Crystals, Volume 13, Issue 9 (September 2023) – 116 articles

The title compound was prepared by reaction of the Schiff base ligand N-(2-hydroxy-1-naphthylidene)leucine with dichlorodimethylsilane in the presence of triethylamine as base. The resulting pentacoordinate silicon complex was characterized by NMR, IR, UV-Vis spectroscopy and melting point. The structure was confirmed by single-crystal X-ray diffraction data. It crystallizes in the monoclinic space group Ic with unit cell dimensions a = 7.2030(6), b = 22.9842(14), c = 10.8946(12) Å, β = 96.141(7)°, V = 1793.3(3) ų, Z = 4. Full article

Chalcones are α,β-unsaturated ketones with great structural diversity and various applications. A chalcone produced by condensation of 2-acetylpyridine with 2-naphthaldehyde (L) was employed for synthesis of two mononuclear complexes: [Eu(L)(hfac)₃(H₂O)]·0.5CHCl₃ and [Tb(L)(hfac)₃], where hfac is the hexafluoroacetylacetonate anion. The chalcone and complexes were structurally characterized by single-crystal X-ray diffraction. The chalcone acts as a chelating bidentate ligand. Luminescent properties of the ligand L and the complexes were investigated in the solid state. For these heteroleptic mononuclear complexes, the emission of the Eu(III) and Tb(III) ions was influenced by the excitation wavelength. Full article

The influence of Yb³⁺ cations substitution for Pr³⁺ on the structure and catalytic activity of (Pr_1−xYb_x)₂Zr₂O₇ powders synthesized via coprecipitation followed by calcination is studied using a combination of long- (s-XRD), medium- (Raman, FT-IR, and SEM-EDS) and short-range (XAFS) sensitive methods, as well as adsorption and catalytic techniques. It is established that chemical composition and calcination temperature are the two major factors that govern the phase composition, crystallographic, and local-structure parameters of these polycrystalline materials. The crystallographic and local-structure parameters of (Pr_1−xYb_x)₂Zr₂O₇ samples prepared at 1400 °C/3 h demonstrate a tight correlation with their catalytic activity towards propane cracking. The progressive replacement of Pr³⁺ with Yb³⁺ cations gives rise to an increase in the catalytic activity. A mechanism of the catalytic cracking of propane is proposed, which considers the geometrical match between the metal–oxygen (Pr–O, Yb–O, and Zr–O) bond lengths within the active sites and the size of adsorbed propane molecule to be the decisive factor governing the reaction route. Full article

Multiferroics are materials crucial for energy-efficient scalable electronics. The implementation of an effective combination of ferroic orderings on the nanoscale requires the design of new multiferroic materials. Recently, there have been observations of magnetoelectricity in the antiferromagnetic Ruddlesden-Popper and perovskite oxides with the interfacial Dzyaloshinskii-Moriya interaction. We propose a model for studying magnetic states and magnetoelectric effects in magnetoelectrically coupled antiferromagnetic–ferroelectric bi-layers with the interfacial Dzyaloshinskii–Moriya interaction. The ground magnetic states are calculated for a system on a rectangular lattice, with Heisenberg spins interacting with each other via an antiferromagnetic exchange interaction and a Dzyaloshinskii–Moriya interaction in the absence of an external magnetic field. Our calculations show that the interfacial Dzyaloshinskii-Moriya interaction in the considered system leads to the stabilization of topological skyrmionic states in a zero magnetic field. We explore transformations of magnetic states considering the changes in the in-plane magnetic anisotropy constant and the magnetoelectric coupling parameter. Our findings have shown the possibility of the existence of several magnetic configurations: a skyrmion lattice, a skyrmion state, and a uniform antiferromagnetic ordering realized at a definite ratio of the system parameters. We determine the areas of the phases existence and the conditions required for spin-reorientation phase transitions. Full article

