Temperature Td Research Articles

Temperature dependent large strain cavitation in ultra high molecular weight polyethylene during tensile deformation

The large strain cavitation stemmed from the fragmentation of the highly oriented amorphous network in the quenched ultra high molecular weight polyethylene was investigated as a function of deformation temperature. The critical stress for initiating such cavitation was found to be dependent on the deformation temperature (Td) in a way being constant below Td of 90 °C but increased with Td above 90 °C. This peculiar deformation temperature dependency of critical stress for the large strain cavitation stress was found to be associated with the activation of the αⅡ-relaxation in the deformed samples. The αⅡ-relaxation temperature increased with the increase of Td, which was attributed to the increase of the stability of the fibrils formed at large strain. The difference between αⅡ-relaxation temperature and deformation temperature showed a one-to-one correspondence to the critical stress of large strain cavitation indicating a stress was required to activate the αⅡ-relaxation at a selected Td to initiate failure of the oriented network so that cavitation in the large strain regime.

Enhanced piezoelectric properties and depolarization temperature in textured (Bi0.5Na0.5)TiO3-based ceramics via homoepitaxial templated grain growth

Enhanced piezoelectric response was usually achieved in (Bi0.5Na0.5)TiO3 (BNT)-based ceramics with sacrifice of depolarization temperature Td, seriously limiting their usage range in electromechanical applications. In this work, we propose to explore piezoelectric anisotropy and domain engineering in composition & microstructure-controlled textured ceramics to resolve this issue. [001]c-textured 0.94(Bi0.5Na0.5)TiO3–0.06BaTiO3 (0.94BNT-0.06BT) ceramics with Lotgering factor F001∼91% were fabricated through homoepitaxial templated grain growth (TGG) via using 0.94BNT-0.06BT microplatelet templates. The textured samples exhibited more ordered domains with facilitated domain switching behavior, being consistent with saturated high polarization achieved at lower electric fields. Increasing F001 to above 60% enables rapid enhancement of piezoelectric response. Notably, compared to non-textured counterpart, the maximally textured ceramics exhibited ∼236% enhanced piezoelectric coefficient (d33∼302 pC/N) and ∼280% enhanced piezoelectric voltage coefficient (g33∼49.8 × 10−3 Vm/N), together with slightly increased depolarization temperature (Td∼106 °C). Moreover, those values are approaching or even higher than the single-crystal values. This work not only provides important guidelines for design and synthesis of novel textured ceramics with improved comprehensive electrical properties, but also can expand application fields of BNT-based ceramics.

Enhanced piezoelectric properties and strong red luminescence in Pr-doped Bi0.5Na0.5TiO3–BaTiO3 multifunctional ceramics

Multifunctional ceramics with the 0.93(Na0.5Bi0.5)1-xPr3+xTiO3-0.07BaTiO3 (abbreviated as BNBT-xPr, x = 0.00, 0.002, 0.004, 0.006, 0.008) were synthesized using the solid-phase reaction method. This study systematically investigated the phase structure, microstructure, dielectric, ferroelectric, piezoelectric, and photoluminescence properties. As the value of x increased, the ceramics underwent a transition from a co-existing rhombohedral (R) and tetragonal (T) phases to a T phase with a slight R distortion. In addition, the grain size decreased, and the relative density increased. The Pr3+ doping led to a decrease in the coercive field and an improved reversible phase transition, accompanied by a reduction in the depolarization temperature (Td) from 91 °C to 41 °C. The ceramic with x = 0.006 showed excellent piezoelectric properties, with a d33 = 201 pC/N and kp = 30.6%. Such properties were ascribed to the appropriate R/T phase ratio, increased relative density, decreased coercive field, and improved reversible phase transition. Moreover, under excitation at 451 nm, the ceramics exhibited bright red emission bands at 611 nm and 655 nm, corresponding to the transitions of 1D2→3H5 and 3P0→3F2, respectively. After polarization, the relative intensity of the emission peak at 655 nm significantly increased due to the changed lattice environment caused by the electric field. These Pr-doped BNBT ceramics demonstrated great potential in applications requiring electro-optic integration and coupling devices as multifunctional materials.

