Scanning transmission electron microscopy (STEM) Z-contrast image has some advantages such as high image resolution (directly revealing the real positions of atoms in crystal), high compositional sensitivity and directly interpretable images, it becomes a powerful tool for investigating the microstructure of materials at atomic scale. In this review, the formation mechanisms, methods and features of the Z-contrast STEM images are introduced, and its applications in the new generation of high-k gate dielectrics (e.g., Hf-based metals oxides, rare-earth oxides and epitaxial perovskite oxides) are also reviewed. After aberration-correction the spatial resolution of the Z-contrast STEM images is as high as the sub-Å level, this technique is invaluable for characterizing the interfacial structures between high-K gate dielectrics and semiconductors. The related results are also introduced.

Nanosized Ce_1-x(Eu_0.5La_0.5)_xO₂ and Ce_1-x(Fe_0.5La_0.5)_xO₂ solid solutions were synthesized via hydrothermal method, and the doping effect was characterized by analyzing the structure and spectrum features of the solid solutions. The results showed that the cell parameters of the solid solutions increased, the absorption edge of the UV diffuse reflectance spectroscopy was drifted, and the characteristic Raman F_2g vibration peak shifted to lower wave numbers. Then the mixtures of Mg₂Ni alloy powders and the solid solution additives were ball-milled to obtain composites. XRD results showed that the fraction of amorphous and nanocrystalline in the as-prepared composites was increased. The hydrogen storage kinetic measurements demonstrated that surface activity and degree of reversibility of the composites was optimized, and the diffusion rate and diffusion coefficient of hydrogen atoms in the bulk of Mg₂Ni were increased.

NiO-YSZ hollow fibers were fabricated via a phase-inversion spinning technique. An YSZ electrolyte film was dip-coated on the outer surface of the fiber and then co-sintered at 1450℃ to form electrolyte/anode hollow fiber half cell. The microstructure of the NiO-YSZ anode was modulated by controlling NMP/ethanol ratio of the inner coagulant during spinning process. Experimental results showed that, with the 1-Methy 1-2-Pyrrolidinone (NMP) content increase from 0 to 30wt%, 50wt%, 70wt% and 100wt%, the microscopy of the anode hollow fibers evolved from a sandwiched structure, i.e. finger-like pore/sponge voids/finger-like pore morphology, to a finger-pore-penetrating structure, leading to porosity increase of the anode. Meanwhile, gas tightness of YSZ electrolyte film, mechanical strength of the reduced dual-layer hollow fibers, and conductivity of anode could decrease. Microtubular fuel cells were fabricated by coating a porous Ag cathode onto the dense YSZ electrolyte film. The concentration polarization in the H₂/air cell decreased with increasing the length of the finger-like pores. The microtubular SOFC made from the anode hollow fibers with 70wt% of NMP-ethanol as the inner coagulant demonstrated the minimum polarization resistance and the highest output performance with 662 mW/cm² power density.

The interfacial polarization resistance (R_c) associated with cathode in solid oxide fuel cell (SOFC) is affected by the electrolyte conductivity. In this work, the effect of electrolyte surface microstructure on the cathode performance was demonstrated by analyzing electrochemical impedance spectra of symmetric cells which consist of porous (La_0.85Sr_0.15)_0.9MnO_3-δ (LSM) and La_0.6Sr_0.4Fe_0.8Co_0.2O_3-δ (LSCF) electrodes with Sm_0.2Ce_0.8O_2-δ (SDC) electrolytes. The SDC electrolytes exhibited different surface microstructures, i.e. different grain sizes and grain boundary densities as a result of various sintering conditions. SEM was used to investigate the SDC surface microstructure parameters and the relationships between these parameters and the polarization resistance ware discussed. It is found that R_c is greatly affected by the SDC surface microstructures and decreases with the decrease of grain size, or the increase of grain-boundary density. Moreover, it is demonstrated that the oxygen ion transfer is significantly increased by decreasing grain size for the oxygen reduction at the LSM cathode.

