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X-ray self-heating is a common by-product of X-ray Free Electron Laser (XFEL) techniques that can affect targets, optics, and other irradiated materials. Diagnosis of heating and induced changes in samples may be performed using the x-ray beam itself as a probe. However, the relationship between conditions created by and inferred from x-ray irradiation is unclear and may be highly dependent on the material system under consideration. Here, we report on a simple case study of a titanium foil irradiated, heated, and probed by a MHz XFEL pulse train at 18.1 keV delivered by the European XFEL using measured x-ray diffraction to determine temperature and finite element analysis to interpret the experimental data. We find a complex relationship between apparent temperatures and sample temperature distributions that must be accounted for to adequately interpret the data, including beam averaging effects, multivalued temperatures due to sample phase transitions, and jumps and gaps in the observable temperature near phase transformations. The results have implications for studies employing x-ray probing of systems with large temperature gradients, particularly where these gradients are produced by the beam itself. Finally, this study shows the potential complexity of studying nonlinear sample behavior, such as phase transformations, where biasing effects of temperature gradients can become paramount, precluding clear observation of true transformation conditions. [ABSTRACT FROM AUTHOR]

We report a theoretical investigation of temperature, size, and composition effects on the structural, energetic, and electronic properties of the (La4O6)n, (La2Ce2O7)n, and (Ce4O8)n nanoclusters (NCs) for n = 10, 18. Furthermore, we investigated the single O vacancy formation energy as a function of the geometric location within the NC. Our calculations are based on the combination of force-field molecular dynamics (MD) simulations and density functional theory calculations. We identified a phase transition from disordered to ordered structures for all NCs via MD simulations and structural analysis, e.g., radius changes, radial distribution function, common neighbor analysis, etc. The transition is sharp for La36Ce36O126, La20Ce20O70, and Ce72O144 due to the crystalline domains in the core and less abrupt for Ce40O80, La40O60, and La72O108. As expected, radius changes are abrupt at the transition temperature, as are morphological differences between NCs located below and above the transition temperature. We found a strong dependence on the O vacancy formation energy (Evac) and its location within the NCs. For example, for La40O60, Evac decreases almost linearly as the distance from the geometric center increases; however, the same trend was not observed for Ce40O80, while there are large deviations from the linear trend for La20Ce20O70. Evac has smaller values for Ce40O80 and higher values for La40O60, that is, almost three times, while Evac has intermediate values for mixed oxides, as expected from weighted averages. Therefore, the mixture of one formula unit of La2O3 with two formula units of CeO2 has the effect of increasing the stability of CeO2 (binding energy), which increases the magnitude of the formation energy of the O vacancy. [ABSTRACT FROM AUTHOR]

During the γ phase–δ phase transition, U-50Zr fuel experiences spinodal decomposition, which has a significant effect on fuel properties. However, little is known about the spinodal decomposition of U-50Zr. The spinodal decomposition behavior in U-50Zr is studied in this research using the phase-field approach. The mechanism of spinodal decomposition from a thermodynamic perspective is studied, and the effects of temperature and grain boundary (GB) on spinodal decomposition are analyzed. It is found that the concentration of U atoms in the U-rich phase formed during spinodal decomposition is as high as 90%. The U-rich phase first appears at the GB position, and precipitation phases appear inside the grain later. Ostwald ripening occurs when larger precipitation phases on the GB absorb isolated smaller precipitation phases inside the grain. The coarsening rate of precipitation phases and the time it takes for spinodal decomposition to achieve equilibrium are both influenced by temperature. [ABSTRACT FROM AUTHOR]

Topological insulators are characterized by exhibiting an internal insulating state but a surface conductor state, which makes them advantageous for applications in novel devices. However, for most given acoustic topological metamaterials, the operating frequency is relatively fixed and the effect of temperature on their topological properties is rarely considered. Therefore, a temperature-tunable acoustic topological insulator is constructed in this paper. The quadruple degenerate Dirac cone formed at Γ point can be opened by adjusting the temperature, causing topological band inversion between the doubly degenerate dipolar and quadrupole states, and achieving topological phase transition. The evolution of its topological state with temperature is numerically investigated and a novel topological acoustic waveguide is constructed. The switching effect of temperature on the waveguide device is verified by numerical simulation and experiment. Non-contact active modulation of edge states in the structure is achieved by temperature-controlled topological phases, exhibiting acoustic switching effects. This study can provide corresponding references for the intelligent control of acoustic topology in noise, vibration, and other aspects. [ABSTRACT FROM AUTHOR]

The matric suction of saline soil is the driving force that causes water migration, and it is of great significance for exploring the mechanism of water and salt migration in saline frozen soil. In order to investigate the effect of phase transition of soil pore solution induced by temperature on the matric suction of saline soil, the matric suction of different types of saline soils was measured by pF meter under different temperature conditions. The natural soil was first washed to obtain the desalinized soil, then different salt mass ratios of sodium chloride and sodium sulfate (0:6, 4:2, 2:4, 6:0) were added into the desalinized soil to model the composite saline soil, the salt content and water content were set to 6% and 20%, respectively. Subsequently, the remolded saline soil was compacted into the test chamber (0.37 m×0.25 m×0.22 m), and its dry density was controlled at 1.6 g/cm³. Hydra Probe II and pF meter were embedded at 11cm of the sample to measure the liquid water content and matric suction versus temperature. Freezing-thawing box (TMS 9 018-R30), produced by Zhejiang Tomos company, was employed to control the experimental temperature by step cooling method. The temperature range was from 30 to -24 °C, and the temperature interval was 3 °C. The data was collected by CR300 at an interval of 6 h. When the experiment was complete, the temperature effect of saline soil matric suction was analyzed and the effect of water/salt phase transition was explored. The experimental results reveal that the matric suction of saline soil increases almost linearly with the decrease of temperature when no phase transition occurs, which is caused by surface tension and wetting coefficient. Different types of saline soils have different effects on the phase transition process of pore solution, resulting in significant differences in the matric suction of different types of saline soils. The mirabilite crystallizes at 19 °C and the second phase transition occurs at -9 °C for the composite saline soil with 2% NaCl+4% Na2SO4, and the phase transition of composite saline soil with 4% NaCl+2% Na2SO4 occurs at 11 and -16 °C.Sodium chloride can inhibit the occurrence of ice formation, then the matric suction caused by ice formation is reduced, and the segregated frost heave caused by water migration is restrained indirectly. Besides, sodium sulfate is prone to crystallization at positive temperatures, and ice is also produced in the secondary phase transition process, both salt crystallization and ice formation increase the matric suction in sodium sulfate soil, and water and salt redistribute in this process, salt expansion and frost heave are induced. For composite saline soil, sodium sulfate mainly affects the salt crystallization of the soil at a positive temperature, while sodium chloride mainly affects the ice formation of the soil at a negative temperature. The different proportions of the two salts cause significant differences in the salt crystallization temperature and the secondary phase transition temperature, resulting in more complex phase transition laws in composite saline soil, and it is more difficult to predict the matric suction of composite saline soil. In addition, this paper further explores the contribution of ice and salt crystallization to the variation of matric suction, providing effective references for a deeper understanding of the relationship between phase transition processes and matric suction in saline soils. [ABSTRACT FROM AUTHOR]

