Broad Temperature Range Research Articles

Analysis of pyroelectric properties in quenched NBT-BT composition

Quenching has recently demonstrated its efficacy in elevating the ferroelectric to relaxor phase transition temperature (TFR) in 0.94Na0.5Bi0.5TiO3-0.06BaTiO3 (NBT-6BT). Consequently, the current investigation comprehensively examines the pyroelectric properties of quenched NBT-6BT. The pyroelectric coefficient is measured using the Byer-Roundy method, incorporating a strategic approach to mitigate the risk of overestimation by implementing cyclic heating and cooling. Quenching enhances the depolarization temperature (Td) by approximately 40 °C, quantified through the temperature-dependent pyroelectric current density (Ip). The maximum pyroelectric current (52nA) and voltage (200V) responses to thermal cycling (15s heating/cooling) were observed in quenched NBT-6BT. The voltage sensitivity figures of merit were equivalent for both furnace-cooled and quenched NBT-6BT. The assessment of pyroelectric energy storage involved charging a 48 nF capacitor in 180s, resulting in a maximum voltage of 38V. The outcomes strongly endorse the quenched NBT-6BT as an efficient pyroelectric material, showcasing promising attributes for applications in sensing and energy harvesting across a broad temperature range.

Boosting Low-E Electro-strain via High-Electronegativity B-Site Substitution in lead-free K0.5Na0.5NbO3-based ceramics

Lead-free piezoelectric actuators emerge as promising substitutes for their lead-containing counterparts to address environmental concerns. However, they often confront a trade-off between low driving electric fields and high electro-strain. Herein, a novel strategy to boost electro-strain under low electric fields is proposed by doping high-electronegativity B-site atoms into perovskite potassium sodium niobate-based ceramics. Our findings reveal that high-electronegativity B-site atoms elevate the covalency of B-O bonding, softening the short-range repulsion and introducing local multiphase coexistence. This leads to more nanoscale domain structures and lower coercive field, thereby enabling large strains to be produced at lower electric fields. Notably, a substantial 0.2% bipolar electro-strain and 0.1% unipolar electro-strain under 10kV cm-1 is achieved in Sr, Sb co-doped potassium sodium niobate ceramics, with a broad working frequency and temperature range, as well as excellent fatigue resistance. This study unveils innovative insights into designing lead-free piezoelectric ceramics with remarkable electro-strain performance and low driving electric field, promising a significant advancement in lead-free piezoelectric materials science and piezoelectric actuators.

Improving the energy storage efficiency and power density of polymer blend in combination with Ti3C2Tx for energy storage devices

Polymer blend-based dielectrics are extensively used because of their broad working temperature range, quick discharging speed, and high power density. The solution casting approach is used to prepare the PVDF/PMMA- Ti3C2Tx nanocomposite flexible energy storage films. The morphology results show that the composite has a homogeneous and dense microstructure. The structural study shows the composition of thin films and confirms the existence of the PVDF β-phase. The thermal analysis showed 31.36 % crystallinity for 20 wt% of nanocomposite (NCs). The values of band gap energy reduced from 3.07 eV to 2.65 eV with increasing Ti3C2Tx concentration (15 wt%). It was found that the almost high dielectric constant values of (̴205) at 100 Hz and loss of 0.078 were suggestive of increased interfacial polarization. The maximal energy density of the NCs is 1.28 J/cm3, and its power density is 4.86 MW/cm3 for 15 wt% NCs. The conductivities of 15 wt% composite increase to 10−9 –10−7 S.cm−1 at 100 Hz, and then it reaches nearly 10−3 S cm−1 when the frequency is raised to 1 MHz. The 2D MXene nanofiller and PVDF macromolecular chain have an improved interface interaction, which results in excellent complete electrical characteristics. The rise in residual polarization can be inhibited by adding PMMA. In this work, adding 2D Ti3C2Tx MXene to PVDF/PMMA blends offers a viable way to create materials that are highly effective at storing energy in capacitors.

