Large Hysteresis Research Articles

Relaxation dynamics of vibrated dense granular media: Hysteresis and nonlocal effects

Understanding the relaxation process of driven dense granular materials is crucial to the avalanche dynamics and earthquake triggering in geophysics. However, quantitative description or prediction of vibrated dense flows remains largely unexplored. Motivated by theoretical models developed for the glass transition, we quantitatively describe the vibration dependency of dynamical heterogeneities in a vibrated inclined flow exhibiting large hysteresis of the avalanche angle. We reveal that increasing vibration intensity weakens the nonlocal effects and susceptibility which are two crucial factors to triggering hysteresis. Combined with the effect of vibration amplitude on the nonlocal effects and the introduction of nonmonotonicity quantified by the peaks of susceptibility, the nonlocal granular fluidity (NGF) model quantitatively reproduces the key features of the hysteresis observed in the numerical simulations and previous experiments. Our work can readily be extended to arbitrary geometries and paves a route toward modeling other complex phenomena in dense granular flow. • The diffusion and relaxation process of vibrated flow are described quantitatively. • The vibration dependency of dynamical heterogeneities is described quantitatively. • The MCT and VTF theories are introduced to make predictions more accurate. • The extended nonlocal granular fluidity model is proposed. • The key features of vibrated incline flow are predicted.

Physical properties and phase diagram of single crystal REBaMn2O6 (RE = Sm, Eu, Gd, Tb, Dy, and Y)

We have carried out a systematic study on antiferromagnetic and charge ordering phase transitions in double-perovskite manganite compounds REBaMn2O6 (RE ​= ​Sm, Eu, Gd, Tb, Dy, and Y) by using single-crystalline samples. In YBaMn2O6, a tiny anomaly near 480 ​K as well as a first-order phase transition near 520 ​K are found in the temperature dependence of resistivity. Synchrotron x-ray single-crystal structure analysis shows that the unit cell is doubled first in the ab plane and further doubled along the c-axis as the temperature decreases. One of the most possible electronic phases between 480 ​K and 520 ​K is Zener polaron ordering. Mn atoms are paired in the ab-plane with seven 3d-electrons localized on each pair. The 3d-electron distribution in each pair begins to become asymmetric below 480 ​K. Similar two-step transitions are also observed for RE ​= ​Tb and Dy. The antiferromagnetic transition at TN ​≃ ​180 ​K is accompanied by a large hysteresis, which is attributable to a simultaneous rearrangement of charge order. The charge rearrangement temperature gradually rises with increasing the RE ionic radius. In SmBaMn2O6, the Néel temperature (TN) is 175 ​K and is lower than charge rearrangement temperature (≃ 200 ​K). These transitions are summarized in a phase diagram with respect to temperature and the ionic radius of RE3+.

Effect of the gate electrodes/water interface on the performance of ZnO-based water gate field-effect transistors

Field-effect transistors can be gated with water as the dielectric due to the formation of electrical double layers at water interfaces, which results in high specific capacitance and low voltage operation. The incorporation of analytes in aqueous suspension influences the water's electrical properties changing the water-gated field-effect transistors (WGFETs) performance and allowing it to be used as sensor and biosensor platforms. However, the material used as a gate electrode can affect the transistor's performance due to several factors, as the metal work function, its electrochemical range, and the presence of physicochemical reactions. Here, we evaluated the performance of WGFETs using spray-deposited zinc oxide (ZnO) as the active layer and five different gate electrodes: graphite pencil (GP), gold (Au), indium tin oxide (ITO), tungsten (W), and tin (Sn). The threshold voltage (VTH) values found were 0.41, 0.44, 1.12, 1.21 and 1.74 V for the Sn, W, Au, GP and ITO electrodes, respectively. The field-effect mobility was strongly influenced by the gate material, varying in the range from 0.07 to 0.46 cm2/Vs. The WGFETs operating with W and Sn gates showed the highest Ion/Ioff ratio and the lowest VTH when compared to the other electrodes. However, this characteristic may be associated with the formation of a natural oxide layer at its interface with water, which could be undesirable from the stability view. The use of ITO as the gate electrode resulted in a large hysteresis and two orders of magnitude smaller current in the output curve compared to Au and GP. Among the materials used as the gate electrode, GP stands out mainly because it gives the lowest subthreshold swing (SS = 90 mV/dec) and the highest transconductance (gm = 0.40 mS). Also, the GP matches with ZnO as biocompatible material for low-cost, eco-friendly, and metal-free electronics. In summary, the results showed that the gate electrode significantly influences the main parameters of the device and, therefore, should be an analysis factor when aiming to use WGFETs as sensors.

