Wide Temperature Span Research Articles

Engineering Multiphase Phase Transitions for Exceptional Electrocaloric Performance and Ultraweak Electrostrictive Response in Ferroelectrics.

In the pursuit of eco-friendly alternatives for refrigeration technology, electrocaloric materials have emerged as promising candidates for efficient solid-state refrigeration due to their high efficiency and integrability. However, current advancements in electrocaloric effects (ECEs) are often constrained by high temperatures and elevated electric fields (E-field), limiting practical applicability. Informed by phase-field simulation, this study introduces a (1-x)Pb(Yb1/2Nb1/2)O3-xPb(Mg1/3Nb2/3)O3 system, strategically engineered to incorporate highly ordered YN and disordered MN mixtures. The synergistic interplay between E-field/temperature-induced polarization reorientation and cation shift initiates multiple ferroelectric-antiferroelectric-paraelectric phase transitions. Our results demonstrate that under a moderate E-field of 50 kV cm-1, the x = 0.22 composition achieves remarkable performance with a giant temperature change (ΔT) of 3.48 K, a robust ECE strength (ΔT/ΔE) of 0.095 K cm kV-1, and a wide temperature span (Tspan) of 38 °C. Notably, the disrupted lattice structure contributes to ultralow electrostrains below 0.008%, with an average electrostrictive coefficient Q33 of 0.007 m4 C-2. The significantly weakened electrostrictive activity favors enhancing the performance stability of subsequent devices. This work introduces an innovative strategy for developing robust electrocaloric materials, offering substantial ΔT and low electrostrains, presenting promising advancements in ECE applications with an extended lifetime.

Metamagnetic phase transition and corresponding magnetocaloric effect in intermetallic Ho1-xTbxCo2 alloys

A comprehensive investigation was conducted to examine the magnetic properties and magnetocaloric effect (MCE) around the phase transition temperature of the intermetallic Ho1-xTbxCo2 (x=0.05, 0.1, and 0.15) alloys. X-ray diffraction (XRD) investigations reveal that the single-phase alloys crystallize in the cubic phase (space group Fd3̅m) at room temperature and undergo a structural transition to the tetragonal phase (space group I41/amd) below their Curie temperatures. These alloys demonstrated a metamagnetic transition around their respective phase transition temperatures, accompanied by a remarkable MCE and negligible hysteresis loss. The Landau free energy study confirmed the existence of the first-order magnetic transition in the aforementioned samples. The spin reorientation occurring below the transition temperature was observed. The studied alloys displayed significant magnetic entropy change (ΔSM) values of 15.6 JKg−1K−1, 15.2 JKg−1K−1, and 13.06 JKg−1K−1 in a wide temperature span over 20 K under a magnetic field change (ΔH) of 5 T for x=0.05, 0.1, and 0.15, respectively. Furthermore, large refrigerant capacities (RC) of 323.6 Jkg−1, 311.28 Jkg−1, and 323.46 Jkg−1 were achieved under ΔH=5 T for these alloys. An unexpected asymmetric broadening of the ΔSM peak was observed as the magnetic field increased. A significant change in the adiabatic temperature (ΔTad) of 5.3–6 K was achieved under ΔH=5 T. The outstanding magnetocaloric performance of studied materials may make them promising for magnetic refrigeration applications within the 87–105 K temperature range.

Wide temperature span and giant refrigeration capacity magnetic refrigeration materials for hydrogen liquefaction

Based on theoretical calculations and experiments, the crystal structure, electronic structure, magnetism, and magnetocaloric effect (MCE) of the Ho5B2C5 compound have been systematically investigated. The Ho5B2C5 compound with a typical metallic nature was found to crystallize in a tetragonal structure belonging to space group P4/ncc (No. 130), and its magnetic ground state was identified as ferromagnetic (FM) ordering based on theoretical and experimental results. Additionally, a second-order magnetic phase transition from FM to paramagnetic around approximately 27 K was observed in the Ho5B2C5 compound, resulting in a large MCE. Under varying magnetic fields (ΔH) from 0 to 7 T, the maximum magnetic entropy change (−ΔSMmax), refrigeration capacity (RC), and δTFWHM are 21.3 J/kg K, 1001.6 J/kg, and 60.2 K (a wide temperature range from 15.2 to 75.4 K), respectively. The outstanding MCE performance of the Ho5B2C5 compound is expected to facilitate the progress of magnetic refrigeration for hydrogen liquefaction.

