Showing papers on "Atmospheric temperature range published in 2022"

Compositionally Graded KNN‐Based Multilayer Composite with Excellent Piezoelectric Temperature Stability

Abstract: The inherent disadvantage of lead-free potassium sodium niobate (KNN)-based ceramics is the severe temperature instability of piezoelectric charge coefficient (d33 ) caused by the polymorphic phase boundary. Herein, a new concept of structural gradient is proposed by designing compositionally graded multilayer composites with multiple successive phase transitions, to solve the challenge of the inferior temperature stability. The structural gradient ceramics exhibit a superior temperature reliability (d33 remains almost unchanged in the temperature range of 25-100 °C), far outperforming the previously reported KNN counterparts with d33 variation above 27% over the same temperature range. The synergistic contribution of the continuous phase transition, the strain gradient, and the complementary effect of each constituent layer leads to the excellent temperature stability, which is also confirmed by phase-field simulation. These findings are expected to provide a new paradigm for functional material design with outstanding temperature stability.

Dielectric temperature stability and energy storage performance of NBT‐based ceramics by introducing high‐entropy oxide

Abstract: In this study, a high-entropy perovskite oxide Sr(Zr0.2Sn0.2Hf0.2Ti0.2Nb0.2)O3 (SZSHTN) was first introduced to Na0.5Bi0.5TiO3 (NBT) lead-free ferroelectric ceramics to boost both the high-temperature dielectric stability and energy storage performance. Excellent comprehensive performance was simultaneously obtained in the 0.8NBT–0.2SZSHTN ceramic with high ε′ value (> 2000), wide ε′-temperature stable range (TCC < 5%, 52.4–362°C), low tanδ value in a wide range (<0.01, 90–341°C) and high energy storage performance (Wrec = 3.52 J/cm3, Wrec and η varies ±6.08% and ±7.4% from 20 to 150°C), which endows it the promising potential to be used in high-temperature environments.

Magnetic refrigeration material operating at a full temperature range required for hydrogen liquefaction

Abstract: Magnetic refrigeration (MR) is a key technique for hydrogen liquefaction. Although the MR has ideally higher performance than the conventional gas compression technique around the hydrogen liquefaction temperature, the lack of MR materials with high magnetic entropy change in a wide temperature range required for the hydrogen liquefaction is a bottle-neck for practical applications of MR cooling systems. Here, we show a series of materials with a giant magnetocaloric effect (MCE) in magnetic entropy change (-∆Sm > 0.2 J cm-3K-1) in the Er(Ho)Co2-based compounds, suitable for operation in the full temperature range required for hydrogen liquefaction (20-77 K). We also demonstrate that the giant MCE becomes reversible, enabling sustainable use of the MR materials, by eliminating the magneto-structural phase transition that leads to deterioration of the MCE. This discovery can lead to the application of Er(Ho)Co2-based alloys for the hydrogen liquefaction using MR cooling technology for the future green fuel society.

Magnetic refrigeration material operating at a full temperature range required for hydrogen liquefaction

Abstract: Magnetic refrigeration (MR) is a key technique for hydrogen liquefaction. Although the MR has ideally higher performance than the conventional gas compression technique around the hydrogen liquefaction temperature, the lack of MR materials with high magnetic entropy change in a wide temperature range required for the hydrogen liquefaction is a bottle-neck for practical applications of MR cooling systems. Here, we show a series of materials with a giant magnetocaloric effect (MCE) in magnetic entropy change (-∆Sm > 0.2 J cm-3K-1) in the Er(Ho)Co2-based compounds, suitable for operation in the full temperature range required for hydrogen liquefaction (20-77 K). We also demonstrate that the giant MCE becomes reversible, enabling sustainable use of the MR materials, by eliminating the magneto-structural phase transition that leads to deterioration of the MCE. This discovery can lead to the application of Er(Ho)Co2-based alloys for the hydrogen liquefaction using MR cooling technology for the future green fuel society.

FeCoNiCr0.4CuX High-Entropy Alloys with Strong Intergranular Magnetic Coupling for Stable Megahertz Electromagnetic Absorption in a Wide Temperature Spectrum.

