Phase Structure Research Articles

Modulation and Enhancement of Red Luminescence in Ca2GdSbO6: Eu3+ Phosphor by Co-Doping with Bi3.

The double perovskite structure of Ca2GdSbO6 as a fluorescent phosphor matrix material possesses a stable structure, making it an excellent candidate for a matrix material. In this study, single-doped Ca2GdSbO6: Eu3+ fluorescent phosphors and Bi3+ sensitized Ca2GdSbO6: Eu3+, Bi3+ fluorescent phosphor materials were synthesized using the high-temperature solid-state method. The luminescence of this phosphor is based on the 5D0→4F2 transition emission of Eu3+ ions, which occurs at 612nm. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), photoluminescence (PL) spectra, high-temperature fluorescence spectra, and fluorescence decay lifetimes to study the phase structure, optical properties, crystal structure, and chemical purity of the samples. The performance of the single-doped phosphor was significantly improved by the addition of Bi3+ sensitizer. The luminescence intensity increased by nearly 100% compared to Ca2GdSbO6: Eu3+ phosphor, with a quantum efficiency increase of 124%. The thermal quenching activation energy was found to be 0.299eV, and the luminescence intensity remained at 70.3% of room temperature at 453K. These results indicate that the co-doping of Bi3+ has a modulation and enhancement effect on the luminescence of Ca2GdSbO6: Eu3+ red phosphor, showing great potential for application in near-ultraviolet-excited white LED devices.

Role of oxygen vacancy in high-entropy Cu1Zn1Al0.5Ce5Zr0.5Ox for CO2 hydrogenation reaction

High-entropy oxides (HEOs) have garnered significant attention in catalysis due to their excellent redox properties and superior stability. In this study, we prepared and investigated a high-entropy oxide, Cu1Zn1Al0.5Ce5Zr0.5Ox, to elucidate the impact of oxygen vacancy density on the CO2 hydrogenation reaction. Comparisons were made with binary or ternary solid solutions composed of the same cations present in this HEO, and possessing the same phase structure. The HEO exhibits a higher surface oxygen vacancy density as evidenced by Raman spectroscopy and XPS. The increased number of oxygen vacancies significantly increases the active sites and enhances the strength for CO2 adsorption. Combined with kinetic analysis, it is suggested that the enhanced CO2 adsorption leads to improved CO2 conversion on the HEO. Moreover, the formation of oxygen vacancies facilitates H2 dissociation and supply, which is pivotal for methanol formation on the HEO. The stability of the HEO Cu1Zn1Al0.5Ce5Zr0.5Ox surpasses that of the medium entropy oxide, showing no significant deactivation after 100 hours of reaction.

Structure and thermomechanical properties of superlattice-stabilized TiNbTaZrSiAlN high-entropy coating

Stabilizing the phase structure is the prerequisite for obtaining excellent properties of film materials. Here, we construct a multi-layer superlattice structure including high-entropy sublayer to further tailor the structure and properties of Al-containing nitride coating. A fully cubic structure of Ti0.11Nb0.14Ta0.13Zr0.14Si0.09Al0.39N/Ti0.55Al0.45N (HEN_M) multilayer is realized by stabilizing the cubic/wurtzite-mixed Ti0.11Nb0.14Ta0.13Zr0.14Si0.09Al0.39N (HEN) sublayers with the cubic Ti0.55Al0.45N template layers. The coherent interface strain increases the hardness to 37.5 ± 1.1 GPa for HEN_M in comparison with the corresponding monolithic coatings with 28.2 ± 0.9 GPa for Ti0.55Al0.45N and 22.2 ± 0.7 GPa for HEN. Simultaneously, the HEN_M multilayer shows the optimal Vickers indentation toughness. All coatings exhibit age-hardening characteristics stemming from the spinodal decomposition. Compared to Ti0.55Al0.45N reaching its peak hardness of ∼32.9 ± 0.9 GPa at 900°C, the sluggish diffusion effect promotes HEN and HEN_M maintaining the maximum hardness of ∼25.6 ± 0.8 GPa and ∼39.6 ± 0.9 GPa upon annealing to 1100 and 1000°C, respectively. In addition, exposed to synthetic air at 850°C for 10 h, Ti0.55Al0.45N coating has been completely oxidized, whereas the HEN and HEN_M coatings only experience partial oxidation with oxide scales of ∼1.52 and 0.78 μm.