Low temperature sintering, structure and electrical properties of BiFeO3-BaTiO3 based piezoelectric ceramics using CuO-B2O3 composite sintering aids

Piezoelectric ceramics usually have high sintering temperature, which cannot meet the low-temperature co-firing requirements of ceramics and metal electrodes in production of micro devices. Here, we studied the effects of CuO-B2O3 binary composite sintering aids on the sintering behavior, phase composition, microstructure, and electrical properties of the bismuth ferrite-barium titanate (0.7BiFeO3-0.3BaTiO3, BFO-BT) based lead-free piezoelectric ceramics. We found that the CuO-B2O3 sintering aids can effectively lower the sintering temperature of the BFO-BT ceramics to 880 ℃, which is far below the melting point of metal electrodes. The BFO-BT based ceramics with 0.5 wt% sintering aids exhibited excellent dielectric, ferroelectric, and piezoelectric properties (εm = 83029, Pm = 38.4 μC/cm2, Pr = 33.8 μC/cm2, d33 = 119 pC/N) with high Curie temperature (TC = 460 ℃). Meanwhile, this ceramic possessed high depolarization temperature (Td) near 300 ℃, demonstrating a good temperature stability of piezoelectricity. This study provides a feasible solution to improve the compatibility of lead-free piezoelectric materials and low-melting point metal electrodes for fabrication of micro piezoelectric devices.

Novel Fused Core Chromophore Incorporating Spirofluorene and Anthracene Groups for Sky-Blue Emission and Solution-Processed White Devices

New blue-light-emitting materials, 2,7-Bis-[1,1′;3′,1″]terphenyl-spiro-fluorene[3,4]naphthalene (TP-AFF-TP) and spiro-fluorene[3,4]-5-terphenylnaphthalene (TP-ASF) were synthesized based on a fused core with anthracene and spirofluorene. The photoluminescence (PL) maximum values of TP-AFF-TP and TP-ASF in film states exhibited 477 nm and 467 nm within the blue region, respectively. Degradation temperature (Td) values for TP-AFF-TP and TP-ASF were very high at 481 °C and 407 °C, respectively. TP-AFF-TP and TP-ASF exhibited power efficiencies (PE) of 1.03 lm/W and 2.39 lm/W, respectively, along with luminance efficiencies (LE) of 2.55 cd/A and 5.17 cd/A, respectively, in nondoped organic light-emitting diode (OLED) devices in which the newly synthesized compounds were employed as emissive layers. The achieved CIE values were (0.25, 0.45) for TP-AFF-TP and (0.17, 0.31) for TP-ASF. Furthermore, when TP-ASF was utilized as one of the emissive materials in solution-processed white OLED devices, the resultant device showcased a notably high LE of 3.13 cd/A, a PE of 2.69 lm/W, and a white CIE value of (0.30, 0.34).

Machine learning-based prediction and interpretation of decomposition temperatures of energetic materials

Exploring the application of machine learning (ML) in energetic materials (EMs) has been a hot research topic. Accordingly, the prediction of the detonation properties of EMs using ML methods has attracted much attention. However, the predictive models for the thermal decomposition temperatures (Td) of EMs have been scarcely reported. Furthermore, the small datasets used in these reports lead to a weak generalization ability of the predictive models. This study created a dataset containing 1022 energetic molecules with Td values of 38–425 ​°C and determined an optimal predictive model through training. The gradient boost machine for regression (GBR) model yielded a coefficient of determination (R2) of 0.65 and a mean absolute error (MAE) of 27.7 for the test set. This study further explored critical features, determining that the prediction accuracy of the models was significantly influenced by descriptors representing molecular bond stability (i.e., the BCUT metrics) and atomic composition (i.e., the Molecular ID). Finally, the analysis of the outlier structure indicated that the model accuracy can be further improved by incorporating features related to molecular interactions. The results of this study help gain a deep understanding of the application of ML in the prediction of EM properties, particularly in dataset construction and feature selection.

