Crystal Stability Research Articles

A novel triethylamine gas sensor based on PrVO4 material by hydrothermal synthesis

Triethylamine (TEA) is a colorless, oily organic compound that can cause serious harm to humans and the environment. Therefore, it is crucial to develop a gas sensor that can rapidly detect TEA. Rare earth vanadate has attracted much attention in the field of sensors due to their strong catalytic effect, good crystallization and chemical stability. In this work, PrVO4 nanorods were synthesized by hydrothermal method. The crystal structure and morphology of PrVO4 were characterized by XRD, SEM, TEM and SAED. The novel PrVO4 gas sensor exhibits excellent gas sensitivity to TEA at 230 °C, including low concentration detection capability, fast adsorption/desorption times (19 s/14 s), good repeatability and long-term stability. In addition, the gas-sensitive mechanism of PrVO4 is briefly discussed. Therefore, PrVO4 can be used as a novel gas-sensitizing material.

Local electronic structure modulation via S substitution enables fast-discharging capability for Li-rich Mn-based oxides cathodes

Anionic and cationic redox reaction contribute to the ultrahigh specific capacities of Li-rich Mn-based oxides cathodes (LMNC). However, the irreversible oxygen evolution and sluggish kinetics result in the continuous capacity decay and poor rate performance, which limited its application as cathode material in lithium-ion batteries. Herein, the local electronic structure of LMNC is appropriately modulated via S2− doping to alleviate oxygen release, stabilize the crystal structure stability, and facilitate Li+ diffusion via facile surface defect engineering. The effect of S2− doping site on the systematically energy is investigated by DFT. Under the guidance of this result, LNMC-S is prepared by co-precipitation and high-temperature solid-phase reaction method. The effect of doping concentration on electrochemical property of LMNC was systematically investigated. The results exhibit that S2− doping can effectively suppress the electronic insulation of Li2MnO3, enhance the transport dynamics of lithium ion and inhibit the phase transition of LMNC sample during charge-discharge process. Thereby, the modified sample exhibits superior electrochemical property, such as the 200th discharge capacity is 184.3 mAh·g−1 under 1C, with a capacity retention rate of 87.6 %. This paper is beneficial for enriching the existing theoretical findings and discoveries, providing theoretical guidance for the preparation of high-performance material.

Exploration of crystal structure, supramolecular organization, and computational studies of a novel pyrazole derivative: A structural and theoretical perspectives

An eminent challenge in contemporary medicine and pharmacy is the identification of powerful, biologically active, and benign anti-COVID drugs. The objective of this work is to synthesize 3-chloro-1-(3-chloropyridin-2-yl)-1H-pyrazole-5-carboxylic acid to investigate its properties using different spectroscopic methods. The crystal structure of the compound is determined using single-crystal X-ray diffraction methodology. Hirshfeld surface analysis was employed to evaluate the impact of intermolecular interactions on crystal packing. The interactions were visually depicted using 2D fingerprint plots, which highlighted the specific surface area associated with each interactant. Indications suggest that the crystal packing is mostly governed by C-H...O and N-H...O interactions, resulting in the formation of S(7) self-motif and R44(24) synthon, which greatly improve crystal stability. Density functional theory (DFT) was employed to better examine the structural and electrical characteristics. Computations were conducted at the 6–311+G(d,p) level to determine the optimal geometry, total energy, HOMO-LUMO gap, and vibrational spectra. The results showed a HOMO-LUMO gap of 3.092 eV, suggesting a moderate amount of stability. Bader et al. employed reduced density gradient (RDG) techniques and topological analysis, taking into account the quantum theory of atoms in molecules (QTAIM), to examine noncovalent interactions. Additionally, the molecule satisfies Lipinski's rule of five and exhibits encouraging pharmacokinetic activities. Additional in-silico investigations, including molecular docking, were conducted on the SARS-CoV-2 spike protein variation to assist in the advancement of enhanced vaccines and therapeutics.