Aluminide Coatings by Means of Slurry Application: A Low Cost, Versatile and Simple Technology

The present study focused on demonstrating the versatility of the slurry deposition technique to produce aluminide coatings to protect components from high-temperature corrosion in a broad temperature range, from 400 to 1400 °C. This is a simpler and low-cost coating technology used as an alternative to CVD and pack cementation, which also allows the coating of complex geometries and offers improved and simple repairability for a lot of industrial applications, along with avoiding the use of non-hazardous components. Slurry aluminide coatings from a proprietary water-based-Cr6+ free slurry were produced onto four different substrates: A516 carbon steel, 310H AC austenitic steel, Ti6246 Ti-based alloy and TZM, a Mo-based alloy. The resulting coatings were thoroughly characterised by FESEM and XRD, mainly so that the identification of microstructures and appropriate phases was reported for each coating. The importance of surface preparation and heat treatment as key parameters for the coating final microstructures was also evidenced, and how those parameters can be optimised to obtain stable intermetallic phases rich in Al to sustain the formation of a protective Al2O3 oxide scale. These coating systems have applications in diverse industrial environments in which high-temperature corrosion limits the lifetime of the components.

High Piezoelectric Performance of KNN-Based Ceramics over a Broad Temperature Range through Crystal Orientation and Multilayer Engineering.

Uninterrupted breakthroughs in the room temperature piezoelectric properties of KNN-based piezoceramics have been witnessed over the past two decades; however, poor temperature stability presents a major challenge for KNN-based piezoelectric ceramics in their effort to replace their lead-based counterparts. Herein, to enhance temperature stability in KNN-based ceramics while preserving the high piezoelectric response, multilayer composite ceramics were fabricated using textured thick films with distinct polymorphic phase transition temperatures. The results demonstrated that the composite ceramics exhibited both outstanding piezoelectric performance (d33~467 ± 16 pC/N; S~0.17% at 40 kV/cm) and excellent temperature stability with d33 and strain variations of 9.1% and 2.9%, respectively, over a broad temperature range of 25-180 °C. This superior piezoelectric temperature stability is attributed to the inter-inhibitive piezoelectric fluctuations between the component layers, the diffused phase transition, and the stable phase structure with a rising temperature, as well as the permanent contribution of crystal orientation to piezoelectric performance over the studied temperature range. This novel strategy, which addresses the piezoelectric and strain temperature sensitivity while maintaining high performance, is well-positioned to advance the commercial application of KNN-based lead-free piezoelectric ceramics.

Cold-induced degradation of core clock proteins implements temperature compensation in the Arabidopsis circadian clock.

The period of circadian clocks is maintained at close to 24 hours over a broad range of physiological temperatures due to temperature compensation of period length. Here, we show that the quantitative control of the core clock proteins TIMING OF CAB EXPRESSION 1 [TOC1; also known as PSEUDO-RESPONSE REGULATOR 1 (PRR1)] and PRR5 is crucial for temperature compensation in Arabidopsis thaliana. The prr5 toc1 double mutant has a shortened period at higher temperatures, resulting in weak temperature compensation. Low ambient temperature reduces amounts of PRR5 and TOC1. In low-temperature conditions, PRR5 and TOC1 interact with LOV KELCH PROTEIN 2 (LKP2), a component of the E3 ubiquitin ligase Skp, Cullin, F-box (SCF) complex. The lkp2 mutations attenuate low temperature-induced decrease of PRR5 and TOC1, and the mutants display longer period only at lower temperatures. Our findings reveal that the circadian clock maintains its period length despite ambient temperature fluctuations through temperature- and LKP2-dependent control of PRR5 and TOC1 abundance.