Adiabatic decompression of paraquadrupolar materials has significant potential as a cryogenic cooling technology. We focus on TmVO4, an archetypal material that undergoes a continuous phase transition to a ferroquadrupole-ordered state at 2.15 K. Above the phase transition, each Tm ion contributes an entropy of kB ln 2 due to the degeneracy of the crystal electric field groundstate. Owing to the large magnetoelastic coupling, which is a prerequisite for a material to undergo a phase transition via the cooperative Jahn--Teller effect, this level splitting, and hence the entropy, can be readily tuned by externally induced strain. Using a dynamic technique in which the strain is rapidly oscillated, we measure the adiabatic elastocaloric response of single-crystal TmVO4, and thus experimentally obtain the entropy landscape as a function of strain and temperature. The measurement confirms the suitability of this class of materials for cryogenic cooling applications and provides insight into the dynamic quadrupole strain susceptibility. [ABSTRACT FROM AUTHOR]

Electric field (E) control of magnetism is a persistent challenge in low-power consumption spintronic devices. A promising way to realize this control is to use the conversemagnetoelectric (ME) effect in insulating multiferroics.Here,we report considerable and repeatable E-modulated magnetization (M) at room temperature and even at 350 K via the significantly enhanced converseME effect near the morphotropic phase boundary (MPB) of the Cr-Mn co-doped (1-y)BiFe1-xCrxO3- yBaTi1-xMnxO3 (0.15 ≤ y ≤ 0.33, 0 ≤ x ≤ 0.03) solid solutions. In situ X-ray diffraction and Raman scattering experiments at different applied E for the sample near the MPB (i.e., y = 0.27, x = 0.03) show E-induced shift, broadening, and splitting in the {002}PC reflection, as well as a nearly monotonous variation in intensity of several phonon modes with E, reminiscent of the E-dependent M behavior. These results indicate that both E-induced lattice distortion and phase transformation dominate the converseME effects in these samples. Our demonstration of the E-regulation of magnetism via the E-sensitive crystal structures in designed insulating multiferroics near MPB may suggest a potential route to obtain efficient low-power spintronic devices. [ABSTRACT FROM AUTHOR]

The effect of temperature on the solubility of lead-bearing solid phases in water distribution systems for different water chemistry conditions remains unclear although lead concentrations are known to vary seasonally. The study objective is to explore the effect of temperature on the solubility of the lead(II) carbonate hydrocerussite under varying pH and DIC conditions. This is achieved through batch dissolution experiments conducted at multiple pHs (6–10) and DIC concentrations (20–200 mg CL−1) at temperatures ranging from 5 to 40 °C. A thermodynamic model was also applied to evaluate the model's ability to predict temperature effects on lead(II) carbonate solubility including solid phase transformations. In general, increasing temperature increased total dissolved lead at high pHs and the effect of temperature was greater for high DIC conditions, particularly for pH > 8. Temperature also influenced the pH at which the dominant lead(II) solid phase switched from hydrocerussite to cerussite (occurred between pH 7.25 to 10). Finally, the model was able to capture the overall trends observed despite thermodynamic data limitations. While this study focuses on a simple lead solid-aqueous system, findings provide important insights regarding the way in which temperature and water chemistry interact to affect lead concentrations. [ABSTRACT FROM AUTHOR]

In this study, the (Ni50Mn34.75In15.25)0.9/(Tb0.3Dy0.7Fe1.92)0.1 composites were prepared by spark plasma sintering method, and the influence of different sintering temperatures on the magnetocaloric effect of the composites was studied. For the composite sintered at 923 K, the adiabatic temperature change at a 1.5-T magnetic field is as high as − 2.8 K, and the effective refrigeration capacity at a 5-T magnetic field reaches up to 190 Jkg−1. This is attributed to the fact that internal stresses generated by the magnetostriction of the Tb0.3Dy0.7Fe1.92 particles assist in the magnetic field-driven inverse martensitic transformation and reduce the critical field for phase transition. As the sintering temperature increases to 1023 K, the thermoelastic martensitic transformation characteristic of the composite disappears, which is attributed to the generation of more Fe-rich and In-poor phases in the composite. [ABSTRACT FROM AUTHOR]

A high temperature MD effect has been observed in Pr3Fe5O12 (PrIG) which is a new member of rare earth iron garnets (RIG) family. Research indicates that this material has two dielectric relaxations in the temperature range from 370 K to 565 K and a dielectric anomaly around 580 K. The first dielectric relaxation is attributed to the conduction for the similar activation energy with conduction. The other dielectric relaxation in the higher temperature range originated from the inhomogeneous structure. And, the coupling between the ferrimagnetic phase transition and the dielectric response was observed at 1 kHz 0.35 T 580K. [ABSTRACT FROM AUTHOR]

A hot-stamping method was established for manufacturing high-strength automotive parts with good shape fixability. The hot-stamping method has recently been applied to high-performance parts with tailored properties. CAE is indispensable for the design of such parts. To design hot-stamped parts, the forming simulation must be coupled with thermal analysis to consider the effect of temperature on formability. The final shape does not need to be predicted because of its good fixability. However, for high-performance parts with tailored properties, predicting the effect of phase transformations on the final shape is important. A CAE method that considers the phase transformation effects was developed to predict the final shape of the hot-stamped parts. The accuracy of the final shape calculation utilizing the CAE method is also investigated. Hotstamping experiments were conducted to obtain parts of different shapes via cooling control, and a CAE analysis of the final shape for each experimental condition was conducted. It was clarified that the final shape varied by changing the cooling process and that the results of CAE, including phase transformation, agreed with the tendency for shape change in the cross-section. [ABSTRACT FROM AUTHOR]

