Properties Of Crystals Research Articles

Self-activated epitaxial growth of ScN films from molecular nitrogen at low temperatures

Unlike naturally occurring oxide crystals such as ruby and gemstones, there are no naturally occurring nitride crystals because the triple bond of the nitrogen molecule is one of the strongest bonds in nature. Here, we report that when the transition metal scandium is subjected to molecular nitrogen, it self-catalyzes to break the nitrogen triple bond to form highly crystalline layers of ScN, a semiconductor. This reaction proceeds even at room temperature. Self-activated ScN films have a twin cubic crystal structure, atomic layering, and electronic and optical properties comparable to plasma-based methods. We extend our research to showcase Sc’s scavenging effect and demonstrate self-activated ScN growth under various growth conditions and on technologically significant substrates, such as 6H–SiC, AlN, and GaN. Ab initio calculations elucidate an energetically efficient pathway for the self-activated growth of crystalline ScN films from molecular N2. The findings open a new pathway to ultralow-energy synthesis of crystalline nitride semiconductor layers and beyond.

Influence of Ionic Liquids on the Functionality of Optoelectronic Devices Employing CsPbBr3 Single Crystals

Regulating the nucleation temperature and growth rates during inverse temperature crystallization (ITC) is vital for obtaining high-quality perovskite single crystals via this technique. Precise control over these parameters enables growing crystals optimized for various optoelectronic devices. In this study, it is demonstrated that incorporating a 1-butyl-3-methylimidazolium bromide (BMIB) ionic liquid into the precursor solution of cesium lead bromide (CsPbBr3) brings about a dual enhancement effect. This includes a reduction in nucleation temperature from 85 °C to 65 °C and a significant improvement in both optoelectronic characteristics and crystal properties. The CsPbBr3 single crystals grown using ITC with BMIB added (method (2)) demonstrate improved chemical and physical properties (crystallinity, lattice strain, nonradioactive recombination, and trap density) compared to CsPbBr3 single crystals produced through conventional 85 °C ITC alone (method (1)). The exceptional quality of CsPbBr3 single crystals produced with the inclusion of BMIB allowed for the development of a highly responsive optoelectronic device, demonstrating heightened sensitivity to green light. The findings of this investigation reveal that the growth of perovskite single crystals assisted by ionic liquid exerts a substantial impact on the characteristics of the crystals. This influence proves advantageous for the development of optoelectronic devices based on single crystals.

Cold and Liquid Crystal Properties of Square-Planar Copper(II) Versus Nickel(II)- Iminophenolate/Naphthalen-2-Olate Schiff Base Complexes.

Reaction of the phenolate or naphthalen-2-olate based Schiff base ligands, (E)-1-((2-ethylphenylimino)methyl)phenol (HL1) or (E)-1-((2-ethylphenylimino)methyl)naphthalen-2-ol (HL2) with nickel(II) and copper(II) acetate provides the complexes bis[(E)-1-((2-ethylphenylimino)methyl)phenolato-ĸ2N,O]Ni/Cu(II), [Ni(L1)2] (1) and [Cu(L1)2] (2), or bis[(E)-1-((2-ethylphenylimino)methyl)naphthalen-2-olato-ĸ2N,O]Ni/Cu(II), [Ni(L2)2] (3) and [Cu(L2)2] (4), respectively. Single crystal X-ray structure determinations for 1, 3 and 4 reveal N2,O2-metal coordination of two chelating Schiff base ligands in a square-planar geometry. Powder X-ray diffractograms confirm the phase purity of the bulk microcrystalline samples. Thermal analyses by differential scanning calorimetry (DSC) and polarized light microscopic (PLM) indicate the copper(II) complexes to exhibit cold crystal (2) and liquid crystal (4) property. Cyclic voltammograms suggest an irreversible electrochemical process with two one electron charge transfer processes in N,N-dimethylformamide. Variable temperature magnetic measurements at the solid-state prove the diamagnetic nature of the low-spin Ni2+ centres in 1 or 3, as expected from the square-planar coordination geometry with rather strong ligands. The complexes expose medium level of antioxidant activity in methanol. Optimized geometry and excited state property by DFT/TD-DFT correspond well to the experimental results of the electronic and molecular structure at the ground state.