Bismuth-based oxides with chemical formula ABiO₃, where A = Ca, Zn, Mg, have been recently synthesized and suggested to host ferroelectricity. As these materials possess favorable optical properties, the presence of ferroelectricity with large polarization would further enhance the possible applications, for example, in photovoltaics by improving the separation of charge carriers. In this work, first-principles Density Functional Theory (DFT) calculations are performed to study the relative stability of the different polymorphs and to investigate the structural, electronic, and ferroelectric properties. Furthermore, the effect of compressive and tensile in-plane strain on the polarization and electronic properties is also considered. Our study suggests that CaBiO₃ should have a large electric polarization (1.8 C/m²) comparable to the one of BiFeO₃. Interestingly, the very high polarization appears with only slightly anomalous values of Born effective charges, which would point out a dominant ionic contribution. Our results call for further studies, both from experimental and theoretical sides, to confirm the large electric polarization CaBiO₃ predicted in this work. For ZnBiO₃ and MgBiO₃, we have demonstrated that, up to large values of strain, the perovskite structure retains favorable ferroelectric and electronic (band gap) properties. Full article

Both intensity and phase information are needed for structure determination by macromolecular X-ray crystallography. The diffraction experiment provides intensities. Phases must be accessed indirectly by molecular replacement, or by experimental phasing. A popular method for crystallising membrane proteins employs a lipid cubic mesophase (the in meso method). Monoolein is the most popular lipid for in meso crystallisation. Invariably, the lipid co-crystallises with the protein recapitulating the biomembrane from whence it came. We reasoned that such a lipid bearing a heavy atom could be used for experimental phasing. In this study, we replaced half the monoolein in the mesophase with a seleno-labelled analogue (Se-MAG), which has a selenium atom in the fatty acyl chain of the lipid. The lipid mixture formed the cubic mesophase and grew crystals by the in meso method of the alginate transporter, AlgE, and the lipoprotein N-acyltransferase, Lnt. Se-MAGs co-crystallised with both proteins and were used to obtain phases for high-resolution structure determination by the selenium single-wavelength anomalous diffraction method. The use of such a mixed lipid system may prove to be a general strategy for the experimental phasing part of crystallographic structure determination of membrane proteins that crystallise via the in meso method. Full article

A series of solid acid compounds, representing the large family M_mH_n(AO₄)_{(m + n)/2}·yH₂O (where M = K, Rb, Cs, NH₄; AO₄ = SO₄, SeO₄, HPO₄, HAsO₄), is characterized by high values of own proton conductivity, which arises as a result of a phase transition through the formation of a dynamically disordered hydrogen bond network. Such superprotonic phase transitions are observed, however, not for all compounds of the family and Rb₃H(SO₄)₂ is one of them. The occurrence of superprotonic phase transitions has been experimentally demonstrated in the (K_xRb_1−x)₃H(SO₄)₂ solid solutions through cation substitution. The high-temperature phases are unstable towards decomposition reaction, and their temperature range of existence is about 1–7 °C. The implementation of superprotonic transitions is discussed in terms of hydrogen bond lengths. Full article

In this study, the results of hydrogen plasma treatments of β-Ga₂O₃, α-Ga₂O₃, κ-Ga₂O₃ and γ-Ga₂O₃ polymorphs are analyzed. For all polymorphs, the results strongly suggest an interplay between donor-like hydrogen configurations and acceptor complexes formed by hydrogen with gallium vacancies. A strong anisotropy of hydrogen plasma effects in the most thermodynamically stable β-Ga₂O₃ are explained by its low-symmetry monoclinic crystal structure. For the metastable, α-, κ- and γ-polymorphs, it is shown that the net result of hydrogenation is often a strong increase in the density of centers supplying electrons in the near-surface regions. These centers are responsible for prominent, persistent photocapacitance and photocurrent effects. Full article

In recent years, “Jin Gao Yu” that has been traded as a kind of jade has appeared in areas of the Luonan and Shangnan counties, Shangluo City, Shaanxi Province, attracting the attention of scholars and consumers for its delicate texture and warm color. In this study, infrared spectroscopy, Raman spectroscopy, X-ray diffraction analysis, and electron microprobe analysis were used to conduct a systematic gemmological test and an analysis of “Jin Gao Yu”. The results show that “Jin Gao Yu” is a compact mineral aggregate dominated by dolomite, which contains quartz mineral inclusions. The color of “Jin Gao Yu” is grayish-white to earthy-yellow, the refractive index is about 1.54, and the relative density is about 2.86. Its crystal structure is basically the same as that of dolomite, both of which are trigonal systems with granular crystalloblastic textures. It has good crystallinity. The recrystallization phenomenon can be seen under a polarizing microscope. This study determined the species of “Jin Gao Yu”, improved its gemological basic data, provided a theoretical basis for the identification of “Jin Gao Yu” in the future, and, also, provided a new direction for the use of dolomite. Full article