First-principles study of binary and ternary phases in Mg-Gd-Ni alloys

Given the high demand for magnesium alloys across industries, it's crucial to enhance their performance by developing alloys with superior characteristics. The performance of magnesium alloys is closely related to the properties of the precipitated phase. However, there has been insufficient exploration of the mechanical properties of precipitated phases in Mg-Gd-Ni alloys. Hence, this paper calculates the formation energy, electronic structure, elastic modulus, and elastic anisotropy of the precipitated phase in Mg-Gd-Ni alloys using first principles. Calculations of formation energies and elastic constants demonstrate that MgGdNi4, Mg2Ni, 18R-LPSO, Mg2Gd, and 14H-LPSO possess commendable thermodynamic and mechanical stability. Elastic modulus calculations reveal a significant increase in the elastic modulus of magnesium, especially the bulk modulus, upon the addition of Gd and Ni elements, increasing from 34.5 GPa to a peak of 84.9 GPa. Furthermore, the strength increments of the corresponding precipitated alloys, calculated based on the elastic modulus, underscore MgGdNi4 as exhibiting the most significant strength increment. The elastic anisotropy of each second phase is evaluated using the elastic anisotropy factor, the three-dimensional surface, and the projection onto each two-dimensional plane. The order of elastic modulus anisotropy for shear and Young's modulus is MgGdNi4 > Mg2Ni > 18R-LPSO > Mg2Gd > 14H-LPSO. This study provides valuable data for regulating properties in magnesium alloys.

Strategic decolorization of rose bengal in an aqueous environment using a zinc oxide-loaded reduced graphene oxide photocatalyst

The environmental and health hazards posed by synthetic organic dyes, such as Rose Bengal, have spurred significant concern in recent years. Herein, a novel zinc oxide/reduced graphene oxide (ZnO/rGO)-based photocatalyst is developed and used for the efficient decolorization of RB dye in aqueous solutions. The as-synthesized nanostructured material is characterized using advanced techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX) mapping to elucidate its crystalline structure, morphology, and elemental composition. The XRD pattern confirmed the wurtzite crystalline phase structure with an average size of 67.8 nm, while SEM imaging verified the successful incorporation of ZnO nanoparticles into the rGO matrix. Further, the as-prepared material was used as a photocatalyst, which demonstrated remarkable performance in RB dye decolorization, achieving ≥96.1 % degradation within just 5 min at a minimal catalyst dosage of 8.0 mg. Moreover, kinetic studies revealed that the decolorization process followed a pseudo-second-order reaction mechanism, further enhancing the understanding of the catalytic behavior. It is more interesting that the catalyst exhibited exceptional reusability for up to seven cycles with only a decrease in catalyst efficiency from 96.1 % to 77.5 %, underscoring its practical viability and sustainability. The significance of this work lies in its contribution to addressing the environmental challenges associated with synthetic dyes, particularly rose bengal, by offering an efficient and reliable photocatalytic solution. The demonstrated efficacy of the ZnO/rGO photocatalyst not only showcases its potential for large-scale rose bengal dye degradation but also suggests broader applicability for the treatment of other synthetic dye pollutants.

Physical, rheological and micro characteristics of ARA/Nano-TiO2 composite modified asphalt before and after short-term aging

This paper aims to investigate the composite application of nanomaterials and natural asphalt in order to enhance the road performance of asphalt pavement. The objective is to develop high-performance modified asphalt that improves the durability, reliability, and load resistance of asphalt roads while reducing resource waste and environmental pollution. The composite modified asphalt was prepared by adding different blends of Albanian natural rock asphalt (ARA) and 1% of nano titanium dioxide (Nano-TiO2), and the basic properties and rheological properties of the asphalt before and after aging were tested by using basic performance tests and temperature scanning tests. Subsequently, the microscopic morphological characteristics of the asphalt were observed by scanning electron microscope and atomic force microscope, and the number of bee structures, the area share of bee structures, root mean square roughness Rq, and arithmetic mean roughness Ra were used as microscopic quantitative indexes. The results indicate that the complex modulus and rutting coefficient of ARA/Nano-TiO2 composite-modified asphalt increase with an increase in ARA dosage when the dosage of Nano-TiO2 is 1%. The asphalt modified with Nano-TiO2 composite blended with 15% ARA exhibits higher residual needle penetration, composite modulus ratio, rutting coefficient ratio and lower softening point increment compared to 70# asphalt. The bitumen modified with titanium dioxide nanocomposite blended with 15% ARA exhibits higher Rq and Ra and a more stable phase structure before and after aging. 15% of ARA/Nano-TiO2 composite-modified asphalt has higher Rq and Ra before and after aging, and its phase structure is more stable. The results show that ARA/Nano-TiO2 composite-modified asphalt has better high-temperature deformation resistance and aging resistance than 70# and that 15% ARA is recommended as the optimum amount of composite-modified asphalt.