3D‐printing continuous plant fiber/polylactic acid composites with lightweight and high strength

AbstractContinuous plant yarn‐reinforced polylactic acid (PLA) composites were produced through in situ 3D printing, focusing on how plant fiber attributes influence the crystallization, mechanical, and rheological properties of the printed composites. The aim of this study was to assess the viability of plant fibers as substitutes for synthetic ones in engineering additive manufacturing. Plant fibers promoted the crystallization of PLA due to their shear induction and nucleation agent induction effects. The inherent triangular void defect during printing decreased with increasing plant fiber‐volume fraction. Rheological analysis revealed a transition to more elastic behavior post‐fiber addition, indicating solid‐like properties. The tensile strength of flax fiber‐yarn/PLA composite (volume fraction of 50.79%) was 342.37% higher than that of pure PLA, with a 22.2% lower density than pure PLA. Flax fiber demonstrated a superior reinforcement effect than carbon fiber in compressive strength for 3D printed honeycomb sheets with lower energy consumption and footprint. Optimizing fiber characteristics holds promise for high‐performance 3D‐printed natural fiber composites, particularly in vehicle applications.Highlights Plant fiber/polylactic acid (PLA) composites were in situ printed with a volume fraction of 50.79%. Plant fibers promoted the crystallization of PLA during the printing process. The tensile strength of flax fiber/PLA increased by 342.3% with a 22.2% lower density than PLA. Flax fiber showed a better reinforcement than carbon fiber in a compressive test of printed honeycomb.

Regulated crystallization and piezoelectric properties of bio-based poly(L-lactic acid)/ diatomite composite fibers by electrospinning

Regulated crystallization and piezoelectric properties of bio-based poly(L-lactic acid)/ diatomite composite fibers by electrospinning

Investigation of non-reciprocity and behavior of defect modes in photonic crystals incorporating Weyl semimetals

Abstract The ability to control the frequency of defect modes in photonic crystals has led to the emergence of novel applications. Researchers have recognized the unique properties of Weyl semimetals and explored their utilization in photonic crystals. This study investigates the non-reciprocal properties in photonic crystals incorporating Weyl semimetals and examines the behavior of defect modes within these crystals. This paper employs a photonic crystal containing Weyl semimetals with two different structures. Initially, the non-reciprocal properties in both structures are examined, followed by an analysis of the behavior of defect modes. The results indicate that only utilizing Weyl semimetal in the photonic crystal does not result in non-reciprocity. The arrangement of layers next to each other, or the geometry, plays a crucial role in non-reciprocity. Additionally, the behavior of defect modes varies depending on the structure type and propagation direction.

Tearing properties, crystallization behavior, microstructure, and morphology of LLDPE with different short branched chain distributions

Abstract The length and distribution of comonomers with short-chain branching (SCB) have a significant influence on the crystallization behavior and crystal structure of polymers, as well as the mechanical properties of the material. This study investigates the crystallization behavior and properties of linear low-density polyethylene (LLDPE) samples with similar density, molecular weight, and branching degree but varying SCB distributions. The results show that LLDPE with butene as the comonomer has a stronger ability to suppress crystallization compared to LLDPE with hexene as the comonomer due to its more uniform SCB distribution. Additionally, among LLDPEs with comonomers of octene, hexene, and butene, the LLDPE with the most uniform SCB distribution exhibits the weakest crystallization ability. Small-angle X-ray scattering (SAXS) and scanning electron microscopy (SEM) results indicate that LLDPE with more uniform distribution of SCB has smaller long-period and more regular lamellar structure. Therefore, LLDPE with more uniform SCB distribution exhibits weaker inhibition ability towards crystallization, leading to less agglomerated phases and weaker phase separation, resulting in higher tear strength.

Structural and Optical Properties of SrTiO3-Based Ceramics for Energy and Electronics Applications

A series of Sr1−xDyxTi1−yNbyO3−δ (0.05 ≤ x, y ≤ 0.10) samples were fabricated using cold compaction, followed by sintering in a (95% N2 + 5% H2) reducing atmosphere. We studied the crystal structure and optical properties of Sr1−xDyxTi1−yNbyO3−δ using X-ray diffraction (XRD) with Rietveld refinement, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and ultraviolet−visible−near-infrared (UV−VIS−NIR) spectroscopy. The sintered Sr1−xDyxTi1−yNbyO3−δ had a tetragonal structure (I4/mcm space group). In the sintered samples, Ti ions existed as a mixture of Ti3+ and Ti4+, and Nb ions existed as a mixture of Nb4+ and Nb5+. The band-gap energies decreased with increasing Dy/Nb concentrations. The incorporation of Ti and Nb ions, the formation of both Ti3+ and Nb4+ ions, and the reduction in band-gap energies are likely highly effective for increasing the electron concentration and the corresponding electrical conductivity. Sr1−xDyxTi1−yNbyO3−δ with high electrical conductivity is suitable for energy and electronics applications.