A sequential fractionation approach to understanding the physicochemical and functional properties of aqueous and enzyme-assisted aqueous extracted black bean proteins

Black bean proteins were sequentially extracted and characterized to determine the contribution of protein classes to the extractability, thermal behavior, and functionality of protein extracts produced by aqueous (AEP) and enzyme-assisted aqueous extraction processes (EAEP). Osborne fractionation showed that 56% of black bean proteins were water-soluble (albumin-rich), 22% salt-soluble (globulin-rich), 16% alkaline-soluble (glutelin-rich) and 0.65% alcohol-soluble (prolamin-rich). Protein extraction yields of 75 and 81% were achieved by AEP (pH 9.0, 50 °C, 1:10 solids-to-liquid ratio, 60 min) and EAEP (same conditions as AEP with 0.5% (w/w) alkaline protease), respectively. Gel electrophoresis demonstrated differences in the protein molecular weight profile in each fraction, as well as extensive proteolysis of major storage proteins in the EAEP. Proteomics revealed that similar proteins were present among the albumin-, globulin-, and glutelin-rich fractions, but in different proportions to yield distinct protein profiles. AEP and EAEP proteins had similar denaturation temperatures (Td = 92 °C) but were lower than the albumin- and globulin-rich fractions. There was not a clear association between solubility, emulsifying, and foaming properties for the protein classes, which highlighted the complex nature of the protein extracts, as well as potential impacts of the honogemization process on the surface properties of the proteins. Proteolysis significantly increased solubility at pH 4.5 (50 vs. 93%) and decreased foaming capacity at pH 4.5 and 7.0, while emulsifying capacity was not affected. Overall, the results demonstrate that enzyme-assisted extraction is a feasible method to increase black bean protein extractability while retaining thermal stability and modifying some functional properties.

Magnesium ions regulated ovalbumin-lysozyme heteroprotein complex: Aggregation kinetics, thermodynamics and morphologic structure

This study aims to investigate the mechanism of magnesium ions regulated ovalbumin-lysozyme (OVA-LYS) heteroprotein aggregation behavior via aggregation kinetics model, exploring the relationship between differential aggregation behavior and protein molecular structure, intermolecular interactions and thermal stability. Results showed that the aggregation rate (kapp) and maximum absorbance (Amax) of the OVA-LYS heteroprotein complex were located between OVA and LYS. Meanwhile, the thermal denaturation temperature (Td) and denaturation enthalpy (ΔH) were between the values of OVA and LYS as well. Compared with OVA, the thermal stability of the OVA-LYS heteroprotein complex increased owing to the electrostatic interactions between OVA and LYS, resulting in slower aggregation rate and lower aggregation degree. Molecular dynamics simulations revealed the molecular conformational changes during OVA-LYS binary protein binding and the stability of the complex conformation. Moreover, MgCl2 weakened the OVA-LYS interactions through Debye shielding while increasing thermal stability, allowing the two proteins to aggregate into amorphous precipitates rather than spherical coacervates. Overall, this study provides information to further understand the regulation mechanism of proteins differential aggregation behavior by ions.

Comprehensive optimization of piezoelectric coefficient and depolarization temperature in Mn-doped Bi0.5Na0.5TiO3-Bi0.5K0.5TiO3-BaTiO3 lead-free piezoceramics

Lead-free Bi0.5Na0.5TiO3 (BNT) piezoelectric ceramics have the advantages of large coercive fields and high Curie temperatures. But the improvement of piezoelectric coefficient (d33) is usually accompanied by a huge sacrifice of depolarization temperature (Td). In this work, a well-balanced performance of d33 and Td is achieved in MnO2-doped 0.79(Bi0.5Na0.5TiO3)-0.14(Bi0.5K0.5TiO3)-0.07BaTiO3 ternary ceramics. The incorporation of 0.25 mol% MnO2 enhances the d33 by more than 40%, while Td remains almost unchanged (i.e., d33=181 pC/N, Td=184 °C). X-ray diffraction (XRD) shows that an appropriate fraction of the small axis-ratio ferroelectric phase (pseudo-cubic, Pc) coexists with the long-range ferroelectric phase (tetragonal, T) under this MnO2 doping. Piezoelectric force microscopy (PFM) has revealed a special domain configuration, namely large striped and layered macro domains embedded with small nanodomains. This study provides a distinctive avenue to design BNT-based piezoelectric ceramics with high piezoelectric performance and temperature stability.

