Bismuth sulfide (Bi2S3) with micro/nanostructures as an important semiconductor material has attracted considerable attention due to its high ionic conductance, high photoelectric conversion efficiency, and large absorption coefficient, which is widely applied in the areas of photocatalysis, energy conversion, sensors, biomedicine, and pollutant disposal. Up to now, various strategies are reported for the morphology-controlled synthesis of micro-nanoscale Bi2S3 and Bi2S3-based materials via manipulating the thermodynamics and kinetics in the chemical fabricating process. However, the Bi2S3 with designed shapes still remains to be developed to well adapt these diverse usages. To conclude, the designed preparation strategies, advanced applications, current challenges, and future expectations of Bi2S3 are discussed to provide some potential suggestions for further promotion of Bi2S3 functional materials.

LiGdF4 and LiTbF4 single crystals are grown by the Bridgman–Stockbarger method from the nonstoichiometric melt comprising 32 mol% RF3 (R = Gd, Tb) and 68 mol% LiF, respectively. Incongruent melting of the single crystals LiGdF4 and LiTbF4 is confirmed by differential scanning calorimetry. For the first time, the crystal structures of LiGdF4 and LiTbF4 are determined by Rietveld method. Also, rare-earth lithium fluoride syntheses from lithium nitrate melts at 400 °С are performed for LiTbF4, LiGdF4, LiYF4, and LiDyF4 compounds. For terbium, the product is a mixture of LiTbF4 and TbF3; and for gadolinium, GdF3 is thus produced. With reference to the related literature, it is concluded that LiGdF4 and LiTbF4 are the thermodynamically stable phases in the ranges from 750 ± 5 to 425 ± 15 °С, and from 782 ± 5 to 400 ± 15 °С, respectively. The metastability of LiGdF4 and LiTbF4, however, does not prevent the use of their single crystals as photonic materials.

The effect of substitution of Cr in 2H-CrSe2 by Fe and Co on its electronic, optical, and magnetic properties is studied by first-principles density functional theory. Spin-polarized semiconducting state is realized in CrSe2 by substitutional doping of Fe and Co, while a semimetallic state is obtained by Fe doping and the magnetic moment after Fe doping is 4.52 μB. On Co substitution, it is observed that the system presents metallic properties, with relatively low light absorption and reflectance, and good transparency. The magnetic moment after Co doping is 2.71 μB. The absorption coefficient of CrSe2 to visible light increases with the doping of Fe and Co, and the peak value is redshifted, which is conducive to the further application of CrSe2 in the field of optoelectronics.

The conventional theory of crystal growth presents an irreversible outward increase of the crystal size through solute deposition on the nuclei; however, the asymptotic solution of the dynamics model of the particle reveals that the crystal growth undergoes a locally reversible inward growth process in the early stage of crystal growth. Immediately after nucleation, some parts of the interface first grow inward through solute rejection along certain crystal orientations from the interface of nucleation, while the other parts of the interface grow outward through solute deposition along other crystal orientations. Until the inward growth attains a certain distance, the interface grows outward along each crystal orientation. This growth behavior is attributed to the interaction between interface morphology of particles with the anisotropic effect of interface kinetics. Through a systematic variation of the anisotropy parameters, the particle exhibits a continuous transition from one growth morphology to other growth morphologies. During the morphological transition process, as initial concentration increases, the growth of the particle is inhibited in the preferred growth directions, whereas it is facilitated in other growth directions. As a result, the interface morphologies of the particle with different petal-shaped morphologies in the early stage of crystal growth are formed.