Tuning phase structure for enhanced electrostrain in Nb5+-doped Bi0.5(Na0.81K0.19)0.5TiO3 lead-free piezoelectric ceramics

The synthesis of Bi0.5(Na0.81K0.19)0.5Ti1−xNbxO3 (BNKT-xNb) lead-free piezoelectric ceramics via the traditional solid-state method, with varying x from 0.5 % to 4.0 %, is reported. Investigating the influence of Nb5+ ions on dielectric, ferroelectric, and electrostrain properties, alongside assessing the temperature stability of electrical properties, unveiled a notable electrostrain of 0.46 % at room temperature under 80 kV/cm for the 2.0 mol.% Nb5+ doped composition. The incorporation of Nb5+ prompted a transition from the ferroelectric to the relaxor phase, facilitating reversible induction into the ferroelectric phase under an external electric field, leading to the observed large electrostrain. Leveraging the first-order reversal curve (FORC) approach, a detailed analysis of the dynamic response process of different phase structures under the influence of the external electric field was conducted. This analysis elucidated that the continuous polarization response near the boundary of ferroelectric and relaxor phases, induced by the external electric field, primarily drives strain enhancement. These findings underscore the effective modulation of phase structure through Nb5+ doping, offering significant advancements in strain properties. This study opens avenues for the utilization of the material in micro actuators and provides valuable insights for the development of high-performance lead-free piezoelectric ceramics.

The critical role of titanium cation for the enhanced Na-ion layer spacing of O3 layered oxide cathode materials

O3-NaNi1/3Fe1/3Mn1/3O2 layered cathode material has been widely concerned by the industry for its advantages of simple preparation, low cost and high theoretical specific capacity. However, due to a series of surface side reactions, some transition metal ions are reduced, resulting in structural Jahn-Teller distortion, leading to poor structural stability. Herein, Ti element is introduced into O3-NaNi1/3Fe1/3Mn1/3O2 cathode material, and the effect of Ti doping on the phase structure and electrochemical properties of the material is analyzed in detail. The results show that Ti doping can enlarge the Na layer spacing and decrease the transition metal layer spacing. Thus, the modified material has a smaller Na ion diffusion barrier and a more stable structure. These advantages give a sample with a doping rate of 2.5 wt% a rate capacity of 74.8 mAh g−1 at 10 C, a capacity retention rate of 86.2 % after 100 cycles at 1 C, and an energy density of 320.5 Wh kg−1 for a full cell structure using a hard carbon anode. This strategy provides a valuable reference for cationic doping to improve the properties of O3 layered transition metal oxides.

Achieving high energy-storage density and high temperature and frequency stability in 0.88BT-0.12BMT lead-free relaxor ferroelectric ceramics via NaNbO3 doping

In this work, 0.88BaTiO3-0.12Bi(Mg1/2Ti1/2)O3-xmol% NaNbO3 (x = 0, 0.5, 1, 1.5, 2) ceramics have been synthesized by using the traditional solid-state route. The effects of NaNbO3 on the phase structure, microstructure, dielectric, ferroelectric, and energy storage properties of the 0.88BaTiO3-0.12Bi(Mg1/2Ti1/2)O3 ceramics have been studied in detail. The ceramic doped with 1.5 mol% NaNbO3 exhibited a releasable energy storage density of 2.287 J/cm3, significantly higher than the undoped sample (1.194 J/cm3). The breakdown strength increases from 130 kV/cm for the undoped sample to 210 kV/cm for the sample doped with 1.5mol% NaNbO3. The enhanced breakdown strength of the 0.88BaTiO3-0.12Bi(Mg1/2Ti1/2)O3-xmol% NaNbO3 ceramics is primarily due to NaNbO3 doping, which produces a wider bandgap, smaller grain size, and higher specific resistance. The 0.88BaTiO3-0.12Bi(Mg1/2Ti1/2)O3-xmol% NaNbO3 ceramic's energy storage performance exhibits great temperature stability, frequency stability, and cycle stability at 120 kV/cm.