The Magnetic Phase Transition of FeRh Modulated by AC Magnetic Field

It is well known that CsCl‐type FeRh undergoes from antiferromagnetic (AFM) to ferromagnetic (FM) phase transition near room temperature with large thermal hysteresis. Therefore, it is particularly essential to find new methods to manipulate the magnetic order of FeRh and reduce thermal hysteresis. Herein, the magnetic phase transition of FeRh film by applying a low‐frequency in‐plane alternating current (AC) magnetic field is successfully manipulated. It is found that under the AC magnetic field, the phase transition of the FM–AFM is promoted, and the heating branch shifts at a rate of −8 K T−1, which causes the thermal hysteresis of FeRh reduction of about 2 K. These phenomena may be attributed to the Zeeman energy and the periodic vibration of domain walls. This work provides the possibility for the realization of low‐power spintronic devices.

White electroluminescence from cross relaxation-free CaSiO3:Tb3+ film on silicon wafer and its concentration dependent white-color tunability

A full-color white light source is continuously required for general lighting applications. Herein, the white electroluminescence (EL) from Tb3+-singly doped CaSiO3 (CSO) thin film on a silicon substrate has been reported for the first time. The EL device has a metal-oxide-semiconductor (MOS) structure which consists of two CSO and SiOx oxide layers on silicon wafer. Above the threshold voltage in AC power, it shows a full-color white EL spectrum with two dominant emission groups of ultraviolet-blue and green-red peaks from the f-f intra-transition of Tb3+ ions without the cross-relaxation effect in the four blue peaks which suffers from their severe cross-relaxation quenching in its photoluminescence spectrum. It is attributed to the strong electric field splitting (Stark effect) which prevents the resonance energy transfer due to energy perturbation. With increasing Tb3+ concentrations, the blue bands get more dominant along with increasing the threshold voltage. Furthermore, we demonstrate the EL-voltage transient behavior with a large hysteresis in a positive voltage polarity.

Anomalous Nernst Effect in Perovskite La0.5Ca0.5CoO3

We report the occurrence of the anomalous Nernst effect (ANE) in polycrystalline perovskite La0.5Ca0.5CoO3. The sample is ferromagnetic below TC = 147 K and resistivity shows non-metallic behavior above and below the TC with only a small negative magnetoresistance (~2%) around TC. Field dependence of magnetization at 10 K shows large hysteresis with a coercive field of 6 kOe but a small magnetization ~ 0.64 Bohr magneton/Co even in a field of 50 kOe, which indicates the presence of magnetically heterogeneous ground state consisting of ferromagnetic and non-ferromagnetic phases. The field dependence of the Nernst thermopower (Sxy) at low temperatures shows complete saturation but the magnetization does not. This indicates that the ANE in La0.5Ca0.5CoO3 depends only on the transport properties of the ferromagnetic phase, while it is not affected by the non-ferromagnetic phase. Due to the higher value of remnant Sxy, the magnetized polycrystalline sample exhibits ANE in absence of an external magnetic field.

