GaN-based light emitting diodes are extensively used for light emitting diodes in the green to ultraviolet (UV) wavelength region and have already been widely used in traffic signals, outdoor displays, full-color displays and back lighting in liquid-crystal displays. Although GaN-based light emitting diodes are commercially available, it is still difficult to manufacture highly efficient GaN-based light emitting diodes due to the high dislocation density and the low light extraction efficiency. Patterned sapphire substrates for GaN-based light-emitting diodes have attracted much interest in recent years because it can not only reduce the threading dislocation density of epitaxial GaN films, but also improve the light extraction efficiency of GaN-based light-emitting diodes. A comprehensive review is presented on the mechanisms responding for performance enhancement of GaN-based light emitting diodes on patterned sapphire substrates, methods of preparing patterned sapphire substrates and pattern-size of patterned sapphire substrates. What is more, improved performance of GaN-based light-emitting diodes on patterned sapphire substrates prepared by different methods and pattern-size are further discussed in detail. In view of the existing problems, the prospects for future development of patterned sapphire substrates are also proposed.

On silicate optical glass substrate, buried optical waveguide stacks were obtained. The stacks were composed of two layers of buried optical channel waveguide at different depth beneath the glass substrate surface, and each layer was manufactured by thermal Ag⁺/Na⁺ ion-exchange and field-assisted ion-diffusion. Microstructure of the optical waveguide chips was observed with optical microscope, and insertion loss of each layer in waveguide stacks is measured. Results show that the buried waveguide stack is composed of two layers of buried waveguide with their core center located at 14 μm and 35 μm, respectively. Beneath the glass surface, core dimension of top layer and bottom layer waveguide are 12 μm×7 μm and 9 μm×8 μm, respectively. Waveguides in both layers are single mode at operating wavelength of 1.55 μm. There is no directional coupling observed between waveguides at different layers. Insertion loss characterization indicates that propagation loss of both layers in the stack is 0.12 dB/cm, and coupling losses with single mode fiber are 0.78 dB/facet and 0.73 dB/facet, for top and bottom layer waveguides, respectively. The analysis suggests that this kind of optical waveguide stack is promising in application of high density integration of glass-based optical chip.

Developing cost-effective methods to prepare dense ceramic interconnect membrane for tubular solid oxide fuel cell (SOFC) stacks is currently considered as a major technical obstacle. In order to improve the co-firing compatibility of SOFC support with both LaCrO₃-based interconnects and Ni-based anodes, double-phase composite NiO/La_0.7Ca_0.3Cr_0.97O_3−δ (LCC97) was designed and then examined as novel SOFC support. Sintering character, microstructure, porosity, electrical conductivity and thermal expansion coefficient of the NiO/LCC97 composites were investigated in detail as a function of NiO content (5wt%, 25wt%, 50wt% and 75wt%). Results indicate that the interconnect material LCC97has desirable chemical and sintering compatibility with NiO. The NiO/LCC97 composite with weight ratio of 1:1 has excellent overall performance which can sufficiently meet the requirements for tubular SOFC support. By using a simple and cost-effective drop-coating/co-firing process, dense LCC97 interconnect thin membrane is successfully prepared on the novel NiO/LCC97(1:1) composite support. This work provides a simple technical solution for dense LaCrO₃-based interconnect fabrication for tubular SOFC stacks.

Scales from fore wings ofPapilio paris was used as templates, by ringing the original fore wings in the precursor and treatment by calcinations, SnO₂ (rutile) which inherited the 3D quasi-periodic structures of original wing scale was fabricated. After that, Au nanoparticles were incorporated in the system of as-prepared SnO₂ to form the Au/SnO₂ nanocomposites. XRD, SEM and TEM were carried out to investigate the morphologies, structures and elemental composition. For measuring Surface-enhanced Raman Scattering (SERS) effects of the Au/SnO₂ substrate, R6G was used as analyte molecules. By analyzing morphologies of this nanocomposites and UV-Vis DRS spectra of different substrates, mechanisms of SERS effects for this Au/SnO₂ nanocomposites substrate were analyzed. The three-dimensional nanostructures of the substrate provide large quantities of Raman ‘hot spots’, meanwhile, the SnO₂ and Au make synergetic contribution to the enhancement effects. The satisfying SERS properties combined with low synthesis costs show the prospective application possibilities of this novel SERS substrate.

