La³⁺-doped SnO₂ hollow micro/nanospheres were prepared by electrospray and calcination techniques with lanthanum nitrate, stannous chloride and polyvinylpyrrolidone (PVP) as raw materials. The formation mechanism of hollow structure was analyzed. The crystalline phase and micromorphology of the samples were examined by thermal gravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM). The microwave absorption properties of La³⁺-doped SnO₂ were determined by a vector network analyzer. The results show that La³⁺-doped SnCl₂/PVP precursor polymer appears smooth spheres with the diameters of 0.5-2.2 μm. The pure rutile structure of SnO₂ forms at 600 ℃, and La³⁺ doping does not change the crystal structure. La³⁺-doped SnO₂ micro/nanospheres appear to be a hollow structure, and the surfaces are made up of massive small particles. The optimum microwave absorption properties of La³⁺-doped SnO₂ hollow micro/nanospheres with the matching thickness of 2 mm can be obtained when the doping ratio of La³⁺ is 0.6% (in mole). The minimum reflectivity can reach -29 dB at 11.1 GHz, and the frequency band with a reflectivity less than -10 dB is 10.0-13.0 GHz. When the doping ratio of La³⁺ is 0.6%, the minimum reflectivity of La³⁺-doped SnO₂ hollow micro/nanospheres shifts to a low frequency as the matching thickness increases. The matching thickness is 4 mm at lower than 8 GHz, thus obtaining the optimum microwave absorption properties. The minimum reflectivity can reach -27 dB at 4.9 GHz, and the frequency band with a reflectivity less than -10 dB is 4.5-5.8 GHz.

Beaded silicon carbide (SiC) nanowires were synthesized via carbothermic reduction of silica in inert atmosphere with bamboo carbon as a carbon source. The morphology, phase and chemical composition of the beaded SiC/SiO₂ nanowires were characterized by scanning electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. The as-synthesized beaded SiC/SiO₂ nanowires with the smooth surface are composed of nanowires with the diameters of 150-200 nm and SiO₂ beads with the diameters of 1-2 µm uniformly distributed on SiC nanowires. The dielectric permittivity of the samples were measured at room temperature at X band (i.e., 8.20-12.40 GHz), and the reflection loss of the samples at different thicknesses was calculated by the transmit line theory. The results show that the effective absorption bandwidth of the composite absorbing materials is 2.32 GHz (R_L<-10 dB) with the thickness of 1.80 mm, and the minimum reflection loss of the sample reaches -43.58 dB.

The effect of electrode structure on the polarization field distribution of piezoelectric ceramic fibers was investigated via the finite element simulation. It is indicated that increasing the electrode spacing and decreasing its width both are beneficial to extend the active electric zone in the fiber and enhance the effective polarization electric field, leading to enhanced piezoelectric properties. Furthermore, the electrode spacing can adjust the polarization more effectively rather than the width does. In addition, macro fiber composites (MFS) were fabricated and the corresponding ferroelectric and piezoelectric properties were characterizatied. The results show that it is an effective way to increase the polarization response of MFC and improve its piezoelectric performance by increasing the spacing and decreasing the width of inter-digital electrode appropriately. The experimental results are consistent with simulated data.

Cu-In-Zn-S(CIZS) quaternary quantum dots (QDs) were prepared via a facile one-step method in aqueous solution. The effects of reaction temperature, cationic concentration and pH value of precursor solution on the phase composition, microscopic morphology and photoluminescence (PL) property were investigated by X-ray diffraction, transmission electron microscopy and fluorescence spectrophotometry. The results show that the crystallinity of QDs can be improved as the reaction temperature is increased, resulting in the increase of PL intensity. The PL intensity of CIZS QDs becomes the maximum value at 95 ℃. The particle size of CIZS QDs gradually decreases with the increase of cationic concentration, causing a blue shift of PL peaks from 634 nm to 617 nm. The optimized cationic concentration of precursor is 1.5 mmol/L. Moreover, the surface defects are effectively passivated by ligands at pH value of 5.0, resulting in the intense emission intensity. Based on the results by Fourier transform infrared spectroscopy, there are lots of functional groups on the surface of QDs, having a superior water solubility of QDs. The CIZS QDs have a promising application prospect in bio-imaging field.

Langbeinite-type K₂Bi_1-xZr(PO₄)₃:xSm³⁺ phosphors were synthesized by a conventional solid-state reaction. The samples were characterized by X-ray diffraction, ultraviolet visible diffuse reflectance spectroscopy, calculation based on the density functional theory (DFT), and photoluminescence spectroscopy. The DFT analysis reveals that K₂BiZr(PO₄)₃ is an insulator with an indirect band gap of 4.26 eV, which can be used as a fluorescent host. The prepared phosphors can be efficiently excited by near-ultraviolet light in the region from 340 to 425 nm and show three dominant emission bands peaking at 562, 600 and 647 nm due to the ⁴G_5/2→⁶H_J (J = 5/2, 7/2, and 9/2) transition of the Sm³⁺ activator, respectively. The optimum doping concentration of Sm³⁺ is 10% (in mole). It is expected that Sm³⁺-doped K₂BiZr(PO₄)₃ can be used as an orange-reddish phosphor for illumination or displays.