Electrocaloric effect with enhanced temperature stability in an interfacial polarization controlled ferroelectric laminated composite

Research on zero-emission lead-free ferroelectric materials is fascinating in the field of solid-state refrigeration due to the observed large electrocaloric phenomenon. However, one of the challenges involved is realizing a large adiabatic temperature change ( ΔT ) over a wide temperature span. Here, a laminated ferroelectric structure with layers, having successive phase transitions covering room temperature, is proposed to overcome this problem. BaTi1−x Sn x O3 with x = 0.08, 0.12, and 0.15 compositions exhibiting the required ferroelectric Curie temperatures was chosen for the component layers. The designed interfacial polarization engineered laminated structure with 0.15/0.08/0.12 compositional layers yielded a value of adiabatic temperature change ΔT max ⩾ 0.6 °C by an indirect method using Maxwell’s thermodynamic equations over a wide temperature span (30 °C–85 °C). The observed results are correlated to the interrelated cumulative effect of reduced interfacial polarization, homogeneous electric field distribution, field-induced phase transitions, and enhanced domain switching, which are the manifestation of the designed laminated geometry.

Electrical characterization of Sn modified barium bismuth zirconate

BaBi4Sn4O15, a Sn-modified ceramic sample of layered ferroelectric oxide family, is developed using a high-temperature mixed oxide route after firing for calcination at 810 °C for 6 h in steps of 50 °C starting from 600 °C. An introductory XRD study of the compound displays the development of the new orthorhombic structured single-phase compound at atmospheric conditions. The electrical behaviors of the compound are investigated in a wide temperature span (30–500 °C) and frequencies ranging from 0.1 kHz to 1 MHz using an impedance analyzer. Dielectric behavior informs that the compound has a phase transition from Ferro to Paraelectric at 370 °C, which is well above room temperature. The impact of temperature and frequency on complex immittance parameters (impedance and modulus) is analyzed using an LCR meter in a broad temperature & frequency span. The electrical properties confirm; (a) the existence of semiconductor-like NTCR (negative temperature coefficients of resistance) behavior, (b) the evidence of the electric relaxation process as a function of temperature, (c) the existence of electric relaxation ascribed to the simultaneous contribution of bulk & bulk interfaces to the electrical behavior, and (d) presence of the non-Debye type relaxation phenomena. The frequency-dependent conductivity follows Jonscher’s universal power law.

Rare-earth element doped barium titanate-based ceramics exhibiting ultra-wide temperature span electrocaloric effect

Electrocaloric effect (ECE) refrigeration stands out as a promising alternative to conventional compression refrigeration owing to its potential for miniaturization, high energy conversion efficiency, cost-effectiveness, and environmental friendliness. However, the practical applications of ECE refrigeration in lead-free ceramics face limitations due to the challenge of achieving a substantial adiabatic temperature change (ΔT) and a wide operating temperature span (Tspan). In this study, we tackle this challenge by introducing rare-earth Sm3+ ions into Ba(Ti0·90Sn0.10)O3 (BTSn) ceramics to enhance their ECE stability. We comprehensively investigate the structural, dielectric, and ECE properties of (Ba1−3x/2Smx) (Ti0·9Sn0.1)O3 (BSmTSn, x = 0−0.03) ceramics. Our findings reveal that the incorporation of Sm3+ ions leads to a reduction in the temperature at which the permittivity reaches its maximum, accompanied by an increased dispersion compared to undoped BTSn ceramics. Particularly noteworthy is the achievement of a ΔT of 0.9 K with a Tspan of 55.5 °C in the x = 0.005 composition. Furthermore, increasing x to 0.01 enables the realization of a wide Tspan of 70 °C, starting from 30 °C. These significant enhancements in the Tspan across all BSmTSn ceramics, facilitated by the introduction of Sm3+ ions, present a promising strategy for optimizing the ECE performance of BaTiO3-based ceramics.

