common machining methods such as laser cutting and EDM (Electrical Discharge Machining) often involve cutting temperatures in the hundreds or even thousands of degrees Celsius, leading to defects such as melting and cracks on the magnet surface. These defects degrade the surface quality and magnetic properties of the magnet. To avoid thermal damage to the magnet during processing, WAWJ (Wet Abrasive Waterjet) cutting was employed on sintered NdFeB. Experimental results indicate that at an ambient temperature of 4.5 °C, the maximum cutting temperature remains below 50 °C, with an average cutting temperature below 25 °C. No heat-affected zones or oxidation layers are exhibited on the cutting surface of the magnet. Jet pressure is identified as the primary factor influencing the maximum cutting temperature, accounting for 96.13 %. With jet pressure increasing from 200 MPa to 280 MPa, the maximum cutting temperature rises from 38.7 °C to 47.9 °C. Furthermore, to validate the necessity of low-temperature cutting for NdFeB magnets, WEDM (Wire Electrical Discharge Machining) and laser cutting were employed on sintered NdFeB magnets. The cutting surfaces of both methods exhibit defects such as cracks, craters, and melting. Compared to the original magnet surface, no significant changes in elemental content were observed on the WAWJ-cut surface. Under high-temperature conditions, the oxidation rate increased, leading to a 18.9 % and 19.8 % increase in oxygen content on the WEDM and laser machined surfaces, respectively. Some neodymium (Nd) and iron (Fe) elements exist in the form of oxides such as FeO and Nd2O3, resulting in loss of magnetism. Moreover, the presence of oxides reduces the continuity of magnetic phases, adversely affecting the magnetic properties of the magnet.

Enhanced temperature stability of Li3Mg2NbO6-based ceramics by using LTC composite additives

Enhanced temperature stability of Li3Mg2NbO6-based ceramics by using LTC composite additives

Realizing Ultrahigh Energy Storage Density in (Bi0.5Na0.5)0.94Ba0.06TiO3-Based Ceramics via Manipulating the Domain Configuration and Grain Boundary Density.

Dielectric capacitors with a high power density are widely used in various pulsed power electronic systems. However, their low comprehensive energy storage performance severely limits the development of these systems in terms of miniaturization and lightweight design. Herein, we achieved decent energy storage performance in a class of (Bi0.5Na0.5)0.94Ba0.06TiO3 (BNTBT)-based ceramics by synergistically manipulating domain configurations and grain boundary densities. High-resolution transmission electron microscopy and piezoresponse force microscopy confirm that composition-driven refined domain configurations with weak polarity effectively improve the polarization response of BNTBT-based ceramics. The results of experimental and phase-field simulation analysis indicate that the refined grain size contributes to its high breakdown electric strength (Eb). Benefiting from the high polarization difference (ΔP) of 32.62 μC/cm2, delayed saturation polarization behavior, and an ultrahigh Eb of 815.00 kV/cm, BNT-based ceramics simultaneously achieve a high energy storage density (Wrec) of ∼12.25 J/cm3 and an efficiency (η) of ∼86.90%. Because of these structure-induced advantages, the ceramics also exhibit good energy storage temperature stability in the range of 30-150 °C. We believe that the findings of this work may provide practical guidance for the development of high-performance energy storage ceramics.

Active phase and amplitude temperature control method for cryostat: A case in the thermodynamic temperature international comparison system

Achieving highly stable temperature control is essential for cryostats. However, the cryocooler used in cryostats, such as the pulse tube cryocooler, produces regular sinusoidal temperature fluctuations due to its inherent working principles. To establish a highly stable temperature environment, an active phase and amplitude control method for suppressing temperature fluctuation is proposed in this paper, by which the optimal phase and amplitude can be predicted in theory. To validate this approach, a thermal response model was developed based on experiments conducted in the thermodynamic temperature international comparison cryostat at approximately 3.7 K. Based on this model, we conducted both single-stage and multi-stage active temperature control experiments. The results demonstrate that the temperature control effect is the best when the active temperature control current is added at the second cold head, the fluctuation of the comparison copper block from 3.3mK to 0.166mK with 94.9 % suppression rate. The multi-stage joint temperature control reduced the temperature fluctuation with an attenuation rate of 95.4 %. These findings offer significant potential for improving temperature stability in future thermodynamic temperature comparison experiments.

Role of ZnO dopant in enhancing piezoelectric characteristics in KNN‐based piezoelectric ceramics

AbstractConsidering that lead‐based piezoelectric ceramics are not conducive to sustainable development, the research and preparation of environmentally friendly lead‐free piezoelectric ceramics has become a new trend. Among them, potassium‐sodium niobate based (KNN‐based) piezoelectric ceramics are considered as the most potential candidates because of their good piezoelectric properties. However, the strong sensitivity to temperature has hindered the further application of KNN‐based ceramics. In this work, the ZnO dopant was introduced in 0.96K0.48Na0.52Nb0.96Sb0.04O3–0.04Bi0.5Na0.5HfO3 ceramics to improve their piezoelectric characteristics. On the one hand, Zn2+ could occupy B‐site and thus enhance the lattice distortion of BO6 octahedra, resulting the enhanced piezoelectric properties including kp = 46%, d33 = 344 pC/N and TC = 282°C in the optimal component with x = 0.01. On the other hand, the defect dipole formed by the acceptor dopant Zn2+ pinned the motion of domain wall, and thus improved the temperature stability over a wide temperature range of 20°C to 180°C, where the descent in unipolar strain decreased from 35% (x = 0) to 23% (x = 0.01). This work provides a point of view about how ZnO dopants make an influence on the KNN‐based ceramics.