Abstract: Electromagnetic (EM) absorbers serving in the megahertz (MHz) band and a wide temperature range (from -50 to 150 °C) require high and temperature-stable permeability for outstanding EM absorption performance. Herein, FeCoNiCr0.4CuX high-entropy alloy (HEA) powders with a unique nanocrystalline structure separated by a thin amorphous layer (NTA) are designed to improve permeability and enhance intergranular coupling. Simultaneously, the long-range anisotropy is introduced via devising the preparation process and tuning the chemical composition, such that the intergranular exchange interaction is further strengthened for stable permeability and EM wave absorption in a wide temperature range. FeCoNiCr0.4Cu0.2 HEAs exhibit a near-zero permeability temperature coefficient (5.7 × 10-7 °C-1) a in wide temperature range. The maximum reflection loss (RL) of FeCoNiCr0.4Cu0.2 HEAs is higher than -7 dB with 5 mm thickness at -50-150 °C, and the absorption bandwidth (RL < -7 dB) can almost cover 400-1000 MHz. Furthermore, FeCoNiCr0.4Cu0.2 HEAs also have a high Curie temperature (770 °C) and distinguished oxidation resistance. The permeability temperature dependence of FeCoNiCr0.4CuX HEAs is investigated in-depth in light of the microstructural change induced by tuning the chemical composition, and a new inspiration is provided for the design of magnetic applications serving in wide temperature, such as transformers, sensors, and EM absorbers.

High‐Ranged ZT Value Promotes Thermoelectric Cooling and Power Generation in n‐Type PbTe

Abstract: Excellent thermoelectric cooling and power generation are simultaneously realized in an n‐type PbTe‐based thermoelectric material. The cooling temperature difference (ΔT) of ≈15.6 K, maximum power density of ≈0.4 W cm−2 and conversion efficiency of ≈1.5% with TC = 295 K and TH = 765 K can be obtained in a single‐leg device composed of PbTe‐30%SnSe‐1.5%Cu. This advanced thermoelectric performance in n‐type PbTe‐30%SnSe‐1.5%Cu mainly originates from its high‐ranged ZT value achieved through optimizing its bandgap, carrier density, and microstructure. The bandgap in PbTe is first reduced by SnSe alloying to facilitate the carrier transport properties at low temperature range (300–573 K). With further tuned carrier density, the average power factor increases from ≈10.2 µW cm−1 K−2 in Pb0.985Sb0.015Te‐30%SnSe to ≈16.2 µW cm−1 K−2 in PbTe‐30%SnSe‐1.5%Cu at 300–773 K. Moreover, microstructure observation reveals high‐density dislocations in PbTe‐30% SnSe‐1.5% Cu, which can dramatically suppress the room‐temperature lattice thermal conductivity from ≈2.21 Wm−1 K−1 in Pb0.985Sb0.015Te to ≈0.53 Wm−1 K−1 in PbTe‐30%SnSe‐1.5%Cu. As a result, a room‐temperature ZT value of ≈0.7 and high average ZT value (ZTave) of ≈0.98 can be obtained in PbTe‐30%SnSe‐1.5%Cu at 300–573 K, which makes its performance comparable to the commercial n‐type Bi2Te3‐based thermoelectric material.

Sodium-ion Battery with a Wide Operation-Temperature Range from -70 to 100 °C.

Abstract: Sodium-ion batteries (SIBs), as one of the potential candidates for grid-scale energy storage systems, are required to tackle extreme weather conditions. However, the all-weather SIBs with a wide operation-temperature range are rarely reported. Herein, we propose a wide-temperature SIB, which involves a carbon-coated Na 4 Fe 3 (PO 4 ) 2 P 2 O 7 (NFPP@C) cathode, a Bismuth (Bi) anode, and a diglyme-based electrolyte. We demonstrate that solvated Na + can be directly stored by the Bi anode via an alloying reaction without the de-solvent process. Furthermore, the NFPP@C cathode exhibits a high Na + diffusion coefficient at low temperature. As a result, the Bi//NFPP@C battery exhibits perfect low-temperature behavior. Even at -70 °C, this battery still delivers 70.19% of the room-temperature capacity. Furthermore, benefitting from the high boiling point of the electrolyte, this battery also works well at a high temperature up to 100 °C. These encourage results might shed light on the exploration of wide-temperature SIBs.

Cr3+-doped InTaO4 phosphor for multi-mode temperature sensing with high sensitivity in physiological temperature range

Abstract: With the increasing demand for non-contact temperature sensing, the development of optical thermometer with excellent performance is more and more compelling. Cr3+-doped InTaO4 phosphor was prepared for the implementation of...