ZnO crystals are employed in numerous industries, but precisely controlling their morphologies is still challenging. In this work, a continuous flow process for synthesizing ZnO crystals is developed based on the co-precipitation method. ZnO crystals at different morphologies, including needle-like, rod-like, flower-like, spindle-like, and nanospheres, are successfully prepared at low temperature. The influence of reaction temperature, pH value, ZnCl2 feeding concentration, and reaction time on the morphology, size, and purity of ZnO crystals is systematically investigated. The results of X-ray diffraction show that the high-purity ZnO can only be produced when the reaction temperature is above 75 °C. The band gap energies of ZnO evaluated by UV–vis diffuse reflectance spectroscopy increase with the synthesis temperature. According to scanning electron microscope (SEM) findings, the size of ZnO crystals is regulated by controlling the reaction time. Interestingly, the morphology of ZnO crystals is changed from 1D to 3D structure by controlling the feeding concentration of ZnCl2. Moreover, a concentration difference mechanism of ZnO crystal morphology evolution is proposed by monitoring the real-time concentration of free Zn2+ ions.

In the present work, the BiFeO3, Bi0.9Ba0.1FeO3, Bi0.9Sm0.1FeO3, and Bi0.9Ba0.05Sm0.05FeO3 nanocrystalline thin films on Pt/TiO2/SiO2/Si (100) substrate are synthesized using the spin coating method, and the structural, morphological, and magnetic properties are systematically investigated. The X-ray diffraction studies reveal that BiFeO3, Bi0.9Ba0.1FeO3, and Bi0.9Sm0.1FeO3 films exhibit a polycrystalline distorted rhombohedra crystal structure and belong to the R3c space group, whereas, Bi0.9Ba0.05Sm0.05FeO3 nanocrystalline film has shown a pure rhombohedral crystal structure. The grain size of the films is found to be 86, 75, and 63 nm for Bi0.9Ba0.1FeO3, Bi0.9Sm0.1FeO3, and Bi0.9Ba0.05Sm0.05FeO3, respectively. M−H measurements show that the magnetization considerably increases with Ba and Sm doping, and the highest magnetization is found to be 29 and 22 emu cm−3 at 10 and 300 K, respectively, in Bi0.9Sm0.1FeO3 film. Further, the blocking temperatures are found to be 100, 150, 130, and 50 K for BiFeO3, Bi0.9Ba0.1FeO3, Bi0.9Ba0.05Sm0.05FeO3, and Bi0.9Sm0.1FeO3, respectively.

Based on mesh reconstruction technology, a 3D solid model of single crystal sapphire (SCS) with global embedded cohesive element is established in this study. Using exponential cohesive zone law (CZL), the anisotropy of SCS can be effectively characterized by assigning the mechanical properties of matrix element and cohesive element. Taking the C-plane SCS model as the research object, the whole process of dynamic evolution of cracks in the model under high-speed surface impact and high concentrated stress impact is reproduced by finite element simulation technology. The simulation is compared with the experimental results from the aspects of crack initiation morphology, crack propagation path, sample fragmentation form, and mechanical response curve. The dynamic compressive strength reaches 1630.3 MPa with the impact velocity of 30 m s–1 in surface impact type. The initial maximum loading force reaches 320 N when the impact velocity is 8.35 m s–1 in the indentation impact type. In addition, by combining the simulation results, this study clarifies the mechanism of strain rate effect exhibited by SCS from the perspective of stress–strain data and crack evolution characteristics. Therefore, the model established in this study can effectively reflect the mechanical behavior of SCS under impact load.

The present work is based on the numerical investigation of thermal stress and the dislocation density of the directional solidification (DS) grown multi-crystalline silicon (mc-Si) ingot. The heat exchanger block (HEB) plays the main role in the growth process, which decides the thermal stress and melt-crystal interface of the mc-Si ingot. The conventional furnace is modified to increase the quality of the mc-Si ingot. The modification on the conventional furnace is done in the insulation block replaced by 1/3rd of the HEB. The HEB enhances the huge amount of heat extraction from the bottom of the crucible. The von Mises stress, dislocation density, and thermal gradient are analyzed. The thermal stress is reduced by the low thermal gradient influenced by the modified HEB. The modified HEB reduces the von Mises stress and dislocation density. The modified furnace system overcomes the conventional case ingot. The result shows that the modified furnace grown mc-Si ingot improves the efficiency of the solar cell.