In-situ measurement of thermal depolarization in tetragonal BS-PT piezoelectric ceramics

High temperature depolarization poses a significant challenge to the practical application of piezoelectric/ferroelectric materials. Determining the depolarization temperature (Td) in such materials is crucial for evaluating their performance under high temperature conditions. Here, we propose a method for observing thermal depolarization by examining the 90º domain switching induced strain. Our results show that the differential thermal expansivities of unpoled and poled tetragonal BiScO3-PbTiO3 (BS-PT) piezoelectric ceramic samples can distinguish between thermal expansion strain and 90º domain switching induced strain. The effectiveness of our proposed method is further confirmed by quantitatively analyzing the 90º domain via X-ray diffraction. Compared to the in-situ resonance-antiresonance impedance spectrum, our method allows for more accurate testing of depolarization temperature, demonstrating significant potential for the direct observation of thermal depolarization in piezoelectric/ferroelectric materials.

Study on preparation and properties of PVDF/CB composite films

Carbon black was often used as a UV stabilizer, due to its ability to absorb high-energy ultraviolet radiation. In this study, carbon black was added to PVDF resin, and PVDF film with carbon black (PVDF/CB composite film) was fabricated using a precision co-extrusion casting mechanism. The properties of the films were characterized by differential scanning calorimetry (DSC), thermogravimetric analyzer (TGA), field emission scanning electron microscope (FESEM), water contact angle (WCA), and universal material testing machine. Furthermore, the DSC results suggested that the melting temperature (Tm) of PVDF/CB composite film was 168.7°C. The TGA results showed that the initial decomposition temperature (Td) of PVDF/CB composite film was 358.9°C. The FESEM observation showed that the surface of the PVDF/CB composite film was smooth without obvious defects. The WCA results indicated that PVDF/CB composite film had good hydrophobicity. In addition, the UV transmittance results presented that PVDF/CB composite film had higher UV aging resistance than that PVDF film.

Valorization of Cellulose-Based Materials from Agricultural Waste: Comparison between Sugarcane Bagasse and Rice Straw.

Sugarcane bagasse and rice straw are major agricultural byproducts often discarded or burned as waste after cultivation, leaving their untapped potential for utilization. In this work, cellulose fibers were extracted from sugarcane bagasse and rice straw using a simple procedure: alkaline treatment with sodium hydroxide, bleaching with sodium hypochlorite, and acid hydrolysis. The obtained cellulosic materials were successfully prepared into milky white and transparent films, of which the transparency slightly decreased with the addition of glycerol. The surface of all the films appeared homogeneous with a random orientation of fibers. The rice-straw (RS) film had a more fragile texture than the sugarcane-bagasse (SBG) film. The FTIR analysis clearly indicated the functional groups of cellulose, as well as glycerol for the films mixed with glycerol. Thermal analysis showed that the native SBG film decomposed at 346 °C, higher than the native RS film (339 °C). The presence of glycerol in the films resulted in slightly lower maximum decomposition temperature (Td,max) values as well as mechanical properties. Regarding water susceptibility, the RS film had a higher percentage than the native SBG and glycerol-mixed SBG films. The extracted cellulose from both sources could form almost spherical-shaped cellulose particles. Thus, through the simple extraction method, sugarcane bagasse and rice straw could serve as excellent sources of cellulose materials for preparing cellulose films and particles, which would be advantageous to the development of cellulose-based materials.

Changes in structural, rheological, and gel properties of egg white protein induced by preheating in the dry state

The knowledge of fundamental rheological concepts is essential to understand the gelling process of egg white proteins (EWP), which can be used to further manipulate the gel performance with desired sensorial attributes. In this study, the rheological and gel properties of EWP as influenced by heating in the dry state were investigated. The structural changes in dry heated EWP (DEWP) were also characterized in terms of morphology, protein stability, and protein microenvironment. The results showed that moderate dry heating induced linear aggregation of DEWP and decreased the denaturation temperature (Td) and enthalpy of denaturation (ΔH). Furthermore, the cross-linking on protein surface led to nonpolar microenvironment of hydrophobic groups, which lays the foundation of improved gel properties. The specific outcomes include the increase in the G'max and the G''max values, k'/k'' values of DEWP dispersions, gel hardness and gumminess of DEWP gels and a decrease in gelation temperature of DEWP dispersions. However, few changes were found in the springiness and cohesiveness of the DEWP gels with increasing dry heating time. Notably, gels prepared with DEWP also had better digestibility. Overall, these results can provide theoretical basis for quality control and sensory evaluation of DEWP in the food industry.