This paper introduces a two-dimensional (2D) numerical simulation of the amplification of space charge waves using negative differential conductance in a typical MOS silicon–germanium (SiGe)-based field-effect transistors (FET) and complementary metal oxide semiconductor (CMOS) technology at 4.2 K. The hydrodynamic model of electron transport was applied to describe the amplification of space charge waves in this nonlinear medium (i.e., the negative differential conductance). This phenomenon shows up in GaAs thin films at room temperature. However, this can be also observed in a strained Si/SiGe heterostructure at very low temperatures (T < 77 K) and at high electric fields (E > 10 KV/cm). The results show the amplification and non-linear interaction of space charge waves in a strained Si/SiGe heterostructure occurs for frequencies up to approximately 60 GHz at T = 1.3 K, 47 GHz at T = 4.2 K, and 40 GHz at T = 77 K. The variation of concentration and electric field in the Z and Y directions are calculated at 4.2 K. The electric field in the Z direction is greater than in the Y direction. This is due to the fact that this is the direction of electron motion. In addition to deep space applications, these types of devices have potential uses in terrestrial applications which include magnetic levitation transportation systems, medical diagnostics, cryogenic instrumentation, and superconducting magnetic energy storage systems. Full article

Groove is widely used in the wicks of heat pipes. In this paper, a laser texture deposition (LTD) process was proposed to texture deposit SiO₂ in rectangular aluminum groove. Both the SEM and XPS analysis revealed that a fluffy SiO₂ layer was deposited on the surface of alumina fluff, which increased the fluff density. Statistically, the density of fluff on the surface of LTD was 1.12 times higher than that on the laser texture (LT) surface, leading to an increase in porosity and decrease in effective capillary radius. This significantly improved the capillary performance of the LTD groove. The results showed that, compared to the Raw and LTD grooves, the increase in height of the LTD groove was enhanced by 2.42 and 1.07 times, respectively, in 5 s, while the capillary performance factor (M) was increased by 2.83 and 1.04 times, respectively, in 1 s. This study introduces a novel process for enhancing the capillary performance of aluminum groove. Full article

Based on the understanding that the essence of secondary recrystallization of Goss texture is to restrain the abnormal growth of {110}<112>, {210}<001> and partial Goss texture {110}<225>, it was concluded that making sharp Goss grow up becomes the only choice. It was proposed that the abnormal growth mechanism of Goss texture was the result of selective generation, directed inheritance, and selective growth. The mechanism explained that the Goss texture was the most easily formed shear texture. In directed inheritance, the Goss texture was required to be highly compatible with the near-constant of the second-phase particle inhibition force, providing an optimal environment for the abnormal growth of the Goss texture by controlling the inhibition force near-constant. The control of the near-constant inhibition force provides an optimal environment for the abnormal growth of the Goss texture. Based on that, the process technology for producing low-temperature nitrided-oriented silicon steels and steel products was successfully developed. Full article

A novel non-centrosymmetric NdSr₄O(BO₃)₃ borate and solid solutions of Nd(Ca_1−xSr_x)₄O(BO₃)₃ (x = 0.0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.7, 1.0) were synthesized by solid-state reactions as well as crystallization from a melt. The crystal structures of the Nd(Ca_1−xSr_x)₄O(BO₃)₃ solid solutions with x = 0.2, 0.5 and 1.0 were determined from single crystal X-ray diffraction data and refined in the monoclinic space group Cm to R_obs = 0.028, 0.034 and 0.028, respectively. The thermal expansion of the samples with x = 0, 0.2 and 0.5 was investigated using powder high-temperature X-ray diffraction in the temperature range of 25–1000 °C. A similarity of the thermal and compositional (Ca-Sr substitution) deformations of Nd(Ca_1−xSr_x)₄O(BO₃)₃ solid solutions is revealed: Heating of Nd(Ca_0.5Sr_0.5)₄O(BO₃)₃ by 1 °C leads to the same deformations of the crystal structure as increasing the amount of Sr atoms in Nd(Ca_0.5Sr_0.5)₄O(BO₃)₃ by 0.26 at% Sr. The SHG signal of the series of Nd(Ca_1−xSr_x)₄O(BO₃)₃ solid solutions has a maximum at approximately x = 0.2. Full article

