Electromagnetic wave absorbers (EMWAs) (i.e. microwave wave absorbers) are important materials for military equipment. Ideal EMWA should exhibit thin matching thickness, low density, broad bandwidth, and strong EM absorption. The recent advances of EMWA were reviewed in this study, and the shortcomings in current studies and approaches for further researches were suggested. Recent researches on EMWAs are mainly focused on the preparation of nanocomposites, doping or surface modification, and changing the micro-morphology and structures of EMWA. However, these studies concentrated on traditional EMWAs and applied researches, which lack of theoretical guidance and breakthrough innovations. Further investigations should pay more attention on the nanocomposites and nanocomposites with structure designing under the guideline of electromagnetic wave theory. Moreover, smart materials and structures and metamaterials are promising EMWAs with excellent properties.

Nanostructured hollow microspheres of iron oxides are promising for the applications in the fields of magnetic storage media, catalysis, pigments, adsorbents, biomedicine, sensors, etc., due to their low toxicity, excellent magnetic properties, chemical stability, biocompatibility, corrosion resistance, low density and high specific surface area. The investigation on hollow microspheres assembled with nanocrystals of iron oxides is of especially scientific interest and technological importance. Herein, we briefly review several novel methods that have been developed in recent years for the preparation of nanostructured hollow microspheres of iron oxides constructed by self-assembly with different building blocks, sizes and hollow interiors. And the potential applications of the as-prepared iron oxide hollow microspheres in the fields of drug delivery, adsorption and photocatalysis are also discussed.

Graphene sheets were prepared by using chemical reduction of a colloidal suspension of graphene oxide sheets in water. After hydrophilic treatment and chemical plating, a layer of nickel particles was uniformly coated on the surfaces of the graphene sheets. The morphologies of the pure graphene (GF) and Ni-coated graphene (NGF), nickel element content on the graphene surface and magnetic properties of the NGF were examined by SEM, EDX and VSM, respectively. The complex relative permittivity and permeability of the NGF absorber were measured by using a microwave network analyzer in the frequency range of 2-18 GHz. The reflection loss curves of the GF and NGF were calculated using computer simulation technique. It is found that in the frequency range of 2-18 GHz, with the increase of the matching thickness, the maximum absorbing peaks of the GF and NGF shift to lower frequency region, so GF and NGF are dielectric loss microwave absorption materials. When the matching thickness is 1 mm, the maximum absorption peak of the GF is -6.5dB at about 7GHz. When the matching thickness is 1.5 mm, the maximum absorption peak of the NGF is -16.5dB at 9.25 GHz and the frequency region in which the maximum reflection loss is more than -10.0 dB is 9.5-14.6 GHz.

Graphene thin films were epitaxial grown on Si(111) substrates by depositing carbon atoms with solid source molecular beam epitaxy (SSMBE). The structural properties of the samples deposited at different substrate temperature (400, 600, 700 and 800℃) were investigated by reflection high energy electron diffraction (RHEED), Fourier transform infrared spectroscope (FTIR), Raman spectroscope (RAMAN) and near-edge X-ray absorption fine-structure (NEXAFS). RAMAN and NEXAFS results indicated that the thin film deposited at 800℃ exhibited the characteristic of graphene, while the thin films deposited at 400℃, 600℃ and 700℃ were attributed to amorphous or polycrystalline carbon thin films. RHEED and FTIR results indicated that C atoms did not bond with Si atoms at the substrate temperature below 600℃, however, above 700℃, C atoms reacted with Si atoms and formed the SiC buffer layer. Furthermore, the better quality of SiC buffer layer could be obtained at 800℃. Thus, high substrate temperature and high-quality SiC buffer layers are essential to the formation of the graphene layers on the Si substrates.

