Properties Of Crystals Research Articles

Multidimensional Resonance Controlled by Critical Size in Printed Binary Colloidal Crystals for High-Contrast Imaging.

Colloidal crystal engineering enables the precise construction of structures with remarkable properties. However, the flexible and synergistic regulation of multiple properties of colloidal crystals remains a significant challenge. Here, we inspire from Brazilian opals to self-assemble polymer nanoparticles in the gaps of a single-layer opal substrate to fabricate large-scale binary colloidal crystals (BCCs). These BCCs have well-defined sizes, compositions, and dimensions, of which the crystallization process is finely controlled by the Marangoni flow. Notably, we find a critical size for the simultaneous and independent regulation of their lattice resonance wavelength and intensity, forming a full-color palette. Moreover, these BCCs as optical coatings allow for high-contrast imaging of microbials, benefiting from strong spatial confinement. Compared to glass in clinical smearing, they have an order of magnitude improvement in chromatism without dyeing. This work demonstrates that BCCs hold great potential in creating multifunctional devices for various applications including information display, biological detection, and optical imaging.

Tuning Structural and Topological Properties of Silicon-Based Orthorhombic Crystals for Enhanced Radiation Shielding

Tuning Structural and Topological Properties of Silicon-Based Orthorhombic Crystals for Enhanced Radiation Shielding

Optical properties of barium borate crystal in the THz range revisited.

Low-temperature phase (β-form) barium borate (BBO) is one of the most important nonlinear crystals that has been widely used for optical second-harmonic generation (SHG), especially with femtosecond sources. There was growing interest in its applications in the direct generation of terahertz (THz) radiations, but it was hindered by the lack of knowledge of its basic properties in the THz range. In a recent study based on first-principles quantum chemistry calculation, we found that the theoretically calculated refractive indices of β-BBO in the THz frequency range do not agree with the previously reported values. To explore the discrepancy between measured and calculated results, we grew and cut β-BBO crystals and performed independent experimental measurements on the refractive indices of BBO crystals. The new data show that the order of ordinary and extraordinary index of β-BBO in the THz range is opposite, contrary to several papers previously reported. Based on the newly acquired material properties, simple geometries fulfilling phase matching (PM) conditions with n o(THz)=n o g r(800nm) for efficient generation of THz radiation through optical rectification in β-BBO are proposed.

Crystal Structure and Magnetic Properties of the Novel Compound ErMn5Ge3

The RE-M-Ge systems (RE: rare earths, M: transition group elements) contain a large number of compounds with special magnetic properties. A novel compound ErMn5Ge3 was found during the investigation on the phase diagram of the Er-Mn-Ge ternary system, and its crystal structure and magnetic properties were investigated. Powder X-ray diffraction results show that ErMn5Ge3 crystallizes in an orthorhombic YNi5Si3-type structure with the space group Pnma (No. 62) and the lattice parameters of a = 13.0524(6) Å, b = 3.8853(7) Å, and c = 11.4027(4) Å. The magnetization curves and isothermal magnetization curves from 100 to 300 K were measured for ErMn5Ge3. Magnetic tests showed that the compound was weakly magnetic and had a Curie temperature of 304 K. It is believed that its magnetic properties are determined by Mn atoms, which are surrounded by a complex environment, leading to uncertainty in the direction of the magnetic moment and hence poor magnetic ordering. This uncertainty simultaneously leads to a significant separation of the ZFC and FZ curves. First-principles calculations confirm that the magnetic properties of ErMn5Ge3 are mainly provided by the Mn atoms, and its magnetic moment is calculated to be about 4.5 μB. A possible magnetic structure model with simultaneous Mn-Mn ferromagnetic/antiferromagnetic coupling is constructed based on the Mn atom spacing, which can well explain the magnetic performance of ErMn5Ge3.

In Situ TEM Study of Electrical Property and Mechanical Deformation in MoS2/Graphene Heterostructures

We present a versatile method for synthesizing high-quality molybdenum disulfide (MoS2) crystals on graphite foil edges via chemical vapor deposition (CVD). This results in MoS2/graphene heterostructures with precise epitaxial layers and no rotational misalignment, eliminating the need for transfer processes and reducing contamination. Utilizing in situ transmission electron microscopy (TEM) equipped with a nano-manipulator and tungsten probe, we mechanically induce the folding, wrinkling, and tearing of freestanding MoS2 crystals, enabling the real-time observation of structural changes at high temporal and spatial resolutions. By applying a bias voltage through the probe, we measure the electrical properties under mechanical stress, revealing near-ohmic behavior due to compatible work functions. This approach facilitates the real-time study of mechanical and electrical properties of MoS2 crystals and can be extended to other two-dimensional materials, thereby advancing applications in flexible and bendable electronics.