Piezoelectric micromachined ultrasonic transducers (PMUTs) have attracted widespread attention due to their high performance, miniaturization, and easy integration with semiconductor processes. In this paper, a PMUT device based on high-performance and lead-free Na_0.5Bi_0.5TiO₃-BaTiO₃ (NBBT) piezoelectric single-crystal thin films was designed for the application of medical high-frequency ultrasonics. Three-dimensional modeling and analysis of PMUT elements on the proposed structure were performed via the finite element method. The relationship between structure configuration in terms of the top electrode and the cavity shape of the bottom was studied. The PMUT properties and its device performance, including resonant frequency, effective electromechanical coupling factor ($k_{eff}^2$), and the static sensitivity of different device structures, were analyzed. In addition, by rotating the Euler Angle $\gamma$ of the NBBT piezoelectric single-crystal film, the static sensitivity and $k_{eff}^2$ of the model are improved to 1.34 when $\gamma$ is rotated to 45 ± 5°. It was shown that the PMUT using rotated NBBT demonstrated an enhanced relative pulse-echo sensitivity of −46 dB and a bandwidth of 35% when the reflective surface was 200 μm. We conclude that the PMUT in accordance with an NBBT piezoelectric single-crystal film designed by simulation offers a high frequency, larger$k_{eff}^2$, and high sensitivity, which provides application prospects in high-resolution and high-frequency medical ultrasonic imaging. Full article

A ternary nanocomposite was prepared using cerium oxide, chitosan, and graphene oxide (CeO₂/CS/GO) using a simple and cost-effective wet chemical method. The physicochemical properties of the developed ternary nanocomposite were examined using X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy with energy-dispersive X-ray spectroscopy, and ultraviolet-visible spectroscopy. Furthermore, the therapeutic behavior of the developed CeO₂/CS/GO composite was assessed using anti-bacterial, anti-fungal, and anti-cancer assays. For Escherichia coli, Staphylococcus aureus, and Salmonella species, 750 µg/mL of the CeO₂/CS/GO composite showed effective anti-bacterial activity, with a zone of inhibition of 9 mm. Additionally, the CeO₂/CS/GO composite’s anti-fungal activity against Aspergillus niger was studied. The anti-cancer properties of different concentrations of the CeO₂/CS/GO composite were assessed on MCF-7 cells, and 18.8% of cells were found to be viable at the maximum concentration of 1000 µg/mL CeO₂/CS/GO and 46.37% at 125 µg/mL. The results of the hemolysis assay performed using human red blood cells and various concentrations of the CeO₂/CS/GO composite indicated that the nanocomposite possesses biological properties. Overall, it can act as a therapeutic platform for breast cancer, bacterial and fungal infections. Full article

This paper addresses the role of multilevel microstructures on the fatigue crack propagation behavior and the tensile properties of lath martensite with different substructure sizes. Microstructure characterization of the alloy was carried out by transmission electron microscopy (TEM), scanning electron microscopy (SEM), electron back-scattering diffraction (EBSD), and optical microscopy (OM). Based on the classic Hall–Petch relationship, the results of tensile tests showed that martensitic block is the effective control unit of yield strength. Furthermore, the plasticity of lath martensite is not sensitive to grain size. The tensile deformation mechanisms were also discussed. Fatigue crack propagation tests revealed that the coarse grain has a higher crack propagation threshold and lower crack propagation rate than the fine grain in lath martensitic steel. The change in the plasticity zone ahead of the crack tip leads to the transitional behavior of the fatigue crack propagation rate. When plasticity zone sizes are equal to the block size, the fatigue crack propagation reverts to a stable propagation stage. Finally, an empirical model was established to predict the fatigue crack propagation rate of the stable propagation stage based on the tensile properties of the lath martensitic steel. Full article