Y_0.5Yb_0.5BCO film was successfully fabricated by fluorine-reduced metalorganic deposition (MOD) method through mixing the same concentrated YBCO and YbBCO precursor solution with 1:1 volume ratio. The film has strong (00l) peaks and well biaxial texture. The surface of the film is dense without any cracks and pores. Besides, the elemental distribution is well-proportioned. It is found that the Yb elemental substitution improves the in-field properties effectively, especially at high fields, although it decreases the critical transition temperature (T_c) of the Y_0.5Yb_0.5BCO film. For example, the Jc value of Y_0.5Yb_0.5BCO film is as higher as 1.26 times than that of the pure YBCO film at 77K and 3T applied field. In order to further improve the property at lower field, 6mol% TaCl₅ is added to Y_0.5Yb_0.5BCO precursor solution to obtain the Ta⁵⁺-doped Y_0.5Yb_0.5BCO film. The current carrying ability of the Ta⁵⁺-doped Y_0.5Yb_0.5BCO film is enhanced within the measured fields.

La₂Zr₂O₇(LZO) buffer layer was prepared on the cube textured nickel alloy substrate with the nitrate as the precursor salts. Combine with the analysis of the thermal pyrolysis property of the precursor salts, and the study of epitaxial growth of LZO films on both of the LAO single crystal and the Ni5W alloy substrate, a optimized processing route is achieved, which is two step heating ways at low temperature together with the ramp heat treatment at high temperature. It is concluded that the pyrolysis process plays the most important role in the texture epitaxy. The orientation analyses reveal the formation of a cube texture, with the FWHM of (222) phi scan and the (400) ω scan of 8.5° and 8.1°, respectively. The SEM image shows the dense and homogeneous film without cracks and holes. The discussions above indicate that the nitrate route is feasible for the preparation of the LZO buffer layer.

The ZrO₂ buffer layer was coated on CoFe₂O₄(CFO) powder via a Sol-Gel method. The coated CFO and 0.92(Bi_0.5Na_0.5)TiO₃-0.02(Bi_0.5K_0.5)TiO₃-0.06BaTiO₃(BNBT) ceramic powder were mixed according to the chemical formula of xCFO/(1-x) BNBT (weight fraction x = 0.05, 0.10, 0.15, 0.20, 0.25, 0.30). Using polyvinyl alcohol (PVA) as binder, the mixture was pressed into disks. After sintered at 1050℃, the xCFO/(1-x) BNBT 0-3 composite ceramic disks were prepared. The X-ray diffraction results show that the ZrO₂ layer can buffer the Fe³⁺ and Co²⁺ ions diffusing from CFO to BNBT during the sintering process. The break-down voltage of the co-fired composites is measured to be 75kV/cm. It is found that the piezoelectric constant, electromechanical coefficient, remnant polarization and dielectric permittivity decrease as the CFO content increasing. Magnetoelectric coefficient (ME) and dielectric loss increase with the CFO content increasing. For a composite disk with dimension of -35mm×1.5mm, the ME coefficient at resonance frequency of 90 kHz is 1.39V/A under a DC magnetic bias of 199 kA/m.

Pressure-induced phase transition of Bi₄Ti₃O₁₂ (BIT) was studied using a shell model via molecular dynamics method. The Ti?Ti short range interaction potential was added to increase the accuracy of the simulation. The calculated spontaneous polarizations of ferroelectric orthorhombic B2cb phase BIT single crystal were 39.4μC/cm² in the x direction and 0 in the z direction at 300K, which were in reasonable agreement with the experimental values. The pressure-induced phase transition of BIT was also calculated. It was observed that BIT single crystal underwent two structural transformations at around 6GPa and 20GPa with increasing pressure from -2GPa to 24GPa. The accompanying symmetry changes may be the same as those observed at ambient pressure at elevated temperature. Thus the results provide a theoretical prediction of the pressure-induced phase transition in BIT.

A novel kind of water based lead zirconate titanate (PZT) ink was developed. Woodpile structures with diameter of micrometer scale were constructed from this ink by using direct write assembly technique. According to the rheological test, the ink shows shear-thinning behavior. Micro-morphology and density test results show that the sintered samples have formed ceramics with high relative density. Measurement of X-ray diffraction (XRD) shows that the main phase of sintered samples is rhombohedral PbZr_0.58Ti_0.42O₃. The value of piezoelectric constant d₃₃ is measured to be 410 pC/N, which shows that the sintered samples exhibit good piezoelectric property. The direct write assembly technique has merits of good designability, rapid forming capability and high precision prototyping, which provide new ideas and methods for the design and application of piezoelectric materials and devices.