A continuous process for preparation of magnesium hydroxide with a forced circulation tubular reactor is proposed. The residence time distribution of the liquid in the reactor at different flow rates is measured, and the parameters of the tanks-in-series model are obtained. Using soluble magnesium salt and ammonia as raw materials, magnesium hydroxide is prepared. The effect of the flow rates on the product quality is investigated. The results show that the smaller the flow rate, the longer the residence time of the liquid in the reactor and the better the dispersion and crystal morphology of the products. When the total volume of the reactor is 300 mL and the flow rates are 5–50 mL min−1, the values of the average residence time of the liquid are 3094–351 s and the parameters of tanks-in-series model are 1.05–1.52. The reactors are closer to the continuous stirred tank reactor. The average particle sizes of the magnesium hydroxide products are 2.32–2.47 µm, and the values of I001/I101 are 1.17–0.89. The crystal morphology is flaky. Being compared with that from magnesium sulfate, the magnesium hydroxide products from magnesium nitrate have smaller particle size and better dispersibility.

Gasar porous Mg–3 wt% Ag alloy is prepared by metal–gas eutectic directional solidification process. The pore structure is related to the solidification mode of the alloy. The pores grow stably under the solidification conditions of planar, cellular, and columnar dendrites but not under the condition of equiaxed dendrites. The numerical simulation shows that the solidification velocity and temperature gradient decrease rapidly with an increase in the sample height, but their ratio remains unchanged. During the solidification process, the solidification mode of the alloy changes from cellular crystals to columnar dendrites, and finally to equiaxed dendrites. The calculated results of the solidification mode transition are consistent with the microstructure morphologies of the Mg–Ag alloy at different heights.

This study aims at synthesizing zinc sulfide (ZnS) thin films using spray pyrolysis method. The effect of the Zn concentration on the physical properties of ZnS is investigated using X-ray diffraction (XRD), scanning electron microscope (SEM), UV–Vis spectrophotometer, photoluminescence (PL), and Raman spectroscopy. XRD shows a preferential orientation along the (111) direction corresponding to the ZnS cubic structure. Based on the XRD results, it is seen that low zinc concentrations compared to sulfur content can increase the crystalline quality of films. Raman spectra confirm the presence of the ZnS cubic structure observed by XRD and show the presence of sprayed ZnS vibrational modes for all films. PL emission spectrum of ZnS confirms the presence of Zn and S atoms at all molar concentrations. SEM reveals densely packed and uniformly distributed grains with precise shapes. The elemental analysis confirms the growth of stochiometric Zn/S ratio. The optical analysis shows a high transmittance around 88% in the visible range of the solar spectrum with optical band gaps varying from 3.4 to 3.6 eV. These properties are interesting and show that ZnS thin films can be used as buffer layers in thin film solar cells applications.

Alpha high-strength hemihydrate gypsum (CaSO4·0.5H2O, α-HH) with a large-size columnar crystal (average size: 135.31 µm, maximum size: 500 µm) is successfully prepared via a NaCl salt bath method using salt gypsum as a raw material. The effects of preparation condition (salt solution concentration, salt bath time) on the crystalline phase and crystal grain size of the α-HH and on the strengths of the cement bulks from α-HH are investigated. Furthermore, to explore the formation mechanism of the large-size columnar crystal of the α-HH, the samples obtained by varying the salt bath time of the reaction system are characterized with field-emission scanning electron microscopy, X-ray diffraction, and laser particle size analysis. Based on the characterization results, a formation mechanism of the large-sized α-HH is proposed. That is, NaCl self-diffusion creates a local high-concentration salt solution environment, which is conducive to the recombination of small-size HH crystals formed by dihydrate gypsum dissolution and HH recrystallization to grow into large-sized α-HH crystals.