Hydrogen‐bonded Engineering Enhancing Phase Transition Temperature in Molecular Perovskite Ferroelastic

Abstract: The broad operating temperature range is sought for molecular ferroic materials who are expected to be applied to flexible and electronic materials. Hydrogen bonds, an effective force between molecules, are important to regulate the molecule structure and their condition, helping a higher temperature range for ferroic materials. Here, we report a molecular perovskite ferroelastic (Me-Hdabco)Rb[BF4]3 (Me-Hdabco = N-methyldabconium) which shows high temperature (T1 = 322.5 K and T2 = 381 K) ferroelastic phase transitions. The ferroelastic phase transition temperature range of (Me-Hdabco)Rb[BF4]3 is significantly increased by 71 K compared with [Meda-bco-F]Rb[BF4]3 (Medabco-F = 1-fluoro-4-methyl-1,4-diazoniabicyclo[2.2.2]octane). Structural analysis and thermal analysis demonstrate the ferroelastic phase transition is mainly attributed to dynamic cations order and disorder transformation. Therefore, new hydrogen bonds generated between cations and the Rb8[BF4]12 frame increase their intermolecular force, which is beneficial to improving the phase transition temperature. This finding has an important impact on the utilization of weak interaction forces to design and optimize functional materials. Appendix S1 Supporting Information Appendix S2 Supporting Moive_S1 Appendix S3 Supporting Moive_S2 Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

Highly Efficient Proton Conduction in the Metal–Organic Framework Material MFM-300(Cr)·SO4(H3O)2

Abstract: The development of materials showing rapid proton conduction with a low activation energy and stable performance over a wide temperature range is an important and challenging line of research. Here, we report confinement of sulfuric acid within porous MFM-300(Cr) to give MFM-300(Cr)·SO4(H3O)2, which exhibits a record-low activation energy of 0.04 eV, resulting in stable proton conductivity between 25 and 80 °C of >10–2 S cm–1. In situ synchrotron X-ray powder diffraction (SXPD), neutron powder diffraction (NPD), quasielastic neutron scattering (QENS), and molecular dynamics (MD) simulation reveal the pathways of proton transport and the molecular mechanism of proton diffusion within the pores. Confined sulfuric acid species together with adsorbed water molecules play a critical role in promoting the proton transfer through this robust network to afford a material in which proton conductivity is almost temperature-independent.

Mixed-valent MgAl2O4:Eu2+/Eu3+ phosphor for ratiometric optical thermometry

Abstract: Novel strategies to obtain remote temperature sensing with good spatial and thermal resolution are in high demand in various applications, where traditional thermometers are inappropriate. The majority of developed luminescence thermometers utilize thermally-coupled levels with their inherent limitation of thermal sensitivity and problems with signal discriminability. We report mixed-valent Eu2+/Eu3+-doped MgAl2O4 phosphor as a ratiometric thermal sensor, which is free of these drawbacks. Different temperature behavior of Eu2+ and Eu3+ emission bands provides luminescence thermometry within range of 298–523 K. High absolute and relative thermal sensitivities of 0.084 K-1 and 0.83% K−1, respectively, as well as sub-degree temperature resolution indicate that MgAl2O4:Eu2+/Eu3+ phosphor is a promising material for optical thermometry.

Organic/Inorganic Hybrid Design as a Route for Promoting the Bi0.5Sb1.5Te3 for High‐Performance Thermoelectric Power Generation

Abstract: Bismuth telluride alloys favor the applications of low‐grade waste heat recovery if their figure‐of‐merits are improved within the larger temperature range from 300 to 523 K. Herein, this work reports a synergistic optimization for Bi0.5Sb1.5Te3 (BST) by incorporating the copper(II) phthalocyanine (CuPc), which is preferentially distributed at the grain boundary of BST after the spark plasma sintering process and suppresses the grain growth of BST. The lattice thermal conductivity of composites is then extensively reduced by the multiscale scattering induced by the CuPc. In addition, the Cu atoms diffuse into the lattice of BST and increase the whole concentration, thus suppressing the bipolar effect. As a result, the average zT value is effectively enhanced from 0.7 to 1.1 in the temperature range between 300 and 523 K. A high conversion efficiency of 6.8% is achieved in a single BST/CuPc5 leg, which is 41.7% higher than that of BST at temperature different ΔT = 223 K. This result proves that the composition optimization of the BST/CuPc is a promising strategy to improve the application of BST‐based TE modules.