Crystallization and melting of Poly(4-hydroxybutyrate) characterized by fast scanning calorimetry

Poly (4-hydroxybutyrate) (P4HB) is a marine biodegradable polyester with promising applications. Unfortunately, the crystallization and melting behavior of P4HB has not been systematically studied, due to the rapid crystallization near room temperature. In particular, the characterization of crystallization and melting of P4HB by fast scanning calorimetry (FSC) has not been reported previously. In this article, the common differential scanning calorimeter (DSC), polarized optical microscopy (POM), atomic force microscopy (AFM) and FSC were performed to investigate the crystallization and melting behavior of P4HB. The results indicated that melt crystallization facilitated the formation of fragmented crystals rather than complete spherulites. Furthermore, the P4HB exhibited a broad crystallization temperature range from −19 °C to 49 °C, and the crystallization and melting of P4HB was notably affected by the temperature, in addition to the heating or cooling rates. The higher crystallization temperature and lower cooling rates facilitated the formation of well-developed crystals. Remarkably, the P4HB is found to be unable to crystallize at heating or cooling rates exceeding 6 K/s. Moreover, double melting peaks could be discerned at moderate isothermal crystallization temperature exhibiting faster crystallization rate. The findings will provide theoretical guidance on how to optimize the processing parameters in modulating the crystallization of P4HB.

A Comprehensive Review of Xanthan Gum-Based Oral Drug Delivery Systems.

Xanthan gum (XG) is an exopolysaccharide synthesized by the aerobic fermentation of simple sugars using Xanthomonas bacteria. It comprises a cellulosic backbone with a trisaccharide side chain connected to alternative glucose residues in the main backbone through α (1→3) linkage. XG dissolves readily in cold and hot water to produce a viscous solution that behaves like a pseudoplastic fluid. It shows excellent resistance to enzymatic degradation and great stability throughout a broad temperature, pH, or salt concentration range. Additionally, XG is nontoxic, biocompatible, and biodegradable, making it a suitable carrier for drug delivery. Furthermore, the carboxylic functions of pyruvate and glucuronic acid offer a considerable opportunity for chemical modification to meet the desired criteria for a specific application. Therefore, XG or its derivatives in conjunction with other polymers have frequently been studied as matrices for tablets, nanoparticles, microparticles, and hydrogels. This review primarily focuses on the applications of XG in various oral delivery systems over the past decade, including sustained-release formulations, gastroretentive dosage forms, and colon-targeted drug delivery. Source, production methods, and physicochemical properties relevant to drug delivery applications of XG have also been discussed.

The preferential occupying effect regulated atomically dispersed Cu site over Cu-SSZ-13 for enhancing NH3-SCR performance

The development of highly active catalysts for selective catalytic reduction of NOx with ammonia (NH3-SCR) at broad temperature range are desirable but challenging. Herein, a preferential occupying effect of Cd regulates atomically dispersed Cu site is proposed for NH3-SCR. Benefiting from the modulation effect of Cd, the temperature of NO conversion above 90 % for Cu-Cd-SSZ-13 is broadened to 160–550 ℃, and hydrothermal stability is significantly improved. The Cd ions prefer to occupy eight-membered rings (8 MRs) favor the generation of Z2Cu2+ at 6 MRs, and the electronegativity of Z2Cu2+ increases due to the introduction of Cd, thus boosting NH3-SCR process by reducing formation energy of key intermediate (NH4NO2) at active Z2Cu2+ site. Noticeably, the preferential occupying of Cd enhances the intrinsic stability of Z2Cu2+ by inhibiting its transformation into inactive CuOx. This work sheds new insight for regulating atomically dispersed Cu site to enhance NH3-SCR performance.

Simultaneous Improvement of Energy Storage Characteristics and Temperature Stability in K0.5Na0.5NbO3-Based Ceramics via LiF Modification.

The splendid energy storage performances with eminent stability of dielectric ceramics utilized in pulsed power devices have been paid more attention by researchers. This scheme can be basically realized through introducing Li+, Bi(Mg2/3Ta1/3)O3, NaNbO3, and LiF into KNN-based ceramics. Under the breakdown strength (BDS) of 460 kV/cm, an outstanding energy storage density (W) of 6.05 J/cm3 with a high energy efficiency (η) of 85.9% is implemented. Within the broad temperature range from 20 to 140 °C, the numerical fluctuations of energy storage characteristics can be maintained at a relatively stable level (ΔWrec ≈ 3.5%, Δη ≈ 2.8%). As for the charging-discharging performances, this component possesses a fast discharging speed (t0.90 ≈ 51 ns) and remarkable temperature stability (the variations are smaller than 3.5%). Additionally, the internal mechanisms of outstanding energy storage properties can be confirmed via crystal structures and domain structures, the content of oxygen vacancies, dielectric and impedance spectra, and phase simulation. Hence, the combination of outstanding energy storage with remarkable thermal stability can be fulfilled in one ceramic system according to this discovery, providing a research thought of developing the materials for dielectric capacitors.