Understanding the nucleation mechanism and boiling heat transfer characteristics of liquid hydrogen is a key issue in the development of liquid hydrogen storage systems. However, the current methods of experimental and mesoscopic or macroscopic scale continuous flow simulations suffer from the problems of large study scales and undetermined initial boundary conditions. The purpose of this study is to reveal the bubble nucleation mechanism and bubble development process of liquid hydrogen on the surface of heating plate at the molecular scale, and to investigate the effect of different heating plate temperature on bubble growth, during thin film boiling. In this research, molecular dynamics simulation is used to combine molecular position distribution with energy analysis and explain the molecular behavior. The effect of heating temperature on different phase transition stages of liquid hydrogen is also investigated by varying the heating surface temperature. In this study, the bubble nucleation, bubble development and merging of liquid hydrogen on the heating surface were successfully observed. It is shown that increasing the heating temperature has a small effect on the bubble growth rate and liquid layer thickness in the nucleation boiling stage, and mainly affects the gas film growth rate in the film boiling stage. The bubbles are extremely unstable at the initial stage of generation. Within 1 fs of the first appearance of bubbles, which are associated with random micro-pits caused by thermal motion of solid atoms, bubbles move on the surface of the heating plate. This study found a phenomenon that bubbles firstly generated and then disappeared. This paper provides a new idea for the nucleation mechanism and boiling heat transfer study of liquid hydrogen. Moreover, it provides a solution to the problems of liquid hydrogen phase change research. • Liquid hydrogen phase transition was observed by molecular dynamics methods. • The effect of wall temperature on film boiling was significant. • Micro-pits on the wall surface promote bubble nucleation. [ABSTRACT FROM AUTHOR]

Neutron diffraction was used to interrogate the temperature-dependent deformation response of a medium-Mn steel. Through in situ measurements of phase content, the deformation response at 298 K was found to consist of phase transformation of the γ-austenite to ε- and α-martensite (TRIP). When strained above 423 K, twinning-induced plasticity (TWIP) became the dominant deformation behavior. At intermediate temperatures, mixed-mode deformation was observed. The various deformation responses are explained relative to the calculated temperature-dependent stacking fault energy curve. For stacking fault energies ≤ 15 mJ/m2, phase transformation associated with stacking fault generation was observed. When the stacking fault energy was ≥ 22 mJ/m2, twinning was recorded. Between these values, a mixed-mode deformation was noted with both twins and ε-martensite being identified; the mixed-mode response is due to the chemical and microstructural inhomogeneity of the alloy. This investigation works to clarify the effect of temperature on medium-Mn stacking fault energy and the associated deformation responses within a single alloy class. [ABSTRACT FROM AUTHOR]

Titanium carbide has attracted widespread attention due to its excellent properties. This study investigates the process of carbon thermally reducing TiO2 to prepare TiC through a combination of thermodynamic analysis and experiments. The effects of temperature, TiO2/C molar ratio, and time on the phase transformation and morphology evolution of the products are investigated. The synthesis of titanium carbide involves the main reduction path of TiO2–Magnéli–Ti3O5–Ti2O3–TiCxO1−x. With the increase in reaction temperature and TiC content, the microstructure transitions from a smooth disc-like structure to a loose and porous layered structure, while the particle size decreases significantly. The carburisation rate of the reduced product is more affected by temperature, according to chemical analysis. The carburisation rate increased from 18.37% to 36.09% for 2 h–10 h of holding time at 1400 °C, and from 51.43% to 77.57% for 2 h–10 h of holding time at 1500 °C. The quantification of the carburisation rate provides a valuable reference for the preparation of titanium carbide by TiO2. [ABSTRACT FROM AUTHOR]

Phase transformations and the evolution of hardness during elevated-temperature annealing of Inconel 718 superalloy manufactured by the laser powder bed fusion (L-PBF) were investigated. The microstructural evolution, elemental analysis, phase formation, and hardening were characterized by scanning electron microscopy, energydispersive spectroscopy, X-ray diffraction, and Vickers indentation test, respectively. It was observed that the effect of annealing treatments is directly governed by the annealing parameters (i.e. time and temperature), for which the hardness measurement as a fruitful and convenient tool can reveal this effect. The increase of the hardness, which was obtained by the annealing (aging) treatments at the temperature range of 800-900°C, indicated precipitation of the Ni3Nb γ" strengthening phase; while owing to the coarsening of precipitates as a result of overaging at this temperature range, the hardness decreased. For instance, the length and aspect ratio of precipitates in the aged sample at 800°C for 1 h are 67.14 nm and 0.32, respectively; while these values in the aged sample at 800°C for 8 h are 78.34 nm and 0.44, respectively. On the other hand, the decrease of the hardness at temperatures of 950 and 1000°C was attributed to the decrease of dislocation density in conjunction with the Ni2Nb Laves phase dissolution. Hence, it is crucial to determine the annealing parameters according to the required microstructure and properties. [ABSTRACT FROM AUTHOR]

In this study, the effect of sintering temperature (1000–1100 °C for 2 h) on phase formation, phase transition, microstructure and electrical properties of lead-free piezoelectric (K0.44Na0.52Li0.04)(Nb0.84Ta0.10Sb0.06)O3 (KNLNTS) solid solution with 0.3 wt%Bi2O3 + 0.4 wt%Fe2O3 + 0.2 wt%CuO additive (abbreviate as modified KNLNTS) was investigated. Modified KNLNTS ceramics were synthesized by the solid-state combustion technique using glycine as fuel. The modified KNLNTS powders were prepared using the calcination condition of 650 °C for 2 h. The XRD pattern of all sintered ceramics exhibited a pure perovskite phase. Using Rietveld refinement to analyze the phase formation showed that the modified KNLNTS ceramics had co-existing phases of orthorhombic and tetragonal in all sintered ceramics and the orthorhombic phase increased when the sintering temperature increased. The average grain size, TO-T, Tc, Pr and Ec increased with increasing sintering temperature. At the sintering temperature of 1025 °C, the modified KNLNTS ceramic showed the best electrical properties (Cε ≈ 6745, Smax ≈0.274% and d*33 ≈ 548 pm/V). The good electrical properties of the modified KNLNTS ceramics makes them good candidates for lead-free applications to replace Pb-based ceramics. [ABSTRACT FROM AUTHOR]

To explore the effect of temperature on the phase transformation of HCP→FCC during compression, the uniaxial compression process of AZ31 magnesium alloy was simulated by the molecular dynamics method, and the changes of crystal structure and dislocation evolution were observed. The effects of temperature on mechanical properties, crystal structure, and dislocation evolution of magnesium alloy during compression were analyzed. It is concluded that some of the Shockley partial dislocation is related to FCC stacking faults. With the help of TEM characterization, the correctness of the correlation between some of the dislocations and FCC stacking faults is verified. Through the combination of simulation and experiment, this paper provides an idea for the in-depth study of the solid-phase transformation of magnesium alloys and provides reference and guidance for the design of magnesium alloys with good plasticity and formability at room temperature. [ABSTRACT FROM AUTHOR]