Synthesis of a TiO2/zeolite composite: Evaluation of adsorption-photodegradation synergy for the removal of Malachite Green

Preparing by a simple method a versatile and sustainable material that can simultaneously perform effectively as an adsorbent/photocatalyst is a real challenge in wastewater treatment technology. In this work, a composite with 10% (wt%) TiO2 nanoparticles supported on zeolite (TiO2-Zeo) was synthesized by a facile-solid-state dispersion method, and characterized for their physicochemical, phase structure, microstructure, and optical properties. Characterization findings, showed that, for TiO2-Zeo catalyst, the zeolitic matrix preserved its initial structure without any alteration, while its gap energy of 3.23 eV was similar to that of the starting TiO2 material, showing that TiO2 nanoparticles were simply deposited on the surface of the zeolite support. TiO2-Zeo photocatalyst, as well as commercial TiO2 nanoparticles, tested here as a photocatalyst model in view of comparison, were used for the removal of Malachite Green dye (MG) from aqueous solution. The adsorption and photodegradation potential of the catalysts was evaluated under the same operating conditions. It was found that the adsorption kinetics for the two materials were relatively slow, and the pseudo-first-order model can describe accurately the adsorption kinetics data. The equilibrium states were reached after 140 min and 150 min for MG/TiO2-Zeo and MG/TiO2 systems. At 0.5 g.L-1 dose of TiO2-Zeo, the adsorption capacity of MG at equilibrium, and the removal efficiency obtained with 25 mg.L-1 and 35 mg.L-1 were 41.2 mg.g-1 (82.3%), and 46.9 mg.g-1 (65.6%), respectively. Whereas, after 240 min UV irradiation, the obtained values in synergistic adsorption-photodegradation dye removal were superior, namely 47.4 mg.g-1 (92.7%) and 63.6 mg.g-1 (90.2%), respectively. On the other hand, within the range of operating conditions considered, the overall kinetic rate of synergistic adsorption-photodegradation was also simulated using the modified Elovich heterogeneous kinetic model in the two following scenarios: for strong and weak adsorption. Based on the goodness-of-fit criteria values obtained with the two used catalysts, the model appeared globally very consistent with kinetic data in both cases, with a perfect agreement in the strong adsorption case.

Novel injectable calcium-magnesium phosphate cement-based composites with piezoelectric properties: advancements in bone regeneration applications

Designing a novel injectable bone cement is an important approach to the success of bone healing in minimally invasive surgeries. As natural bone has a piezoelectric property, which is crucial in bone regeneration, this study focused on the development of a novel injectable composite bone cement with piezoelectric properties. For the composite composition, calcium and zirconium doped barium titanate (BCZT) was used for its piezoelectric property, while calcium phosphate and magnesium phosphate cement (CMPC) were preferred for its bone-like properties. In this framework, first BCZT, CMPC, and their composites were prepared, and their phase structures, particle size distributions, and piezoelectric and dielectric properties were investigated. Then, the composite bone cements were prepared by mixing CMPC with BCZT in three different ratios (20%, 30%, and 40%). Next, polysorbate 80 solution was added to the cement mixtures to prepare the injectable pastes. Finally, injectability, setting time, and compressive strength of the composites were assessed. As a result, the composite bone cement containing 30% BCZT has the potential to be used as an injectable bone cement in invasive orthopedic surgery.

Experimental and DFT investigations of Al-doped ZnO nanostructured thin films

Al doped ZnO thin films at different concentrations have been successfully synthesized, characterized experimentally, and investigated theoretically by density functional theory (DFT). The crystal structure analysis was carried out using X-ray diffraction (XRD) data. Wurtzite structures of a single phase with a preferred orientation along the (002) plane are obtained. The surface morphology has been investigated by atomic force microscopy (AFM) which showed homogeneous and compact surfaces with spherical shape grains that change to a wave like nematic structure with increasing Al doping rate. For a complete characterization, experimental and theoretical analysis of optical and electrical properties have been done using UV–Vis spectrophotometry, the four-probe method, electronic band structure and density of states calculations, and the Boltz-Trap code based on the semi classical theory of Boltzmann. Both, experimental and theoretical, studies indicate an increase in gap energy with high transparency in the visible region and electrical conductivity improvement due to a non-localized state around the Fermi level. The experimental and theoretical studies agree well and show a similar tendency of the results. Therefore, these properties of Al-doped ZnO open a new avenue for optoelectronic and photonic device applications.