The phase change hysteresis characteristics ofNa2HPO4·12H2O: A molecular dynamics study

• The hysteresis degree of DSP is decreased after encapsulation. • The reason for the hysteresis is the difference in the molecular structure during the heating and cooling process. • The system energy of encapsulated DSP is mainly decided by “randomly distributed” molecules. • Molecular dynamics simulation of pure DSP and encapsulated DSP. There is a phenomenon of inconsistent melting and solidification behavior of PCM, which is called phase change hysteresis, generally expressed by the difference between melting temperature (T m ) and solidification temperature (T s ). The hysteresis degree (T m -T s ) is proportional to the energy loss of the system, if the temperature is beyond the operating temperature range of the system, the latent heat of the PCM cannot be exploited. The phase change hysteresis and supercooling were regarded as the same concept in previous studies no matter simulations or experimental research, which will lead to large errors. It is believed that there is a large hysteresis degree of inorganic PCM besides higher supercooling degree, poor chemical stability, and serious phase separation phenomenon, like Na 2 HPO 4 ·12H 2 O(DSP), which is prone to dehydrate from Na 2 HPO 4 ·12H 2 O to Na 2 HPO 4 ·7H 2 O during the heating and cooling process.DSP is adsorbed by SiO 2 via hydrogen bond, van der Waals force, and capillary effect, which can solve the above shortcomings. There are certain limitations in studying the hysteresis properties of PCM via experimental methods. As so far, the hysteresis properties of inorganic hydrated salts are rarely discussed in related papers, the reason for the hysteresis phenomenon is not explained, and the nucleation mechanism is not clear. Therefore, a composite phase change material (CPCM) model with DSP as the core and mesoporous silica MCM-41 as the shell was established in this work. The phase change hysteresis (PCH) characteristics are studied by analyzing the radial distribution function (RDF), self-diffusion coefficient(D), and density. The molecular motion of the interface layer was studied by the molecular dynamics(MD) method, and the arrangement of microscopic particles before and after adsorption was compared. The results showed that the hysteresis degree of DSP decreases to 1.5 °C after encapsulation by SiO 2 , which is because the effect of “Near-range ordered” molecules tend to disappear. After experimental verification, there is a 20% error between the simulation and experimental results. In addition, the reason for the hysteresis is the difference in the molecular structure that determines the energy of the system during the heating and cooling process. The purpose of this paper is to explain the reasons for the hysteresis from the view of microscopic and to provide a basis for the design of LHTES systems.

Inactive (PbI2)2RbCl stabilizes perovskite films for efficient solar cells.

In halide perovskite solar cells the formation of secondary-phase excess lead iodide (PbI2) has some positive effects on power conversion efficiency (PCE) but can be detrimental to device stability and lead to large hysteresis effects in voltage sweeps. We converted PbI2 into an inactive (PbI2)2RbCl compound by RbCl doping, which effectively stabilizes the perovskite phase. We obtained a certified PCE of 25.6% for FAPbI3 (FA, formamidinium) perovskite solar cells on the basis of this strategy. Devices retained 96% of their original PCE values after 1000 hours of shelf storage and 80% after 500 hours of thermal stability testing at 85°C.

Improved Stretchable and Sensitive Fe Nanowire-Based Strain Sensor by Optimizing Areal Density of Nanowire Network.

Flexible strain sensors, when considering high sensitivity and a large strain range, have become a key requirement for current robotic applications. However, it is still a thorny issue to take both factors into consideration at the same time. Here, we report a sandwich-structured strain sensor based on Fe nanowires (Fe NWs) that has a high GF (37–53) while taking into account a large strain range (15–57.5%), low hysteresis (2.45%), stability, and low cost with an areal density of Fe NWs of 4.4 mg/cm2. Additionally, the relationship between the contact point of the conductive network, the output resistance, and the areal density of the sensing unit is analyzed. Microscopically, the contact points of the conductive network directly affect the sensor output resistance distribution, thereby affecting the gauge factor (GF) of the sensor. Macroscopically, the areal density and the output resistivity of the strain sensor have the opposite percolation theory, which affects its linearity performance. At the same time, there is a positive correlation between the areal density and the contact point: when the stretching amount is constant, it theoretically shows that the areal density affects the GF. When the areal density reaches this percolation threshold range, the sensing performance is the best. This will lay the foundation for rapid applications in wearable robots.