Cerium as a crystalline phase stabilizer of α-TCP and its hydration and photothermal properties

Bone cement with photothermal properties can treat bone defects caused by bone tumors while killing residual tumor cells or preventing recurrence. In this study, trace amounts of cerium ions were introduced to enhance the crystal stability of α-TCP, thereby improving the hydration properties of α-TCP and obtaining excellent photothermal properties. The experimental results showed that the content of α-TCP in CON-TCP was 96.05 %, and the content of α-TCP in 1% Ce-TCP was 99.77 %, with an increase of 3.87 %; the compressive strength of 0.5% Ce-CPC hydrated for 5d increased from 16.6 MPa±2.18 MPa to 32.16 MPa±2.77 MPa, with an increase of 93.73 %. The temperature of 0.5% Ce-CPC can be raised to 50.9°C in two minutes under the irradiation of 808 nm laser, which is an increase of 31.5% compared with that of 38.7°C in the blank group. Therefore, trace cerium-doped calcium phosphate bone cement has excellent physicochemical and photothermal properties, and it is a promising composite bone cement material, and the results of the present study are expected to be used to treat bone defects in bone tumors.

Chitosan/La catalyzed synthesis of novel ferrocenated spiropyrrolizidines: Green synthesis, crystallographic, DFT and Hirshfeld surface studies

A novel polymeric catalytic system, utilizing chitosan-bounded lanthanum (chitosan/La), facilitated the formation of spiropyrrolizidine hybrids in higher yield. These hybrids were synthesized via one-pot three component 1,3-dipolar cycloaddition reaction involving ferrocenated chalcones, and azomethine ylides. The chemical structures were elucidated using various spectroscopic techniques and further confirmed via X-ray crystallography of a compound 3. Density functional theory (DFT) calculations executed followed by Gaussian 09 and GaussView 5.0 software provided insights into the optimal structure of molecular compounds. The computational analysis employed the 6–311G++ (d,p) higher-order basis set and the B3LYP method. Additionally, Hirshfeld surface analysis was utilized to predict crystallographic shapes, revealing van der Waals interaction contributing to crystal stabilization.

Structural Investigation and Hirshfeld Surface Analysis of 2-6-Dimethoxy-4-((2-Nitrophenylimin)Methyl)Phenol

Introduction: The reaction between 4-hydroxy-3,5-dimethoxyenzaldehyde and 2-ni-troaniline has been discovered, and the final product has been identified such as 2-6-dimethoxy-4-((2-nitrophenylimin)methyl)phenol (C1). METHOD: X-ray diffraction examination per-formed on a single crystal provided conclusive evidence regarding the structure. Crystallography reveals that the two molecules A and B that were enclosed within the asymmetric unit are struc-turally distinct from one another. C-H···O, N-H···O, and O-H···O bonding is primarily respon-sible for the crystal packing stability. H-O and off-set stacking interactions also contribute to the crystal packing's overall stability. Results: To do further research into the intermolecular interactions, the Hirshfeld surface analy-sis technique is utilized. It is possible to determine the partiality of the interatomic contacts to create crystal packing interactions by computing the improvement ratio for those contacts. In addition, computational research is carried out with the B3LYP/6-31G(d,p) model to determine the amount of energy that is required for molecular pairs to interact. Conclusion: The study concluded the roles those different kinds of interaction energy play in maintaining the stability of the molecular pair.

Crystal phase stability and barocaloric efficiency of (NH4)3WO2F5

Calorimetric, dilatometric and pressure studies of (NH4)3WO2F5 were performed over a wide temperature range, including the Pm-3m ↔ Pa-3 phase transition. Comparison of the obtained results with data for related fluorides (NH4)3SnF7 and (NH4)3TiF7 undergoing the same structural changes showed a significant role of chemical pressure in the formation of thermal and barocaloric properties. A decrease in anomalous entropy in oxyfluoride, ΔS0 = 12.2 J/mol·K, is accompanied by a significant increase in sensitivity to hydrostatic pressure, dT0/dp = 93 K/GPa, the preservation of a large change in anomalous deformation δ(ΔV/V)0 = 0.45 % and a small temperature hysteresis, δT0 < 1 K. This combination of thermal characteristics has led to both a significant increase in extensive and intensive barocaloric parameters in the low pressures area, and to their high reversibility in the modes of increasing and decreasing pressure.