Citrulline is a non-protein amino acid that acts as a metabolic intermediate in the urea cycle and arginine synthesis. It is present in some foods, although its name derives from watermelon (Citrullus vulgaris), from which it was first identified. Under normal conditions, Citrulline exists as a zwitterion in aqueous solutions since its carboxylic and amine groups can act as Lewis donors to chelate metal cations. In addition, Citrulline possesses in the aliphatic chain a terminal ureide group, which could also coordinate. Although Citrulline is comparable to other classical amino acids, its coordination chemistry has yet to be explored. Only two metal complexes have been reported, and the copper complex is a polymeric and insoluble material. As part of our search for active Casiopeina^® analogs, we created a more soluble complex by combining 2,2′-Bipyridine into a new mixed material, resulting in the mononuclear complex [Cu(Bipy)(Citr)(H₂O)(NO₃)]·H₂O. Single-crystal X-ray diffraction, spectroscopic methods (FT-IR, UV-Vis, Raman), and mass spectrometry characterized the material. Interestingly, both isomers of Citrulline, R(D), and S(L) are present in the same crystal. In addition, the molecular structure and electronic properties of the complex were calculated using density functional theory (DFT). Non-covalent interactions were characterized using the atoms-in-molecules (AIM) approach and Hirshfeld surface (HS) analysis. This ternary complex containing Citrulline and 2,2′-Bipyridine will be used for docking calculations and preliminary biological studies using calf thymus DNA (CT-DNA) and plasmid pUC19 as a first approximation to cytotoxic activity against cancer cell lines. Full article

Focal research has been conducted on medium-entropy alloys (MEAs) that exhibit a balanced combination of strength and plasticity. In this study, the microstructure, dynamic mechanical properties, and texture evolution of an as-cast medium-entropy CoCr_0.4NiSi_0.3 alloy were investigated through dynamic compression tests at strain rates ranging from 2100 to 5100 s⁻¹ using the Split Hopkinson Pressure Bar in order to elucidate the underlying dynamic deformation mechanism. The results revealed a significant strain rate effect with dynamic compressive yield strengths of 811 MPa at 2100 s⁻¹, 849 MPa at 3000 s⁻¹, 919 MPa at 3900 s⁻¹, and 942 MPa at 5100 s⁻¹. Grains were dynamically refined from 19.73 to 3.35 μm with increasing strain rates. The correlation between adiabatic temperature rise induced by dynamic compression and dynamic recrystallization was examined, revealing that the latter is not associated with adiabatic heating but rather with phase transition triggered by the dynamic stress during compression. The proportion of Σ3ⁿ (1 ≤ n ≤ 3) grain boundaries in deformation specimens increases with increasing strain rates during dynamic compression. The formation of specific three-node structures enhances both strength and plasticity by impeding crack propagation and resisting higher mechanical stress. In the as-cast state, significant anisotropy was observed in the MEA. As strain rates increased, it transited into a stable {111}<112> F texture. The exceptional dynamic properties of strength and plasticity observed in the as-cast state of the MEA can be attributed to a deformation mechanism involving a transition from dislocation slip to the formation of intricate arrangements, accompanied by interactions encompassing deformation nanotwins, stacking faults, Lomer–Cottrell locks, stair-rods, and displacive phase transformations at elevated strain rates. Full article

This study introduces an innovative integration of hyperbolic metamaterials (HMMs) and photonic crystals (PtCs), each possessing unique dispersion properties that effectively manipulate the propagation of light. We present a PtC waveguide consisting of arrays of HMM nanorods, denoted as HMM PtCs. This waveguide configuration enables the realization of a high figure of merit (FOM) nano-sensor. HMMs and PtCs share the same underlying physics. HMMs can generate surface plasmonics, while PtCs offer a bandgap for the waveguide. This configuration presents a novel sensing solution that directly couples surface plasmonics and waveguide modes. By modifying the refractive indices of the surrounding materials, the PtC waveguide exhibits alterations in absorption and transmission, allowing for the detection of temperature, pressure, and material variations. The refractive indices of the surrounding materials can be adjusted based on the sensor’s intended application. For instance, when the sensor is utilized for temperature sensing, thermal infrared materials can serve as the surrounding medium. As the temperature rises, the refractive index of the surrounding material changes accordingly, impacting the waveguide modes and thereby altering absorption and transmission. We utilized the finite element method to conduct numerical simulations in order to assess the absorption and transmission characteristics of the proposed system. Given that this approach involves a full electromagnetic calculation based on Maxwell’s equations, it closely approximates real-world scenarios. The employed numerical method demonstrates the remarkable performance of this proposed system, achieving a sensitivity of 324.16 nm/RIU (refractive index unit) and an impressive FOM of 469.58 RIU⁻¹. These results signify a substantial improvement over surface plasmonic sensors, which typically exhibit limited FOMs. The direct coupling between surface plasmonics and waveguide modes provides a distinct advantage, allowing the proposed sensor to deliver a superior performance. As a consequence, the HMM PtC waveguide sensor emerges as an exceptionally appealing option for photonic sensing applications. The complexity of the proposed system presents a fabrication challenge. Nevertheless, as fabrication technology continues to advance, we anticipate that this issue can be effectively resolved. The proposed HMM PtC waveguide holds vast potential across diverse fields, including biology, medicine, and clinics, representing an exciting advancement for both industry and scientific research. Full article