The Li-rich layered Li(Li_0.17Ni_0.2Mn_0.58Co_0.05)O₂ oxide was prepared by a spray-drying method. Subsequently, the surface modification with TiO₂(B) nanocrystallites (2wt%, 4wt%, 6wt%, 8wt%) was introduced into the Li-rich layered Li(Li_0.17Ni_0.2Mn_0.58Co_0.05)O₂ oxide by precipitation method. It is demonstrated that there is no obvious change in the crystallographic structure of the Li-rich layered Li(Li_0.17Ni_0.2Mn_0.58Co_0.05)O₂ oxide based on the analysis of XRD, SEM and TEM, while only the surface of the oxide is modified with TiO₂(B) nanocrystallites. It is indicated from DSC curves that the thermal stability of Li-rich layered oxide is obviously improved by the surface modification with TiO₂(B) nanocrystallites. Correspondingly, the large discharge capacity of 296.4 mAh/g and high coulombic efficiency of 84.5% are obtained at 0.1C rate (1C=300 mA/g) in the first cycle for the Li-rich layered oxide after the surface modification with TiO₂(B) nanocrystallites (4wt%). Moreover, the capacity retention after 100 cycles is increased from 69.5% for the pristine sample to 80.2% for the TiO₂(B)-modified sample. Even at 2C rate, the large discharge capacity of 166.5 mAh/g is still obtained for the TiO₂(B)-modified sample. Apparently, it is demonstrated from the above results that the surface modification with TiO₂(B) nanocrystallites can improve the thermal stability and electrochemical performance of the Li-rich layered Li(Li_0.17Ni_0.2Mn_0.58Co_0.05)O₂ oxide.

Upconversion transparent ceramics K_0.5(1-y)Na_0.5(1-y)Li_yNb_1-yBi_yO₃-Er_0.005Yb_0.005x(Er³⁺/Yb³⁺:KNNLB, x=0-3, y=0-0.09) were fabricated by hot-press sintering process using LiBiO₃ as additives. The microstructure, optical transparency and upconversion fluorescence were investigated．The results show that the crystalline phase of the ceramics is orthorhombic-perovskite structure．The ceramics are well densified, and the grain size of the ceramics is about 0.5 μm．These ceramics present good transparency in the infrared and the long-wavelength visible regions, but the optical transparency declines rapidly in the visible region as the amount of Yb³⁺ and Er³⁺ ions increases．The transparency of the ceramics with y = 0.06 and x = 0 reaches 45% in the visible region and over 95% in the infrared region(the thickness of the sample is 0.5 mm)．The strong upconversion fluorescence is observed when the ceramics are excited by the 900 nm-wavelength light of an xenon lamp．

Periodic gradient Si-rich SiN_x (G-SRSN) thin films and single-layer Si-rich SiN_x (S-SRSN) thin films were deposited on monocrystalline silicon wafers and quartz substrates by combination of magnetron co-sputtering and rapid photo-thermal annealing. Raman spectroscope, grazing incident X-ray diffraction (GIXRD), transmission electron microscope (TEM), Fourier transform infrared (FTIR) spectroscope and photoluminescence (PL) were used to analyze the structure, bonding configurations and luminescence of the films. Raman, GIXRD and TEM results show that the crystalline fractions of G-SRSN and S-SRSN thin films are 41.7% and 39.2%, respectively. Quantum dots density of G-SRSN thin film is 4.4 times higher than that of S-SRSN thin film. The FTIR spectra demonstrate that both G-SRSN and S-SRSN films are Si-rich SiN_x, but Si content of the former is lower than that of the later. PL spectra suggest that the G-SRSN thin films possess a lower radiative recombination defect density than the G-SRSN thin films.