The experimental analysis of ignition responses of mildly impacted Ammonium Perchorate (AP) particles was performed based on an optimized drop‐weight system equipped with a High‐Speed Camera (HSC). The experimental results suggested that the jetting phenomena observed by HSC is the result of the energy released by gaseous products, which push the pulverized or melted particles to splash radially. In the process of complex stress stimulation, AP particles experienced four stages of compaction, solid phase transition, sputtering, and ignition. In addition, with the increase in temperature, AP particle sensitivity increased. At room temperature, AP particles are insensitive particles. When the temperature is 50 °C, the ignition threshold of AP particles is 40 cm. However, when the temperature increases to 100 °C, the ignition threshold is 35 cm. Finally, particle friction and rapid gas compression are the main reasons for the ignition of AP particles during impact loading. [ABSTRACT FROM AUTHOR]

To improve the robustness of frequency-modulated continuous-wave (FMCW) distance measurement systems, we clarified the effect of temperature changes in the surroundings. In particular, the temperature change causes a phase change between the slow-axis and fast-axis polarization of the optical fiber, which in turn causes a distance error. Numerical analysis using a model of the phase state of polarization revealed that a distance gain error occurs in the reference fiber interference unit and a distance offset error occurs in the measurement fiber interference unit of the FMCW distance measurement system. We propose two measurement-error reduction methods that suppress the phase change in polarization in accordance with the characteristics of each interference unit. Experimental evaluations showed that the measurement errors were reduced from 5 μm to 1 μm and the temperature robustness of the system was improved. • To improve the robustness of frequency-modulated continuous-wave (FMCW) distance measurement systems, we clarified the effect of temperature changes in the surroundings. • We found that the temperature change causes a phase change between the slow-axis and fast-axis polarization of the optical fiber, which in turn causes a distance error. • We propose two measurement-error reduction methods that suppress the phase change in polarization. • Experimental evaluations showed that our proposed method was effective, and the temperature robustness of the system was improved. [ABSTRACT FROM AUTHOR]

Transversal temperature distribution and phase transformation of the strip steel in hot rolling process are analyzed by thermographic observations and thermal simulation tests. The effects of transversal temperature distribution and phase state on strip profile are investigated by finite element (FE) simulations, in which the material model of the strip steel is generated from the thermal simulation tests and a constitutive model. FE calculation shows that the decreased temperature at the edge causes smaller strip crown with the dual‐phase state, while it leads to edge bulges in strip profile under single‐phase state. With the convex temperature distribution, large strip crown is witnessed under dual‐phase state; small crowns or even edge bulges appear under the single‐phase state. For the concave temperature distribution, opposite conclusions are drawn compared with the convex temperature distribution. Measures to prevent edge bulges and control the strip crown are proposed and applied to industrial production. Reheating the edge area and assigning large target crown to the former stand of the finishing mill can avoid the edge bulges. Strip crown of the steel is more significantly affected by the bending force under dual‐phase state than that under single‐phase state. [ABSTRACT FROM AUTHOR]

Due to its high bonding energy and low self-diffusion coefficient, silicon nitride (Si3N4) ceramics cannot form a dense structure with prolonged high-temperature insulation or by raising the sintering temperature. To improve the density of the sintered Si3N4 ceramics, additives are added to promote the rearrangement–dissolution–precipitation process of the crystal grains. However, the liquid phase formation temperature of different sintering aid chemical compositions varies, making it challenging to isolate the mechanism and the effect of liquid phase formation temperatures on sintering. Hence, we developed three sintering aids, namely Y2O3-Al2O3 (YA), Y2Si2O7 (Y2S), and Y2Si2O7-Al6Si2O13 (Y2SM), with homologous elements and different liquid phase formation temperatures. These sintering aids can form a liquid phase with SiO2 on the surface of Si3N4 at varying temperatures. We analyzed the sintered Si3N4 ceramic's density, volume shrinkage rate, and microstructure to verify the YA's lower liquid phase formation temperature effect, providing more rearrangement time and increasing sintering density. Conversely, sintering aids with too low liquid phase formation temperatures are more prone to volatilize during high-temperature sintering stages, thereby reducing sintering density. This research found that different liquid phase formation temperatures do not affect the α→β phase transition temperature of Si3N4 ceramics. We also evaluated the Y2S sintering aid contents' effect on Si3N4 ceramics sintering. The results revealed that aiding sintering with too little Y2S content is insufficient for liquid phase production, and hence does not improve sintering density. Conversely, excessive liquid phase can improve density and refine grain size but increases weight loss rate during sintering due to volatilization. [ABSTRACT FROM AUTHOR]

In this work, BiOCl films were obtained by tape casting using BiOCl powders synthesized by the co-precipitation method. The effect of the film's sintering temperature (300 °C–600 °C) on the morphology, chemical composition, crystalline phases and optical characteristics was studied. The obtained BiOCl powders showed a flake-like morphology, a tetragonal crystalline structure without secondary phases and a wide band gap of 3.53 eV. For BiOCl films, results indicated that as the sintering temperature increased the flake-like shaped particles changed to rectangular ones while the amount of chlorine in the films decreased. A phase transition from tetragonal BiOCl to monoclinic Bi 24 O 31 Cl 10 was also observed as the sintering temperature increased. Consequently, optical studies revealed that the band gap of BiOCl films decreased from 3.03 eV to 2.82 eV. FTIR analysis demonstrated that the organic groups were removed from the films only for sintering temperatures above 400 °C. The Rhodamine B dye adsorption capacity of BiOCl films decreased with increasing sintering temperature. The results obtained allow us to conclude that BiOCl films are suitable for use in DSSC when the sintering temperature is in the range of 400–500 °C. [ABSTRACT FROM AUTHOR]