Despite the ubiquity of the crystallization of sodium chloride (NaCl) throughout history, few detailed, well-controlled quantitative studies of the kinetics of NaCl crystallization have been published. Taking advantage of recent advances in technology such as image analysis for crystallite counting and ‘high-throughput’ techniques for characterizing the highly stochastic nucleation process, we report on a detailed examination of the primary and secondary nucleation kinetics of NaCl, crystallized from solution, in water (H₂O) and in the isotopologue D₂O. We show that crystallization conditions, especially sample agitation, have a very significant effect on crystallization kinetics. We also critically evaluate the workflow employed and the associated nucleation/growth models used to interpret its results, comparing outcomes from NaCl with those from organic crystal systems with which the workflow was originally developed and demonstrated. For primary nucleation, some key assumptions of the workflow and data interpretation are called into question for the NaCl system. Even so, it can still provide direct measurements of secondary nucleation and crystal growth from crystal counting and sizing, providing valuable characterization under consistent controlled conditions to enhance and ‘bring up to date’ the literature on the crystallization of this ubiquitous system. Full article

Indocyanine green (ICG) shows promise for diagnosing and treating tumors due to its good photothermal and fluorescent properties. In this study, sodium heparin (SH)-stabilized ICG/nano-hydroxyapatite (SH-ICG/nHAP) suspension was ultrasonically prepared to achieve photothermal and photodynamic collaborative therapy (PTT/PDT) for treating tumors. The nHAP had a short rod-like shape and a drug-loading capacity of 13.3% for ICG, corresponding to a drug-loading efficiency of 88.6%. In addition, the SH-ICG/nHAP suspension showed a very low release of ICG in PBS (7.4) and a slightly improved release in acidic buffers (6.5, 5.5), indicating an excellent binding ability of nHAP for ICG. The resulting SH-ICG/nHAP showed good suspension stability. Under an 808 nm near-infrared (NIR) laser, SH-ICG/nHAP showed good photothermal properties and could produce reactive oxygen species (ROS). Under the irradiation of an 808 nm NIR laser at 0.8 W/cm² for 5 min, SH-ICG/nHAP was found to significantly inhibit HepG2 cells proliferation (78.58%), similar to free ICG. In vivo, SH-ICG/nHAP was found to exert an improved inhibitory effect on tumor growth compared to free ICG. Biocompatible and stable SH-ICG/nHAP suspension like this could be a promising system for the PTT/PDT of tumors. Full article

In this work, an oxidized g-C₃N₄ film was successfully synthesized using a two-step acid treatment and electrophoretic deposition method. The delocalized π-system of the oxidized g-C₃N₄ film was extended via an annealing treatment. We investigated the influence of hydrogen bonding reversibility and the oxidation treatment of g-C₃N₄ on the photoelectrochemical property and photocathodic protection for 304 stainless steel (304 SS). The resulting oxidized g-C₃N₄ photoelectrode with an extended π-system presents a remarkably enhanced photogenerated electron transfer capability from the photoelectrode to 304 SS (photoinduced OCP negative shift of −0.55 V_AgCl) compared with oxidized g-C₃N₄ and protonated g-C₃N₄. The oxidation of g-C₃N₄ facilitates the formation of a porous structure and the introduction of abundant oxygen functional groups, which could promote the effective separation and transport of photogenerated electron–hole pairs. The hydrogen bonding reversibility contributes to the extension of the delocalized π-conjugation system, which could enhance light absorption efficiency. Meanwhile, the annealing treatment is beneficial for prolonging the lifetime of photoelectrons, which could reduce the recombination rate of charge carriers. In addition, to understand how the oxidation treatment and annealing treatment affect the charge transfer behavior, the electronic band structure was investigated, and we found that the oxidized g-C₃N₄ film with an extended π-system possesses a more negative conduction band position, which could reduce the energy barrier of the photogenerated electron transfer. Full article