Double-layer of titanium dioxide and Pr-doped calcium hydroxide were coated on the surface of mica by liquid phase deposition, and followed by calcination to form the Pr-doped calcium titanates fluorescent layer. The resultant CaTiO₃:Pr³⁺/TiO₂-mica fluorescent pearlescent pigments were characterized by photoluminescence excitation (PLE) and emission (PL), automatic colorimeter (AC), X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM), respectively. The fluorescent pearlescent pigments obtained at the calcium oxide cladding ratios of 5.3%, the praseodymium/calcium nitrate molar concentration of 0.2%, and the calcinations temperature of 900 ℃, show good pearl property with homogeneous, dense and smooth surface, and relatively high fluorescence intensity. The excitation spectrum of these fluorescent pearlescent pigments consists of three bands at 264, 304 and 380 nm. The maximum emission wavelength is found to be a red light of 613 nm, corresponding to the transition for ¹D₂→³H₄.

Sr₂Si₅N₈:Eu²⁺ phosphors were prepared by carbothermal reduction and nitridation method using Sr₂CO₃, Si₃N₄ and Eu₂O₃ as raw materials, and C as main reduction agent. The influence of C, Sr₂CO₃ and Eu²⁺ contents on phase composition and photoluminescence properties of as-prepared phosphors were investigated. The experimental results indicate that single-phase Sr₂Si₅N₈:Eu²⁺ is produced with molar ratio n_c/n_Si3N4=9/5. Excessive Sr₂CO₃ addition contributes to the N contents of the as-prepared phosphors, which enhances emission intensity. There is an asymmetric wide emission peaks between 550 nm and 700 nm due to the electron transfer of Eu²⁺ from 4f⁶5d¹ to 4f⁷ excited by 450 nm. Increasing Eu²⁺ concentration from 1.5mol% to 20mol%, the luminescence intensity hits the maximum value at Eu²⁺ concentration of 2mol% followed by continuous decline. Meanwhile the emission peak position is red-shifted from 608 nm to 641 nm, and the CIE chromaticity coordinates varies from (0.606, 0.393) to (0.656, 0.343), which indicates that Sr₂Si₅N₈:Eu²⁺ is a promising phosphor for white LEDs.

CO₂ hydrogenation was carried out over Ru/TiO₂ catalysts prepared by wet impregnation method. It was found that CO₂ methanation (CO₂ + 4H₂ → CH₄ + 2H₂O) could be catalyzed by Ru/TiO₂ both under UV irradiation and heating. Results showed that CH₄ was the only C-contained product under UV irradiation in temperature range from 150-350℃, while both CH₄ and CO (minor product) were formed at temperature higher than 400℃ under heating conditions. This indicated that reaction temperature affected obviously on selectivities of products. For all the catalysts with different Ru loadings, CO₂ conversion increased firstly and then decreased from 150℃ to 550℃, and corresponding maximum value of CO₂ conversion of 77.58% was achieved at 350℃ over 1.5wt% Ru/TiO₂ catalysts. Further increasing of reaction temperature over 400℃ led to the increase of CO selectivity. Based on reaction data, XRD, XPS and N₂ adsorption-desorption characterization results, we found that CO₂ hydrogenation occurred in different ways under UV irradiation and heating conditions (150-550℃). Under UV irradiation, excited electrons were firstly trapped by Ru site and then these electrons reduced CO₂ species, which was adsorbed on Ru surface to form CH₄ via RuC intermediate. However, under heating condition (150-550℃), H₂ was first decomposed into H atoms over Ru site, then the adsorbed CO₂ species on Ru site was reduced by H atoms to form RuC intermediate. Finally, RuC reacted with H atoms to produce CH₄. Although CO₂ hydrogenation was taken place via same intermediate under UV irradiation and heating conditions, the RuC intermediate was formed in different ways, i.e., the activation of CO₂ was induced in the different routes, therefore the different selectivities of products were obtained under UV irradiation and heating at temperature higher than 400℃ consequently.