Recently, perovskites have shown great promise as a semiconductor material with the advantages of low-temperature fabrication, controllable band gap, and high carrier lifetime. In the field of X-ray detection, a number of workers have developed green and stable and efficient lead-free halide chalcogenides in pursuit of stable performance and biological safety. This article has done the following three works: It introduces the basic principles of X-ray detection briefly. The outstanding works that have been done are summarized in terms of sensitivity, signal-to-noise ratio, and detection limit, and their laws are summarized. The optoelectronic properties of lead-free halide perovskites are summarized, the prospects of lead-free perovskites in the field of X-ray detection are foreseen.

Biomedical applications make high demands on the development of novel bioactive materials, which are often based on functionalized calcium phosphates (CaPs). In this study, pure nanoscaled hydroxyapatite (HAp) and modified HAp with titanium dioxide (TiO2) with both nano- and microparticles are successfully synthesized from the reactants calcium hydroxide and orthophosphoric acid in a wet chemistry reaction. The obtained powders are sintered in a temperature range of 750 °C–1400 °C to study their thermal decomposition behavior. The phase composition and the surface morphology are characterized using X-ray diffraction, scanning electron microscopy, and energy dispersive X-ray spectroscopy with element mapping. Lysozyme adsorption experiments reveal significantly higher adsorption on the samples modified with nanoparticles. Sintered samples modified with both TiO2 particle sizes show HAp decomposition to β-tricalcium phosphate (β-TCP) as well as the formation of perovskite (CaTiO3) in different portions depending on the TiO2 particle size. TiO2 nanoparticles support anatase to rutile transformation at lower temperatures than TiO2 microparticles. The results show that the examined HAp/TiO2 composites may serve as a starter material for tailormade biomaterials with specific composition by variation of the sintering temperature and the TiO2 particle size.

Transparent and homogeneous SrPb3Br8 single crystals with the size of Ø25 mm × 50 mm are grown by the modified vertical Bridgman method. X-ray diffraction results reveal that the middle part of the crystal is pure in chemical compositions, while the tip part contains low content of Sr(PbBr3)2(H2O)5. X-ray photoelectron spectroscopy analysis points out the absorption to C, O-containing substances of the pristine surfaces of SrPb3Br8 wafers. The Raman results prove the low phonon energy of the SrPb3Br8 (116 cm−1). Transmission spectra demonstrate its wide transparent range (0.37–25 µm) and high transmittance in the mid-infrared range except for several absorption lines. Moreover, Hall measurements show that the SrPb3Br8 sample is n-type conductive at 110–300 K, and the Hall coefficient RH, resistivity ρ and mobility µH decrease as temperature increases while the carrier concentration n has an opposite trend. The conduction mechanism and scattering mechanism of SrPb3Br8 crystal at different temperatures has been studied by analyzing ln(|RH|)−T−1, n−T and µH−T curves, and the dominant donor defect ionization energy ED is calculated to be 0.077 eV.

The performance of CdZnTe detectors is not only influenced by the growth of crystal, but also by the quality of the interface layer between the crystal and the electrode. A model of CdZnTe detector with metal–semiconductor–metal structure is developed to investigate the effects of the interface on the space charge and electric field distribution. Atomic force microscopy, current–voltage (I–V) analysis, and energy spectra under 241Am irradiation are adopted to investigate the effects of argon (Ar) plasma treatment on the interface and performance of CdZnTe detectors experimentally. The simulation results show that the interface layer with low density of surface state and thin thickness can form a more uniform space charge and electric field distribution. Due to the decrease of voltage drop across the interface, the leakage current at 200 V of CdZnTe detector with Ar plasma treatment is reduced from 159 to 44 nA cm−2, and the full-width at half-maximum under 241Am is improved from 9.3% to 8.2%, as compared to conventional Br-MeOH treatment.