Indentation size effect at shallow indentation depths still remains a challenge as it cannot be correctly described by the Nix–Gao model based on the concept of strain gradient plasticity and geometrically necessary dislocations. The reasons for this discrepancy may be various, and multiple microstructural factors may play a role at the nanoscale. In the present paper, the breakdown of the Nix–Gao model was explored in electrodeposited nickel with different grain size/shape and crystallographic orientation. Crystallographic orientation has no significant effect on the indentation process at shallow depths if plastic deformation has already developed. On the other hand, decreasing the grain size leads to constrained plastic deformation in the grains below the indenter and to an effective plastic zone expansion. Further grain refinement down to the nanograin material leads to a change in the plastic deformation mechanisms to grain boundary-mediated deformation and a more pronounced breakdown of the Nix–Gao model. Full article

Vehicle displays are becoming more integrated into our daily lives. Achieving a premium driving experience demands the display panel to have high-resolution density and sufficient brightness, particularly when exposed to intense ambient light, as direct sunlight can obscure the displayed images. Combining Barten’s model and diffraction theory, the performance of both infotainment displays and head-up displays (HUDs) is evaluated. For infotainment displays, over 800 nit brightness is essential for the driver to discern 55 pixel-per-degree (PPD) patterns under direct sunlight. For HUDs, a delicate balance between resolution density, brightness, transparency, and image quality must be exercised. By slightly reducing the resolution density to 50 PPD, the transparent micro-LED panel can concurrently achieve a reduced background image blur, low required display brightness (~4000 nits), and high background transmittance (~90%). Full article

As nano-electronic technology makes electronic devices gradually microscopic in size and diversified in function, obtaining new materials with superior performance is the main goal at this stage. Interfaces formed by adjacent layers of material in electronic devices affect their performance, as does the strain caused by lattice mismatch, which can be simulated and analyzed by theoretical calculations. The common period of the cell changes when the van der Waals (vdW) material is twisted. Therefore, it is a significant challenge to determine the common supercell of two crystals constituting the interface. Here. we present a novel cell matching algorithm for twisted bilayer vdW materials with orthogonal unit cells, where the resulting common supercell remains orthogonal and only angular strains exist without linear strains, facilitating accuracy control. We apply this method to 2-Pmmn twisted bilayer borophene. It can automatically find the resource-allowed common supercell at multiple rotation angles or fix the rotation angle to find the proper accuracy. Full article

In light of external bias potential separating charge carriers on the photocatalyst surface, piezo materials’ built-in electric field plays a comparable role in enhancing photocatalyst performance. The synergistic effect provided by combining piezo materials assures the future of photocatalysis in practical applications. This paper discusses the principles and mechanisms of piezo-photocatalysis and various materials and structures used for piezo-photocatalytic processes. In piezo-photocatalyst composites, the built-in electric field introduced by the piezo component provides bias potential and extracts photocatalytically generated charge carriers for their subsequent reaction to form reactive oxygen species, which crucially affects the catalytic performance. In the composites, the shape and structure of substrate materials particularly matter. The potential of this technology in other applications, such as energy generation and environmental remediation, are discussed. To shed light on the practical application and future direction of the technique, this review gives opinions on moving the technique forward in terms of material development, process optimization, pilot-scale studies, comprehensive assessment of the technology, and regulatory frameworks to advance practical applications, and by analyzing its principles, applications, and challenges, we hope to inspire further research and development in this field and promote the adoption of piezo-photocatalysis as a viable treatment method for treating emerging pollutants in wastewater. Full article

Ultrapure composite nanostructures combining semiconductor and metallic elements as a result of ultrafast laser processing are important materials for applications in fields where high chemical purity is a crucial point. Such nanocrystals have already demonstrated prospects in plasmonic biosensing by detecting different analytes like dyes and bacteria. However, the structure of the nanocomposites, as well as the control of their properties, are still very challenging due to the significant lack of research in this area. In this paper, the synthesis of silicon–gold nanoparticles was performed using various approaches such as the direct ablation of (i) a gold target immersed in a colloidal solution of silicon nanoparticles and (ii) a silicon wafer immersed in a colloidal solution of plasmonic nanoparticles. The formed nanostructures combine both plasmonic (gold) and paramagnetic (silicon) modalities observed by absorbance and electron paramagnetic resonance spectroscopies, respectively. A significant narrowing of the size distributions of both types of two-element nanocrystals as compared to single-element ones is shown to be independent of the laser fluence. The impact of the laser ablation time on the chemical stability and the concentration of nanoparticles influencing their both optical properties and electrical conductivity was studied. The obtained results are important from a fundamental point of view for a better understanding of the laser-assisted synthesis of semiconductor–metallic nanocomposites and control of their properties for further applications. Full article

