Crystal Research and Technology最新文献

Cover image provided courtesy of Jianguang Zhou, Research Center for Analytical Instrumentation, Institute of Cyber-Systems and Control, State Key Laboratory of Industrial Control Technology, Zhejiang University, China.

Exploring new haloplumbate hybrids and understanding the structure-activity relationships are of great significance for further promoting their applications in the photovoltaic fields. Herein, with the in situ-formed [Hmd]⁺ (md = 2-methyl-1,3-diazinane) templates, a new organic–inorganic hybrid iodoplumbate, namely [Hmd]PbI₃ (1), is successfully constructed and then structurally characterized using multiple technical approaches. X-ray crystallography studies show that compound 1 features the typical 1D chain-like motifs of [Pb₂I₆]_n²ⁿ⁻, generating the 3D supermolecular network by the extensive hydrogen bond interactions. Interestingly, compound 1 exhibits the semiconductive behavior, with an optical band gap of 2.72 eV. More attractively, the title compound has good photoelectric switching performances under the alternating light irradiation, whose photocurrent densities compete well with or surpass those of many metal halide counterparts. Further theoretical analyses reveal that the title compound has a more dispersive band structure (especially the value band) that facilitates the transport of charge carriers, which may be the main origin of its excellent optoelectronic performance. Presented in this paper also bring the studies of Hirshfeld surface, X-ray photoelectron spectroscopy (XPS) as well as thermogravimetric analysis.

The development of eco-friendly, high-efficiency polyoxometalates (POMs) catalysts is vital for advancing catalytic oxidation and electrochemical detection in environmental protection. Herein, a POM-based Cu^II-containing complex with the molecular formula [H(4-AP)]₈[Cu₂(H₂O)₄(P₂Mo₅O₂₃)₂]·8H₂O (1) (4-AP = 4-aminopyridine) is synthesized using the hydrothermal method, and the crystal structure is determined by single X-ray diffraction (SXRD), infrared (IR) spectroscopy, and powder X-ray diffraction (PXRD). Structurally, complex 1 exhibits a one dimension (1D) chain arrangement, composed of Cu^II ions and Strandberg-type (P₂Mo₅O₂₃)⁶⁻ anionic clusters. These 1D chains are further interconnected through [H(4-AP)]⁺ ligands, resulting in the formation of a two dimension (2D) supramolecular network. Complex 1 serves as an outstanding heterogeneous catalyst for the oxidation of methyl phenyl sulfide (MPS), demonstrating a remarkable conversion rate of 99% for MPS and a selectivity of 98% toward methyl phenyl sulfoxide (MPSO). In addition to its catalytic capabilities, complex 1 is also employed in the electrochemical detection of Fe^III and Cr^VI ions, with low limits of detection (LODs) at 4.92 µm for Fe^III and 7.82 µM for Cr^VI.

As a biodegradable and biocompatible polymer material, polyglycolic acid is attracting more and more attention in the field of polymeric and biomedical materials. Consequently, the study of the transformation between different crystal forms of glycolide, the monomer of polyglycolic acid, is of great importance, because crystal forms of glycolide determine the stabilities and properties of polyglycolic acid products polymerized under different conditions in industry. Herein, this article reports the synthesis and crystallization of α- and β-glycolide controlled by the type of organic solvents and/or temperatures, during which an intermediate crystal form of β′-glycolide is newly observed. The transformation between α-, β-, and β′-glycolide is investigated in detail, and the stabilities of different crystal forms are illustrated via the controlled experiments under different relative humidity (RH) as well as the theoretical calculations, which should provide fundamental concepts and guidance for the industrial production of glycolide and optimization of polyglycolic acid products.

Direct InN growth is demonstrated and characterized on a sapphire (Al₂O₃) substrate by plasma-enhanced metal–organic chemical vapor deposition using high-density nitrogen (N₂) microstrip-line microwave plasma. N₂ plasma irradiation at 650 °C for 20 min forms AlN on Al₂O₃ substrate. No peak regarding metallic In droplets is detected from InN/Al₂O₃ regardless of N₂ plasma irradiation. InN is found to be rotated 30° with their a-axis oriented to become $��\left[��10�\overline{1}�0��\right]�$ InN // $��\left[��11�\overline{2}�0��\right]�$ Al₂O₃. The transition layers are confirmed at the InN/Al₂O₃ interface regardless of N₂ plasma irradiation. The surface of InN consisted of large undulations with root mean square values >30 nm, suggesting that strain relaxation introduces misfit dislocations.