Throughout history, objects with fivefold symmetry have been a popular topic of interest for artists, philosophers, and scientists. This may be because fivefold symmetry is very conspicuous in nature. In the case of crystals, fivefold rotational symmetry is mathematically forbidden, and macroscopic crystals exhibiting fivefold symmetry have never been shown to exist. Nevertheless, in the nanoworld, nanoparticles are often found with decahedral and icosahedral shapes that have an overall pseudo-fivefold symmetry. These structures are observed at many length scales, from 1 nm up to 1 µm. In this review, several reasons for the stability of fivefold nanoparticles are discussed. These include the formation of twin boundaries, surface reconstruction faceting, and other factors.

Mg(OH)2’s dissolving properties have a considerable influence on its application performance. This study aims to improve the dissolving properties of Mg(OH)2 by modifying its crystal structure. Mg(OH)2 crystals with a large diameter-to-height ratio (≈40) structure are synthesized via a glycine-assisted MgO hydration method utilizing glycine's differing adsorption energy on the (001) and (110) surfaces of Mg(OH)2 (−306.2 and −277.4 kJ mol−1). Compared to the control sample, the results of the dissolution kinetics investigation indicate that glycine-assisted hydration considerably improves the apparent reaction rate constant of dissolution from 0.0020–0.0071 to 0.0039–0.0120 min−1. The enhanced dissolving properties are mostly induced by the large and thin crystal grain structure, which disintegrates easily during the dissolution process, exposing more reactive sites. The findings reported in this study provide a new approach to improving the dissolving properties of Mg(OH)2 that can enable its enhanced use in various applications.

The effect of zinc substitution at the Cu2+ site and germanium substitution at the Ti4+ site in bismuth copper titanate, Bi2/3Cu3Ti4O12, is investigated. Composition with x = 0.05 is synthesized by semi-wet route in the system Bi2/3Cu3Ti4−xGexO12 (BCTGO) and Bi2/3Cu3−xZnxTi4−xGexO12 (BCZTGO) that are sintered at 1123 K for 8 h. Crystal structure has remained cubic. The phase formations of these ceramics are confirmed by the X-ray diffraction. The microstructural analysis of the samples is done by scanning electron microscopy and tunneling electron microscopy. Elemental analysis is performed by energy dispersive X-ray spectroscopy. X-ray photoelectron spectroscopy suggests that all elements present in these ceramics are in proper oxidation states. The dielectric constant is found high for BCTGO-0.05 ceramic. The specific capacitances of BCTGO-0.05 and BCZTGO-0.05 are found to be 13.05 and 15.7 F g−1, respectively. Optical band gap values (Eg) of BCTGO-0.05 and BCZTGO-0.05 ceramics are found as 1.77 and 1.91 eV.

This study proposes a method to enhance the efficiency and optical properties of silicon solar cells made from as-cut boron-doped p-type multicrystalline silicon (mi-Si) wafers through acid-based chemical texturization. Achieving lower reflectance is crucial for improving solar cell efficiency, and this can be attained through optimized chemical etching. The research demonstrates achieving a reflectance below 2% on the wafer surface after optimal chemical etching. Wet chemical etching is employed as the surface treatment method, using the same chemical etchant with varying conditions for the texturing process. The study compares temperature-maintained chemical etching and without temperature maintenance. The chemicals used include HF + HNO3 + CH3COOH at temperatures of 50 °C and room temperature, with etching durations of 2, 5, 10, and 15 minutes, respectively. The as-cut boron-doped p-type mc-Si wafer grains are analyzed using UV-vis spectroscopy, optical microscopy, Fourier transform infrared spectroscopy, thickness profilometry, scanning electron microscopy, and X-ray diffraction spectroscopy, both before and after etching. Among the different conditions tested, the chemical etchant HF + HNO3 + CH3COOH at 50 °C for a 5-minute etching duration yields favorable results, with reflectivity below 2%. The orientation of mc-silicon wafer grains is determined using X-ray diffraction spectroscopy.