A low dielectric polysiloxane with hydro-oleophobicity and improved mechanical properties based on magnolol derivative crosslinker

With the development of the microelectronics industry and the increasing concern for sustainability, there is an urgent need to prepare low dielectric materials from bio-based feedstocks. In this work, an allylated-magnolol (A-M) was synthesized as a crosslinker for fluorinated polymethylhydrosiloxane (F-PMHS) to obtain a low dielectric polysiloxane (M/F-PSO). M/F-PSO exhibited excellent dielectric properties with a dielectric constant of 2.73 and a dielectric loss of 0.0074 at 100 MHz. This was mainly attributed to the synergistic effect of the hard-polarization CF bond and the hindering molecular stacking structure of biphenyl. In addition, M/F-PSO had good hydro-oleophobicity (θwater = 108° and θglycol = 105°), which is brought about by the low surface energy CF3 and the rigid hydrophobic structure of A-M. The water absorption of M/F-PSO was only 0.13 % after 48 h immersion in deionized water. Owing to the introduction of rigid structure and good dispersion of A-M in F-PMHS, the tensile strength of M/F-PSO was up to 5.00 MPa, which is 432 % higher than that of pure polysiloxane (PSO). Moreover, the thermal stability of M/F-PSO was comparable to that of PSO, with an initial decomposition temperature (Td, 5%) as high as 440.30 °C. These results demonstrated the feasibility of introducing renewable bio-resource magnolol into polysiloxane to prepare low dielectric materials with excellent hydro-oleophobicity and mechanical properties.

Sensitizers of Metal Complexes with Sulfur Coordination Achieving a Power Conversion Efficiency of 12.89.

In the study to improve the light absorption range and intensity of dye sensitizers in the visible region and promote their photovoltaic performance, five novel polymeric metal complexes with sulfur coordination (BDTT-VBT-Ni, BDTT-VBT-Cu, BDTT-VBT-Zn, BDTT-VBT-Cd, and BDTT-VBT-Hg) to be used as D-A-π-A motif dye sensitizers were designed, synthesized, and characterized. In these polymeric metal complexes with sulfur coordination, the metal complexes with sulfur coordination of benzodithiophene derivatives are used as auxiliary electron acceptors, 8-quinolinol derivatives are used as π-bridge and electron acceptors, and thienylbenzene-[1,2-b:4,5-b'] dithiophene (BDTT) are used as electron donors. The effect of different metal complexes with sulfur coordination on the photovoltaic performance of dye sensitizers has been systematically studied. Under AM 1.5 irradiation (100 mW cm-2), the devices of dye-sensitized solar cells (DSSCs) based on five polymeric metal complexes with sulfur coordination exhibited a short-circuit current density (Jsc) of 13.43, 15.07, 18.00, 18.99, and 20.78 mA cm-2, respectively, and their power conversion efficiencies (PCEs) were 7.10, 8.59, 10.68, 11.23, and 12.89%, respectively, and their thermal decomposition temperatures (Td) were 251, 257, 265, 276, and 277 °C, respectively. The result shows that the Jsc and PCE of five polymeric metal complexes increase by degrees, and the PCE of BDTT-VBT-Hg is up to 12.89%, which is because of the strength of the coordination bonds between Ni(II), Cu(II), Zn(II), Cd(II), and Hg(II) and sulfur increases in turn so that the electron-withdrawing ability and electron-transfer ability of auxiliary electron acceptors is enhanced. These results provide a new way to develop stable and efficient metal complexes with sulfur coordination dye sensitizers in the future.