Characterization of Crystal Properties and Defects in CdZnTe Radiation Detectors

CdZnTe-based detectors are highly valued because of their high spectral resolution, which is an essential feature for nuclear medical imaging. However, this resolution is compromised when there are substantial defects in the CdZnTe crystals. In this study, we present a learning-based approach to determine the spatially dependent bulk properties and defects in semiconductor detectors. This characterization allows us to mitigate and compensate for the undesired effects caused by crystal impurities. We tested our model with computer-generated noise-free input data, where it showed excellent accuracy, achieving an average RMSE of 0.43% between the predicted and the ground truth crystal properties. In addition, a sensitivity analysis was performed to determine the effect of noisy data on the accuracy of the model.

Synthesis and structure of a non-van-der-Waals two-dimensional coordination polymer with superconductivity

Two-dimensional conjugated coordination polymers exhibit remarkable charge transport properties, with copper-based benzenehexathiol (Cu-BHT) being a rare superconductor. However, the atomic structure of Cu-BHT has remained unresolved, hindering a deeper understanding of the superconductivity in such materials. Here, we show the synthesis of single crystals of Cu3BHT with high crystallinity, revealing a quasi-two-dimensional kagome structure with non-van der Waals interlayer Cu-S covalent bonds. These crystals exhibit intrinsic metallic behavior, with conductivity reaching 103 S/cm at 300 K and 104 S/cm at 2 K. Notably, superconductivity in Cu3BHT crystals is observed at 0.25 K, attributed to enhanced electron-electron interactions and electron-phonon coupling in the non-van der Waals structure. The discovery of this clear correlation between atomic-level crystal structure and electrical properties provides a crucial foundation for advancing superconductor coordination polymers, with potential to revolutionize future quantum devices.

Understanding the Role of NHC Ditopic Ligand Substituents in the Molecular Diversity and Emissive Properties of Silver Complexes.

Silver bis(carbene) complexes featuring ditopic N-heterocyclic carbene (NHC) ligands have been synthesized which enable the assembly of supramolecular architectures via reaction with silver triflate. Through a systematic exploration of crystal structures and emissive properties, this study investigates the impact of the substituents on the NHC ditopic ligands [R-Im-2-Z-py], where R = Me, benzyl (Bz), or 2-naphthylmethyl (NaphCH2), and Z = H or Cl in the structural framework and emissive properties observed in the silver bis(carbene) or polynuclear species. Remarkably diverse structural motifs emerge in both of them, predominantly influenced by the choice of R wingtip and second by the Z substituent. Also the emissive quantum yield of the complexes is mostly governed by the selection of the R wingtip and further modulated by the Z substituent. Several of the mono and polynuclear complexes exhibit complex emissive profiles, including the observation of dual emission phenomena. Particularly noteworthy is the complex [Ag(NHC)]2]OTf (R = Bz, Z = Cl), which demonstrates an exceptionally intense single blue emission with a remarkable solid-state quantum yield (Φ) of 24%.

Evolution from micropinned to polymeric alloy structure of XLPE‐PS: Improving electrical properties and mechanism

AbstractThis research investigates the transition from a micropinned to a polymeric alloy structure in crosslinked‐polyethylene‐polystyrene (XLPE‐PS). Incorporating 2 wt% 10 μm PS particles into low‐density polyethylene (LDPE) and crosslinking with 2 wt% dicumyl peroxide (DCP) forms XLPE‐PS structures. The polymeric alloy structure, formed at 220°C extrusion, contrasts with the micropinned formed at 150°C. Morphological, thermo‐structural, chemical, and crystal properties are examined to understand their impact on electrical properties and charge transport mechanisms. Results indicate that the polymeric alloy effectively resolves void/crack issues, whereas the micropinned exhibits phase separation. Both structures exhibit a benzene‐crosslinked network, and variations in these structures lead to significant changes in thermo‐structural, chemical, and crystalline properties. The polymeric alloy XLPE‐PS shifts the polyethylene (PE) hkl crystal planes, confirming phase shift and optimal alloying. The structural alterations reveal deeper traps and higher densities in the polymeric alloy XLPE‐PS, leading to significantly improved electrical properties, including reduced DC conductivity by up to 1.3 and 0.7 decades at 30 and 90°C, and increased DC breakdown strength by up to 40.34% and 16.17% at 30 and 90°C, respectively, compared with micropinned XLPE‐PS. This research offers insights into stable high‐voltage insulation development.