A convenient and effective strategy was used to develop a novel carbon/carbon nanotubes (C/CNT) hybrid membrane by incorporating multi-walled carbon nanotubes (MWNT) into PMDA-ODA polyimide precursor through controlled pyrolysis process at 600℃. Transmission electron microscope, X-ray diffraction and gas permeation experiments were employed to investigate the microstructural characteristics and gas separation performance of hybrid carbon membrane. Results show that the as-prepared C/CNT hybrid membrane has excellent gas (H₂, CO₂, O₂, N₂ and CH₄) separation properties as compared with pure carbon membrane, and the O₂ permeability of hybrid carbon membrane increases by nearly 4 times reaching 1576 Barrer, while the O₂/N₂ permselectivity decreasing by only 17%. It is believed that carbon membrane doped by MWNT can make effective use of the interfacial gaps formed between MWNT and carbon matrix to reconstruct the pore structure of hybrid carbon membrane, which helps to increase the gas diffusion ability and further improve the gas permeability of hybrid carbon membrane.

Pt/TiO₂ thick film gas sensors were modified by dipping method in H₂PtCl₆ contained solution. In order to get different Pt/TiO₂ surface states, the thick films were treated with different process. Microstructural and morphological characteristics were investigated by XRD and SEM. The resistance-oxygen partial pressure relationship was used to calculate activation energy (E) of this film. Steady-state resistance and dynamic response of the sensor exposed to H₂/O₂ were tested, separately. The results indicated that the steady-state resistance which affected by “spill-over” effect arose from the Pt distribution states. However, the response time was associated with the activation energy (E). Sensors with lower activation energy exhibited a faster rate of response when the magnitude of response was approximately uniform.

Thelayered compound K₄Nb₆O₁₇ was prepared via high temperature solid reaction, and PbS intercalated K₄Nb₆O₁₇ (designated as K₄Nb₆O₁₇/PbS) photocatalyst was synthesized via direct ion exchange, alkylamines intercalation and sulfurization procedures. The as-prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), ultraviolet-visible diffuse reflection spectra (UV-Vis) and photoluminescence measurement (PL), energy dispersive X-ray detector (EDS) and X-ray fluorescence spectrometer (XRF). The photocatalytic performance of these catalysts for hydrogen production was also investigated in the presence of Na₂S and Na₂SO₃ sacrificial reagents. The absorption edge of K₄Nb₆O₁₇ shifted to visible light region after the intercalation of PbS. K₄Nb₆O₁₇/PbS photocatalysts exhibit higher activities for photocatalytic hydrogen production under both UV light and visible light irradiation, and the amounts of hydrogen produced are 123.94 mmol/(g cat) and 0.66 mmol/(g cat) after 3 h irradiation, respectively. The mechanism of charge separation is also discussed.

A series of molybdic oxide/ceria (MoO₃/CeO₂) composite catalysts with different MoO₃ concentrations (0, 5wt%, 7.5wt%, 10wt%, 12.5wt%, 15wt% and 20wt%) were prepared by hydrolysis of ammonium molybdate and the supports of CeO₂ at 70℃. The crystal structure, the morphology and interaction between MoO₃ and CeO₂ on the surface of the prepared MoO₃/CeO₂ composite catalysts were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscope (FT-IR), X-ray photoelectron spectrometer (XPS), scanning electron microscope (SEM) and energy dispersive spectrometer (EDS), respectively. The catalytic activities of the prepared catalysts were evaluated by the electrolysis sulfuric acid solution. Results show that the catalytic activity of MoO₃/CeO₂ composite catalysts are superior compared with that of pure CeO₂, and the optimal concentration of MoO₃ is12.5wt%. The MoO₃ content threshold value of composite catalysts is between 12.5wt% and 15wt%, and it is identified that the Mo-O-Ce bond forms at the interface of MoO₃ and CeO₂ in the composite catalysts. Moreover, more surface Mo-O-Ce bond over the MoO₃/CeO₂ composite catalysts will further benefit the improvement of the catalytic activity.

The novel Bi₂WO₆ and Fe³⁺/Bi₂WO₆ photocatalysts were fabricated separately via a reverse microemulsion method. The effect factors including synthesis temperature, pH value, molar ratio of water to surfactant (ω) and Fe³⁺ doping on the structure, morphologies and photocatalysis performance of photocatalysts were studied in detail. These results show that Bi₂WO₆ possesses a high degree of crystallinity of nano-spherical structure with the size of 15–25 nm. The photodegradation rate of methylene blue (MB) is 93.8% as the Bi₂WO₆ photocatalyst was synthesized at 150℃. The results reveal that the photodegradation rate of MB reaches 97.8% as ω is 27. It’s found that the photodegradation rate of MB for 1.03% Fe-doped Bi₂WO₆ sample has increased to 90.2%, which is two times higher than that of pure Bi₂WO₆.