Inductive and Capacitive Hysteresis of Halide Perovskite Solar Cells and Memristors Under Illumination

The current–voltage curves of memristors exhibit significant hysteresis effects of use for information storage and computing. Here, we provide a comparison of different devices based on MAPbI3 perovskite with different contact configurations, from a 15% efficient solar cell to a pure memristor that lacks directional photocurrent. Current–voltage curves and impedance spectroscopy give insights into the different types of hysteresis, photocapacitance, and inductance present in halide perovskites. It is shown that both halide perovskite memristors and solar cells show a large inverted hysteresis effect at the forward bias that is related to the presence of a chemical inductor component in the equivalent circuit. Based on the results, we classify the observed response according to recombination current in devices with selective contacts, to voltage-activated single-carrier device conduction in devices with symmetric contacts. These findings serve to gain an understanding of the mechanism of memristor currents in mixed ionic-electronic conductors such as halide perovskites. We establish the link in the electrical response between solar cells and memristors.

Research on Mobile Machinery NOx Emission Control Based on a Physical Model and Closed-Loop Control

Mobile machinery means a power-driven vehicle that is specifically designed and constructed to perform work on or off the road. To reduce the nitrogen oxide (NOx) emissions that come from mobile machinery, a combination of a physical model and closed-loop control is applied to the selective catalytic reduction (SCR) system. Based on the design of the variable cross-section extended exhaust structure, the differential pressure measurement was achieved, and the physical model of the exhaust flow based on the differential pressure was established. Based on the analysis of the heat and mass transfer process of the SCR catalyst, a prediction model for the internal temperature field of the catalyst was established by combining the upstream and downstream exhaust temperature sensors. Using the SCR downstream nitrogen oxides signal and the proportional–integral–derivative (PID) closed-loop control algorithm, segmented PID closed-loop control under the large hysteresis response of the SCR system was realized. The above algorithms were used to form the control code through MATLAB/Simulink and downloaded to the embedded microprocessor. The test results show that the established model can realize the real-time calculation of the exhaust gas flow rate and the internal temperature of the catalyst. Under steady-state conditions, the calculation error of the exhaust flow rate is less than ±3%, and the calculation error of the catalyst temperature is less than ±5%. Under transient conditions, the calculation error of the exhaust flow rate is less than ±9%, and the calculation error of the catalyst temperature is less than ±8%. The nitrogen–oxygen signal-based PID closed-loop algorithm can improve the nitrogen–oxygen conversion efficiency and control accuracy of the model.

High-Stretchability, Ultralow-Hysteresis ConductingPolymer Hydrogel Strain Sensors for Soft Machines.

Highly stretchable strain sensors based on conducting polymer hydrogel are rapidly emerging as a promising candidate toward diverse wearable skins and sensing devices for soft machines. However, due to the intrinsic limitations of low stretchability and large hysteresis, existing strain sensors cannot fully exploit their potential when used in wearable or robotic systems. Here, a conductingpolymer hydrogel strain sensor exhibiting both ultimate strain (300%) and negligible hysteresis (<1.5%) is presented. This is achieved through a unique microphase semiseparated network design by compositing poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) nanofibers with poly(vinyl alcohol) (PVA) and facile fabrication by combining 3D printing and successive freeze-thawing. The overall superior performances of the strain sensor including stretchability, linearity, cyclic stability, and robustness against mechanical twisting and pressing are systematically characterized. The integration and application of such strain sensor with electronic skins are further demonstrated to measure various physiological signals, identify hand gestures, enable a soft gripper for objection recognition, and remote control of an industrial robot. This work may offer both promising conducting polymer hydrogels with enhanced sensing functionalities and technical platforms toward stretchable electronic skins and intelligent robotic systems.