Light-Driven Adaptive Molecular Crystals Activated by [2+2] and [4+4] Cycloadditions.

Photomechanical crystals act as light-driven material-machines that can convert the energy carried by photons into kinetic energy via shape deformation or displacement, and this capability holds a paramount significance for the development of photoactuated devices. This transformation is usually attributed to anisotropic expansion or contraction of the unit cell engendered by light-induced structural modifications that lead to accumulation and release of stress that generates a momentum, resulting in readily observable mechanical effects. Among the available photochemical processes, the photoinduced [2+2] and [4+4] reactions are known for their robustness, predictability, amenability to control with molecular and supramolecular engineering approaches, and efficiency that has already been elevated to a proof-of-concept smart devices based on organic crystals. This review article presents a summary of the recent research progress on photomechanical properties of organic and metal-organic crystals where the mechanical effects are based on [2+2] and [4+4] cycloaddition reactions. It consolidates the current understating of the chemical strategies and structure-property correlations, and highlights the advantages and drawbacks of this class of adaptive crystals within the broader field of crystal adaptronics.

Rationalization of the structural, electronic and photophysical properties of silver(I) halide n-picolylamine hybrid coordination polymers.

Hybrid coordination polimers based on AgX (with X = Cl, Br) and 2-, 3-, 4-picolylamine ligands, obtained by means of solvent-free methods, show peculiar luminescence properties that are strongly influenced by their structural motif, which in turn is defined by the adopted isomer of the ligand. A comprehensive study, combining photophysical methods and DFT calculations, allowed to rationalize the emissive behaviour of such hybrid coordination polymers in relation to their crystal structures and electronic properties. By means of luminescence measurements at variable temperatures, the nature of the emissive excited states and their deactivation dynamics was interpreted, revealing XMLCT transitions in the [(AgX)(2-pica)]n compounds, a TADF behaviour in the case of 3-pica derivatives, and a dual emission at room temperature for the [(AgX)(4-pica)]n family. The presence of low energy CC states, permitted by argentophilic interactions, is also considered in [(AgX)(2-pica)]n, whose structures are characterized by single/double inorganic chains, and in [(AgX)(4-pica)]n, where discrete dimeric Ag2X2 units are present. These findings open new avenues for the design and application of luminescent AgX-based hybrid materials.

Metastable fcc-Ru/fcc-RuO2 Heterointerphase for Hydrogen Evolution.

The metastable crystal structure is difficult to synthesize and maintain but normally acts as special active sites with improved functional properties. Herein, a moderate crystallographic transformation strategy is used to effectively synthesize metastable RuO2. By controlling the degree of oxidation, we constructed different heterophase Ru/RuO2 catalysts. The results show that the metastable fcc-Ru/fcc-RuO2 heterointerphase holds an improved crystal structure matching property accompanied by enhanced water dissociation and appropriate adsorption capacity for intermediates, achieving a current density of 10 mA cm-2 at a low potential of 11.2 mV. This study provides an effective extension for the crystal phase design of catalysts.

Synthesis, crystal structure, hirshfeld study, DFT analysis, molecular docking study, antimicrobial activity of β-enaminonitrile bearing 1H-pyran

3-Amino-1-(3,4-dimethoxyphenyl)-8-methoxy-1H-benzo[f]chromene-2-carbonitrile (3-ABC, 4) was prepared and affirmed through the spectral data and single crystal X-rays diffraction. The molecule spatial attributes were revealed by the three-dimensional Hirshfeld surface, which is validated by comprehensive statistical evaluations. The key interactions that contribute to the crystal's stability and properties, such as π–π stacking and H⋯X contacts, were highlighted. The dominant forces in the crystal were explained by energy framework calculations and density functional theory analyses, which also show the geometric optimization aspects and molecular reactivity indicators. The focus is on the investigation of frontier molecular orbitals, aromaticity, and π–π stacking abilities. The research concluded by identifying electron density distributions, aromatic features, and possible reactivity sites, offering a complete picture of the compound's structural and electronic landscape. Compound 4 was screened for its antimicrobial capability against three Gram-positive, three Gram-negative bacteria, and three fungi, utilizing the reference antibiotic drug Ampicillin, Gentamycin, and Ketoconazole. Compound 4 exhibited favorable antimicrobial activities that were lower/resembled the reference antimicrobial agents with an IZ range of 15–31 mm. In addition, MIC, MBC, and MFC were assessed and screened for the target molecule 4, unveiling its revealing antimicrobial activities. Lastly, the molecular docking evaluation was implemented for the molecules interaction with the DHFR protein. The compounds exhibit significant interactions with the EGFR protein's active site.