Series TZC/ATS catalysts and the tungsten-added samples, with Ti_0.8Zr_0.2Ce_0.2O_2.4 (TZC for short) as active component and Al₂O₃-TiO₂-SiO₂ (ATS for short) as catalyst carrier, were prepared by extrusion method. Effects of tungsten incorporation on catalytic performance and tolerance towards K₂O and CaO poisoning of TZC/ATS for deNO_x by NH₃ selective catalytic reduction (NH₃-SCR) were mainly studied, and anti K₂O and CaO poisoning abilities between the TZCW_0.4/ATS and the V₂O₅(WO₃)/TiO₂ were comparatively analyzed. Moreover, the specific surface, solid-phase structure, morphology and surface acidity of the catalysts were characterized by techniques of N₂-BET, XRD, SEM and NH₃-TPD, respectively. Results showed that the TZCW_0.4/ATS catalyst exhibited the highest catalytic activity and the best stability for deNO_x by NH₃-SCR when the Ti/Zr/Ce/W molar ratio of the active component was 4:1:1:0.4. Furthermore, tungsten incorporation greatly enhanced the anti K₂O and CaO poisoning abilities of the TZCW_0.4/ATS catalyst, and these anti-poisoning abilities of the TZCW_0.4/ATS were much stronger than those of the V₂O₅(WO₃)/TiO₂. The promotional effect on catalytic deNO_x performance was caused by increased specific surface area and enhanced surface acidity of the TZCW_0.4/ATS catalyst after tungsten incorporation.

Doping magnesium into La₂Ce₂O₇ can increase its thermal expansion coefficient (TEC) and decrease its thermal conductivity (TC), thus improve its performance for thermal barrier coating (TBC). (La_1-xMg_x)₂Ce₂O_7-x ceramics were prepared by Sol-Gel method. Powder X-Ray diffraction results revealed that (La_1-xMg_x)₂Ce₂O_7-x showed the identical structure as La₂Ce₂O₇ (defect-fluorite type), and the crystal parameter decrease with increasing x value in the range of 0≤x≤0.4, and MgO occurred in the product when x?0.4. The TEC of (La_1-xMg_x)₂Ce₂O_7-x sample (0≤x≤0.4) with the same composition increases with the increasing temperature, whereas the TC presents the opposite trend. At the same temperature, the TEC of the (La_1-xMg_x)₂Ce₂O_7-x sample (0≤x≤0.4) with different composition increases with increasing x value whereas the TC increases firstly and then decreases with the increasing of x value, where x=0.2 nearby as turning point. In addition, possible mechanisms of the influence of Mg doping on the structure, crystal parameter, TEC and TC of La₂Ce₂O₇ are discussed.

Co²⁺-Ni²⁺-Fe³⁺--LDHs (layered double hydroxides, LDHs) materials were synthesized by using trisodium citrate (TSC) assisted homogeneous precipitation technology. The influences of TSC amount on the basal spacing and morphology of the obtained materials were investigated by changing TSC amount from 0.6 mmol/L to 3.0 mmol/L. Then the deintercalation of carbonate ions from a Co²⁺-Ni²⁺-Fe³⁺--LDHs materials with different basal spacing and shape morphology were investigated by socking in a NaCl-HCl mixed solution. The results indicated that LDHs with basal spacing of 0.776 nm and well-defined hexagonal shapes was obtained when TSC optimized amount was between 0.6-1.0 mmol/L, exhibiting a good anion exchange property. Thus a series of materials intercalated by, , , and CH₃(CH₂)₁₁anions were obtained. When TSC amount was up to 1.5 mmol/L, a new layered structure of LDHs with basal spacings of 0.770 nm and 0.691 nm was observed with rose-like morphology consisting of reunion hexagonal shapes, decreasing its anion exchange property. When TSC amount was further increased to 3.0 mmol/L, the layered structure of LDHs with a basal spacing of 0.681 nm was observed with ball-shaped like morphology consisting of reunion hexagonal shapes, leading to its anion exchange property disappear.