NaBiF₄:Yb³⁺/Er³⁺ upconversion nanoparticles were synthesized by a solvothermal method. The effects of reaction temperature and time on the composition, morphology and luminescence properties of NaBiF₄:Yb³⁺/Er³⁺ were investigated. The results show that increasing the reaction temperature and time in the solvothermal reaction properly enhance the crystallinity of NaBiF₄:Yb³⁺/Er³⁺, and improve the upconversion luminescence efficiency. It is easy to produce the bismuth at the temperature of >220 ℃. In addition, the upconversion luminescence intensity of NaBiF₄:Yb³⁺/Er³⁺ can be also enhanced via Rb⁺ ion doping. The green and red emissions of NaBiF₄:Yb³⁺/Er³⁺ doped with 5 mol% Rb⁺ ions increase to 1.73 and 1.5 times, respectively. The temperature sensitivity of the upconversion luminescence was examined. The fluorescence intensity ratio of the samples at 300-500 K was characterized by a fluorescence intensity ratio (I_FIR) technique. It is indicated that the NaBiF₄:Yb³⁺/Er³⁺ samples could have a potential application in the field of temperature sensor.

Graphitic carbon nitride (g-C₃N₄) nanosheet was synthesized by a facile fabrication method. Melamine was treated by a thermal polycondensation process. Pure g-C₃N₄ was treated by acid etching, heat etching and coupling with NH₄Cl. The crystalline structure, morphology, specific surface area, band structure and visible absorption of the material were evaluated by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy analysis, X-ray photoelectron spectroscopy, Raman spectroscopy, specific surface area (BET analysis), ultraviolet visible diffuse reflection spectroscopy and Mott-Schottky curve analysis, respectively. The photocatalytic activity was estimated by the degradation of Rhodamine and tetracycline hydrochloride solution under visible light irradiation. The results show that a clear, ordered, 2D nanosheet g-C₃N₄ structure with a layer thickness of 47 nm is formed, and the maximum specific surface area is a maximum (22 m²/g) when the mole ratio of melamine to NH₄Cl is 5∶4. The photocatalytic performance of bulk g-C₃N₄ is enhanced after treatment. The photocatalytic degradation rate of the sample treated with melamine and NH₄Cl at a ratio of 5∶4 is 3.4 times greater than that of untreated g-C₃N₄. The sample degrades 83.2% tetracycline hydrochloride solution for 4 h.

A zirconia nanopowder was prepared by a sol-gel method using ZrOCl₂·8H₂O as zirconium source and polyethylene oxide-polypropylene oxide-polyethylene oxide (P123) as a dispersant. In the preparation, carbon nanoparticles generated via carbonization of P123 have an effect on the dispersion of zirconia particles, thus obtaining zirconia nanopowder without impurity ions via water washing/alcohol washing. The results show that zirconia nanopowder with a narrow particle size distribution and a median size (D50) of 158 nm can be obtained at a mass ratio of P123 to zirconia of 80% and calcination temperature of 1 100 ℃. This method could be used as an environmentally friendly and efficient approach for the preparation of the nanopowder

Tm, Ho:Gd₃Ga₅O₁₂ (Tm, Ho:GGG) nanopowders were synthesized via the sol-gel method. Tm, Ho:GGG ultrafine powders were synthesized by using Ga(NO₃)₃ and Gd(NO₃)₃ as raw materials and by replacing Gd with certain amounts of Tm and Ho. The phase structure, thermal stability, particle size, and morphology of the Tm, Ho:GGG ultrafine powers were analyzed by X-ray diffraction, infrared spectroscopy, scanning electron microscopy, thermogravimetry-differential thermal analysis, and fluorescence spectroscopy. The results revealed that a pure GGG phase was obtained after the calcination of Tm, Ho:GGG at 900 ℃, and the obtained nanopowder had a uniform particle size of 70-90 nm, good dispersibility, and fluidity. The fluorescence analysis determined that the strongest peak of the fluorescence emission spectrum was at 1 950 nm, which was associated with the ⁵I₇→⁵I₈ transition of Ho³⁺.