Multi-Modal Sensing Ionogels with Tunable Mechanical Properties and Environmental Stability for Aquatic and Atmospheric Environments.

Ionogels have garnered significant interest due to their great potential in flexible iontronic devices. However, their limited mechanical tunability and environmental intolerance have posed significant challenges for their integration into next-generation flexible electronics in different scenarios. Herein, the synergistic effect of cation-oxygen coordination interaction and hydrogen bonding is leveraged to construct a 3D supramolecular network, resulting in ionogels with tunable modulus, stretchability, and strength, achieving an unprecedented elongation at break of 10800%. Moreover, the supramolecular network endows the ionogels with extremely high fracture energy, crack insensitivity, and high elasticity. Meanwhile, the high environmental stability and hydrophobic network of the ionogels further shield them from the unfavorable effects of temperature variations and water molecules, enabling them to operate within a broad temperature range and exhibit robust underwater adhesion. Then, the ionogel is assembled into a wearable sensor, demonstrating its great potential in flexible sensing (temperature, pressure, and strain) and underwater signal transmission. This work can inspire the applications of ionogels in multifunctional sensing and wearable fields.

Reversible Giant Barocaloric Effect with Broad Working Temperature Range in an Amorphous Ethylene Propylene Diene Monomer.

The barocaloric effect of a solid material is an intense research topic due to its potential application in solid-state refrigeration. Among the proposed candidates, elastic polymers are distinctive because their barocaloric responses are independent from a pressure-induced phase transition which makes it possible to realize a broad working temperature range in principle. However, the barocaloric performance of most elastic polymers diminishes significantly as temperature decreases. In this work, giant and reversible barocaloric effects were observed in a broad working temperature range from 252 to 345 K in an amorphous polymer of ethylene propylene diene monomer, which are much higher than the investigated crystalline and partially crystallized ones. It is demonstrated that the degree of crystallinity can be a key factor responsible for the mobility of polymer chains and the corresponding barocaloric performance at low temperatures. The reversible giant barocaloric effects, broad working temperature regions, low cost, and absence of pressure-transmitting fluid make the ethylene propylene diene monomer attractive for solid-state barocaloric refrigeration.

A Super-Ionic Solid-State Block Copolymer Electrolyte.

Polymer solid-state electrolytes offer great promise for battery materials with high energy density, mechanical stability, and improved safety. However, their low ion conductivities have so far limited their potential applications. Here, it is shown for poly(ethylene oxide) block copolymers that the super-stoichiometric addition of lithium bis(trifluoromethanesulfonyl) imide (LiTFSI) as lithium salt leads to the formation of a crystalline PEO block copolymer phase with exceptionally high ion conductivities and low activation energies. The addition of LiTFSI further induces block copolymer phase transitions into bi-continuous Fddd and gyroid network morphologies, providing continuous 3D conduction pathways. Both effects lead to solid-state block copolymer electrolyte membranes with ion conductivities of up to 1·10-1Scm-1 at 90°C, decreasing only moderately to 4·10-2Scm-1 at room temperature, and to >1·10-3Scm-1 at -20°C, corresponding to activation energies as low as 0.19eV. The co-crystallization of PEO and LiTFSI with ether and carbonate solvents is observed to play a key role to realize a super-ionic conduction mechanism. The discovery of PEO super-ionic conductivity at high lithium concentrations opens a new pathway for fabrication of solid polymer electrolyte membranes with sufficiently high ion conductivities over a broad temperature range with widespread applications in electrical devices.

Neuromodulator-induced temperature robustness in a motor pattern: a comparative study between two decapod crustaceans.