The purpose of this study is to synthesize and explore the relationship between the optical properties and gas-sensing performance of ZnO nanowires (NWs). Well-aligned ZnO nanowire (NW) arrays were synthesized on a silicon substrate using the thermal evaporation method without any catalyst or additive. The structures, surface morphologies, chemical compositions, and optical properties of the products were characterized using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) together with energy-dispersive spectroscopy (EDS), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), and photoluminescence (PL) spectroscopy, and their gas-sensing properties for NO₂ were examined. The results showed that single-crystalline ZnO NWs with high density grow uniformly and vertically on a Si substrate. The FESEM and TEM images indicate that ZnO NWs have an average diameter of roughly 135–160 nm with an average length of roughly 3.5 μm. The results from XRD confirm that the ZnO NWs have a hexagonal wurtzite structure with high crystalline quality and are highly oriented in the [0001] direction (i.e., along the c-axis). The deconvoluted O 1s peak at ~531.6 eV (29.4%) is assigned to the oxygen deficiency, indicating that the ZnO NWs contain very few oxygen vacancies. This observation is further confirmed by the PL analysis, which showed a sharp and high-intensity peak of ultraviolet (UV) emission with a suppressed deep-level (DL) emission (very high: I_UV/I_DL > 70), indicating the excellent crystalline quality and good optical properties of the grown NWs. In addition, the gas-sensing properties of the as-prepared ZnO NWs were investigated. The results indicated that under an operating temperature of 200 °C, the sensor based on ZnO NWs is able to detect the lowest concentration of 1.57 ppm of NO₂ gas. Full article

The microstructures and mechanical properties of Mg–3Sn–0.1Ca–xMM (mischmetal, x = 0.3, 0.6, and 0.9 wt.%) alloys were investigated. Optical microscopy (OM), scanning electron microscopy (SEM) and X-ray diffraction spectroscopy (XRD) were used to characterize the microstructures and phase constitutions of the cast and rolled alloys. Room temperature tensile tests were conducted to obtain the mechanical properties and macro-textures to evaluate the texture weakening effect results of the MM. The results show that an abundance of second phase formed, confirmed as the (Ca,MM)MgSn phase, and the volume fraction increased with the increasing MM addition. The tensile yield strength of the as-cast alloys increased with the MM addition, but the elongation decreased. All of the rolled Mg–3Sn–0.1Ca–xMM alloys showed a strong basal texture, and only slightly decreased in intensity after annealing treatment due to the particle-stimulated nucleation of recrystallization. The as-annealed Mg–3Sn–0.1Ca–0.6MM alloys exhibited the highest tensile strengths of 266.5 ± 3.3 MPa and 136.1 ± 3.7 MPa, which are mainly ascribed to grain refinement strengthening, Orowan strengthening and texture strengthening. Full article

As a result of the high-throughput ab initiocalculations, the set of 34 stable and novel half-Heusler phases was revealed. The electronic structure and the elastic, transport, and thermoelectric properties of these systems were carefully investigated, providing some promising candidates for thermoelectric materials. The complementary nature of the research is enhanced by the deformation potential theory applied for the relaxation time of carriers (for power factor, PF) and the Slack formula for the lattice thermal conductivity (for figure of merit, ZT). Moreover, two exchange-correlation parametrizations were used (GGA and MBJGGA), and a complete investigation was provided for both p- and n-type carriers. The distribution of the maximum PF and ZT for optimal doping at 300 K in all systems was disclosed. Some chemical trends in electronic and transport properties were discussed. The results suggest TaFeAs, TaFeSb, VFeAs, and TiRuAs as potentially valuable thermoelectric materials. TaFeAs revealed the highest values of both PF and ZT at 300 K (PF${}_p$ = 1.67 mW/K${}^2$m, ZT${}_p$ = 0.024, PF${}_n$ = 2.01 mW/K${}^2$m, and ZT${}_p$ = 0.025). The findings presented in this work encourage further studies on the novel phases, TaFeAs in particular. Full article