Successive phase transitions–induced multiple boundaries and unprecedented electrocaloric effect in Pb(Yb1/2Nb1/2)O3–Pb(Mg1/3Nb2/3)O3 system

AbstractTemperature stability of electrocaloric effect (ECE) is a thorny problem in ferroelectrics (FE). A general method is to design ferroelectric‐to‐relaxor phase transition at a sacrifice of electrocaloric (EC) strength. The Pb(Yb1/2Nb1/2)O3 antiferroelectrics (AFE) + Pb(Mg1/3Nb2/3)O3 relaxors strategy designed in this work is effective to tackle this dilemma [(1 − x)PYN–xPMN, x = 0.08–0.36]. PMN addition induces a successive phase transition and dual phase boundaries of ferrielectric (FIE)‐nonergodic relaxor (NER) and NER‐ergodic relaxor (ER), where ferroelectric polarization/strain and ECE reach a local maximum. Thermally stable ΔT is unexpectedly achieved in FIE (x = 0.14) and NER (x = 0.24), except for a generality for ER state (x = 0.30). A dome‐like variation trend is observed in x = 0.14 and 0.24 with a wide temperature span of ∼60 and ∼55 K (±15%ΔTmax). Notably, x = 0.24 NER possesses a large directly measured ΔTmax ∼0.64 K simultaneously. Dielectric/ferroelectric properties clarify that two‐stage transition of AFE rigid‐order de‐texture and dissociation of de‐textured AFE domains into polar nano‐entities accounts for thermal stability of ΔT as the alternation of ordered antipolar domains to disorder relaxors serves as a buffer to compensate for the thermal‐shock enhanced random field. This work not only accounts for the underlying mechanism for thermal stability of ΔT at FIE and NER side for the first time in physics but also provides an exotic approach to seek for high‐performance EC materials in practical applications.

Ho6FeSb2: Potential magnetic refrigerant with improved magnetocaloric effect

The magnetic and magnetocaloric characteristics of Ho6FeSb2 have been investigated. The compound crystallizes in Fe2P type hexagonal crystal structure (P6‾2m) with lattice parameters a, b = 8.1046 Å and c = 4.1470 Å. There are 2 second-order ferromagnetic transitions occurring at temperatures T1 = 56 K and T2 = 34 K. The occurrence of subsequent second-order transitions opens the door to hysteresis-free magnetocaloric effect across wide temperature span. The study utilizes different magnetocaloric figures of merit, including isothermal magnetic entropy change, relative cooling power, and temperature-averaged entropy change. The alloy has a maximum relative cooling power of 710 J/kg in 0–5 T, with the temperature-averaged entropy change value being close to the isothermal magnetic entropy change value, making it suitable for hysteresis-free magnetocaloric applications. We have studied the electrical transport properties of the alloy and estimated a maximum magnetoresistance of −9% around T1.

An ultra broadband NIR phosphor LiScSnO4:Cr3+ with emission wavelength peaking at 900 nm for component analysis

Near-infrared phosphor conversion light-emitting diode (NIR pc-LED) is a widely used ideal NIR light source due to its unique advantages of low cost, energy saving, compactness and long operational lifetime. However, there is currently a scarcity of appropriate phosphor for NIR light sources utilized in spectral detection, with emission peak larger than 850 nm and steady spectrum output of ultra broadband spectra. Here, a broadband Cr3+ activated LiScSnO4 (LSS) phosphor (λex-max = 460 nm) matching the pump band of commercial blue LED chips has been developed, which shows a long wavelength NIR emission peaking at 900 nm. Cr3+ simultaneously replace the Wyckoff site co-occupied by Sc and Sn in LSS. Due to the difference of local environment of the specific crystal field, two different wide emission bands are caused. These two broad emission bands both contribute to the broadband luminescence with a full width at half maximum (FWHM) of 227 nm. Benefiting from the crystallography consistent Wyckoff position occupation of Cr3+ ions, the spectral distribution of LSS:Cr3+ exhibit excellent stability over a wide temperature span (80–423 K). The broadband NIR pc-LED prototype based on LSS:Cr3+ shows great potential in NIR spectrum detection, night vision imaging applications.

