A seriesof g-C₃N₄-ZnO composites were synthesized by a hydrothermal method, and the structural and morphological properties of as-prepared composites were using characterized X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The gas sensing properties of g-C₃N₄-ZnO composites were investigated. The results indicate that the content of g-C₃N₄ in the composite has an effect on the gas sensing performances of the materials. 9% g-C₃N₄-ZnO composite exhibits the optimized gas sensing properties at 300 ℃. The response to 1×10^-6 acetic acid vapor reaches 1.8, and the response/recovery time at different concentrations of acetic acid vapor (i.e., 10^-6-10^-3) is shorter than 36 s.

Tribological properties of three different silicate natural mineral powders, i.e., sepiolite, attapulgite and serpentine as lubricating oil additives were investigated in an UMT-3 tribometer. The morphologies and elemental components of the worn surfaces were analyzed by scanning electron microscopy (SEM), energy dispersive spectrometry (EDS) and X-ray photoelectron spectroscopy (XPS). The relationship between the structure of silicate as well as its anti-wear and friction reducing mechanism were discussed. The results indicate that all three silicate powders can provide excellent tribological properties as lubricating oil additives. Compared to 500SN, these additives have lower friction coefficients and wear volumes, which are 2.4%-25.5% and 37.4%-56.2%, respectively. The friction films are formed with iron oxide, silicon oxide and graphite when silicate powder additives are used, providing the excellent anti-wear and friction reducing properties. Unlike serpentine, attapulgite and sepiolite have a fibrous structure, and the TOT crystal structure is easier to form the frictional films with more oxides and graphites, leading to the superior tribological performance at a higher load.

Zeolite L with a Si/Al moles ratio of 1.9 was synthesized from initial concentrated gel in the absence of organic templates. The crystallization behavior and the crystal microstructure during crystallization were analyzed by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, nitrogen adsorption-desorption and energy dispersive X-ray spectroscopy. The effects of synthesis parameters such as synthesis time, aging time and molar compositions on the crystal growth were investigated. The results show that as-synthesized zeolite nanocrystals possess hierarchical structure. Pure zeolite L with a high crystallinity was obtained within a wide ratio range of gel SiO₂/Al₂O₃ of 20-100. Moreover, the adsorption performance of the samples under the optimized synthesis conditions were evaluated via the equilibrium adsorption of pure gases CO₂, CH₄ and N₂ at 25 ℃. Zeolite nanocrystals exhibit a high CO₂ adsorption capacity.

Thin and dense zeolite T membranes with a thickness of 5 μm on low-cost mullite tubular supports were synthesized via two-stage varying-temperature crystallization (TSVTC) with homogeneous liquid precursors. Effect of precursors on the crystal morphology and pervaporation performance of as-synthesized membranes, and synthesis time/temperature during the two-stage hydrothermal crystallization process was investigated. The results show that zeolite T membranes synthesized under optimized conditions have an enhanced pervaporation performance (i.e., the high flux of 4.3 kg/(m²·h), and the separation factor of 2 000 in water/isopropanol (10/90, mass ratio) aqueous solution at 348 K). These membranes show a good reproducibility and a long-term hydrothermal stability as well.

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.