Achieving high piezoelectric performance in Pb(Mg1/3Nb2/3)O3–PbTiO3 ferroelectric single crystals through pulse poling technique

To maximize the piezoelectric performance of Pb(Mg1/3Nb2/3)O3–PbTiO3 (PMN–PT) single crystals, a pulse poling (PP) method is proposed in this study. This study investigates the effects of pulse poling on the piezoelectric and dielectric properties of these PMN–PT single crystals and explores the polarization rotation mechanisms. Our findings indicate a significant improvement in the piezoelectric properties postpulse poling. The optimal PP conditions are identified as 30 pulse numbers at a pulsed electric field of 5 kV/cm. The dielectric constant ɛT33/ɛ0 and piezoelectric coefficient d33 of PMN–0.28PT post PP are 7000–7700 and 2200–2530 pC/N, respectively, representing increases of 49% and 66% compared with those of postdirect current poling (DCP). Additionally, the domain structures of the PMN–0.28PT single crystals after various DCP and PP treatments are examined and compared using piezoelectric force microscopy. The enhanced piezoelectric properties are attributed to the finer domain structures, as well as increased domain wall density achieved through PP. This research introduces a novel domain engineering approach to improve the electromechanical properties of relaxor ferroelectric single crystals.

Preparation and property of (NaZn)3+-substituted Sc2Mo3O12 ceramics with negative thermal expansion

To modulate the negative thermal expansion (NTE) performances of Sc2Mo3O12 ceramics, (NaZn)3+-substituted Sc2Mo3O12 ceramics were prepared via solid-state reactions. The crystal phase, morphology, and NTE properties of the NaxZnxSc2−x(MoO4)3 (0 ≤ x ≤ 1) samples were investigated. XRD results reveal that NaxZnxSc2−x(MoO4)3 samples undergo a change in crystal structure from orthorhombic to hexagonal phase due to (NaZn)3+ doping. (NaZn)3+ introduction also promotes grain growth and increases the density of the NaxZnxSc2−x(MoO4)3 ceramics. With the increase in (NaZn)3+ substitution, NaxZnxSc2−x(MoO4)3 ceramics exhibit stronger NTE, and the thermal expansion coefficients (CTEs) improve from −4.74 × 10−6 to −8.77 × 10−6 °C−1 in 30–650 °C. High-temperature XRD results reveal that the hexagonal NaxZnxSc2−x(MoO4)3 samples exhibit anisotropic NTE. With the increase in (NaZn)3+ substitution, the linear CTEs of the a and b axes decreased from −13.17 × 10−6 to −15.93 × 10−6 °C−1, while one of the c axes decreased from 18.38 × 10−6 to 12.27 × 10−6 °C−1. Consequently, hexagonal NaxZnxSc2−x(MoO4)3 samples present stronger NTE as the content x rises.

A Discovery of Pressure-Induced New Semiconductor Electronic Phase Transitions by DFT Calculations: Introducing a Glimpse of a Novel Semiconductor Family.

This study introduces a discovery of pressure-induced new semiconductor electronic phase transitions. A novel semiconductor family that exhibits pressure-induced nonmonotonic changes in band gaps was found and meets the definition of phase transitions, challenging the traditional understanding of linear and monotonic band gap modification through pressurization. Our findings suggest a complex interplay of atomic spacing and electron orbital contributions under varying pressure conditions, resulting in the variation of band gaps. This behavior, which includes three distinct steps: first, narrowing, second, broadening, and third, narrowing again and ultimately metalizing; some compounds could bypass step 1, has potential applications in piezoelectric and semiconductor technologies. We propose two new semiconductor electronic phase transitions (SEPT) associated with specific inflection points in the pressure-dependent band gap curve. Our results open avenues for further research into the electronic properties of crystals under high pressure, with the ultimate goal of uncovering the more profound physical principles governing these phenomena.