Scope and design of diversified supramolecular synthons of 5-hydroxyisophthalic acid: Crystallographic and theoretical investigations

The designed creation of cocrystals between 5-hydroxyisophthalic acid and diverse N-donor bases has been investigated by supramolecular synthon formations. The structures of four binary cocrystals are determined using single crystal X-ray diffraction technique. The resemblances and distinctions in supramolecular synthon structures have been analyzed and discussed. The interaction pattern changes with alteration in the structure and basicity of the N atoms of the respective bases. The acid···pyridine hetero-synthon, a supramolecular synthon between unlike functional groups, plays a major role in forming all the cocrystals. Apart from acid···pyridine synthon, hydroxyl···pyridine hetero-synthons are observed in HPA:DPE-I and HPA:DPE-I cocrystal. Whereas, acid···hydroxyl heterosynthons are found in HPA:AZO and HPA:TMP cocrystals. As hetero-synthons are energetically preferred regarding homosynthons, the latter is not observed in the structures. It is noticed that apart from strong O–H···N hydrogen bonds, comparatively weak C–H···O hydrogen bonds are also crucial in crystal packing and stability. DFT calculations along with Hirshfeld analysis have been performed to estimate the energetic characteristics of different interactions and crystal packing of the aforementioned cocrystals. Further, energetic characteristics of the synthons involving distinct non-covalent interactions, such as O–H···N, C–H···O and C–H⋯π interactions, are explored by intricate combination of computational methods i.e. QTAIM analysis and the non-covalent interaction (NCI) plot index.

Liquid crystal droplets formation and stabilization during phase transition process

Abstract The study of phase transition processes in liquid crystals (LCs) remains challenging. Most thermotropic LCs exhibit a narrow temperature range and a rapid phase transition from the isotropic (ISO) to the nematic (N) phase, which make it difficult to capture and manipulate the phase transition process. In this study, we observed the evolution of small droplets during the ISO-N phase transition in ferroelectric nematic (NF) LC RM734. After doping with metal nanoparticles (NPs), the temperature range of the phase transition broadened, and the droplets formed during the phase transition remained stable, with their diameter increasing linearly with temperature. In addition, droplets doped with NPs can be well controlled by an external electric field. This discovery not only aids in understanding the fundamental mechanisms of LC phase transitions but also provides a simple alternative method for preparing droplets, which is potentially valuable for applications in optoelectronic devices and sensors.

Preparation and Properties Study of CsPbX3@PMMA Luminescent Resin.

Perovskite as an emerging semiconductor luminescent material has attracted widespread attention due to its simple preparation, high luminescence quantum yield, high color purity, tunable spectrum, and ability to cover the entire visible light band. However, due to the influence of water or other highly polar solvents, oxygen, temperature, and radiation, perovskite nanocrystals will aggregate or collapse in the lattice, eventually leading to luminescence quenching. This study starts from the postprocessing of perovskite, uses methyl methacrylate as the monomer and TPO as the photoinitiator, and encapsulates the perovskite powder prepared by the hot injection method through ultraviolet light initiation. A method is proposed to improve the luminescence and crystal structure stability of perovskite. By eliminating the influence of environmental factors on perovskite nanocrystals through the dense structure formed by organic polymers, the resistance of perovskite to strong polar solvents such as water will be greatly improved, and it has great potential in the protection of perovskite. Finally, by changing the proportion of halogen elements in the perovskite resin to change the color of the luminescent resin, a fluorescent coating emitting light in all visible light bands is prepared. Fluorescent coatings are widely used in life and industry fields such as plastics, sol, and paper.