Effects of carbon concentration on the local atomic structure of amorphous GST.

Ge-Sb-Te (GST) alloys are leading phase-change materials for data storage due to the fast phase transition between amorphous and crystalline states. Ongoing research aims at improving the stability of the amorphous phase to improve retention. This can be accomplished by the introduction of carbon as a dopant to Ge2Sb2Te5, which is known to alter the short- and mid-range structure of the amorphous phase and form covalently bonded C clusters, both of which hinder crystallization. The relative importance of these processes as a function of C concentration is not known. We used molecular dynamics simulation based on density functional theory to study how carbon doping affects the atomic structure of GST-C. Carbon doping results in an increase in tetrahedral coordination, especially of Ge atoms, and this is known to stabilize the amorphous phase. We observe an unexpected, non-monotonous trend in the number of tetrahedral bonded Ge with the amount of carbon doping. Our simulations show an increase in the number of tetrahedral bonded Ge up to 5 at.% C, after which the number saturates and begins to decrease above 14 at.% C. The carbon atoms aggregate into clusters, mostly in the form of chains and graphene flakes, leaving less carbon to disrupt the GST matrix at higher carbon concentrations. Different degrees of carbon clustering can explain divergent experimental results for recrystallization temperature for carbon doped GST.

Influence of glass-phase structure on the degradation of rare-earth (Y2O3, La2O3)-doped CaO–Al2O3–SiO2–B2O3 glass-ceramics in citric acid solution

Liquid-phase sintering anorthite (LSA) glass-ceramics with degradation in citric-acid solution have been prepared from CaO–Al2O3–SiO2–B2O3 low-melting compositions. By means of the chemical corrosion of the glass phases, LSA glass-ceramics are effectively degraded in the citric acid solution. Then, the influence of B2O3 and rare-earth (RE) on the structures of glass phases, the degradation of LSA glass-ceramics in the citric-acid solutions, and the dielectric properties are investigated systematically. The results suggest that when the B2O3 molar ratio in the composition CaO–Al2O3–SiO2–B2O3 is 0.5, doping LSA glass-ceramics with RE can reduce the quantity of bridging oxygen and [BO4] units in the glass phase, as well as the degree of network connection of [AlO4] units in the glass network. Conversely, when the B2O3 molar ratio is decreased down to 0.3, doping RE into LSA glass-ceramics increases the quantity of bridging oxygen and [BO4] units for glass phase. This improvement in chemical stability effectively impedes the degradation of LSA glass-ceramics in citric-acid solutions. Concurrently, the degradation mechanism of LSA glass-ceramics in citric acid solution is analyzed and explained in terms of classical glass corrosion theory, while the microstructural characteristics of LSA glass-ceramics are utilized to investigate their dielectric properties. It indicates that the dielectric loss and dielectric constant of LSA glass-ceramics are significantly lowered as a result of the existence of the glass phase. Especially when the B2O3 molar ratio in the composition CaO–Al2O3–SiO2–B2O3 is 0.3, and the La2O3 doping percentage into LSA glass-ceramics is 0.5 wt%, the LSA glass-ceramics exhibit the lowest dielectric loss value of 3.13 × 10−3 and εr = 4.17. Developing the LSA glass-ceramic with degradation in organic acids can provide a new idea for the recycling and disposal of e-waste.

Influences of strain rate on mechanical behaviors of unsaturated and quasi-saturated loess under varying drainage conditions