Enhancing optical properties in sulphamic acid single crystals through caesium doping for advanced NLO applications

Enhancing optical properties in sulphamic acid single crystals through caesium doping for advanced NLO applications

The Effect of the Surface Treatment on TiO2 Particles When Used as a Filler on Crystallization and Mechanical Properties of Polylactic Acid Composites. Case of Study: Silane Coupling Agents and Dicarboxylic Acids Were Used as Surface Modifiers

ABSTRACT This article analyzes the effect of the type of surface modification (using silane coupling agents and dicarboxylic acids) on titanium dioxide particles used as fillers in polylactic acid composites, which were exposed to a photodegradative process. The thermomechanical properties of the composites were analyzed; it was found that the silane coupling agent with Imidazole allowed the composites to have Young’s modulus values 60% lower than the composite without filler. On the other hand, the crystallization rate was 30% higher for composites with azelaic Acid attached to TiO2 particles than for composites without filler at a cooling rate of 5°C min−1. Once degraded composites containing azelaic acid were the least brittle, with a minor increment in Young’s Modulus compared to pure polylactic acid composites. When a mixture of modified titanium dioxide particles (with imidazole and either azelaic acid or pimelic acid) was used, there was a synergistic effect regarding photostability.

Ultralow thermal conductivity in Si–Ge nanograin mixtures: A cost-effective granular material for thermoelectric applications

This paper presents a theoretical study of the thermal conductivity of Si–Ge nanograin mixtures using a multiscale computational methodology based on solving the Boltzmann transport equation for phonons with first-principles techniques. A size-dependent correction factor is developed to account for the spatial dependence of the phonon distribution function on nanograin size, with parameters derived from the phonon properties of infinite Si and Ge crystals. This approach makes it possible to accurately calculate the thermal conductivity within a single nanograin, using force constants obtained from first-principles calculations. Thermal energy transport by phonons across grain boundaries is modeled by accounting for phonon transmission by two-phonon processes, weighting specular, and diffuse transmission for each phonon mode as a function of the root-mean-square roughness of the boundary relative to the phonon wavelength. The boundary thermal conductance model, previously validated against experimental data, is implemented using first-principles techniques. This approach excludes specular transmission for phonon modes with specific symmetries while ensuring conservation of the total number of modes in each symmetry class. The study examines the influence of grain size, nanograin mixture composition, temperature, and boundary asperities on the thermal conductivity of nanograin mixtures.

Solvation modeling and optical properties of CdSO4-Doped L-Valine crystals

The utilization of computational solvation models for crystals proves effective in determining the amalgamation of molecular structures within the crystal medium, offering valuable insights into optimized crystal properties. This study focuses on identifying the arrangement of molecular strips within the crystal, crucial for recognizing active planes and the presence of non-linear optical (NLO) properties. To delve into the crystal's intricacies, a computational model was developed, and conformational analysis was conducted to ensure NLO property. The synthesis of the CdSO4-doped L-Valine metallo-organic complex crystal was achieved through the melt-freezing technique. The computational model was constructed to elucidate the formation of sub-planes within a confirmed orthorhombic crystal lattice. Mapping the molecular charge distribution with the dispersion of charge gradient facilitated the identification of chemical potential inhibition and its equipotential nodal domains. The estimation of electron density potential over critical points of the core carbons provided further insights. Chemical dynamics on the electron content of molecules for NLO properties were investigated by screening control parameters. The inelastic scattering ability of heteronuclear bonds for enhancing boosting potential was observed. Interactive frontier orbitals of degenerate energy states were illustrated, and the chemical potential of molecular zones was analyzed in-depth.

All-in-one quantum diamond microscope for sensor characterization

Ensembles of nitrogen-vacancy (NV) centers in diamond are a leading platform for sensing and imaging magnetic fields at room temperature, in part due to advances in diamond growth. An essential step to improving diamond material involves the characterization of crystal and NV-related properties, such as strain and paramagnetic impurities, which can shift and broaden the NV resonances used for sensing. Full sample characterization through wide-field imaging enables both fast and detailed feedback for growers, along with the estimation of sensing performance before use. We present a quantum diamond microscope tailored for millimeter-scale wide-field mapping of key quantum properties of NV-diamond chips, including NV ensemble photoluminescence intensity, spin-lattice relaxation time (T1), and spin-coherence lifetimes (T2 and T2*). Our design also allows for lattice stress/strain and birefringence magnitude/angle mapping, and their in situ correlation with NV properties.