Widening of working temperature range in Mn5-xCuxGe3 (x = 0.1 and 0.3) magnetocaloric compounds by compositional tuning

This study presents the effect of Cu doping on the fundamental properties, magnetocaloric effect, and critical behavior of Mn5Ge3 system. Mn5-xCuxGe3 compounds with x = 0.1 and 0.3 conform D88-hexagonal structure. The unit cell volume decreases, and MnI-MnI distance increases with Cu content. This modifies the exchange interaction and impacts Curie temperature and saturation magnetization accordingly. The critical exponents β and γ of x = 0.1 compound are of 3D Ising class, while the x = 0.3 compound shows non-conventional behavior with its γ lying within the 3D Ising framework and β lying between 3D XY and Heisenberg classes. Both the compounds have extended-type spin interactions, and the decay of the exchange integrals has been calculated. Mn5-xCuxGe3 compounds clearly outperform most materials of Mn5Ge3 class in terms of the magnetocaloric effect. They show an appreciable reversible isothermal entropy change across a wide temperature span with a large relative cooling power near the room temperature effect. These compounds can be combined with other suitable Mn5Ge3 materials and used in ‘active magnetic regenerative (AMR)’ systems as layered refrigerants for more efficient magnetocaloric cooling.

Separator-free Zn-ion Battery with Mn:V3O7·H2O Nanobelts and a Zn2+-Polyacrylamide Semisolid Electrolyte with Ultralong Cycle Life.

Vanadium based oxides are immensely suitable for zinc-ion-batteries (ZIBs) due to their layered and stable crystal structures. In this study, Mn doped V3O7·H2O nanobelts were synthesized and used as cathodes in ZIBs for the very first time and the doped oxide exhibited an enhanced capacity of 258 mAh g-1 compared to its undoped counterpart (208 mAh g-1) at the same current density of 40 mA g-1. Mn:V3O7·H2O outperforms the V3O7·H2O due to the superior bulk electrical conductivity as well as higher nanoscale current carrying capability imparted by a high proportion of mixed valent states of Mn3+, Mn2+, V5+, and V4+ and the smaller crystallite size that affords short diffusion lengths for Zn2+ ions. The Mn:V3O7·H2O cathode is coupled with a Zn2+ ion conducting polyacrylamide gel electrolyte and a Zn flakes/activated carbon (Zn Fs/C) composite anode to yield a unique separator free Mn:V3O7·H2O/Zn2+-PAM gel/Zn-Fs/C battery. The cell exhibits a capacity of ∼205 mAh g-1 (at 40 mA g-1) and retains 99% of its original capacity after 3500 cycles. The Zn2+-PAM gel shows a high ionic conductivity in the range of 5.9 to 28.2 S cm-1, over a wide temperature span of 0 to 70 °C, and a wide electrochemical potential stability window of -0.5 to +2.3 V, thus rendering it suitable for low temperature applications as well. The gel also inhibits dendritic growth of Zn over the Zn-Fs/C anode through regulated flow of Zn2+ ions during charging, prevents cathode dissolution, and improves cycle life via preservation of structural integrity of the Mn:V3O7·H2O cathode after 200 charge-discharge cycles. This is a highly scalable cell configuration and opens up opportunities to produce long lasting batteries completely free of costly separators with a semisolid free-standing electrolyte and a robust doped oxide.

2D Antiferroelectric Hybrid Perovskite with a Large Breakdown Electric Field And Energy Storage Density

AbstractEnergy conversion and storage devices are highly desirable for the sustainable development of human society. Hybrid organic–inorganic perovskites have shown great potential in energy conversion devices including solar cells and photodetectors. However, its potential in energy storage has seldom been explored. Here the crystal structure and electrical properties of the 2D hybrid perovskite (benzylammonium)2PbBr4 (PVK‐Br) are investigated, and the consecutive ferroelectric‐I (FE1) to ferroelectric‐II (FE2) then to antiferroelectric (AFE) transitions that are driven by the orderly alignment of benzylamine and the distortion of [PbBr6] octahedra are found. Furthermore, accompanied by field‐induced AFE to FE transition near room temperature, a large energy storage density of ≈1.7 J cm−3 and a wide working temperature span of ≈70 K are obtained; both of which are among the best in hybrid AFEs. This good energy storage performance is attributed to the large polarization of ≈7.6 µC cm−2 and the high maximum electric field of over 1000 kV cm−1, which, as revealed by theoretical calculations, originate from the cooperative coupling between the [PbBr6] octahedral framework and the benzylamine molecules. The research clarifies the discrepancy in the phase transition character of PVK‐Br and shed light on developing high‐performance energy storage devices based on 2D hybrid perovskite.