Band sorting based on global continuity of eigenvalues and topological properties of phononic crystals

Band sorting is critical to obtaining physical properties from eigenvalues and eigenvectors that constitute the band diagram. We propose a band sorting method based on the global continuity and smoothness of the eigenvalues on the parameter space. Several strategies based on the connection between neighbor eigenvalues and how to sweep the parameter space are introduced to recognize level crossing degeneracies and level repulsion degeneracies. Eigenvectors are then reassigned to each band according to their corresponding eigenvalues. As an example, the band diagram of a 2D phononic crystal is sorted, and the group velocity and Berry curvature are compared before and after band sorting. The Berry curvature shows unexpected eigenvector discontinuities, indicating that our method based on the eigenvalues only is more reliable than methods based on the eigenvectors. Our proposed method is general and allows for studying the transport and topological properties of periodic materials.

Crystal structure and elastic properties of parabreyite: a new high-pressure ring silicate in the CaSiO3 system

Crystal structure and elastic properties of parabreyite: a new high-pressure ring silicate in the CaSiO₃ system

Effect of SiO2 monocrystalline substrate orientation on the crystal structure and properties of VO2 film

The VO2 films were deposited on the AT-, X-, Y- and Z-SiO2 monocrystalline substrates with the magnetron sputtering. The effects of the substrate crystal planes, (011), (2—10), (100) or (001), on the crystal structure, surface morphology, optical properties and phase transformation characteristics of the VO2 film were investigated. The crystal structure differences among the VO2 films deposited on the four substrates were attributed to the lattice mismatch between the SiO2 monocrystalline substrate and the VO2 film, which led to the generation of internal stress within the VO2 film, causing the VO2 to present a diversity of crystal plane and phase at the interface. Among them, the VO2 film exhibited the M-phase on the AT- and X-SiO2 substrates, while a mixture of the M-phase and the R-phase on the Z- and Y-SiO2 substrates. The complex crystal structure resulted in the various surface morphologies, the VO2 particles on the Z- and Y-SiO2 substrates presented a smaller size and gap, as well as a more uniform distribution than those on the AT- and X-SiO2 substrates. All the VO2 films exhibited the metal-insulator phase transition during both the thermal cycling and the laser irradiation cycling processes. The Z-SiO2 substrate had a positive effect on the phase transition performance of the VO2 film, which got a thermochromic phase transition threshold of 64.62 ℃ and an infrared switching ratio of 78.99% at the wavelength of 2500nm. And its photoinduced phase transition threshold was 36.43W/cm², and its infrared switching ratio reached 59.00% under the 1989 nm laser irradiation.

Topological structure, rheological characteristics and biological activities of exopolysaccharides produced by Saccharomyces cerevisiae ADT

Saccharomyces cerevisiae ADT is an edible fungus, with limited research on its exopolysaccharides (EPS). Three types of exopolysaccharides (EPS60, EPS80, and EPS100) were obtained through multiple purification steps using varying concentrations of ethanol in this study. The topological structure, rheological properties, and biological characteristics of EPS were investigated. High performance liquid chromatography (HPLC), Fourier transform infrared spectroscopy (FTIR), and nuclear magnetic resonance (NMR) analyses indicated that the three EPS are primarily made up of mannose with a small amount of glucose. Acetyl groups were also found, along with the presence of α-type pyranose and β-type pyranose. The Congo Red test and X-ray diffraction results reflected the absence of a triple helix structure and crystal properties. Atomic force microscopy (AFM) revealed the self-assembly of three exopolysaccharides into various topological structures under different concentration gradients, and a clear network structure of entangled chains was observed. EPS60, EPS80 and EPS100 displayed pseudoplasticity, weak gel behavior and thermal stability. Significantly, EPS exhibited antioxidant activity in a dose-dependent manner and showed no acute cytotoxicity to RAW264.7 and HEK293T cells. Therefore, EPS in this study is anticipated to be utilized in natural antioxidants, medications, and functional materials.

Defects and performance of CdTe and CZT detectors

Cadmium Telluride and Cadmium Zinc Telluride detectors are used in various environments in high-energy, nuclear, medical and astrophysics. They are high-Z materials and have high interaction probability with high energy X-rays and gamma rays. However, the crystal properties, especially various defects have impact on the charge collection efficiency. In this paper we studied the response of the crystallographic defects to estimate their impact on detector performance.