Ionic substitutions in the Cu3TeO6 structure type and magnetic properties of “medium entropy” Cu3/2Mn1/2Co1/2Fe1/2SbO6

Cubic antiferromagnet Cu3TeO6 demonstrates interesting magnetic properties. Aimed at modification of them, we tried multiple ionic substitutions in its structure. However, single-phase materials could only be prepared with large fraction of the Jahn-Teller ions (Cu2+ and Mn3+), although formally isostructural bixbyites R2O3 (R4O6) with R = Sc, In, Tl, Sm…Lu exist with no Jahn-Teller ions. Moreover, ions having highest octahedral crystal field stabilization energy (Ni2+ and Cr3+) were found least tolerable. This points to Cu3TeO6 as a separate structure type, distinct from classical bixbyites. We report crystal structure, magnetic and thermodynamic properties of a rare single-phase multicomponent preparation, Cu3/2Mn1/2Co1/2Fe1/2SbO6. The dc magnetic studies show that the formation of the ground spin-cluster state at T = 18 K is preceded by a broad anomaly at ∼122 K. Both specific heat and ac susceptibility data rule out the long-range magnetic ordering, in contrast to closely related Cu2MSbO6 (M = Mn or Fe).

Excitonic properties and solar harvesting performance of Cs2ZnY2X2 as quasi-2D mixed-halide perovskites

Due to their low toxicity and high-temperature stability, lead-free quasi-2D metal halide perovskites (MHPs) are promising materials for optoelectronic applications. However, understanding their structural and optoelectronic properties, especially excitonic effects (electron-hole pair, e-h), is challenging due to their quantum well topology. We propose an efficient protocol for band gap correction of Cs2ZnX (X = Cl4, Br2Cl2, and I2Cl2) and Cs2PbI2Cl2 (used as a benchmark) quasi-2D MHPs. This protocol is based on a relativistic quasiparticle approach (DFT-1/2) using density functional theory (DFT). We first examined the hybrid contributions of the halide alloys, leading to excitonic characterization using the Bethe–Salpeter equation within the maximally localized Wannier functions tight-binding method. This method provides a cost-effective approach for describing e-h quasiparticle effects. Additionally, we analyzed the crystal structure, thermodynamic stability, and optoelectronic properties of the newly synthesized Zn-based systems, focusing on their structural stability mechanisms. We found a correlation between the allocation of Cs+ cations in the crystal structure and the formation of two distinct stabilization patterns, influenced by the radii of the metal (Zn or Pb) and halide components. The relativistic correction of the band gap energies yielded results within 10 % of the experimental values. Furthermore, incorporating e-h quasiparticle effects for Cs2PbI2Cl2 resulted in an exciton binding energy of 0.160 eV, in excellent agreement with experimental data. This work represents a significant advance in the optoelectronic characterization of Cs2ZnX systems, previously unexplored for their excitonic properties.

Quantitative detection of plasticizer migration in starch/polyvinyl alcohol film with UV-Vis and GC-MS/MS

In this work, the migration of urea and/or formamide plasticizers in crosslinked starch/polyvinyl alcohol (PVA) films under UV irradiation has been accurately quantified by using a combination of GC-MS/MS and UV–Vis analysis. The crosslinked starch/PVA films, prepared with different amide plasticizers (urea, formamide, urea-formamide), were characterized via scanning electron microscopy (SEM), X-ray diffraction (XRD), differential scanning calorimetry (DSC), and X-ray photoelectron spectroscopy (XPS). After 7 days of UV irradiation, the starch/PVA film plasticized with urea-formamide (A7-SPF-UF) exhibited a flat surface morphology, high crystal stability, and highest thermal stability. The migration ratio of urea and formamide for A7-SPF-UF was also quantified to be 3.2 % and 4.5 %, respectively, using GC-MS/MS and UV–Vis analysis, indicating optimal migration resistance. The synergistic effect of urea and formamide as plasticizers built the dense network structure of An-SPF-UF and improved the UV aging resistance, toughness and durability of the film. On one hand, this enhances the market competitiveness of the products; on the other hand, it promotes the development of environmentally friendly materials, aligning with sustainability requirements.