Dense Bi_1.5Y_0.3Sm_0.2O₃ (BYS)-La_0.8Sr_0.2MnO_3–d(LSM) hollow fiber membrane was fabricated by the combined phase inversion/sintering technique. The hollow fiber possesses an asymmetric structure: a finger-like porous structure near the inner surface and a dense layer near the outer surface. The outlet oxygen content is related to the oxygen partial pressure on the core and shell side and the length of the hollow fiber. Because the oxygen partial pressure on the permeated side increases along the axis, the hollow fiber is evenly divided into n segments. The oxygen permeation process is simulated by a plug flow model in combination with the Wagner theory. The simulation results are consistent with the measured results, which is a good guide for estimating oxygen production capacity of membrane components.

Al₂O₃ films were deposited directly onto the surface of graphene by H₂O-based atomic layer deposition (ALD) method, where physically absorbed water molecules acted as oxidant and the growing temperature changed from 60℃ to 260℃. The morphology of Al2O3 films was characterized by atomic force microscope (AFM). AFM images revealed that the distribution of physically adsorbed H₂O molecules on the surface of graphene decided the morphology of Al₂O₃ film, and conformal and uniform Al₂O₃ film was achieved with the root mean square (RMS) roughness of 0.26 nm when the growing temperature was around 100-130℃. X-ray photoelectron spectroscopy (XPS) analysis showed that the O/Al ratio was close to stoichiometric condition of 1.5. Raman spectroscopy analysis revealed that H₂O-based ALD process did not destroy the structure of graphene. The growing temperature in the H₂O-based ALD process had significant impact on the initial nucleation and the growth of Al₂O₃ films.

TiB₂/TiC composites were in situ fabricated through spark plasma sintering (SPS) technique using Ti and B₄C powders as starting materials. The phase constituent of the samples was analyzed by X-ray diffraction techniques and microstructures were observed by scanning electron microscope. The Vickers hardness, fracture toughness and MSP strength at room temperature was measured by indentation method and Modified Small Punch (MSP) test. The results showed that the TiB₂/TiC composite fabricated by one-step sintering (sintering at 1550℃ for 6 min) has an average grain size greater than 1 μm with MSP strength of 844 MPa. While the TiB₂/TiC composite with an average grain size of about 200 nm could be fabricated by two-step sintering (at higher sintering temperature of 1550℃ and lower holding temperature of 1450℃) and its MSP strength reached as high as 1095 MPa.

In order to study the effects of Vickers cracks on the mechanical properties of solid-phase-sintered silicon carbide (SSiC for short) ceramics, the indentation cracks and the crack profiles were observed after loading 0.1–100 N loads on the SSiC samples by SEM. The critical indentation load for Vickers crack initiation in SSiC ceramics lies between 0.1 N and 0.2 N. Indentations by loads lower than 0.5 N have limited influence on bending strength. And if the indentation loads is higher than 10 N, the obtained hardness floats around 24.2 GPa and the cracks are half-coin type. The proper Vickers indentation load range for SSiC ceramic hardness and toughness tests are determined to be 10 N or above.

Using silicon powder as the precursor to improve the wear resistance of Ti₅Si₃ coating was in situ successfully synthesized on Ti substrate by laser cladding. Friction and wear behavior of Ti₅Si₃ coatings under different normal loads and sliding speeds wear test conditions were evaluated using a UMT-2MT friction and wear tester. It is found that the prepared coating is mainly composed of Ti₅Si₃ and Ti phases. The high resolution transmission electron microscopy results confirm further the existence of Ti₅Si₃ compound in the prepared coating. Ti₅Si₃ coating has spherical and block-like microstructure. The Ti₅Si₃ coating shows a high average hardness of approximately 840 HV_0.2, which is about 4.4 times as that of Ti substrate. Tribological properties of the prepared Ti₅Si₃ coating were systematically evaluated. It is found that the Ti₅Si₃ coating can improve the wear resistance of Ti. The wear mechanism of Ti₅Si₃ coating is abrasive and adhesive wear when sliding against GCr15 steel ball under all wear conditions.