While temperature fluctuations pose significant challenges to the nervous system, many vital neuronal systems in poikilothermic animals function over a broad temperature range. Using the gastric mill pattern generator in the Jonah crab, we previously demonstrated that temperature-induced increases in leak conductance disrupt neuronal function and that neuropeptide modulation provides thermal protection. Here, we show that neuropeptide modulation also increases temperature robustness in Dungeness and green crabs. As in Jonah crabs, higher temperatures increased leak conductance in both species' pattern-generating lateral gastric neuron and terminated rhythmic gastric mill activity. Likewise, increasing descending modulatory projection neuron activity or neuropeptide transmitter application rescued rhythms at elevated temperatures. However, decreasing input resistance using dynamic clamp only restored the rhythm in half of the experiments. Thus, neuropeptide modulation increased temperature robustness in both species, demonstrating that neuropeptide-mediated temperature compensation is not limited to one species, although the underlying cellular compensation mechanisms may be distinct.

Insight on thermodynamic and thermoelectric properties of Ge based perovskites AGeO3 (A = Mg, Cd) for energy harvesting applications: A DFT approach

In this manuscript, transport properties like thermoelectric and thermodynamic properties of AGeO3 (A = Mg, Cd) perovskites have been performed in detail along with effect of chemical potential on various thermoelectric parameters. Furthermore, we present the electronic effects and thermodynamic stability of these materials. The MgGeO3 and CdGeO3 alloys have a gap of 3.368 and 2.555 eV, respectively, making them indirect band gap semiconductors. Furthermore, using a constant relaxation time approximation and semiclassical Boltzmann theory, the thermoelectric (TE) properties of both materials have been studied. The lattice thermal conductivity magnitudes for MGeO3 and CdGeO3 are 7.47 W/mK and 21.55 W/mK, respectively, at 300 K. Power Factor (PF) has been measured at approximately 0 chemical potential, or approximately 14 (1011 W/K2 ms) at 1200 K, 7.5 (1011 W/K2 ms) at 700 K, and 3.5 (1011 W/K2 ms) at 300 K for both MgGeO3 and CdGeO3. At room temperature, the electrical conductivities of MgGeO3 and CdGeO3 were measured to be 1.43 × 1015W/mK and 1.08 × 1015W/mK, respectively. Over a broad temperature range (0–1200 K), the thermodynamic parameters, such as heat capacity, entropy, thermal expansion, and Debye temperature, were also computed and discussed.

Unraveling the Interplay between Stability and Flexibility in the Design of Polyethylene Terephthalate (PET) Hydrolases.

The accumulation of polyethylene terephthalate (PET), a widely used polyester plastic in packaging and textiles, has led to a global environmental crisis. Biodegradation presents a promising strategy for PET recycling, with PET hydrolases (PETase) undertaking the task at the molecular level. Unfortunately, PETase operates only at ambient temperatures with low efficiency, limiting its industrial application. Current engineering efforts focus on enhancing the thermostability of PETase, but increased stability can reduce the structural dynamics needed for substrate binding, potentially slowing enzymatic activity. To elucidate the balance between stability and flexibility in optimizing PETase catalytic activity, we performed theoretical investigations on both wild-type PETase (WT-PETase) and a thermophilic variant (Thermo-PETase) using molecular dynamics simulations and frustration analysis. Despite being initially designed to stabilize the native structure of the enzyme, our findings reveal that Thermo-PETase exhibits an unprecedented increase in structural flexibility at the PET-binding and catalytic sites, beneficial for substrate recruitment and product release, compared to WT-PETase. Upon PET binding, we observed that the structural dynamics of Thermo-PETase is largely quenched, favoring the proximity between the catalytic residues and the carbonyl of the PET substrate. This may potentially contribute to a higher probability of a catalytic reaction occurring in Thermo-PETase compared to WT-PETase. We suggest that Thermo-PETase can exhibit higher PET-degradation performance than WT-PETase across a broad temperature range by leveraging stability and flexibility at high and low temperatures, respectively. Our findings provide valuable insights into how PETase optimizes its enzymatic performance by balancing stability and flexibility, which may contribute to future PETase design strategies.

Polarization-Doped InGaN LEDs and Laser Diodes for Broad Temperature Range Operation.