Analysis on optical, thermal and third-order nonlinear properties of L-histidine hydrochloride monohydrate single crystal

This research contributes valuable insights into the understanding of third-order nonlinear optical effects in L-histidine hydrochloride monohydrate (LHHC) single crystal, offering a foundation for future work in optimizing its properties for practical applications in the field of nonlinear optics. It presents a systematic analysis into the LHHC crystal properties harvested by slow evaporation solution (SEST) method. Originally, structure of the compound was confirmed through single crystal x-ray diffraction and powder x-ray diffraction analysis. FTIR analysis was performed to get information about molecular composition of the compound. The assessment of the optical quality of LHHC single crystal was done by UV–Visible and photoluminescence spectroscopies. TG-DTA was employed to assess the stability of the single crystal under different temperature conditions. Z-scan technique, with an open aperture (OA) & closed aperture (CA) configuration, was employed to comprehensively explore the third-order nonlinear response of LHHC single crystal. The nonlinear absorption coefficient β is determined to be 5.32 × 10−10 cm W−1. The NLR index (n2) is calculated as −2.72 × 10−15 cm2 W−1.

Unveiling the optoelectronic features and physical stability of novel Cs2HgPdI6: Computational insights

In recent years, researchers have been devoted to search for novel stable halide perovskite materials with outstanding photovoltaic performance. Herein, through density functional theory (DFT) calculations, we uncover for the first time the crystal stability, structural parameters, optoelectronic features, and photovolatic performance of Cs2HgPdI6. The Jahn−Teller-distorted Cs2HgPdI6 is detected by its structural feature. The stability of novel Cs2HgPdI6 is completely ensured by means of the DFT calculations. Accurate electronic structure calculations show that Cs2HgPdI6 exhibits an appropriate fundamental gap (1.278 eV). This band gap is mainly determined by the interaction between the I-5p and Pd-4d orbitals. Additionally, Cs2HgPdI6 has good carrier mobility and an ultra-low exciton binding energy. Meanwhile, it also exhibits relatively weak anisotropic optical properties and strong visible-light absorption. The large theoretical conversion efficiency of 31.7 % is illustrated for Cs2HgPdI6. Overall, our research highlights the great potential of this novel compound for photovoltaic applications.

Zn-substituted Co3O4 crystal anchored on porous carbon nanofibers for high performance supercapacitors

Metal-organic frameworks (MOFs) are a promising class of electrode materials for supercapacitors. In this work, MOF-derived transition metal oxide/carbon nanofiber composites (ZnCoO/C) are synthesized through a freeze-drying method followed by a carbonization process. The crystal structure of the ZnCoO/C product is regulated by changing the ratio of Co to Zn, which in turn influences its electrode properties. The electrochemical tests reveal that the ZnCoO/C-2 electrode demonstrates an impressive specific capacitance of 356.3 F g-1 at 1 A g-1 and maintains a capacitance retention exceeding 77 % after 10,000 cycles, which exhibits a good cycling stability. It is found that appropriate Zn substitution can diminish the crystallinity of the material, augment the active sites, and enhance the specific capacitance of the electrode material. Considering the heteroatom substitution tends to introduce vacancy defects in the crystals, this work theoretically explores the effect of oxygen vacancies on the electrode materials. As the oxygen vacancy concentration increases, the band gap and the adsorption energy of the models decrease; conversely, the formation energy of the models shows an increasing tendency. This indicates that an increase in oxygen vacancies can enhance the electrical conductivity of electrode materials and facilitate their kinetic process but destroy the stability of crystal. This research explores the interplay between the microstructure and the electrochemical performance of electrode materials, providing a foundational reference for the design of structurally optimized high-performance electrodes and further elucidating the energy storage mechanisms in supercapacitors.

