CrystEngComm最新文献

Nanoparticles of poly(vinylidene fluoride) (PVDF) have been prepared by a precipitation method. The influence of preparation conditions, such as the stirring rate, temperature and molecular weight, on the morphology and crystalline structures, especially the polymorphic behavior, has been studied in detail. It is found that the average size of PVDF nanoparticles is mainly affected by the medium temperature and molecular weight, while the size distribution is influenced by all these factors. The crystallinity is less affected by the molecular weight but increases evidently with increasing temperature and stirring rate. The influence of these factors on the polymorphic behavior is complicated. First, a simultaneous increase in both β and γ phases has been achieved by increasing the stirring rate. Second, the β-PVDF crystals increase remarkably, whereas the γ-PVDF crystals decrease slightly with decreasing temperature, resulting in an obvious increase in the electroactive phases. Moreover, the increase in the PVDF molecular weight negatively affects the β-phase formation but positively affects the γ-phase formation, leading to an almost constant content of the electroactive phases. Ultimately, PVDF nanoparticles with the highest β-phase content of 74.6% and an overall electroactive phase content of 88.1% are prepared with 180 kDa PVDF under 2000 rpm and at 0 °C.

Mechanochemical synthesis offers synthetic pathways to new materials that are inaccessible via traditional solvent-based approaches. In this work, we evaluated how mechanochemical synthetic variables (e.g. time, frequency, liquid assisted grinding (LAG), metal precursors) impacted the products obtained from reactions containing La(III) and ethylenediaminetetraacetic acid (EDTA). We found that tuning mechanochemical parameters (i.e., time and frequency) affected reactivity and use of different La(III) salt precursors (La₂O₃, LaCl₃·7H₂O, LaPO₄·xH₂O, La(NO₃)₃·6H₂O, and La(OOCCH₃)₃·1.5H₂O) led to variations in solid-state products. Reactivity trends were largely consistent with trends in the relative lattice energies of the lanthanum starting materials, with the outlier (La₂O₃) potentially undergoing additional hydroxylation on particle surfaces during LAG. Two products were successfully isolated and structurally characterized using electron diffraction, including a 1-D chain and a 2-D sheet prepared from La₂O₃ (LaEDTA1) and LaCl₃·7H₂O (LaEDTA2), respectively. Detailed structural analysis revealed protonation sites on EDTA ligands that contribute to overall charge neutrality of both compounds. Infrared spectroscopy further confirmed ligand protonation in LaEDTA1 and LaEDTA2, while thermogravimetric and elemental analysis measurements provided complementary characterization information. Finally, field emission scanning electron microscopy results confirmed the elemental compositions of both products, with trace levels of iron observed that likely originate from stainless-steel milling media.

In this work, we successfully synthesized Ce⁴⁺-doped, Tb³⁺-doped, and Ce⁴⁺/Tb³⁺ co-doped Sr_1.5Ca_0.5Al₂SiO₇ (SCASO) using the high-temperature solid-state method under atmospheric conditions. Our experimental results reveal that SCASO:aCe⁴⁺ exhibits strong violet-blue luminescence at 392 nm when excited at 338 nm. For SCASO:bTb³⁺, the optimal excitation and emission wavelengths are 371 nm and 538 nm, respectively, with a lower emission intensity and a yellow-green visual color. Both SCASO:aCe⁴⁺ and SCASO:bTb³⁺ achieve optimal sintering at 1400 °C, with doping concentrations of a = 0.01 and b = 0.08. Different from the common internal transition luminescence of Ce³⁺, there is an efficient energy transfer between Ce⁴⁺ and Tb³⁺ in the Ce⁴⁺/Tb³⁺ co-doped SCASO system (SCASO:aCe⁴⁺,bTb³⁺) due to the existence of the Ce⁴⁺–O²⁻ charge transfer band. At 338 nm excitation, the Tb³⁺ emission showed a super enhancement effect with a maximum enhancement of 1813.6%, breaking the limit of no more than 10-fold enhancement of FRET. Moreover, by adjusting the a and b values in SCASO:aCe⁴⁺,bTb³⁺, the emission color of the samples can be continuously tuned from violet-blue to yellow-green. Additionally, SCASO:aCe⁴⁺ and SCASO:aCe⁴⁺,bTb³⁺ demonstrate long afterglow emission lasting over one hour, attributed to the trapping levels in the SCASO host's defect energy levels, a property absent in SCASO:bTb³⁺. Based on these experimental results, we provide a comprehensive and reasonable theoretical interpretation of the luminescence mechanisms for SCASO:aCe⁴⁺ and SCASO:bTb³⁺, the super-enhanced Tb³⁺ emission in SCASO:aCe⁴⁺,bTb³⁺, and the long-afterglow emission process.

This review explores how flows and microfluidics manipulate inorganic crystal nucleation, growth, and self-organization under far-from-equilibrium conditions. Different microfluidic platforms—including continuous-flow, droplet-based, and emerging paper-based devices—are presented for their ability to control mixing, supersaturation, and polymorph selection. Analytical tools, both in situ (optical, spectroscopic, XRD, TEM) and ex situ (SEM, UV-vis, Raman), to provide multi-scale insights into crystallization dynamics are presented. The review highlights how microfluidics enables precise tuning of morphology and kinetics, reproduces biomimetic conditions, and allows crystal self-organization into complex architectures. Finally, current challenges such as clogging are discussed alongside perspectives for integrating advanced characterization techniques and extending microfluidic crystallization strategies to new material systems.