Combinatorial Optimization of Grain Size and Domain Morphology Boosts the Energy Storage Performance in (Bi0.5Na0.5)TiO3-Based Dielectric Ceramics.

Lead-free dielectric ceramics exhibiting excellent energy storage capacity, long service life, and good safety have been considered to have immense prospects in next-generation pulsed power capacitors. However, it is still challenging to simultaneously achieve large recoverable energy density (Wrec), high efficiency (η), and excellent charge-discharge performance. Herein, we fabricated lead-free (1 - x)(Bi0.5Na0.5)TiO3-x(Sr0.7Bi0.1La0.1)TiO3 ((1 - x)BNT-xSBLT) dielectric ceramics, and a good balance between Wrec ∼ 4.15 J/cm3 and η ∼ 93.89% under 333 kV/cm, as well as superior charge-discharge properties (power density PD ∼ 185.42 MW/cm3, discharge energy density Wd ∼ 2.2 J/cm3, and discharge time t0.9 ∼ 53.8 ns under 250 kV/cm), was achieved in 0.6BNT-0.4SBLT ceramics. The good energy storage performance can be attributed to the synergistic contributions of significantly enhanced Eb caused by grain refinement and the large ΔP values induced by polar nanoregions (PNRs) under a high external electric field. Moreover, the 0.6BNT-0.4SBLT ceramics also present excellent temperature stability of energy storage properties (the variations of Wrec and η less than 0.45% and 0.14%, respectively) over a temperature range of 25-185 °C. These figures of merit make 0.6BNT-0.4SBLT ceramics the most promising candidate for energy storage capacitors in advanced pulse power systems.

Enhanced energy storage performance of tungsten bronze structured BaNb2O6-modified (Bi0.5Na0.5)TiO3 ceramics

The rapid development of the electronic devices and increasing attention to environmental problems have put forward a huge demand for high-performance lead-free dielectric energy storage ceramics. In this work, tungsten bronze structured BaNb2O6 (BN) modified perovskite structured (Bi0.5Na0.5)TiO3 (BNT) ceramics, BNT-xBN (0 <x< 0.15), were prepared to optimize the energy storage performance of BNT. The results show that the lattice distortion and dielectric relaxation behavior of BNT ceramic can be induced by BN addition. Meanwhile, the introduction of tungsten bronze structured BN results in the grain refinement and the increasing of resistivity, thereby significantly enhancing the electrical breakdown strength (Eb). Accordingly, the BNT-0.1BN ceramic displays good energy storage performance with high recoverable energy density (Wrec ∼ 3.41 J/cm3) at an great Eb of 358 kV/cm, accompanied by the wide temperature stability at 30–150 °C (Wrec varies within ±12.8 %, efficiency (η) varies within ±6.7 %). The enhanced energy storage performance demonstrates that introducing tungsten bronze structure is a feasible method to prepare high-performance perovskite energy storage ceramics.

Temperature stability of hard-axis collapse and recoil-curve overshoot in Co films

Temperature stability of hard-axis collapse and recoil-curve overshoot in Co films

Enhancing piezoelectric coefficient and thermal stability in lead-free piezoceramics: insights at the atomic-scale

Given the highly temperature-sensitive nature of the polymorphic phase boundaries, attaining excellent piezoelectric coefficient with superior temperature stability in lead-free piezoceramics via direct compositional design remains a formidable challenge. We demonstrate the synergistic improvement of piezoelectric coefficient and thermal stability in lead-free piezoceramics via atomic-scale local ferroelectric structure design. Via modulation of the local Landau energy barrier at doping sites, we effectively mitigate fluctuations in piezoelectric d33. Our approach achieves an impressive d33 of ~430 pC/N with a minimal temperature fluctuation range (△d33 ~ 7%) across the room temperature to 100 °C in potassium sodium niobate ceramics. Further optimization through annealing extends this temperature up to 150 °C (△d33 ~ 8%) while maintaining a high d33 of ~380 pC/N, rivaling the performance of classic temperature stable lead zirconate titanate. This work establishes a framework for addressing the dilemma between high piezoelectric coefficient and inadequate temperature stability in lead-free piezoceramics.

Investigation and Improvement of the Bias Temperature Instability in Carbon Nanotube Transistors

Investigation and Improvement of the Bias Temperature Instability in Carbon Nanotube Transistors