Single-crystal silicon carbide (SiC) is an important semiconductor material for the fabrication of power and radio frequency (RF) devices. The major technique for growing single-crystal SiC is the so-called physical vapor transport (PVT) method, in which not only the thermal field but also the fluid-flow field and the distribution of gas species can be hardly measured directly. In this study, a multi-component flow model is proposed that includes the inside and outside of a growth chamber and a joint between the seed crystal holder and crucible which allows exchanges of the gas species. The joint is simulated as a thin porous graphite sheet. The Hertz-Knudsen equation is used to describe the sublimation and deposition. The convection and diffusion are described by the Navier–Stokes equations and mixture-averaged diffusion model, in which the Stefan flow is taken into account. The numerical simulations are conducted by the finite element method (FEM) with a multi-physics coupled model, which is able to predict the fluid flow field, species distribution field, crystal growth rate, and evolution of the molar concentration of dopant gas. Using this model, the effects of several experimental conditions on the transport of gas species and the growth rate of single-crystal SiC are analyzed.

Indium selenides (InSe) is a promising layer-structured semiconductor with broad potential applications in photovoltaics, diodes, and optic devices, but its thermoelectric performance is limited by the high thermal conductivity. In this work, by alloying high-performance thermoelectric SnSe in InSe, the In_0.5Sn_0.5Se crystal is prepared via a zone melting method. The density of In_0.5Sn_0.5Se crystal is measured as 5.81 g cm⁻³ which is between the density of pure SnSe and InSe. The XRD measurements indicate that the grown In_0.5Sn_0.5Se crystal consists of InSe and SnSe crystals with a preferred orientation along (00l) and (h00) planes, respectively. SEM and EDS analysis reveal that eutectic InSe and SnSe phases interdigitate with each other. The thermogravimetry analysis shows a slow decrease at a temperature ≈700 °C. In_0.5Sn_0.5Se crystal displays a n-type conduct behavior, the electrical conductivity σ is ≈0.02 Scm⁻¹ at room temperature and increases to 8.4 Scm⁻¹ under 820 K. The highest power factor PF is estimated to be ≈0.36 µWcmK⁻² near 570 K. The InSe-SnSe phase boundaries lead the thermal conductivity of In_0.5Sn_0.5Se crystal to be as low as 0.29 Wm⁻¹K⁻¹. Due to the low lattice thermal conductivity, In_0.5Sn_0.5Se crystal shows a ZT value of 0.04 at 600 K in this work.

In this study, phosphogypsum (PG) is simulated by doping fluorine and phosphorus ions in an analytically pure reagent of gypsum dihydrate. The influence of fluorine and phosphorus impurity and content on the dehydration reaction process of phosphogypsum and its crystalline micromorphology is assessed during the preparation of α-type gypsum hemihydrate in the reversed-phase microemulsion system and its mechanism. The results show that when the fluorine content increases from 0 to 1.0 mol L⁻¹ (ωNaF = 1.0 mol L⁻¹), the dehydration process of dihydrate gypsum will be greatly slowed down. Scanning electron microscopy (SEM) analysis showed that even a small amount of F− (ωNaF = 0.2 mol L⁻¹) can significantly inhibit the formation of α-type hemi-hydrated gypsum. When ωH₃PO₄ = 0.10 mol L⁻¹, the water of crystallization content in the solid phase of the sample decreased to 5.24% after 90 min, which is significantly lower than during the same period of the benchmark group. However, there is a threshold value for the effect of phosphorus on the microscopic morphology of the α-type gypsum hemihydrate crystals, when ωH₃PO₄ ≤ 0.04 mol L⁻¹, the crystal morphology is basically unaffected. Moreover, when ωH₃PO₄ continued to increase, the defects on the crystal surface increased.

Due to the ecocompatibility with carbonate-based substrates, Ca(OH)₂ nanoparticles are currently used for cultural heritage conservation such as wall paintings. However, the nano Ca(OH)₂ still suffers from different forms and poor uniformity, limiting its application potential. Also, there is a lack of systematic comparative studies between nano Ca(OH)₂ and the commonly used wall painting reinforcement materials. In this study, homogeneous hexagonal nano Ca(OH)₂ particles with a size of ≈100 nm are successfully prepared through the convenient chemical liquid phase method and by utilizing surfactants to control the growth. The resulting nano Ca(OH)₂ is less agglomerated and has superior crystalline morphology, prolonged suspension time, and more suitable carbonation time in comparison to commercial Ca(OH)₂ materials. Additionally, the reinforcement effect of the resulting nano-Ca(OH)₂ with that of the commonly used pigment layer reinforcement materials such as AC33, B72, Tetraethyl orthosilicate, WPU (Waterborne polyurethane) and commercial Ca(OH)₂ is systematically compared. The synthesized nano Ca(OH)₂ penetrated wall painting blocks to a depth of 683 µm, three times deeper than commercial Ca(OH)₂, achieving moderate color deviation, higher flexural strength (0.529 MPa), and bond strength (1.105 mg cm⁻²), thus highlighting its potential in wall painting reinforcement and expanding its application scope.