This work reports on the possibility of sustaining a stable operation of polarization-doped InGaN light emitters over a particularly broad temperature range. We obtained efficient emission from InGaN light-emitting diodes between 20 K and 295 K and from laser diodes between 77 K and 295 K under continuous wave operation. The main part of the p-type layers was fabricated from composition-graded AlGaN. To optimize injection efficiency and improve contact resistance, we introduced thin Mg-doped layers of GaN (subcontact) and AlGaN (electron blocking layer in the case of laser diodes). In the case of LEDs, the optical emission efficiency at low temperatures seems to be limited by electron overshooting through the quantum wells. For laser diodes, a limiting factor is the freeze-out of the magnesium-doped electron blocking layer for temperatures below 160 K. The GaN:Mg subcontact layer works satisfyingly even at the lowest operating temperature (20 K).

Fluorine-Rich Electrolyte Additive for Achieving Dendrite-Free Lithium Anodes at Low Temperatures.

The practical application of lithium metal anodes is significantly impeded by poor interfacial stability and uncontrolled dendrite growth. Herein, we introduce methyl trifluoroacetate (MTFA), a low-melting-point small molecule, as an electrolyte additive in an ether-based electrolyte. This additive facilitates the formation of an in situ composite solid electrolyte interphase (SEI) layer that is rich in LiF and features an ester-based flexible matrix. The resulting composite layer exhibits high ionic conductivity and mechanical stability, effectively regulating the lithium deposition behavior over a broad temperature range and inhibiting dendrite formation. Based on MTFA, the Li||Li symmetrical cell achieves a lifespan exceeding 5000 h at room temperature and 800 h at -20 °C, both with ultralow overpotential and exceptional cycling stability. In Li||LiFePO4 full cells with a high-area loading (10.52 mg cm-2) and an N/P ratio of 1.68, an average capacity decay of merely 0.096% per cycle is observed over 200 cycles. Even at -20 °C, the Li||LiFePO4 cell shows a CE of over 99% and maintains stable cycling performance. This work provides an innovative approach for optimizing lithium metal anode interfaces and enhancing low-temperature operation capabilities through the use of electrolyte additives.

Self-diffusion is temperature independent on active membranes.

Molecular transport maintains cellular structures and functions. For example, lipid and protein diffusion sculpts the dynamic shapes and structures on the cell membrane that perform essential cellular functions, such as cell signaling. Temperature variations in thermal equilibrium rapidly change molecular transport properties. The coefficient of lipid self-diffusion increases exponentially with temperature in thermal equilibrium, for example. Hence, maintaining cellular homeostasis through molecular transport is hard in thermal equilibrium in the noisy cellular environment, where temperatures can fluctuate widely due to local heat generation. In this paper, using both molecular and lattice-based modeling of membrane transport, we show that the presence of active transport originating from the cell's cytoskeleton can make the self-diffusion of the molecules on the membrane robust to temperature fluctuations. The resultant temperature-independence of self-diffusion keeps the precision of cellular signaling invariant over a broad range of ambient temperatures, allowing cells to make robust decisions. We have also found that the Kawasaki algorithm, the widely used model of lipid transport on lattices, predicts incorrect temperature dependence of lipid self-diffusion in equilibrium. We propose a new algorithm that correctly captures the equilibrium properties of lipid self-diffusion and reproduces experimental observations.

A non-symmetric room-temperature tristriazolotriazine liquid crystal

Tristriazolotriazine (TTT) has emerged as an easily accessible electron-deficient heterocyclic core for discotic liquid crystals (LCs). Materials that are liquid-crystalline at room temperature, i.e., do not crystallize in ambient conditions, are of particular interest when the LC state is prone to offer advantages in optoelectronic devices, e.g., for anisotropic charge or exciton transport, or anisotropic light emission. However, there has been no report of non-symmetric TTT LCs, i.e., with unequal arms. Here, we report two non-symmetric compounds derived from the TTT core. Their non-symmetry, combined with a high number of peripheral alkyl chains, is found to promote Colh mesomorphism over a broad temperature range including room temperature. The non-symmetry also induces an increase in the emission quantum yield, compared to symmetric analogs.