Dendritic-like mesoporous silica particles (DMS) were prepared via a developed oil-water biphase stratification approach using cetyltrimethylammonium bromide, tetraethoxysilane, triethanolamine, and n-hexane as starting materials. The ceria nanoparticles were grafted onto the DMS surfaces using cerium nitrate as a cerium source and hexamethylene tetramine as a precipitant, and core/shell structured DMS/CeO₂ composites were obtained. The samples were characterized by scanning electron microscopy, transmission electron microscopy, low-angle X-ray diffraction, selected area electron diffraction, and nitrogen adsorption-desorption analysis. The elastic contact between an individual particle and a probe was evaluated by atomic force microscopy. The compressive elastic moduli of the DMS particles before and after ceria coating were calculated by fitting the force curves based on the Derjaguin-Müller-Toporov model. The results show that the DMS samples (ca. 92 nm in particle size) have central-radial three-dimensional mesopores with an average pore size of 6.9 nm. The average particle size of DMS/CeO₂ is about 106 nm, and the thin layer of ceria nanoparticles (i.e., 5-8 nm) is uniformly coated onto the cores. The compressive modulus of DMS particles is (3.7±1.2)GPa, further revealing that an enlarged pore size contributs to the elastic response enhancement for mesoporous silica materials. The compressive modulus of DMS/CeO₂ [i.e., (6.6±1.9)GPa] is much lower than that of bulk ceria materials, and much closed to that of DMS cores. The elastic response of DMS/CeO₂ derives from the cores, and the coated ceria nanoparticles contributed to the surface hardness enhancement.

Manganese dissolution is one of the important factors that result in the deterioration of the performance of manganese based cathode materials. It directly causes the loss of electrode active materials and induces manganese depositing on the negative electrode surface along with the migration of manganese, leading to a series of side reactions and irreversible loss of capacity. The mechanisms of manganese dissolution and deposition were summarized and the effect of manganese dissolution and deposition on lithium batteries was analyzed. The methods to inhibit manganese dissolution and deposition were proposed, and the development of manganese-based cathode materials was prospected as well.

In quantum dot sensitized solar cells (QDSCs), many tiny cracks appear in porous titanium dioxide (TiO₂) photoanode film during sintering process, which seriously blocks electron transport, leading to the significant decrease of solar cell performance. Multi-walled carbon nanotubes (MWCNTs) with the unique tuber structure and excellent electrical conductivity were used to modify the micro-cracks structure in TiO₂ photoanode films. The effect of mass fraction (i.e., 0%, 0.01%, 0.05%, 0.1% and 0.5%) of MWCNTs on the property of QDSCs photoanode was investigated. The crystal phase and micromorphology of photoanodes were characterized. According to the morphology analysis results, moderate MWCNTs and TiO₂ nanocrystals are uniformly mixed, and MWCNTs penetrated the micro-cracks in photoanode films. However, excess MWCNTs would aggregate into clusters that introduce many defects. CdS and ZnS quantum dots (QDs) were prepared on the above-mentioned photoanodes by a successive ionic layer adsorption and reaction (SILAR) method. QDSCs were assembled using QDs sensitized MWCNTs/TiO₂ photoanodes, CuS as a counter electrode and a polysulfide electrolyte as an electrolyte, and its volt-ampere characteristic (J-V) curve was measured. The results show that QDSCs with 0.05% MWCNTs/TiO₂ photoanode have the optimum photoelectric performance (i.e., the open-circuit voltage (V_oc) of 0.65 V, the short-circuit current density (J_sc) of 11.51 mA/cm² and the power conversion efficiency (PCE) of 3.14%.

The gelling activity of hemihydrate phosphogypsum (HPG) is poor and its setting process is slow due to the effect of soluble impurities such as P₂O₅ and F^-. Compared to cement clinker, the strength of HPG modified with lime as a hemihydrate phosphogypsum filling cementitious material (HCM) for goaf filling can be improved. The setting time and bleeding rate of HCM decrease rapidly and then increase slowly, and the compressive strength reverses with the increase of lime. Also, the concentration of total phosphorus and fluoride in the HCM leaching solution gradually decreases to below the standard values from the National Standard of Class I Solid Wastes. For the filling performance and environmental protection, the optimum mass fraction of lime in HCM is 2.0%. Lime can transform soluble P₂O₅ and F^- into insoluble precipitates such as Ca₃(PO₄)₂ and CaF₂ to accelerate HPG hydration, increase the number of dihydrate gypsum crystal contact points, and further improve the HCM filling performance. The experimental pH value of HCM leaching solution is lower than the theoretical value, indicating that P₂O₅ in crystal can dissolve into soluble P₂O₅ in the process of HPG hydration, thus leading to a decreased alkalinity of backfill.

The preparation of hemihydrate gypsum crystals with different morphologies by using additives has attracted much attention. Recent research work on the use of organic, inorganic and composite additives to control the growth of hemihydrate gypsum crystals into fibrous gypsum whiskers or short columnar high-strength α gypsum was summarized. The regulation mechanism of organic and inorganic additives on the nucleation and growth process of hemihydrate gypsum crystals was represented. Some problems that need to be further studied in this field were analyzed. This review can provide a reference for the crystal growth control of hemihydrate gypsum crystals and similar crystal materials.