The surrounding rocks are subjected to ultralow temperatures in applications like liquid nitrogen fracturing, underground storage of liquefied natural gas and polar constructions etc. The mechanical properties of sandstone with different saturations under freezing temperature and after one ultralow temperature freeze–thaw cycle test conditions were investigated in this study. The uniaxial compressive strength (UCS) of both dry and saturated samples increases with the decrease in temperature except at − 90 °C under freezing temperature test conditions, while the UCS of saturated samples is lower than that of dry samples after one ultralow temperature freeze–thaw cycle due to the water softening effects and the damage induced during the water–ice phase transition. The failure patterns of dry samples are more complex than those of saturated samples under freezing temperature, which is also indicated in the lower brittleness index for the saturated samples. The ice cohesion effect and its creep deformation increase the plastic deformation, while decreasing the Young's modulus of saturated samples under freezing temperature. In addition, the ice net formed in the connected pores significantly increases the sample tensile strength and makes its failure less severe. The UCS, Young's modulus and brittleness index decrease with saturation under − 120 °C, while the tensile strength increases with saturation. Porosity reduction measured by computerized tomography for the saturated samples after one freeze–thaw cycle is largest at − 120 °C compared with those at − 60 °C and − 180 °C, which is certified by the pore filling shown in scanning electron microscope images. Highlights: Tensile strength is more sensitive to the variations of subzero temperatures compared with the compression strength. The cohesion and creep deformation of ice increase the plastic deformation while decrease the elastic modulus. Porosity reduces after one freeze-thaw cycle due to pore filling. Compression strength and brittleness index decrease while tensile strength increases with the saturation under − 120℃. Failure patterns of dry samples are more complex than those of saturated samples under low temperatures. [ABSTRACT FROM AUTHOR]

Ocean reanalysis products are used to examine salinity variability and its relationships with temperature in the western equatorial Pacific during 1950–2018. An ensemble empirical mode decomposition (EEMD) method is adopted to separate salinity and temperature signals at different time scales; a focus is placed on interdecadal component in this study. Pronounced interdecadal variations in salinity are seen in the region, which exhibits persistent and transitional phases in association with temperature. A surface freshening is accompanied by a surface warming during the 1980s and 1990s, but saltening and cooling in the 2000s, with interdecadal shifts occurring around in the late 1970s, late 1990s, and during 2016–2018, respectively. Determined by anomaly signs of temperature and salinity, their combined effects can be density-compensated or density-uncompensated, correspondingly acting to produce density variability that is suppressed or enhanced, respectively. The temperature and salinity effects are phase- and depth-dependent. In the subsurface layers at 200 m, where salinity and temperature anomalies tend to be nearly of the same sign during interdecadal evolution, their effects are mostly density-compensated. The situation is more complicated in the surface layer, where variations in sea surface salinity (SSS) and sea surface temperature (SST) exhibit different signs during interdecadal evolution. SST and SSS tend to be of opposite sign during the persistent phases with their effects being density-uncompensated; but they can be of the same sign during the transitional periods and the corresponding changes in SST and SSS undergo density-compensated relationships. Examples are given for the relationships among these fields which exhibit phase differences in sign transitions in the late 1990s; salinity effects are seen to cause a delay in phase transition of density anomalies. Furthermore, the relative contributions to interdecadal variabilities of density and stratification are quantified. The consequences of interdecadal salinity variability are also discussed in terms of their effects on local SST. [ABSTRACT FROM AUTHOR]

BaTiO3 ceramic powders are prepared by the solid phase reaction method. BaTiO3 ceramic powders are sintered at different temperatures for 3 h. The tetragonal phase of BaTiO3 powder is confirmed by XRD. It was found that as the sintering temperature increased, the grain size, density, and dielectric constant of BaTiO3 ceramics increased. All the BaTiO3 ceramic samples sintered at various temperatures for 3 h show the diffuse phase transition and the diffuseness parameter and curie-Weiss constant are also calculated. BaTiO3 ceramic samples sintered at 1200 °C show well-grown grain boundaries. The ferroelectric nature of sintered BaTiO3 ceramic samples studied using P-E hysteresis measurements. [ABSTRACT FROM AUTHOR]

A computational model has been developed to study the effect of the tilt angle (15, 30, 45, and 60°) and pouring temperature (893, 903, 913, and 923 K) on the phase change behavior of the hypoeutectic binary alloy Al–7Si. The analysis has been done with the help of the obtained temperature field, solid fraction evolution, as well as the Si distribution and macrosegregation. The two-dimensional multiphase volume-averaging transient model is used for computational modeling, incorporating phase diagram information, enthalpy-updating scheme, composition–solid fraction coupling, and variation in the thermophysical properties inside a mushy zone. It is observed that the effect of the tilt angle on the cooling rate is much superior to the pouring temperature effect. Moreover, the formation of eutectic plateau and negative macrosegregation are observed near the surface of the tilted plate in the eutectic temperature zone. Negative macrosegregation becomes high near the exit of the tilted surface. [ABSTRACT FROM AUTHOR]

Temperature treatment during the processing of meatballs is intended to prevent contamination. However, the heat treatment more frequently harms the food structure and loses major nutrients of meatballs. The Arrhenius model has been used to observe the heat-treatment effect on the degradation of food quality. The meatballs samples with edible coating were observed under dynamic temperature storage. The purpose of this study was to use the Arrhenius model to evaluate the heat-treatment relationship on the pH change during dynamic storage conditions: uncontrolled ranging 24 to 31°C, while the studied temperature treatment was ranging between 50 to 90°C for 15 minutes. The results showed an obvious relationship between the heat-treatment aspects for preventing bacteria growth during storage. The evaluation of the Arrhenius model result indicates peak nutrition loss phase transition was found in the temperature treatment range of 83 to 90°C, and the optimum heat-treatment level at 78°C or 148.15 kJ mol-1 for developing packaging or preservation methods. [ABSTRACT FROM AUTHOR]

The effect of the action of temperature on the structure and phase composition of an Fe3C/Fe7C3/P-phase/Cam composite obtained by mechanosynthesis of Fe–75 at % C has been studied by the methods of X‑ray diffraction, Mössbauer spectroscopy, thermogravimetric analysis, and differential scanning calorimetry. It is shown that the structural and phase changes at heating have a multistage character. In the temperature range 315–400°C crystallization of the paramagnetic P-phase with generation of Fe3C and/or Fe7C3 occur. In the course of heating to higher temperatures, complete decomposition of carbide Fe7C3 (in the range 450–550°C) and partial decomposition of Fe3C (at 600°C and above) are observed. After cooling from 800–1000°C the mechanocomposite consists of α-Fe, cementite Fe3C, and graphite. The phase transformations are accompanied by the processes of composite oxidation with the formation of Fe3O4 oxide and its subsequent reduction. The P-phase is a disorded amorphous carbide Fe1 – xCx, which is characterized by magnetic ordering at the temperature of liquid nitrogen. [ABSTRACT FROM AUTHOR]

The transformation of liquid water into solid ice is arguably the most important phase transition on Earth. A key aspect of such transformation is the speed with which ice grows once it is nucleated. There are contradictory experimental results as to whether the ice growth rate shows a maximum on cooling. Previous simulation results point to the existence of such a maximum. However, simulations were performed at constant temperature with the aid of a thermostat that dissipates the heat released at the ice-water interface unrealistically fast. Here, we perform simulations of ice growth without any thermostat. Large systems are required to perform these simulations at constant overall thermodynamic conditions (pressure and temperature). We obtain the same growth rate as in previous thermostatted simulations. This implies that the dynamics of ice growth is not affected by heat dissipation. Our results strongly support the experiments predicting the existence of a maximum in the ice growth rate. By using the Wilson-Frenkel kinetic theory, we argue that such maximum is due to a competition between an increasing crystallization thermodynamic driving force and a decreasing molecular mobility on cooling. [ABSTRACT FROM AUTHOR]