Transparent AlON ceramic which exhibit excellent optical and mechanical properties is a potential alternative to sapphire for the application of IR windows and armor. In this work, transparent AlON ceramics were successfully prepared by solid-state reaction sintering. The effects of sintering aids and holding time on densification of AlON ceramics were investigated. The phase composition and microstructure of the ceramics were characterized by XRD and SEM, respectively. In-line transmittance of the ceramics was measured by spectrophotometer. The results show that co-doping of MgO and Y₂O₃ as sintering aid is more effective to enhance densification of AlON ceramics than the doping of MgO or Y₂O₃. With doping level of 0.08wt%Y₂O₃, the transmission of ceramics increases with the increase of MgO content. Co-doped with 0.08 wt% Y₂O₃ and 1wt% MgO, the ceramics (1mm thick) sintered at 1950℃ for 12h in N2 atmosphere have an in-line transmission of 60% (at 600nm).

A green phosphor, KBaPO₄:Tb³⁺, was synthesized by the high temperature solid-state method, using Li₂CO₃, Na₂CO₃, K₂CO₃, BaCO₃, NH₄H₂PO₄, NH₄Cl, Tb₄O₇ and CeO₂ as starting materials. After these individual materials were blended and grounded thoroughly in an agate mortar, the homogeneous mixture was heat-treated at 950℃ for 3 h, and the phosphors were obtained. The samples was characterized by powder X-ray diffraction (XRD) (D/max-rA, Cu Ka, 40 kV, 40 mA, λ=0.15406 nm). The spectral characteristics of these phosphors were measured by a SHIMADZU RF-540 fluorescence spectrophotometer. KBaPO4:Tb3+ phosphor shows several emission peaks located at 437, 490, 545, 586 and 622 nm which correspond to the ⁵D₃→⁷F₄ and ⁵D₄→⁷F_J=6. 5, 4, 3 transition of Tb³⁺, respectively, and the highest emission peak is 545 nm. Monitored at 545 nm emission, the excitation spectrum consists of several bands, and the highest peak locates at 380 nm. The effects of Tb³⁺ doping content, the compensators (Li⁺, Na⁺, K⁺ or Cl^-), and the sensitize activator Ce³⁺ on the emission intensity of KBaPO₄: Tb³⁺ phosphor are studied. The results show that the emission intensity can be controlled by the above factors, and the intensity can be enhanced by the selection of the optimal condition. It indicates that KBaPO₄:Tb³⁺ is a promising green phosphor for white light emitting diodes.

InVO₄/MWCNTs photocatalyst was synthesized by a hydrothermal method using acid-treated multi- walled carbon nanotubes (MWCNTs) as a support. The prepared InVO₄/MWCNTs photocatalyst was examined by X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), Brunauer-Emmett-Teller (BET) nitrogen adsorption, Fourier transform infrared spectroscopy (FTIR) and UV-Vis diffuse reflectance spectrum (UV-Vis DRS). The photocatalytic activity of the as-prepared samples was determined by the degradation of gas-phase benzene under visible light (λ>420 nm) irradiation. The results show that the InVO₄ particles are uniformly anchored on the surface of MWCNTs with average size of 100 nm. The specific surface area and the optical absorption of InVO₄/MWCNTs are remarkably improved, as compared with that of the pure InVO₄. After photocatalytic oxidation for 4h, the conversion rate of benzene over the InVO₄/MWCNTs is 41.0%, which is 1.5 times as much as that of the InVO₄ or 3 times greater than that of the N-doped TiO₂, respectively. Simultaneously, the mineralization rate of benzene on the InVO₄/MWCNTs is 43.4%. The enhanced photocatalytic performance of the InVO₄/MWCNTs is related to the excellent electron-transporting properties of the MWCNTs, which acts as a trap for photogenerated electron.