Investigation of the Unsteady Behaviour of a Laminar Separation Bubble Using Infrared Thermography

The laminar separation bubble (LSB) that forms on the suction side of a modified NACA 64_3 − 618 airfoil at a chordbased Reynolds number of Re = 200000 is studied using wind tunnel experiments. First, the LSB is characterized over a range of static angles of attack, using surface pressure measurements and infrared thermography (IT). For the conditions tested, excellent agreement between the techniques is obtained, showing an upstream shift of the bubble with increasing angle of attack. For the study of steady LSBs, the infrared approach is superior, given its higher spatial resolution and experimental simplicity. The complexity is then increased to study the influence of aerodynamic unsteadiness on the bubble. For this purpose, a pitching-type motion is imposed on the wind tunnel model, testing reduced frequencies up to k = 0.25. While surface pressure measurements are not affected by the change in experimental conditions, the infrared approach is limited by the thermal response of the surface. To overcome this limitation, an extension of the recently proposed differential infrared thermography (DIT) method is considered. With this method, the unsteady behavior of the LSB can be partially detected. Both experimental techniques indicate a hysteresis in bubble location between the pitch up and pitch down parts of the motion, caused by the effect of the aerodynamic unsteadiness on the adverse pressure gradient. However, the DIT measurements indicate a larger hysteresis, which is attributed to the thermal response time of the model surface.

(Digital Presentation) CeOx Capping for Ferroelectric Y:HfO2 Films

In recent years, HfO2 has been paid a lot of attention as a ferroelectric material due to its excellent scalability and complementary-metal-oxide-semiconductor (CMOS) process compatibility [1]. Some of the issues of ferroelectric HfO2 are wake-up and fatigue effect, increase and decrease of remanent polarization (P r) along with switching cycles, and low endurance. Generally, these phenomena are understood as a result of the increase and redistribution of oxygen vacancies (VO) in HfO2 films [2]. By the way, it is reported that CeOx can release and absorb oxygen from adjacent oxides [3]. In this study, we propose the stacking structure of CeOx and ferroelectric HfO2 to improve endurance and investigate electric properties and voltage application sequence to suppress the fatigue effect.5 mol% Y-doped HfO2 (Y:HfO2) and CeOx capping layers of metal-ferroelectric-metal (MFM) capacitors were deposited by atomic-layer-deposition (ALD) with W bottom and top electrodes by sputtering. Post metallization annealing (PMA) was performed at 450 and 500oC for the various duration. Figure 1 shows hysteresis loops of the capacitors with and without CeOx capping annealed at 450oC for 20 minutes. Large hysteresis on CeOx capping is observed even same annealing temperature and duration. Enhancement of transformation to ferroelectric phase can be explained as tensile stress to Y:HfO2 due to the difference of coefficient of thermal expansion (CTE) between CeOx and Y:HfO2. Variation of switching polarization (P SW), the difference between positive and negative P r, as a function of the number of switching cycles is also investigated and shown in figure 2. Both capacitors are annealed at 500oC for 100 minutes to crystallize. In the case of without CeOx capping, continuous wake-up effect and breakdown over 3×107 times switching are observed. On the other hand, the capacitor with CeOx capping shows a slight wake-up effect and fatigue after 106 times switching, additionally, endurance is improved to 3×109 times switching. The reason why fatigue and prolonging endurance occur is suspected that oxygen ions in the CeOx layer pin polarization domains and compensate VO in Y:HfO2. To suppress fatigue, we propose the recovery process by positive DC voltage application to top electrodes. In figure 3, hysteresis loops of the capacitor with CeOx capping before and after recovery voltage application. One can observe the larger hysteresis after recovery.This work was supported by JST-COI (JPMJCE1309). One of the authors, Kazuto Mizutani, was supported by The FUTABA Foundation.[1] T. S. Boscke, et al., Appl. Phys. Lett., 99, 102903 (2011). [2] M. Pesic, et al., Adv. Funct. Mater., 26, pp. 4601–4612 (2016). [3] M. Mamatrishat, et al., Vacuum, 86, pp. 1513-1513 (2012). Figure 1

(Invited) Combinatorial Synthesis and Interface Analysis for Development of High Dielectric Constant Thin Films