Comprehensively enhanced strain performance in PIN-PMN-PT ferroelectric ceramics via composition and orientation engineering

Excellent overall strain performances (i.e., low hysteresis, giant strain, and wide temperature span) are highly desirable in commercial high-precision displacement actuators to satisfy different application scenarios. However, any single means, e.g., compositional design or orientation engineering can hardly achieve the overall improvement of strain properties in ceramics. In this work, an approach of integrating compositional design (Sm and Mn co-doping) and orientation engineering (<001>-textured) is proposed to enhance the strain performance of 0.27Pb(In1/2Nb1/2)O3-0.40Pb(Mg1/3Nb2/3)O3-0.33PbTiO3 (PIN-PMN-PT) comprehensively. Initially, with the co-doping of Sm and Mn, the hysteresis of PIN-PMN-PT is substantially decreased to approximately 0.43 times that of the undoped material. Subsequently, 5 wt% BaTiO3 (BT) templates were added during the tape-casting process to orient the grains in 1 mol% Sm and Mn-doped PIN-PMN-PT ceramics. This resulted in a unique "4R" domain configuration with a reduced domain size of 0.13 µm. As a result, the domain wall energy was lowered, and the strain strength was increased to 0.35% at 70 kV/cm with low hysteresis to 8.94%. Moreover, the "clamping effect" in textured ceramics generates additional stress due to the lattice mismatch between the matrix grains and the BaTiO3 template, which inhibits the rhombohedral to the tetragonal phase transition. In addition, the fluctuation of strain value was only 8.5% over a wide temperature range of 30–150 °C, demonstrating excellent temperature stability. As a result of the combined effect of ion doping and orientation engineering, the overall strain performance in PIN-PMN-PT has been improved, providing a novel approach to designing superior and practical displacement actuators.

Elastocaloric Waste/Natural Rubber Materials with Various Crosslink Densities.

The characterization of the mechanical behavior of elastocaloric materials is essential to identify their viability in heating/cooling devices. Natural rubber (NR) is a promising elastocaloric (eC) polymer as it requires low external stress to induce a wide temperature span, ΔT. Nonetheless, solutions are needed to further improve DT, especially when targeting cooling applications. To this aim, we designed NR-based materials and optimized the specimen thickness, the density of their chemical crosslinks, and the quantity of ground tire rubber (GTR) used as reinforcing fillers. The eC properties under a single and cyclic loading conditions of the resulting vulcanized rubber composites were investigated via the measure of the heat exchange at the specimen surface using infrared thermography. The highest eC performance was found with the specimen geometry with the lowest thickness (0.6 mm) and a GTR content of 30 wt.%. The maximum temperature span under single interrupted cycle and multiple continuous cycles were equal to 12 °C and 4 °C, respectively. These results were assumed to be related to more homogeneous curing in these materials and to a higher crosslink density and GTR content which both act as nucleating elements for the strain-induced crystallization at the origin of the eC effect. This investigation would be of interest for the design of eC rubber-based composites in eco-friendly heating/cooling devices.