Effects of wetting temperature and Ti₃SiC₂ constituent elements Si and Ti on the wettability of Cu/Ti₃SiC₂ system were investigated in vacuum via sessile drop technique. The results show that the wettability of Cu/Ti₃SiC₂ system is fairly well at elevated temperature because of the reaction between Cu and Ti₃SiC₂. The reaction zone in Cu/Ti₃SiC₂ interface becomes larger and deeper with the temperature increasing, and which leads to the decrease in contact angle. Its reaction rate is accelerated when the temperature exceeds 1250℃. The minimum contact angle of 15.1° is measured at 1270℃. XRD and SEM results indicate that the reaction products are TiC_x and Cu_xSi_y, and the reaction layer is mainly consisted of Cu, Ti₃SiC₂, TiC_x and Cu_xSi_y depending on the wetting temperature. The wettability of Cu/Ti₃SiC₂ system is improved by the reaction layer. Adding alloying element Si or Ti to Cu is harmful to the wettability between Cu and Ti₃SiC₂ since Si inhibits the decomposition of Ti₃SiC₂ and Ti hinders the infiltration of Cu into Ti₃SiC₂.

A bioinspired polydopamine (PDA) layer was deposited on titanium surface by simply dipping the substrate into an alkaline dopamine solution. The in vitro bioactivity of the polydopamine coated titanium was assessed by incubation in simulated body fluids (SBF). The results showed that surface-anchored catecholamine moieties in polydopamine enriched the interface with calcium ions, facilitating the deposition of hydroxyapatite. Silver nanoparticles (AgNPs) were metallised on the PDA-grafted titanium surface in mild aqueous environments. About 14% silver release as Ag⁺ ions were found after 5 d when the surfaces were exposed to deionized water. The AgNPs showed an efficient microbicidal activity against Staphylococcus Aureus bacterial strains, while not significantly affecting osteoblast cells (MC3T3-E1) viability.

To solve the problem that nano-hydroxyapatite (nHA) crystals aggregation and non-uniformly distribution in nano-hydroxyapatite/chitosan (CS) composite microspheres, nHA/CS microspheres were prepared through in situ biomimetic method in water-in-oil (W/O) emulsions. The physical and chemical properties of the composite microspheres were investigated by scanning electronic microscopy (SEM), X-ray energy-dispersive spectroscope (EDS), X-ray diffraction (XRD), fourier transform infrared spectroscope (FTIR) and laser particle size analyzer. The results indicate that the composite microspheres are spherical with average size of 8.62 μm and disperse uniformly. Moreover, the nHA crystals are dispersed uniformly within composite microspheres and bonded with CS matrix. The composite microspheres have great potential in bone tissue engineering and drug delivery system.

A bi-crystalline mesoporous titania (meso-TiO₂) with anatase and rutile composite nanocrystal frameworks was prepared and then modified by carbon doping (C-meso-TiO₂), silver nanoparticle loading (Ag-meso-TiO₂), and carbon-silver codoping (Ag-C-meso-TiO₂). The visible-light photocatalytic activities of the samples were evaluated by the degeneration of aqueous methylene blue (MB) solution under visible-light irradiation (wavelength >420 nm). The prepared bi-crystalline mesoporous samples showed obviously higher visible-light photocatalytic activity than that of the commercial anatase titania nanoparticles (NPs). Ag-C-meso-TiO₂ exhibited the highest visible-light photocatalytic activity which could be attributed to the band gap narrowed by the doped carbon and the plasmon electron transfer from Ag NPs to the titania matrix, and the corresponding MB degeneration rate reached 65% after 180 min visible-light irradiation while that of the commercial titania NPs just reached 7%.

Al₂O₃/Al-steel mesh-Al laminated composites with “sandwich” Al-steel mesh-Al layer as interlayer, which was consisted of two Al foils and one steel mesh, were prepared by vacuum hot pressing at 580℃ and 1.5 MPa. The results indicate that the interface of Al₂O₃/Al is bonded tightly and no reaction is observed. Intermetallic compound (IMC) is detected in Al/steel interface which improves the connection conditions between the steel and Al. The laminated composites have much higher fracture toughness, work-of-fracture than that of the Al₂O₃ monolith, as well as having a close strength to Al₂O₃. Crack blunting and arresting, crack bridging, interface debonding, and ductile deformation of “sandwich” Al-steel mesh-Al layer are the main reasons for improving the toughness and work-of-fracture of laminated composites. Low-velocity impact results suggest that the Al₂O₃/Al-steel mesh-Al laminated composites have good impact resistance.