Compound semiconductor-based power devices such as SiC and GaN require high-temperature operational passive devices such as a capacitor. SiC based active devices are capable of operating over 250°C. For module and system level advancement, the high-temperature operational passive should be developed urgently. In the case of capacitors, current available capacitors can efficiently function up to 175°C only. Therefore, a thin film capacitor that can be operated at high-temperatures and integrated monolithically in the proximity of active device should be developed. In this talk, I will introduce our achievements of development of high temperature operational dielectric film materials and its interface control of metal/oxide stacking structure mainly.By employing combinatorial method and the thermal diffusion theory, we found some candidates for the dielectric materials based on ferroelectric materials. The BaTiO3 based relaxor ferroelectrics with a high dielectric constant (> 200) and free of hazardous elements are promising candidates. Among the BaTiO3 based relaxor ferroelectrics, we have chosen x[BaTiO3]-(1-x)[Bi(Mg2/3Nb1/3)O3] (BT-BMN). The permittivity of 400 and the stability <8% from room temperature to 400°C has been obtained, which are promising as a high-temperature dielectric medium. For the practical device application, a thermal stable electrode on the dielectrics is also required. To control the interface stability of the electrode/BT-BMN interfaces, several electrodes were investigated by photoelectron spectroscopy (PES). From the viewpoints of the oxidization energy, cost, and Bi thermal diffusion energy, RuO2, TiC, and TaC were selected as the electrode candidates to compare with the Pt electrode. To probe the interface structure and the band alignment non-destructively, we employed a combination of conventional x-ray PES using Al Kα light source (SXPES: hν= 1486.6 eV) and hard x-ray PES (HAXPES, hν= 5.95 keV). HAXPES is a powerful tool for investigating heterostructure interfaces due to its longer inelastic mean free path (IMFP) than that of SXPES. The IMFP of Pt 4f7/2, which was the heaviest element with the shortest IMFP in our measurement, was 4.68 nm, and HAXPES probed approximately 15 nm (probing depth: 3×IMFP) below the surface. For the Pt electrode, which is usually used as an electrode for Bi-contained oxides, the Bi diffusion into the electrode layer and the change of band alignment were clearly observed after annealing at 400°C. In contrast, the TiC electrode inhibited the Bi diffusion and did not show any change of the band alignment after annealing, meaning that the TiC electrode is a potential candidate for the electrode of Bi-contained oxide for high temperature operational devices.In the presentation, we also introduce the development of new high-k gate materials for GaN and Ge channels by combining the combinatorial method and HAXPES analysis. For a Ge channel, which has been attracting a lot of attention as a replacement for the Si channel used in current Si-based metal-oxide-semiconductor (CMOS) devices. This is because the Ge channel has high electron and hole mobility, which lead to a higher drive current, and Ge has a narrower band gap than Si thus allowing supply voltage scaling. However, Ge has the same issue as Si, namely an unintentionally oxidized layer with a low dielectric constant (~5.6) can form at an oxide/Ge interface. Furthermore, in contrast with SiO2, which is a good insulating layer for MOS devices, GeOx is thermodynamically unstable and water soluble. These properties cause high defect densities at the interface between high-k and Ge and a large hysteresis in the capacitance-voltage characteristic. To overcome these issues, we have proposed the direct growth of (110) rutile TiO2 or non-oxide materials on (100) Ge substrates.

Conversion reaction-based transition metal oxides as anode materials for lithium ion batteries: recent progress and future prospects

The rapid increase in demand for high-performance lithium ion batteries (LIBs) has prompted the development of high capacity anode materials that can replace/complement the commercial graphite. Transition metal oxides (TMOs) have attracted great attention as high capacity anode materials because they can store multiple lithium ions (electrons) per unit formula via conversion reaction, resulting in high specific capacity (700-1,200 mAh g&lt;sup&gt;-1&lt;/sup&gt;) and volumetric capacity (4,000-5,500 mAh cm&lt;sup&gt;-3&lt;/sup&gt;). In addition, TMOs are cheap, earth-abundant, non-toxic and environmentally friendly. However, there have been no reports of practical LIBs using conversion-based TMO anodes, because of several major problems such as large voltage hysteresis, low initial Coulombic efficiency (large initial capacity loss), low electrical conductivity, and large volume changes (100~200%). This review summarizes the recent progress, challenges and opportunities for TMO anode materials. The conversion reaction mechanism, problems and solutions of TMO anode materials are discussed. Considering iron oxide as a promising candidate, future research directions and prospects for the practical use of TMO for LIB are presented.