Preparation, characterization, and performance evaluation of composite films of polyvinyl alcohol/ cellulose nanofiber extracted from Imperata cylindrica

In recent years, production of cellulose nanofiber (CNF) from waste materials has achieved great interest owing to their renewable nature, biodegradability, high mechanical properties, economic value, and low density. Because Polyvinyl alcohol (PVA) is a synthetic biopolymer with good water solubility and biocompatibility, the composite material formed of CNF and PVA, is a sustainable way of monetizing to address environmental and economic issues. In this work pure PVA, PVA/CNF0.5, PVA/CNF1.0, PVA/CNF1.5, and PVA/CNF2.0 nanocomposite films were produced using the solvent casting approach with the addition of 0, 0.5, 1.0, 1.5, and 2.0 wt% of CNF concentrations respectively. The strongest water absorption behaviour was found as 25.82% for pure PVA membrane, followed by PVA/CNF0.5 (20.71%), PVA/CNF1.0 (10.26%), PVA/CNF1.5 (9.63%), and PVA/CNF2.0 (4.35%). The water contact angle of 53.1°, 47.8°, 43.4°, 37.7°, and 32.3° was formed between water droplet and the solid-liquid interface of pure PVA, PVA/CNF0.5, PVA/CNF1.0, PVA/CNF1.5, PVA/CNF2.0 composite films respectively. The SEM image clearly shows that a network structure like a tree form at the PVA/CNF0.5 composite film, where the sizes and number of pores are apparent. XRD analysis suggested that unique peaks found at 2θ = 17.5°, 28.1°, 33.4°, and 38° for nanocomposites indicating new crystal plane generated upon cross-linking in presence of malic acid. The maximum loss rate temperature (Td,max) for PVA/CNF0.5, PVA/CNF1.0, PVA/CNF1.5 was determined by TG analysis to be around 273.4 °C. FTIR studies suggested that PVA/CNF0.5 composite film showed the highest peak at 1428 cm−1 as compared to other PVA/CNF composite films representing the presence of higher crystalline band in the composite film matrix. PVA/CNF0.5 composite film was found to have a surface porosity and mean pore size of 27.35% and 0.19 μm respectively, classifying it in the MF membrane category. The maximum tensile strength (TS) of 5.27 MPa was found for PVA/CNF0.5, followed by PVA/CNF1.0, PVA/CNF1.5, pure PVA, and PVA/CNF2.0. The maximum young's modulus (111 MPa) was found for PVA/CNF1.0, followed by PVA/CNF0.5, PVA/CNF2.0, PVA/CNF1.5, and pure PVA, which could be attributed to the cyclization of the molecular structures by cross-linking. PVA/CNF0.5 exhibits greater elongation at break (21.7) than the other polymers, indicating a material's ability to undergo significant deformation before failure. Performance evaluation of the PVA/CNF0.5 composite film showed that 46.3% and 92.8% yield were found in the retentate for 200 mg/L of BSA, and 5 × 107 CFU/mL respectively. However, more than 90% E. coli was retained by PVA/CNF0.5 composite film, therefore absolute rating of this membrane is 0.22 μm. The size of this composite film may be therefore considered in the range of MF.

Preparation and fluorescence performance of high elastic core-shell structure composite fibers based on electrospun nanofibers

Fluorescent fibers with light weight and good mechanical properties provide exciting opportunities for the development of flexible optical sensing textiles. This could accelerate the realization of the wearable technology goal of functional and large area display. Here, we synthesized a polyimide containing 20% pyrene group (Py-20) with excellent fluorescence and thermal properties. Then, fluorescent composite fibers with core–shell structure were prepared by using Py-20 electrospun membrane as surface layer and polyurethane (TPU) fiber as inner layer. The diameter and thickness of surface fluorescent fibers was 500 nm and 100 μm, respectively. Polarized infrared spectra analysis proved that the aggregation of polymer molecular chains in electrospun fiber could be reduced effectively. The DR (DR = I∥/I⊥) values of polymer film and electrospun fibers were 0.7553 and 0.5955, respectively. Therefore, the fiber samples exhibited higher fluorescence intensity than the polymer film. The maximum photoluminescence peaks of electrospun and composite fibers were located at about 595 nm. In addition, thanks to interlaced layered structure of electrospun fibers, the fluorescent composite fiber maintained a relatively uniform morphology at 40.84% (strain) and 4.96 MPa (stress). Importantly, this Py-20/TPU composite fiber could meet the complex weaving process of yarns and display bright yellow-orange colors under ultraviolet light irradiation. Thermal analysis exhibited that the initial decomposition temperature (Td) of composite fiber in the air could reach to 269 °C. This fiber material will become a competitive candidate in smart textiles with the excellent luminescence, mechanical and thermal properties.