Visible light-driven photocatalyst K₄Ce₂Nb₁₀O₃₀ was prepared by polymerizable complex (PC) process  using dissolvable niobium oxalate as precursor. Characterizations of XRD, BET, SEM and UV-Vis showed that the sample prepared from PC process presented smaller particles (20-50 nm) and higher specific surface areas than the sample from conventional high temperature solid state reaction (SSR) method. As for their photocatalytical activities for water decomposition under visible light irradiation (λ > 400 nm), the sample prepared by PC method showed higher H₂ evolution activities than that of sample prepared by SSR as a result of the higher surface areas and finer crystal particles of sample prepared by PC. Moreover, the sample prepared by PC methods realized the overall pure water splitting under λ > 300 nm irradiation condition.

N-F-codoped TiO₂ semiconductor Sol (N-F-TiO₂) was synthesized by Sol-Gel method, and N-F-TiO₂ film was prepared on soda-lime glass using silk-screen printing. X-ray diffraction (XRD) of N-F-TiO₂ exhibits significant diffraction peaks representing the characteristic of anatase phase and contain trace amount of brookite. X-ray photoelectron spectroscope (XPS) test indicates that N element exists with N-Ti-O bonding in the crystals, while F element exists as a dopant in the lattice of TiO₂ or adsorbs on the surface of N-F-TiO₂. Diffuse reflectance spectra (DRS) of N-F-TiO₂ shows increased absorption in the range of 300-500 nm compared with that of undoped TiO₂ film. Antibacterial abilities of N-F-TiO₂ films under 60min UV and visible light irradiation are identified using E.coli. The prepared N-F-TiO₂ films exhibit excellent antibacterial abilities as observed both in bacterial surviving test and cell membrane damaging test. After the irradiation of UV-A, the relative survival percentage of E.coli decreases to 0 and the maximum content of malonaldehyde (MDA) is 1.4 nmol/mg (cell dry weight). Under the visible light irradiation, relative survival percentage of E.coli decreases to 10% and the maximum content of malonaldehyde is 0.9 nmol/mg (cell dry weight).

The perovskite nanoparticle materials La_0.75Sr_0.25Mn_0.5Co_0.5O_3-δ were prepared in YSZ porous layer by infiltration technology. An impedancemetric-type NO₂ sensor was prepared with the nanoparticle materials as sensing electrode and YSZ as solid state electrolyte. The crystalline phase and microstructure of sensing electrode in the NO₂ sensor were investigated by XRD and SEM. The result of XRD indicated that perovskite LSCM was obtained in porous YSZ after infiltrating precursor solution and heat-treatment. SEM analysis demonstrated that the grain size of LSCM was 50-100 nm, and the LSCM nanoparticles were closely incorporated with YSZ frames in porous layer. The sensing characteristics of the present device were also investigated at 450-600℃. The results suggested that the sensor showed preferential sensitivity to NO₂ with NO₂ concentration from 0 to 1000uL/L. When frequency was fixed at  0.1 Hz, the total impedance of the sensor changed almost linearly with NO₂ concentration. The real response time of the sensor to NO₂ gas was around 40s at gas flow rate of 400mL/min. It is also found that the response of sensor is stable at given time and the sensor has good anti-interference to O₂ and CO₂.

Li₄Ti₅O₁₂ nanoarrays were prepared with sol-filling template method. The morphology and structure of Li₄Ti₅O₁₂ nanoarrays were characterized by SEM, EDS and XRD. The experimental results show that spinel Li₄Ti₅O₁₂ nanoarrays with average diameter of 70nm are obtained by repeating the following steps for four times: immersing the porous AAO in sol of 0.8mol/L under -0.1MPa and drying at 80℃, then roasting at 900℃ for 20h in the air. The diameter and length of Li₄Ti₅O₁₂ nanoarrays are controlled by diameter, thickness, sol concentration and filling times, with the crystalline structure rested on the roasting time and temperature. On the basis of characterization for nanoarrays, a possible formation mechanism is supposed.