Effects of stripe domains on the loading-unloading hysteretic behavior of monodomain nematic elastomers

The stress-director coupling of monodomain nematic elastomers may lead to soft deformation and the appearance of stripe domains under uniaxial tension. Based on a continuum mechanical model and finite element method, we investigated the loading-unloading hysteretic behavior of thin monodomain nematic elastomer sheets. Under orthogonal uniaxial loading tests, stripe domains appeared in the center of the specimens after the critical strain was reached. Furthermore, a stress peak was observed, which was followed by a stress plateau. During unloading, these stripe domains did not disappear, and the unloading curve was significantly lower than the loading curve, resulting in large stress-strain hysteresis and unloading residual strain. Additionally, the presence of stripe domains led to an increased strain rate correlation in stress-strain curves, while significantly extending the period of strain recovery without unloading constraints.

Multiple magnetic phase transitions and magnetocaloric effects of perovskite manganite

Perovskite La0.7Ca0.3Mn0.9Cu0.1O3 manganite was prepared and examined by X-ray diffraction. Multiple magnetic phase transitions and magnetocaloric effect were represented based on magnetic and specific heat measurements. The sample undergoes a first-order ferromagnetic - paramagnetic transition with a large thermal hysteresis, where the Arrott plots show negative slopes. A charge ordered phase occurs at TCO = 162 K, which can be melted under a sufficiently large magnetic field (µ0H ≥ 1 T) and thus result in a spin reorientation. The step-like jump of magnetization at Tb = 42 K in warming curves is caused by a blocked state, which is overcome by applying a magnetic field and leads to a metamagnetic transition. The successive multiple magnetic phase transitions broaden the operating temperature span and contribute to a large refrigerant capacity, in spite of mediocre magnetic entropy change and adiabatic temperature change. The adiabatic temperature change and phase transition mechanism were also discussed based on the recorded specific heat data.

Capillary coalescence of two partially immersed slender structures

We study the onset of coalescence between two slender structures quasi-statically withdrawn from a liquid bath. When partially immersed, they interact with each other through the capillary force induced by their menisci. As they are removed from the bath, their dry length increases and they become easier to bend until the capillary force is strong enough to trigger contact. Surprisingly, the structures snap to contact from a finite distance at a critical dry length. The transition to coalescence is thus subcritical and exhibits a large hysteresis loop between two stable states. An analytical coalescence criterion is derived and agrees well with experimental data for rods and lamellae. This simple elastocapillary model is a first step to better understand the elastocapillary coalescence of slender structures in fluid capture systems.

Large electrostrictive coefficient with optimized Electro-Strain in BNT-based ceramics with ergodic state

Electric field-induced high strain with low hysteresis and large electrostrictive coefficient are necessary for high-precision displacement actuators. Many works focused on achieve large strain through electric field-induced nonergodic-ergodic phase transition, while the accompanied large hysteresis hinders their practical application. Here, (1-x)(Bi0.54Na0.46)0.94Ba0.06TiO3-xSrTiO3 (BNBT-xST, x = 0.1, 0.2, 0.3, 0.4 and 0.5) ceramics are fabricated by a conventional solid state reaction method. The ergodic relaxor phase in BNBT ceramics was effectively regulated by doping SrTiO3. Finally, we achieve a high electro-strain of 0.17% with ultra-low hysteresis of 7.2% (@70 kV/cm) for × = 0.3 ceramics, and a large electrostrictive coefficient Q33 of 0.0251 m4/C2 (@70 kV/cm) with low strain hysteresis of 8.3% for × = 0.4 ceramics. This work provides a method for optimizing the strain-hysteresis trade-off and improving electrostrictive coefficient Q33 of BNT-based ceramics.