Data-driven Radiative Magnetohydrodynamics Simulations with the MURaM Code

We present a method of conducting data-driven simulations of solar active regions and flux emergence with the MURaM radiative magnetohydrodynamics (MHD) code. The horizontal electric field that is derived from the full velocity and magnetic vectors is implemented at the photospheric (bottom) boundary to drive the induction equation. The energy equation accounts for thermal conduction along magnetic fields, optically thin radiative loss, and heating of coronal plasma by viscous and resistive dissipation, which allows for a realistic presentation of the thermodynamic properties of coronal plasma that are key to predicting the observational features of solar active regions and eruptions. To validate this method, the photospheric data from a comprehensive radiative MHD simulation of solar eruption (the ground truth) are used to drive a series of numerical experiments. The data-driven simulation reproduces the accumulation of free magnetic energy over the course of flux emergence in the ground truth with an error of 3%. The onset time is approximately 8 minutes delayed compared to the ground truth. However, a precursor-like signature can be identified at the correct onset time. The data-driven simulation captures key eruption-related emission features and plasma dynamics of the ground truth flare over a wide temperature span, from to . The evolution of the flare and coronal mass ejection as seen in synthetic extreme ultraviolet images is also reproduced with high fidelity. This method helps to understand the evolution of magnetic field in a more realistic coronal environment and to link the magnetic structures to observable diagnostics.

Electrical Conductivity and Molar Volume of (LiCl-KCl)eut.–CsCl Molten Mixtures

The electrical conductivity of (LiCl-KCl)eut.–CsCl molten mixtures has been measured over a concentration range of 0–100 mol % CsCl and in a wide temperature span (624–1180 K). The measurements were carried out in quartz cells of the capillary type with platinum electrodes using the AC-bridge method. The molar volume of these mixtures was estimated using similar literature data. The maximum deviations of the molar volume from the additive values are ∼2%. Molar conductivity and its activation energy were calculated using the derived molar volume data. It was found that the electrical conductivity of all melts increases with increasing temperature and decreases with increasing CsCl concentration. In the molten (LiCl-KCl)eut.–CsCl mixtures, the significant negative deviations of the specific and molar electrical conductivities from additive values are observed over the whole concentration range, which indicates that the replacement of one alkaline cation by those, significantly different in size, is accompanied by a noticeable rearrangement of interparticle bonds. Therefore, the complexation in the system becomes different. According to the obtained data on electrical conductivity, the liquidus line of this system was built.

Characterization of vB_ValM_PVA8, a broad-host-range bacteriophage infecting Vibrio alginolyticus and Vibrio parahaemolyticus.

Phage therapy was taken as an alternative strategy to antibiotics in shrimp farming for the control of Vibrio species of Vibrio parahaemolyticus and Vibrio alginolyticus, which cause substantial mortality and significant economic losses. In this study, a new Vibrio phage vB_ValM_PVA8 (PVA8), which could efficiently infect pathogenic isolates of V. alginolyticus and V. parahaemolyticus, was isolated from sewage water and characterized by microbiological and in silico genomic analyses. The phage was characterized to be a member of the Straboviridae family with elongated head and contractile tail by transmission electron microscopy. Genome sequencing showed that PVA8 had a 246,348-bp double-stranded DNA genome with a G + C content of 42.6%. It harbored totally 388 putative open reading frames (ORFs), among them 92 (23.71%) assigned to functional genes. Up to 27 transfer RNA (tRNA) genes were found in the genome, and the genes for virulence, antibiotic resistance, and lysogeny were not detected. NCBI genomic blasting results and the phylogenetic analysis based on the sequences of the large terminase subunits and the DNA polymerase indicated that PVA8 shared considerable similarity with Vibrio phage V09 and bacteriophage KVP40. The phage had a latent period of 20 min and a burst size of 309 PFUs/infected cell with the host V. alginolyticus, and it was stable over a broad pH range (4.0-11.0) and a wide temperature span (-80°C to 60°C), respectively, which may benefit its feasibility for phage therapy. In addition, it had the minimum multiplicity of infection (MOI) of 0.0000001, which revealed its strong multiplication capacity. The shrimp cultivation lab trials demonstrated that PVA8 could be applied in treating pathogenic V. parahaemolyticus infection disease of shrimp with a survival rate of 88.89% comparing to that of 34.43% in the infected group, and the pond application trails confirmed that the implementation of PVA8 could rapidly yet effectively reduce the level of the Vibrio. Taken together, PVA8 may be potential to be explored as a promising biological agent for Vibrio control in aquaculture farming industry.