Microstructure and composition driven ferroelectric properties of Er3+ doped lead-free multifunctional 0.94Bi0.5Na0.5TiO3-0.06BaTiO3 ceramics

The x mol Er3+ doped 0.94Bi0.5Na0.5TiO3-0.06BaTiO3 (BNT-BT:xEr3+) ceramics were prepared and their microstructure, electric and luminescent properties were systematically investigated. The microstructure, electric and photoluminescent properties of BNT-BT:xEr3+ ceramics are strongly dependent on the Er3+ composition. The crystal parameters and grain sizes of BNT-BT ceramics strongly depend on Er3+ composition due to the different replacement positions of Er3+ with the increase of Er3+ composition. The ferroelectric and dielectric properties are firstly enhanced due to the decrease of crystal defects, and then suppressed because of the decrease of grain size and the phase transition from R3c to P4bm phase with the increase of Er3+ composition. The discharge energy storage density is improved with a relative change of 67.58% for BNT-BT:1.0%Er3+ ceramics. Furthermore, the depolarization temperature Td and the relaxor antiferroelectric temperature TRE are decreased with the increase of Er3+ composition. But the Curie temperature Tm is enhanced for x< 0.6% as the A-site doping limits the transition from ferroelectric to paraelectric phase. The BNT-BT:xEr3+ ceramics exhibit a strong green emission at 548 nm under the excitation of 487 nm light. The investigation provides a new opportunity in exploring electro-optical coupling materials.

Tailoring hydrogen adsorption and desorption properties of Li-doped SV (single vacancy) monolayer h-BN systems using ab initio calculations

This study uses density functional theory (DFT) technique to examine the hydrogen molecules (H2) storage on Li-decorated h-BN monolayer. The results of DFT have proven that Li-doped h-BN system can hold up to 9H2 with the adsorption energy lying in between −0.31 eV and −0.24 eV/H2 at ambient condition. However, the calculated average adsorption energy for 9H2 is −0.240 eV/H2 with hydrogen storage capacity of 5.96 wt.%, which is according to the United States Department of Energy. Partial density of state was computed for each configuration to provide additional justifications for the H2 storage on Li-doped h-BN monolayer. The hybridization shows a significant interaction between H2 and Li atom, and most of their hybrid peaks were observed in the energy range from −7.5 to −1 eV. Moreover, the H2 desorption simulations achieved via the ab initio molecular dynamics. The computed desorption temperature TD is 306 °K, which is a suitable operating temperature. Hence, our research demonstrates that Li-doped h-BN is a thermally stable and viable hydrogen storage material for hydrogen storage systems.

Thermal Behavior of Pea and Egg White Protein Mixtures.

The partial substitution of animal protein by plant protein is a new opportunity to produce sustainable food. Hence, to control the heat treatment of a composite protein ingredient, this work investigated the thermal behavior of mixtures of raw egg white (EW) and a laboratory-prepared pea protein isolate (PPI). Ten-percentage-by-weight protein suspensions prepared with different PPI/EW weight ratios (100/0, 75/25, 50/50, 25/75, 0/100) at pH 7.5 and 9.0 were analyzed by differential scanning calorimetry (DSC) and dynamic rheology in temperature sweep mode (T < 100 °C). The DSC data revealed changes in the thermal denaturation temperatures (Td) of ovotransferrin, lysozyme, and pea legumin, supposing interactions between proteins. Denaturation enthalpy (∆H) showed a high pH dependence related to pea protein unfolding in alkaline conditions and solubility loss of some proteins in admixture. Upon temperature sweeps (25-95 °C), the elastic modulus (G') of the mixtures increased significantly with the EW content, indicating that the gel formation was governed by the EW protein. Two thermal sol-gel transitions were found in EW-containing systems. In particular, the first sol-gel transition shifted by approximately +2-3 °C at pH 9.0, probably by a steric hindering effect due to the presence of denatured and non-associated pea globulins at this pH.