Quasi-isentropic compression of liquid water beyond 5 GPa rapidly creates ice VII on 1–10 ns time scales. The onset of this phase transition can be modified by changing the initial temperature of the liquid sample and/or the compression rate. These effects were studied using the Sandia Thor-64 pulsed power machine. Increasing the initial temperature pushes freezing above the previously reported 7 GPa metastable limit. Slower compression allows freezing to occur below the metastable limit, though the compression rate has a greater effect at an elevated temperature than at room temperature. [ABSTRACT FROM AUTHOR]

We report the modifications in the electronic properties of single phase polycrystalline BaTiO3 due to ferroelectric to paraelectric phase transition revealed by temperature dependent synchrotron based x-ray absorption and valence band spectroscopy. Valence band spectra show a strong temperature dependence of Ti-3d and O-2p hybridized states around the phase transition. It is observed that Ti-O hybridization is stronger in the paraelectric phase, which is also supported by multiplet calculations at the Ti L-edge. We also find a reduced crystal field value in the paraelectric phase than in the ferroelectric phase, which is caused by volume expansion and a reduction in tetragonal distortion. [ABSTRACT FROM AUTHOR]

We report the modifications in the electronic properties of single phase polycrystalline BaTiO3 due to ferroelectric to paraelectric phase transition revealed by temperature dependent synchrotron based x-ray absorption and valence band spectroscopy. Valence band spectra show a strong temperature dependence of Ti-3d and O-2p hybridized states around the phase transition. It is observed that Ti-O hybridization is stronger in the paraelectric phase, which is also supported by multiplet calculations at the Ti L-edge. We also find a reduced crystal field value in the paraelectric phase than in the ferroelectric phase, which is caused by volume expansion and a reduction in tetragonal distortion. [ABSTRACT FROM AUTHOR]

The competition among multiple solid phases determines the final microstructures of a material. Such competition can originate at the very beginning of the solidification process. We report the results of molecular dynamics simulation of the phase competition between the hexagonal close-packed (hcp), face-centered cubic (fcc), and body-centered cubic (bcc) phases during the solidification of pure Tb. We found that the liquid supercooled below the hcp melting temperature has both bcc and hcp/fcc nuclei, but only the bcc nuclei grow such that the liquid always solidifies into the bcc phase, even at temperatures where the hcp phase is more stable. The hcp phase can only form in the last liquid droplet or at the bcc grain boundaries. Depending on the bcc grain orientations, the hcp phase jammed between the bcc grains either completely disappears or slowly grows via a solid-state massive transformation mechanism. Once the hcp phase becomes large enough, the stresses associated with its appearance can trigger a martensitic transformation. Yet, not the entire bcc phase is consumed by the martensitic transformation and the remaining bcc phase is transformed into the hcp phase via the solid-state massive transformation mechanism. Finally, if the supercooling is too large, the nucleation becomes almost barrier free and the liquid solidifies into a structure consisting of ultra-fine hcp and bcc grains after which the bcc phase quickly disappears. [ABSTRACT FROM AUTHOR]

The combined effects of the atomic-layer-deposition (ALD) temperature (220 °C–280 °C) and metal electrodes (TiN and Mo) on the ferroelectric properties of Hf0.5Zr0.5O2 films were studied. Regardless of the metal electrode, a tetragonal–orthorhombic–monoclinic phase evolution sequence was observed with increasing ALD temperature after post-metallization annealing. However, the phase transition temperature slightly changed depending on the metal electrode, which was predetermined based on the as-deposited states. Additionally, the out-of-plane orientation of the final orthorhombic grains was highly dependent on the crystallographic alignment of the metal electrode grains, resulting in different values of the maximum remanent polarization. In terms of long-term reliability, the fatigue characteristics were highly dependent on the electrode characteristics, and the wake-up characteristics were mainly affected by the initial phase distribution determined by both the ALD temperature and metal electrode. [ABSTRACT FROM AUTHOR]

Iron chromite powders were synthesized via solution combustion route using iron(III) nitrate nonahydrate and chromium(III) nitrate nonahydrate as starting materials, as well as glycine–urea, glycine–citric acid, and glycine–ethylene glycol mixtures as fuels. The effect of postheating at different temperatures on the structure, molecular, microstructure, and chromatic properties of powders and tiles colored by in‐glaze powders was studied. The X‐ray diffraction patterns showed that as‐synthesized powders were obtained in crystalline FeCr2O4 phases moreover, postheating of the powders led to d‐space shift and oxidation and formation of (Fe,Cr)2O3 solid solution phase regardless of fuel type. Phase transformation of FeCr2O4 to (Fe,Cr)2O3 solid solution was observed at 500/750°C depending on the dominant phase of as‐synthesized particles. Fourier transform infrared analysis illustrated that the band positions of octahedral M–O and tetrahedral M–O bonds were shifted due to Fe cations movement from their position and lattice shrinkage by increasing of post‐heating temperature. Moreover, scanning electron micrographs showed that Fe0.7Cr1.3O3 semispherical fine particles were formed from porous spongy FeCr2O4 particles due to oxidation and phase transformation during the postheating. Furthermore, chromatic properties of the samples were represented. The color properties of the pigments showed that the formation of brown pigments is provided with the phase transformation from FeCr2O4 to (Fe,Cr)2O3 at a temperature of up to 750°C. Moreover, increasing the color purity to this temperature is related to the removal of residual carbonaceous matters. The chromatic properties of the glazed tiles colored using the pigments showed that postheating between 250 and 500°C led to more brown appearance. [ABSTRACT FROM AUTHOR]

The effect of temperature on the deformation response of Fe-18% Cr-10% Ni polycrystalline alloy is studied in this work. The stress-strain curve of the alloy is shown to be changed significantly with decreasing temperature due to a strain-induced γ-α' phase transition. To calculate the stress-strain curves, the correction coefficients taking into account the volume fraction of the martensitic phase are added to the Ludwigson equation. A comparative analysis reveals the good correlation between experimental and theoretical stress-strain diagrams of the Fe–Cr–Ni alloy in both high and low temperature ranges. [ABSTRACT FROM AUTHOR]