Low field electrocaloric effect at isotropic-ferroelectric nematic phase transition.

Electrocaloric effects (ECE) in solid state materials, such as ferroelectric ceramics and ferroelectric polymers, have a great impact in developing cooling systems. Herein, we describe the ECE of a newly synthesized ferroelectric nematic liquid crystal compound at the isotropic-ferroelectric nematic (I-NF) phase transition. While the Joule heat completely suppressed the ECE in a DC field, in an AC field with E < 1.2 V μm-1 and f ≥ 40 Hz, an increase in optical transmittance was observed, which in comparison with a zero-field transmittance versus temperature plot indicated a shift in the transition temperature. These findings implied that one can induce the desired phase transition using an electric field via ECE with an EC responsivity of ∼1.7 × 10-6 km V-1. Notably, the required electric field was two orders of magnitude smaller than the typical fields for other EC materials. EC effects observed under such low fields is a unique property of ferroelectric nematic liquid crystals. Furthermore, the specific EC energy could be increased considerably by reducing the ionic content, thus suppressing the Joule heat.

Impact of -OH surface defects on the electronic and structural properties of nickel oxide thin films.

Nickel oxide-based thin films and nanomaterials are a current focus of intense research efforts due to the broad range of end uses in a variety of applications. While the chemico-physical properties of bulk NiO crystals, characterized by a wide band gap (4.0-4.3 eV), antiferromagnetic ordering and p-type character, have been extensively studied, for NiO films/nanomaterials the microscopic-level relationships between the surface defect structure and electronic properties are far from being completely elucidated. In the present work, we show that, by using density functional theory with the Hubbard correction (DFT+U), -OH surface defects, almost ubiquitous on oxide surfaces, can directly influence the electronic structure of NiO(100) model slabs. Depending on the exact defect chemical structure and surface defect density, the energy gap of the -OH bearing NiO(100) system can be engineered, and its behaviour can be modulated from p-type to n-type. The insights provided herein may be of importance for the modulation of NiO nanosystem properties as a function of specific applications, an important issue for their eventual real-world utilization.

Prediction methods for phonon transport properties of inorganic crystals: from traditional approaches to artificial intelligence.

In inorganic crystals, phonons are the elementary excitations describing the collective atomic motions. The study of phonons plays an important role in terms of understanding thermal transport behavior and acoustic properties, as well as exploring the interactions between phonons and other energy carriers in materials. Thus, efficient and accurate prediction of phonon transport properties such as thermal conductivity is crucial for revealing, designing, and regulating material properties to meet practical requirements. In this paper, typical strategies used to predict phonon transport properties in modern science and technologies are introduced, and relevant achievements are emphasized. Moreover, insights into the remaining challenges as well as future directions of phonon transport-related exploration are proposed. The viewpoints of this paper are expected to provide a valuable reference to the community and inspire relevant research studies on predicting phonon transport properties in the near future.

Mechanical properties of FeNiCoAlTaB single crystal

Mechanical properties of FeNiCoAlTaB single crystal

The effect of hydrostatic pressure on electric transport properties of bulk black arsenic phosphorus single crystals

Black arsenic phosphorus AsxP1-x (b-AsxP1-x), as a novel two-dimensional material, has recently attracted great attention owing to their exotic physical properties. Here, we report a systematic study of the pressure dependence of electric transport properties in b-As0.75P0.25 single crystal. At ambient pressure, b-As0.75P0.25 shows an extrinsic semiconducting behavior, and the magnetoresistance (MR) has an obvious dependence on the magnetic field direction, resulting in an anisotropic MR effect. With the applied hydrostatic pressure, the crystal exhibits a tendency towards metallic behavior, whereas at pressures above 1.0-1.3GPa, the resistivity starts to increase at low temperatures. This picture is simultaneously supported by low temperature high-pressure MR measurements. Taking into account the negative and positive contributions to the MR, we have been able to propose a modified two-band model to describe the MR properties. The analysis of the MR data reveals the coexistence of high-mobility electrons and holes with nearly identical carrier densities. Above the critical pressure, the density of the electron that remains dominant increases with pressure while the electron mobility decreases significantly under pressure, leading to a transition in resistivity. This work has implications to both the fundamental understanding of bulk b-As0.75P0.25 and studies of two-carrier correlated materials.

Influence of shape on crystal structure and optical properties of heterocyclic conjugated molecules

Multi-ring, thiophene based heterocycles participate in discrete non-covalent interactions that dictate crystal packing of conjugated molecules, which also form a variety of polymorphs with different optical properties.