The mineral assemblages, chemical composition, microstructure and spectral characteristics of quartzite jade from Taxkorgan, Xinjiang were investigated by polarized microscopy, electron microprobe (EPMA), laser Raman spectroscopy and ultraviolet-visible-near infrared spectroscopy (UV-Vis-NIR), and the coloration mechanism was discussed as well. The result indicates that quartzite jade from Taxkorgan consists of mainly granoblastic textured α-quartz and different amounts of epidote, dolomite, clinochlore, titanite, K-feldspar, pyrite, chalcopyrite, hematite and goethite. A combination of Fe³⁺ d-d electron transition and Fe²⁺—Fe³⁺ charge transfer in the crystal structure of epidote is the main reason for green color. Yellow and brownish red colors are primarily attributable to nano-micron-sized goethite and hematite within quartz particles or in cracks, and some related peaks in their first-order derivative UV-Vis-NIR spectra are located at 433-434 nm, 512-538 nm and 591 nm, respectively.

In order to improve the utilization efficiency of vermiculite mineral resources and expand the added value of expanded vermiculite products, an high expansion rate expanded vermiculite (HEV) with was prepared by a chemical treatment-baking heating method with industrial vermiculite from Xinjiang as a raw material. The structure and morphology, optimal preparation process and expansion mechanism of HEV were investigated. The results show that the expansion rate of the HEV is approximately 70 times greater than that of the expanded vermiculite prepared by conventional methods. The preparation mechanism of HEV is related to the mosaic structure of phlogopite, hydrophlogopite and vermiculite in the raw material. This structure can form massive cavities in the industrial vermiculite layer, effectively hindering the escape of internal gas. As a result, the industrial vermiculite has a better thermal expansion performance. The preparation method can improve the application efficiency of industrial vermiculite resource and reduce the production cost. The HEV can be used as a low-cost precursor for vermiculite nanomaterials.

The surface of hydromagnesite particles were modified by a wet-modification method. The influences of type and dosage of surface modifier, slurry concentration, modification temperature and time on the contact angle and activation index of hydromagnesite particles were investigated. The modified hydromagnesite particles were characterized by contact angle measurement, X-ray diffraction, Fourier transform infrared spectroscopy, thermogravimetric analysis and scanning electron microscopy. The results show that a suitable modifier is sodium stearate and the optimum condition is slurry concentration of 50 g/L, modifier dosage of 4% (in mass fraction) of modified hydromagnesite particles, modification temperature of 75 ℃ and time of 50 min. Under the optimum condition, the contact angle of modified product is 130.9° and the activation index is 99.97%. There is little influence of surface modification on the phase composite, chemical structure, thermal decomposition and morphology of hydromagnesite particles. The essence of the modification of hydromagnesite particles is that the hydrophilic group of sodium stearate is absorbed on the particle surface due to the physical adsorption and the hydrophobic group faces outward. Therefore, the surface of hydromagnesite particles changes from hydrophilic to hydrophobic.

In order to analyze the material removal mechanism in the precision machining process of the cleavable brittle gallium oxide crystal, a diamond indenter was used in a model G200 nanoindenter to determine the nanomechanical properties of two main crystal faces (100) and (010) of β-Ga₂O₃, respectively. Based on the nanoindentation test, the crystal faces both have a "pop-in" phenomenon. The first pop-in loads are 4.31 mN and 5.42 mN, respectively. Based on the variable load nanoscratch test and atomic force microscopy, the crystal faces both have a "pile-up" phenomenon, and the plastic domain processing features appear in the middle of the scratching process. The scratching depths of the crystal faces are 96.5-576.8 nm and 84.6-421.6 nm, respectively

To investigate the growth of high anisotropic planar dendrites, the growth process and the shape of silicon planar dendrites considering both dynamic anisotropy and interfacial energy anisotropy were simulated by a lattice Boltzmann method coupled based on a cellular automata (LBM-CA) model. The related dynamic anisotropic equation was proposed and verified. The effects of interfacial energy anisotropy, dynamic anisotropy and undercooling on the growth of planar dendrites were analyzed. The results show that the planar dendrites exhibit more intense anisotropy than non-planar dendrites, the anisotropy of planar dendrites increases with the increase of interfacial energy anisotropy coefficient, and the anisotropy of planar dendrites increases significantly with the growth rate and partial orientation loss. The planar dendrites grow, and the anisotropy and orientation loss increase with the increase of undercooling. The growth rate, length and number of secondary dendrite arms increase with the increase of kinetic anisotropy.