Although time-dependent deformation of geomaterials underpins slope-failure prediction models, the influence of strain rate on shearing strength and deformation behavior of loess remains unclear. The consolidated undrained (CU) and drained (CD) triaxial testing elucidated the impact of strain rate (0.005–0.3 mm/min) on strength envelopes, deformation moduli, pore pressures, and dilatancy characteristics of unsaturated and quasi-saturated loess. Under drained conditions with a controlled matric suction of 50 kPa, increasing strain rates from 0.005 mm/min to 0.011 mm/min induced decreases in failure deviatoric stress (qf), initial deformation modulus (Ei), and cohesion (c), while friction angles remained unaffected. Specimens displayed initial contractive volumetric strains transitioning to dilation across varying confining pressures. Higher rates diminished contractive volumetric strains and drainage volumes, indicating reduced densification and strength in the shear zone. Under undrained conditions, both unsaturated and quasi-saturated (pore pressure coefficient B = 0.75) loess exhibited deteriorating mechanical properties with increasing rates from 0.03 mm/min to 0.3 mm/min. For unsaturated loess, reduced contractive volumetric strains at higher rates manifested relatively looser structures in the pre-peak stress phase. The strength decrement in quasi-saturated loess arose from elevated excess porewater pressures diminishing effective stresses. Negative porewater pressures emerged in quasi-saturated loess at lower confining pressures and strain rates. Compared to previous studies, the qf and Ei exhibited rate sensitivity below threshold values before attaining minima with marginal subsequent influence. The underlying mechanism mirrors the transition from creep to accelerated deformation phase of landslides.

Simultaneously improving thermal conductivity, mechanical properties and metal fluidity through Cu alloying in Mg-Zn-based alloys

Mg-Zn-based alloys have been widely used in computer, communication, and consumer (3C) products due to excellent thermal conductivity. However, it is still a challenge to balance their mechanical performance and thermal conductivity. Here, we investigate microstructure, mechanical performance, thermal conductivity and metal fluidity of Mg-5Zn (wt.%) alloy after Cu alloying by experimental and simulation methods. First, Mg-5Zn alloy consist of α-Mg matrix and interdendritic MgZn phases. As the Cu content increases, however, MgZn phases disappear but intragranular Mg2Cu and interdendritic MgZnCu phases appear in Mg-5Zn-Cu alloys. Besides, the grain size of α-Mg phase is refined and the volume fraction of MgZnCu phase increases as the Cu content increases. Second, Cu addition is found to improve thermal conductivity of Mg-5Zn alloy remarkably. Especially, Mg-5Zn-4Cu alloy exhibits the best thermal conductivity of 124 W/(m·K), which is mainly due to the significant reduction in both solid solubility of Zn in the α-Mg matrix and lattice distortion of α-Mg matrix. Moreover, a stable crystal structure of MgZnCu phase also contributes to an increased thermal conductivity based on first principles and molecular dynamics simulations. Third, Cu addition simultaneously enhances strength and ductility of Mg-5Zn alloy. Tensile yield strength and elongation of Mg-5Zn-6Cu alloy reach 117 MPa and 18.0 %, respectively, which is a combined result of refinement, solution, second phase, and dislocation strengthening. Finally, combined with a phase field simulation, we found that Cu addition enhances metal fluidity of Mg-5Zn alloy. On the one hand, Cu alloying not only delays dendrite growth but also prolongs solidification time. On the other hand, MgZnCu phase stabilizes the dendrite growth of the α-Mg phases by reducing energy consumption during solidification of liquid metal. This work demonstrates that Cu alloying is an ideal strategy for synergistically improving the thermal conductivity, mechanical performance and metal fluidity of Mg-based alloys.

Cholesteric liquid crystal phase variations within nanotubes: an in-depth analysis of the influences of twist radius and molecular pitch

ABSTRACT This study investigates the self-assembly and phase transitions of cholesteric liquid crystals (CLCs) when confined in nanotubes, specifically focusing on the variations in their molecular structures. A dissipative particle dynamics method was used to investigate how the changes in helix radius ( r LC ) and pitch ( P ) affect the behaviour of the LCs. For pitches of 24, 12, and 6, the orientation order parameter ( P 2 ) showed distinct trends during cooling. Smaller helix radii resulted in isotropic to nematic to smectic phase transitions, whereas larger radii resulted in a novel smectic phase with spiral structures (Sm s ). Circumferential local-order parameters ( P 2 r and P 2 z ) were introduced to better characterise the phases, and a disordered spiral-structure phase (Sm s 2 ) with local perturbations was observed. The transitions between isotropic, nematic, and smectic phases, highlighting the influence of the pitch and helix radius, were observed from the phase diagrams. Smaller pitches and radii prevented the formation of stable structures; however, specific combinations induced characteristic spiral structures in the smectic phase. These results provide new insights into the self-assembly of confined CLCs, which have potential applications in the design of photonic devices and LC-based sensors. This study advances our understanding of phase control in quasi-one-dimensional systems and highlights the importance of molecular variations in liquid crystal behaviour.