Improving work temperature span and reversibility of magnetoelastic transition of (Mn,Fe)2(P,Si) alloys by Mg doping

Magnetocaloric materials with wide working temperature span and reversible magnetic transition are beneficial for the magnetic refrigerator. Besides of giant magnetocaloric effect, (Mn,Fe)2(P,Si) alloys exhibit significant thermal/magnetic hysteresis and a narrow working temperature span. In this work, the impact of Mg doping on the phase structure and magnetocaloric effect of Mn1.05Fe0.9P0.5Si0.5-xMgx alloys has been studied. The results show that all samples crystallize into Fe2P-type main phase with little impurity phase. After Mg doping, the lattice parameter a of the main phase increases from 6.027(0) Å to 6.049(0) Å and c decreases from 3.488(6) Å to 3.480(6) Å, which leads to the increase of Curie temperature. Density functional theory calculation results confirm that the Mg atom located on the 2c site can increase the covalent bond length, and then enhance the ferromagnetic coupling between atoms leading to the increase of Curie temperature. Moreover, the first-order magnetic phase transition of Mn1.05Fe0.9P0.5Si0.5-xMgx alloys is inhibited with the increase of Mg content, which results in the decrease of thermal/magnetic hysteresis and the increase of the effective working temperature span. For Mn1.05Fe0.9P0.5Si0.48Mg0.02 alloy, it has a Curie temperature of about room temperature, effective refrigeration capacity of 291.7 J·kg−1, working temperature window of 46 K and magnetic entropy change of 9.4 J·kg−1·K−1. The alloy can be an excellent candidate in room temperature magnetic refrigeration devices with a wide temperature span.

Characterization and Genomic Analysis of a Bacteriophage with Potential in Lysing Vibrio alginolyticus

Vibrio alginolyticus is one of the major pathogens causing vibriosis to a variety of aquatic animals as well as bringing about severe food safety concerns. Nowadays, phage therapy has received increasing attention as an alternative to the antibiotics that have being limited for use in aquaculture industries. In this work, a potent bacteriophage, vB_ValM_PVA23 (PVA23), which efficiently infects pathogenic strains of V. alginolyticus, was isolated from sewage water and characterized by microbiological and genomic analyses. Based on the transmission electronic observation, the phage was characterized to be the Myoviridae family. It has a latent period of 10 min and a burst size of 203 PFUs/infected bacterium, and was stable over a broad pH range (5.0−11.0) and a wide temperature span (−80 °C to 60 °C), respectively. Genome sequencing results show that PVA23 has a 246,962-bp double-stranded DNA with a G + C content of 41.25%. The lab and plant shrimp farming trials demonstrated that phage preparation derived from PVA23 out-performed the chemical disinfectant iodine treatment in the prevention of V. alginolyticus propagation, and the phage application could rapidly yet significantly reduce the level of V. alginolyticus in the pond within 12 h, with negligible rebound observed. These results suggests that phage PVA23 has the potential to be used as an anti-V. alginolyticus agent in aquaculture industries.

Large electrocaloric effect over a wide temperature span in lead-free bismuth sodium titanate-based relaxor ferroelectrics

For efficient solid-state refrigeration technologies based on electrocaloric effect (ECE), it is a great challenge of simultaneously obtaining a large adiabatic temperature change (ΔT) within a wide temperature span (Tspan) in lead-free ferroelectric ceramics. Here, we studied the electrocaloric effect (ECE) in (1-x)(Na0.5Bi0.5)TiO3-xCaTiO3 ((1-x)NBT-xCT) and explored the combining effect of morphotropic phase boundary (MPB) and relaxor feature. The addition of CT not only constructs a MPB region with the coexistence of rhombohedral and orthorhombic phases, but also enhances the relaxor feature. The ECE peak appears around the freezing temperature (Tf), and shifts toward to lower temperature with the increasing CT amount. The directly measured ECE result shows that the ceramic of x = 0.10, which is in the MPB region, has an optimal ECE property of ΔTmax = 1.28 K @ 60 °C under 60 kV/cm with a wide Tspan of 65 °C. The enhanced ECE originates from the electric-field-induced transition between more types of polar nanoregions and long-range ferroelectric macrodomains. For the composition with more relaxor feature in the MPB region, such as x = 0.12, the ECE is relatively weak under low electric fields but it exhibits a sharp increment under a sufficiently high electric field. This work provides a guideline to develop the solid–state cooling devices for electronic components.