Modeling the melting temperature of semiconductor nanocrystals

Exploring the thermal stability of semiconductor crystals at the nanoscale is of great significance for the design, fabrication, and application of modern quantum devices. In this paper, we propose a thermodynamic model to predict the melting temperature of semiconductor nanocrystals, which is in good agreement with the experimental results of Si, Bi, CdS, and CdSe. In addition, when the size decreases, the drop of melting temperature curves tends to be synchronized with the size-dependent solid/liquid interface energy and surface stress ratio γsl(D)/f(D), which reveals the physical origin of the decrease in the melting temperature of the semiconductor nanocrystals.

Carbon quantum dots derived from rice straw doped with N and S and its nanocomposites with hydroxypropyl cellulose nanocomposite

As biomass, rice straw (RS) is often valorized as a precursor of green products. In this respect, the RS-based carbon quantum dots (CQDs) are synthesized doped with N and S during the preparation. Synergistic doping with lipoic acid and ethylenediamine can vastly increase the yield of CQD from rice straw from 6.14 % to 62.8 %, and sulfur doping plays a more important role on the surface functional groups of the quantum dots. Further assessment is achieved toward the performance of SN-CQDs-hydroxypropyl cellulose nanocomposites. The optical behavior of synthesized SN-CQDs, and the critical concentration of its liquid crystal behaviors, at which the anisotropic phase begins to emerge, is approximately 1 %. Incorporating it into HPC, especially at 5 %, provided nanocomposite films with effective liquid crystal, tensile strength, and thermal stability. This sample's texture reveals a planar structure with colors ranging from yellow to red. The synergistic effect of incorporating SN-CQDs is shown by improving the strength to ~282.1 %, and the activation energy increased from 583.6 kJ.mol−1 to 615.1 kJ/mol. HPC-SN-CQDs can be assembled into an LED device, emitting warm light, of which CIE coordinate is (0.34,0.43).

Influence of compositional variation of Li3InCl6 on the solid-electrolyte property

Li3InCl6 (LIC) is a promising halogen-based solid electrolyte. This study investigates the influence of compositional variations in LIC on its properties as a solid electrolyte using deep-learning-assisted computational simulations. Introducing vacancies to create LIC compositions with elemental deficiencies enhances the mobility of Li ions. However, while Cl deficiency increases Li-ion mobility, it also induces instability in the crystal structure by facilitating Cl ion movement. In contrast, generating vacancies exclusively for Li ions significantly boosts Li-ion conductivity while maintaining a stable anionic superlattice structure. Therefore, minimizing Cl vacancies while promoting a Li-deficient state is recommended as an effective compositional design strategy to enhance the solid electrolyte performance of LIC while ensuring crystal structure stability.

Pivotal Role of Modifiable A-Site Doping in Enhancing Valence Stability and Excited State Dynamics of MnO6.

The controlled regulation of A-site in rare earth manganate perovskites can orderly arrange the electronic states, leading to the emergence of unique transport properties. However, it is challenging to balance crystal structure stability and property variations during the multi-ion doping. In this study, a series of multivalent manganate perovskites are synthesized by hydrothermal method through the A-site multielement doping, which enables the manganese atoms with varying valence states to orderly arrange at the B site. Powder X-ray diffraction (PXRD) and X-ray absorption spectra (XAS) confirm that the splitting of the K─O hybrid orbitals in the crystal effectively prevents any distortion of the MnO6 octahedron, thereby facilitating the ordered arrangement of Mn (III) -Mn (IV) -Mn (V) at the B-site and promoting superstructure formation. The transient absorption spectra (TAS) reveals that the sequential arrangement of Mn (III) - Mn (IV) - Mn(V) better forms the charge transfer channels, and thereby makes the photodynamic properties of the sample composition-dependent. These photodynamic properties will facilitate the study of exciton-electron coupling behavior in LCKMO crystals during electrical transport.