Tuning the Poisson’s ratio of two-dimensional model network materials with application to 2D-silica bilayer structures

A fundamental understanding of the elastic properties of 2D network structures is highly beneficial for research and applications of 2D materials. In this context, Poisson’s ratio has been studied elaborately for different crystallographic structures of crystalline phases of bilayer silica structures. This paper focuses on the elastic structure–property relationship of crystalline and vitreous polymorphs of plane network materials. We generate defective crystalline network states and seven sets of disordered states, each with a different level of network heterogeneity, using a dual Monte Carlo bond switching algorithm. Firstly, uniaxial tensile deformation is applied to a model material in a two-dimensional framework, concentrating only on the in-plane network topologies. Secondly, uniaxial tensile deformation is applied to bilayer silica structures, considering the out-of-plane morphology of the material. Mechanical testing is performed using the athermal quasistatic deformation protocol, which allows one to study the influence of the network topology exclusively without any thermal disturbances. We show that manipulating the network heterogeneity allows one to directly tune the Poisson’s ratio of the material, creating possibilities for novel mechanical applications.

Fabrication of Highly Sensitive Electrochemical Sensor Based on Chromium-Doped Ferrite Nanoparticles: Hybrid Graphene Nanosheets for the First Voltammetric Determination of Asenapine Maleate in Formulations and Human Plasma

Ferrite nanoparticles are interesting materials given their unique physical and chemical properties and wide applications. A novel electrochemical sensor based on a series of chromium-nano-ferrites {Fe3+[Fe2+Fe3+ (1-x)Cr3+ x ]O4; x (0.0–1.0} was fabricated for determination of Asenapine maleate (ASE.M). X-ray diffraction revealed the formation of crystallite nano-particles of lattice constant of (8.299–8.345 Å) with a single phase of cubic inverse spinel structures. Particle size and specific surface area were (9.10–27.60 nm) and (60–175 m2g−1) using Transmission electron microscopy and Brunnauer-Emmett-Teller (BET) analysis, respectively. Among this Cr x Fe(3−x)O4 series, (CrFe2O4; x = 1) was appeared to get the smallest particles size and highest BET surface area. The charge transfer resistance (RCT) of (2220, 1680, 765, and 490 Ω) were achieved for Cr x Fe(3−x)O4 NPs/CPE (x = 0.0, 0.4, 0.8, and 1.0), respectively. CrFe2O4 performance was then improved via incorporation of 2D-graphene atomic crystals in a new ferrite-graphene nanocomposite of [0.25%(w/w) CrFe2O4 NPs: 7%(w/w) graphene nanosheets]. The feasibility of this sensor is achieved for determination of ASE.M in brand Saphris® and local Asenapine pharmaceutical products. In addition, a wide linear concentration range of (6.5 × 10−9–1.0 × 10−6 M) with LOD value of 8.88 × 10−10 M were achieved in human plasma.

Characterization of microstructures and mechanical properties of laser welded TWIP steel plate

In the present study, laser welding of medium-thick TWIP steel plates was studied and the microstructures and mechanical properties of the welded joints obtained at varied welding speeds were characterized. It is shown that a full penetration was achieved in the welded joint, which exhibits a keyhole-shaped configuration. The welded joint displays a single austenitic phase and typical solidification structure composed of cellular, columnar and dendrite grains. With increasing the welding speed, the grains in both the central fusion zone and adjacent heat-affected zone were refined. The latter was attributed to inadequate recrystallization because of decreased heating time at elevated welding speed. The mechanical properties of all welded joints were lower than those of base metal, in which the decline of elongation was more serious than that of strength. This is attributed to the formation of thick columnar crystals and the Al2O3 core-shell structured nanoscale precipitates in the grains of the fusion zone. Moreover, there existed a certain degree of non-uniformity in the microstructures and mechanical properties along the thickness direction of welding seam, and the samples in the upper area of welding seam showed better comprehensive properties than the lower ones. When welded at a moderate speed as 1.0 m/min, the welding seams exhibited the best mechanical properties and the least difference across the thickness direction of the welding seam. This is because the moderate welding speed resulted in the most beneficial macro- and micro-structures as well as grain boundary characteristics.