The vanadium solution was prepared by the mixture of hydrogen peroxide and vanadium pentoxide in sulphuric acid solution. The solubility mechanism of vanadium pentoxide was investigated. The valence and concentration change of vanadium solution were characterized by UV-Vis and ICP measurement in the following electrolysis procedure. △H and △G of the reaction were calculated. The results showed that the reaction was exothermic. The electrochemical activity was characterized by the charging and discharging experiment. And the results showed that the high current efficiency, voltage efficiency and energy efficiency of 93.6%, 98.1% and 91.9% were obtained at the current density of 2.4 mA/cm², respectively. This indicated that the prepared vanadium solution was suitable for vanadium redox-flow battery.

ZrW₂O₈ thin films were deposited on quartz substrates by pulsed laser deposition method. Effects of substrate temperature on the microstructure, composition, surface roughness and morphology of the ZrW₂O₈ thin films were observed by X-ray diffraction (XRD) and atomic force microscope (AFM). The thickness and optical transmittance of the ZrW₂O₈ thin films were measured by surface profilometer and spectrophotometer respectively. The negative thermal expansion property of the ZrW2O8 thin film was measured by high temperature X-ray diffraction. The results indicate that the as-deposited ZrW₂O₈ thin films deposited at the substrate temperature of room temperature, 550℃ and 650℃ are amorphous phase, and the cubic ZrW₂O₈ thin film can be obtained after annealing at 1200 ℃ for 3 min and then quenching in water. With the increase of deposition temperature, the surface roughness decreases markedly. The optical transmittances of the ZrW₂O₈ thin films prepared at different condition are about 80%, and the negative thermal expansion coefficient of the resulting cubic ZrW₂O₈ thin film is -11.378×10^-6 K^-1 in the temperature range from 20℃ to 600℃.

Effect of D-sorbitol addition on rheological properties of aqueous alumina suspensions dispersed with poly (acrylic acid) (PAA) was investigated. The results showed that for the aqueous alumina suspensions with 30vol%?40vol% solids loadings, small amount of D-sorbitol can significantly enhance the stability of alumina suspensions with PAA at pH=9.0. When the total amount of dispersant was 0.5wt% and the concentration of D-sorbitol was 20%, the viscosity of suspensions was the lowest. In addition, the suspensions dispersed with binary dispersant were less sensitive to ionic strength than the suspensions containing just the PAA. The role of PAA and D-sorbitol in the alumina suspensions was characterized by FTIR spectroscope. Based on the rheology and FTIR measurements, a schematic model was established to depict the mechanism for the effect of D-sorbitol in the presence of PAA. D-Sorbitol was absorbed both on alumina surface and the absorbed PAA, leading to an enhanced steric hindrance thus resulting better stability of the suspensions.

Stoichiometric MgAl₂O₄ spinel nanoparticles were synthesized by microwave assisted combustion reaction from aluminium nitrate nanohydrate (Al(NO₃)3·9H₂O) and Sol-Gel prepared magnesium hydroxide (Mg(OH)₂) in the presence of urea ((NH₂)₂CO) as a fuel, in about 20 min of irradiation. X-ray diffraction (XRD) studies reveal that microwave assisted combustion synthesis route yields single-phase spinel nanoparticles with larger crystalline size (around 75 nm) than other conventional heating methods. Scanning electronic microscope (SEM) images show nanoparticles with spherical shape and homogenous morphology. The surface area measurements (SBET) show crystals with 2.11 m²/g and 0.0033 mL/g pore volume.

Bismuth telluride thin films with layered nanostructure have been fabricated by radio frequency (RF) magnetron sputtering. Thin films were deposited at various substrate temperatures and durations with a single Bi₂Te₃ target. The microstructures and chemical compositions of these films were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive spectroscope (EDS). Electrical transport property and Seebeck coefficient were measured on these thin films. The results show that substrate temperature is a key factor on the microstructure and transport property of bismuth telluride thin films. High temperature is beneficial for the formation of layered nanostructure and the enhancement of power factor. The highest power factor was obtained on the thin film deposited at 400℃. However, Te deficiency was observed in these thin films. Thus thermoelectric property would be further enhanced by optimizing composition of these thin films.