The construction of new haloargentate hybrids with semiconductor nature and photoelectric performances is very fascinating, yet remains challenging. Herein, using in situ-generated [Co(2,2-bipy)₃]²⁺ and [Ni(2,2-bipy)₃]²⁺ metal-complex cations as structure-directing agents, we successfully fabricated two new members of the haloargentate family, namely [NH₄][Co(2,2-bipy)₃]₂Ag₆I₁₁ (1) and [NH₄][Ni(2,2-bipy)₃]₂Ag₆Br₁₁ (2), respectively. These two compounds are structurally isomorphic and contain two-dimensional [Ag₆X₁₁]_n⁵ⁿ⁻ (X = I and Br) anionic layers, which are perforated with large hexagonal windows. The characterization of the optical properties of compounds 1 and 2 shows that they exhibit optical band gaps of 1.75 and 2.84 eV, respectively, demonstrating visible light-responsive semiconductor behavior. Under alternating light irradiation, the two as-synthesized materials possess good photoelectric conversion abilities, with their photocurrent densities (0.20 and 0.22 μA cm⁻² for 1 and 2, respectively) observed to be comparable with many excellent metal halide competitors. Further, density functional theory calculations disclose that these photosensitive metal complexes play key roles in charge transfer and carrier transport, ultimately resulting in satisfactory photoelectric performances. Additionally, Hirshfeld surface analysis, thermogravimetric studies, and X-ray photoelectron spectroscopy characterization of the title compounds were also conducted in this work.

The discovery and construction of novel two-dimensional (2D) materials are driving forces for technological advancement. Among them, violet phosphorus (VP)-a structurally ordered and thermodynamically stable allotrope of phosphorus-exhibits a well-defined layered framework, superior crystallinity, and enhanced environmental stability compared with black phosphorus. However, the absence of an efficient and controllable growth strategy has severely constrained both its fundamental understanding and functional implementation. Herein, tellurium (Te) and iodine (I) were introduced as mineralizers in a chemical vapor transport (CVT) system to drive the transformation of amorphous red phosphorus into highly crystalline VP. This method enables rapid and uniform crystal growth, yielding plate-like VP with strong (004) orientation, sharp lattice fringes, and a remarkably high yield (∼95%) within 15 h. The analysis of the structure and optical properties reveals significant light absorption activity, and it has a band gap of approximately 1.8 eV, indicating excellent semiconductor and light response characteristics. Furthermore, compared to black phosphorus, the as-grown VP crystals exhibit robust air stability, maintaining their structural integrity and optical characteristics over extended periods. This work provides an efficient and scalable route to produce high-quality VP crystals, thereby advancing their applications in next-generation optoelectronics, photodetection, and energy conversion systems.

The study of mineral inclusions in diamonds is attracting increasing interest among the scientific community of mineralogists and petrologists. A question that has recently been addressed is whether the shape of solid inclusions is immutable once trapped in the diamond or it can evolve over time until it manifests an equilibrium form. In this paper, we approach this topic by means of thermodynamic and kinetic considerations. The concept of equilibrium shape is revisited by inserting the Gibbs–Wulff theorem into a new perspective to fit the context of a mineral inclusion. We then demonstrate that it is currently not possible to determine the equilibrium shape of a mineral inclusion in a diamond, due to the large number of calculations that need to be performed. Successively, kinetic considerations on the formation of the equilibrium shape are made. It is shown that the shape evolution of an inclusion requires a significant amount of mass transfer at constant volume and the data currently at our disposal do not allow the estimation of the time needed to reach the equilibrium shape.

Dynamic molecular crystals with switchable proton conduction are highly attractive for understanding and developing high-performance solid-state proton conductors (SSPCs). Herein, a reversible structural switching was achieved between {[Ni₂(btca)(tmdp)₂(H₂O)₆]·6H₂O}_n (Ni·6H₂O; H₄btca = 1,2,4,5-benzenetetracarboxylic acid; and tmdp = 4,4′-trimethylenedipyridine) and {[Ni₂(btca)(tmdp)₂(H₂O)₆]·2H₂O}_n (Ni·2H₂O) via single-crystal-to-single-crystal (SCSC) transformation during partial dehydration and rehydration processes. AC impedance spectroscopy confirmed that the proton conductivity, which is highly dependent on temperature and humidity, is reversibly modulated by partial dehydration/rehydration cycles, switching the material between a superprotonic state (Ni·6H₂O, >50 °C, and 95% RH) and a non-superprotonic state (Ni·2H₂O, <10⁻⁴ S cm⁻¹, and low RH). The tuning of the 1D hydrogen-bonded water chains is responsible for the reversible electrical switching. This work highlights that the guest species can serve as a switch to regulate proton conduction in coordination polymers and suggests an effective strategy for the construction of dynamic SSPCs via a mixed bipyridyl–tetracarboxylate strategy.

The thermal decomposition processes of defective β-octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (β-HMX) crystals containing different concentrations of nitric acid, acetic acid and acetone solvents were simulated by using the ReaxFF-lg molecular dynamics method. The presence of the defects triggers the formation of localized high-temperature regions. The defective systems containing nitric acid can produce a higher temperature peak. The evolution trends of the numbers of unstable intermediate products, final products, and clusters over time during thermal decomposition are consistent between the defect systems and the ideal system. The presence of the defects mainly causes differences in the numbers of these products. When the concentrations of solvent molecules in the defective systems are the same, the presence of nitric acid is more favorable for the formation of unstable intermediate products (NO₂) and final products (CO₂, H₂O, and N₂), while the presence of acetone is more favorable for the formation of H₂.