Waste mussel shell stacking with a significant odor and toxicity which are hazardous to human constitutes a serious environmental hazard. For utilization of waste mussel shell resource, granule of mussel shell (YBCC) was prepared from waste mussel shell by removing cuticle, crushing, grinding and shearing emulsification and was introduced as a filler to reinforce polypropylene (PP). The characterization results of YBCC show that the mainly composition of YBCC is aragonite (CaCO₃) platelets and the particle size distribution range of YBCC powder is from 40 nm to 500 nm, the proportion of organic components of YBCC is about 2.04wt% and YBCC has a good thermal stability. The mechanical behavior of PP/YBCC composite shows a higher yield strain, yield strength, tensile strength and elongation at break than traditional commercial calcium carbonate (CMCC) filled PP. Yield strength of PP/YBCC composite with 3wt% YBCC is improved by about 11.1%. A small content (about 1wt%) of YBCC can promote the heterogeneous nucleation for PP crystallization and the formation β-crystalline PP. Using mussel shell for producing bio-filler is valuable for industrial production and practical application as fillers for reinforcing polymers.

Nanoscale praseodymium-doped zircon yellowish pigment was prepared by a two-step new method using ZrOCl₂•8H₂O, Na₂SiO₃•9H₂O and Pr₆O₁₁ as raw materials. Intermediate nanopowders were hydrothermally synthesized firstly, then these intermediate powders were calcined at high temperatures to produce nanoscale Pr-zircon yellowish pigment. The products were characterized by XRD, TEM, SEM, reflectance spectra and the CIE L*a*b* parameters. The pH of hydrothermal solution, the hydrothermal temperature and the heat treatment temperature are main factors that influenced the quality of pigment. Low pH is favorable for decreasing the calcination temperatures and producing the pigment with good dispersion and homogeneous sizes. The product with best pigment performance is obtained at the reaction conditions as follows, pH=3.5 of hydrothermal solution, hydrothermal temperature of 220℃ and heat treatment temperature of 900℃.

Well-crystallized MgAl₂O₄ nanopowders were prepared by calcining a powder mixture of Al(OH)₃ and MgSO₄ at 800℃, and then washing with water. The effect of Mg/Al atomic ratios on the particle sizes and agglomeration degrees, and sintering behavior of MgAl₂O₄ nanopowders were studied by differential thermal and thermogravimetric analysis (DSC/TG), X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM). The obtained MgAl₂O₄ nanopowders have an average particle size of 12 nm, a narrow size distribution, and weak agglomeration. The formation of MgAl₂O₄ can be attributed to a solid-state reaction between γ-Al₂O₃ and MgSO₄. Besides, these MgAl₂O₄ nanopowders own an excellent sinterability, e.g., a relative density of 95% can be achieved after sintered at 1450℃ for 1 h.

LiFePO₄ nanoparticles coated with a carbon layer were synthesized by a hydrothermal reaction-calcination process, using Fe₂O₃ as an iron source and ascorbic acid as carbon source. The amount of ascorbic acid have an effect on the structure, phase and carbon amount of the final product. With 1 g ascorbic acid used in the reaction, the particle sizes of synthesized LiFePO₄/C nanocomposites are in a range of 220–280 nm. Using as the cathode materials for the lithium-ion batteries, the as-prepared material shows high capacity and good cycle stability (159 mAh/g at 0.1C over 500 cycles), as well as good rate capability.

Cu-TiO₂ heterostructure nanoparticles were successfully synthesized via a novel one-step self-assemble hydrothermal method using polyethylene glycol as the soft template. The nanospheres were characterized in light of the chemical composition and morphology using X-ray diffraction (XRD) and transmission electron microscope (TEM), respectively. The products are composed of cubic copper and anatase TiO₂. Interfaces between Cu (101) and TiO₂ (111) were observed by HRTEM. In addition, the nanoparticles size could be controlled by adjusting the polymerization degrees of PEG. The accommodations of the particle sizes were mainly caused by Cu nanospheres rather than TiO₂. A possible synthetic mechanism which interprets the formation of Cu-TiO₂ heterogeneous nanoparticles could be ascribed to the hydrogen bonds between Cu(NH₃)²⁺ and PEG. UV-Vis absorption spectra indicated that the prepared product has strong absorbency in the visible region. Therefore, the unique interface nanomaterial could be used as a potential class of the materials platform as visible-light-driven photocatalyst and electrode on enhancing the photoelectric properties of solar cells.