This paper presents the effect of fumed silica modification and calcination temperature on the physicochemical properties of photocatalysts and their activity under the UV-VIS and VIS light range. The materials were obtained by hydrolysis of titanium tetraisopropoxide (TTIP) combined with a calcination step. The obtained nanomaterials were characterized using analytical methods such as X-ray diffraction XRD, FT-IR/DRS infrared spectroscopy, UV-Vis/DRS spectroscopy and SEM scanning electron microscopy. BET specific surface area and zeta potential were also measured. It was observed that SiO2 modification inhibited the transformation phase of anatase to rutile and the increase in crystallite size during calcination. The calcination process contributed to a change in the surface character of photocatalysts under study from positively to negatively charged. The photocatalytic activity of samples was identified by determining the methylene blue decomposition under UV-VIS and VIS light. Experimental results showed that the addition of SiO2 and the calcination process increased the photoactivity. The obtained materials showed higher activity compared to the reference samples. It was found that the degree of dye removal increased along with increased calcination temperature. The highest activity was observed for photocatalyst SiO2(11.1%)/TiO2_600. [ABSTRACT FROM AUTHOR]

Compositional zoning in plagioclase feldspar is an important archive of the temporal, compositional and thermal evolution of magmatic systems. Modelling diffusion of Mg in plagioclase is commonly used to estimate the timescales of magmatic processes that operate weeks to decades before eruption. To do this, however, requires knowledge of how the anorthite composition influences plagioclase-melt partitioning of Mg. The nature of this relationship has yet to be properly constrained, with inconsistencies between early empirical models, natural observations and more recent thermodynamic models. Here we compiled a data base of 965 calculated plagioclase-melt partition coefficients of Mg using mineral rim-melt pairs from phase equilibria experiments and natural samples. The data set includes a comprehensive range of plagioclase compositions (An 13 –An 92), melt compositions (46.5–78.2 wt% SiO 2) and temperatures (720–1430 °C). We find that the dependence of the partition coefficient on anorthite content has a major inflection at compositions that correspond to the C 1 ¯ – I 1 ¯ structural phase transition (An 60 at 1000 °C): with a positive dependence in the C 1 ¯ domain, and a negative dependence in the I 1 ¯ domain. We also find that this change in partitioning behaviour can explain Mg distributions in natural plagioclases observed in mafic to silicic systems including the Galápagos, Santorini, Krakatau, Toba and Cerro Galán. We have developed a new empirical model for the partitioning of Mg in plagioclase that takes into account this structural transition, in addition to the effects of temperature and melt composition. The dichotomous nature of the partitioning of Mg between plagioclase and melt has significant implications for diffusion chronometry, with the shape of Mg 'quasi steady state' profiles being controlled by the structural state of plagioclase. Compositional profiles that were previously interpreted to show little diffusion, may be close to a quasi steady state and vice versa. This re-evaluation will be highly influential for understanding thermal states and magmatic histories at a range of tectonic settings. [ABSTRACT FROM AUTHOR]

• The splitting test of heat-treated CSTBD granite specimens was simulated using GBM. • The effect of thermal cracks on mode-I and mode-Ⅱ fracture behaviors was investigated. • The moment tensor algorithm was used to obtain the AE source information during loading. To investigate the effects of thermally induced microcracks on the pure mode-I and mode-Ⅱ fracture behaviors of the granite, a Grain-based model (GBM) was used to build cracked straight-through Brazilian disc (CSTBD) granite specimens. Splitting tests were conducted on the CSTBD specimens treated at various temperatures under pure mode-I and mode-Ⅱ loadings, and the moment tensor algorithm was utilized to record the acoustic emission (AE) events generated by fracture during loading. The results indicate that thermally induced microcracks predominantly consist of intergranular and intragranular tensile cracks, with quartz phase transition significantly increasing the number of intragranular tensile cracks. With the increase in heat-treatment temperature, thermally induced microcracks gradually guide the initiation direction of load-induced cracks, making the crack propagation path more tortuous. The AE characteristics reveal that the fracture behavior of the CSTBD specimen heat-treated at 600 ℃ transitions from brittle to ductile. Furthermore, thermally induced microcracks can constrain the propagation distance of load-induced cracks, increasing the small-scale AE events and the b -value, thereby reducing the AE magnitude during failure. [ABSTRACT FROM AUTHOR]

This study aims to explore the influence of various aging temperatures on the microstructure and mechanical properties of TC21 forgings. Basket-weave microstructures were prepared via quasi-β forging followed by annealed at 900 °C for 1.5 h and aged at 530 °C, 560 °C, and 590 °C for 4 h, and then their tensile performance, impact toughness, and fracture toughness were examined. Results indicate that higher aging temperatures not only facilitate the segregation of Al element, resulting in a reduction in the effective size (dα laths , the width/length ratio) of primary α laths (α laths) and their amount, but also promote phase transition, inducing an increase in the effective size (dα fine) of secondary fine α (α fine) lamellae. While both dα laths −1/2 and dα fine −1/2 have a linear relationship with the strength, which was analyzed using the Hall–Petch relationship, the more pronounced interface strengthening effect and hindering crack propagation mainly results from the α laths. Moreover, the plasticity declines significantly as the proportion of the α laths phases decreases. Thus, for strength and plasticity, the α laths are a much more important factor than the α fine lamellae. However, although the synergistic deformation and fracture of both the α laths and α fine phases can consume a larger impact initiation energy, the enhancement of the impact energy of the alloy is primarily related to a high precipitation amount of the α fine lamellae. Furthermore, the decrease in dα laths promotes the misorientation and accumulation of dislocations between α laths interfaces, hindering the enhancement of K IC (fracture toughness) by forming transgranular fractures. Conversely, the increase in K IC attributed to the energy consumed in the plastic deformation region at the crack tip, due to the α fine lamellae compensates for the energy, resulting in a reduction in the crack propagation path. Therefore, the α fine lamellae may play a more crucial role in increasing the toughness of alloys, in particular the impact toughness of the TC21 alloy. • The higher interface strengthening effect mainly results from the primary α lath (α lath). • The reduction of content for both α laths and α fine phase negatively impact plasticity. • Synergistic effect of α laths and α fine phase remarkably improves the toughness. [ABSTRACT FROM AUTHOR]

This study focuses on the effect of the substrate temperature (TS) on the quality of VO2 thin films prepared by DC magnetron sputtering. TS was varied from 350 to 600 °C and the effects on the surface morphology, microstructure, optical and electrical properties of the films were investigated. The results show that TS below 500 °C favors the growth of V2O5 phase, whereas higher TS (≥500 °C) facilitates the formation of the VO2 phase. Optical characterization of the as-prepared VO2 films displayed a reduced optical transmittance ( T ˜ ) across the near-infrared region (NIR), reduced phase transition temperature (Tt), and broadened hysteresis width (ΔH) through the phase transition region. In addition, a decline of the luminous modulation (Δ T ˜ lum) and solar modulation ( Δ T ˜ sol ) efficiencies of the as-prepared films have been determined. Furthermore, compared with the high-quality films reported previously, the electrical conductivity (σ) as a function of temperature (T) reveals reduced conductivity contrast (Δσ) between the insulating and metallic phases of the VO2 films, which was of the order of 2. These outcomes indicated the presence of defects and unrelaxed lattice strain in the films. Further, the comparison of present results with those in the literature from similar works show that the preparation of high-quality films at TS lower than 650 °C presents significant challenges. [ABSTRACT FROM AUTHOR]

The thermal behavior of salts of the type [Co(NH3)6]X3 [X = Cl, Br, I] has been the object of considerable interest since early in the twentieth century. As noted, some of the early measurements on the trichloride complex recorded what appeared to be an "anomaly" occurring in its heat capacity. Our studies, however, indicate a far more complex behavior in which (a) DSC measurements between 100 and 300 K show a glass transition at ca. 200 K corresponding to the previously-mentioned "anomaly"; (b) the glass transition is observed in both the heating and cooling cycles, but the exact details are dependent on the rate at which the process is carried out in either direction; (c) parallel crystallographic studies using samples from the same batches as those in the DSC studies document that the origin of the thermal changes are due to torsional motions of the –NH3 hydrogens about the Co–N vector, evidence of the formation of a complex structure (condis crystalline mesophase) with a variety of order–disorder (entropically-diverse) material of differing stability and mobility; (d) inasmuch as there are four independent [Co(NH3)6]+ cations in the asymmetric unit (Z' = 3), an additional reason for the complexity of the DSC observations is due to the sequential degree of torsional disorder induced thermally during the heating cycle on each of the four individual specimens of the asymmetric unit; (e) similar behavior is observed in the cooling cycle, but, the "re-orientation" of the thermally excited –NH3 ligands to a "cooler" more-orderly condition is considerably more sluggish (hysteresis)—thus, the observed differences in the recorded rates mentioned above; (f) finally, and not surprisingly, observations carried out with different crystals of (1) the same batch and (2) different batches show the same general behavior, but the specific details vary considerably, indicating that the history (provenance) of the crystal preparation is crucial to the exact results observed in each case. [ABSTRACT FROM AUTHOR]

Computational methodology is proposed to simulate time dependent temperature variations via thermostat approach. The methodology is applied to study pyroelectricity under nonequilibrium conditions in prototypical ferroelectric PbTiO3. It is found that at room temperature the nonequilibrium effects in pyroelectricity begin manifesting above 1.0 THz and originate from the overlap with the intrinsic soft mode frequency. Therefore, the proposed computational methodology can be used to predict equilibrium pyroelectric response by choosing a frequency of temperature variation below the intrinsic polar mode frequencies for the material. Probing the dynamics of ferroelectric phase transition with the proposed methodology revealed that it takes about a nanosecond for the computational supercell to undergo phase transition. It is concluded that computational techniques capable of simulating picoseconds can be used to compute pyroelectric response from nonequilibrium dynamical approach while those that can reach nanoseconds are suitable for simulating phase transitions in ferroelectrics. [ABSTRACT FROM AUTHOR]

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Computational methodology is proposed to simulate time dependent temperature variations via thermostat approach. The methodology is applied to study pyroelectricity under nonequilibrium conditions in prototypical ferroelectric PbTiO3. It is found that at room temperature the nonequilibrium effects in pyroelectricity begin manifesting above 1.0 THz and originate from the overlap with the intrinsic soft mode frequency. Therefore, the proposed computational methodology can be used to predict equilibrium pyroelectric response by choosing a frequency of temperature variation below the intrinsic polar mode frequencies for the material. Probing the dynamics of ferroelectric phase transition with the proposed methodology revealed that it takes about a nanosecond for the computational supercell to undergo phase transition. It is concluded that computational techniques capable of simulating picoseconds can be used to compute pyroelectric response from nonequilibrium dynamical approach while those that can reach nanoseconds are suitable for simulating phase transitions in ferroelectrics. [ABSTRACT FROM AUTHOR]

Lead-free piezoelectric ceramics have been widely used for aerospace and power generating industrial and medical imaging applications in ultrasonic transducers and noninvasive therapy. Bismuth-layered structure ferroelectrics (BLSF) are the potential candidates for high-temperature piezoceramics. In the present work, the influence of calcination temperature is studied on the structural, dielectric, piezoelectric and ferroelectric properties of strontium bismuth niobate (SBN) ceramics prepared by conventional solid-state reaction method. X-ray diffraction studies reveal the maximum orthorhombic distortion for the sample calcined at 1000 °C. Scanning electron micrographs display the effect of calcination treatment on the microstructures. Dielectric studies indicate a sharp phase transition with minimum losses for the sample calcined at 1000 °C. The highest value of piezoelectric charge constant (d33 = 14pC/N) and remnant polarization (2Pr = 11.2 µC/cm2) was obtained for the sample calcined at 1000 °C. The changes in structural, dielectric and piezoelectric properties have been correlated. [ABSTRACT FROM AUTHOR]

0.9KNbO3-0.1BaTiO3 ceramics, with a bimodal grain size distribution and typical tetragonal perovskite structure at room temperature, were prepared by using an induced abnormal grain growth (IAGG) method at a relatively low sintering temperature. In this bimodal grain size distribution structure, the extra-large grains (~10–50 μm) were evolved from the micron-sized filler powders, and the fine grains (~0.05–0.35 μm) were derived from the sol precursor matrix. The 0.9KNbO3-0.1BaTiO3 ceramics exhibit relaxor-like behavior with a diffused phase transition near room temperature, as confirmed by the presence of the polar nanodomain regions revealed through high resolution transmission electron microscope analyses. A large room-temperature electrocaloric effect (ECE) was observed, with an adiabatic temperature drop (ΔT) of 1.5 K, an isothermal entropy change (ΔS) of 2.48 J·kg−1·K−1, and high ECE strengths of |ΔT/ΔE| = 1.50 × 10−6 K·m·V−1 and ΔS/ΔE = 2.48 × 10−6 J·m·kg−1·K−1·V−1 (directly measured at E = 1.0 MV·m−1). These greatly enhanced ECEs demonstrate that our simple IAGG method is highly appreciated for synthesizing high-performance electrocaloric materials for efficient cooling devices. [ABSTRACT FROM AUTHOR]