Cu/SiO2 nano-composite thin films were prepared by a sol–gel method. The structure and optical property of the films were investigated with a special emphasis on the influences of Cu content. Cu particles were basically spherical and dispersed in the SiO2 matrix. The optical absorption peaks due to the surface plasmon resonance of Cu particles were observed in the wavelength range of 550–600 nm. The absorption property is enhanced with increasing Cu content, showing a maximum value in the films with 30 at.% Cu. Increasing Cu content above 30 at.% results in a decrease in absorption intensity. The absorption peak shows a red-shift trend with increasing Cu content from 5 to 30 at.% and then turns to blue-shift by further increasing the Cu content from 30 to 35 at.%. The band gap Eg decreases with increasing Cu content from 10 to 30 at.% but increases by further increasing Cu content.

Au nanoparticles dispersed NiO composite films were prepared by a chemical solution method. The phase structure, microstructure, surface chemical state, and optical absorption properties of the films were characterized by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, and Uv-vis spectrometer. The results indicate that Au particles with the average diameters of 35–42 nm are approximately spherical and disperse in the NiO matrix. The optical absorption peaks due to the surface plasmon resonance of Au particles shift to the shorter wavelength and intensify with the increase of Au content. The bandwidth narrows when the Au content increases from 8.4wt% to 45.2wt%, but widens by further increasing the Au content from 45.2wt% to 60.5wt%. The band gap Eg increases with the increase of Au contents from 8.4wt% to 45.2wt%, but decreases by further increasing the Au content.

The corrosion behavior of AZ91 magnesium alloy in dilute NaCl solutions was studied using electrochemical measurements, whereby a corrosion map in terms of electrode potential and chloride concentration [Cl−] was obtained. AZ91 alloy exhibited the corrosion and passivation zones in dilute NaCl solutions. The passivation zone became narrow with increasing [Cl−]. The values of open-circuit potential were in the passivation zone when the [Cl−] was less than 0.5 mol/L. XRD patterns showed the presence of the Mg(OH)2, Mg5(CO3)4(OH)2·8H2O and MgO phases in the corrosion product, whereas the latter two phases found in the passive film.

Lead-free piezoelectric NaxK1−xNbO3 (x = 0.3–0.8) (NKN) ceramics were fabricated by normal sintering at 1060°C for 2 h. Microstructures and electrical properties of the ceramics were investigated with a special emphasis on the influence of Na content. The grain size of the produced dense ceramic was decreased by increasing Na content. A discontinuous change in the space distance was found at the composition close to Na0.7K0.3NbO3 ceramic, which indicates the presence of a transitional composition between two different orthorhombic phases, which is similar to the behavior of morphotropic phase boundary (MPB) in NaxK1−xNbO3 ceramics. Such MPB-like behavior contributes to the enhanced piezoelectric coefficient d33 of 122 pC/N, planar-mode electromechanical coupling coefficient kP of 28.6%, and dielectric constant ɛr of 703, respectively for the Na0.7K0.3NbO3 ceramic. Cubic temperature TC and the transitional temperature TO-T from orthorhombic to tetragonal phase are observed at around 420°C and 200°C, respectively.

N-type Bi2Te3 thermoelectric materials were firstly prepared by spark plasma sintering (SPS) using mechanically alloyed powders and then annealed at 423–593 K for 10–144 h. The samples were characterized by X-ray diffraction, scanning electron and optical microscope, and the Hall coefficient, electrical resistivity and Seebeck coefficient were measured. The effects of annealing conditions on the electrical transport properties were studied on the basis of the effective-medium-theory (EMT) and antisite defect model. The electrical transport properties of Bi2Te3 were reduced by annealing at 523 K and 593 K, but were improved by annealing at 423 K from 10 h to 144 h. The good property stability of the SPSed Bi2Te3 annealed at 423 K is attributed to the fact that lattice defects are reduced by appropriate annealing treatments.

Ti-Modified (Na0.5K0.5)(TixNb1−x)O3 (NKNT) piezoelectric ceramics were fabricated by double-layer buried powder process at 1020°C for 2 h. The microstructures, and piezoelectric and dielectric properties of the lead-free NKNT ceramics were investigated. X-ray diffraction results indicated that Ti4+ had diffused into the (Na0.5K0.5)NbO3 lattices to form a solid solution with a perovskite structure. The introducing of Ti into the (Na0.5K0.5)NbO3 solid solution effectively reduced the sintering temperature and densified the microstructure with a decreased grain size. The highest relative density reached more than 90%. The highest piezoelectric dielectric coefficient d33 and planar mode electromechanical coupling coefficient kp were 110 pC/N and 19.5%, which were obtained in the NKNT ceramic with 1 mol% Ti. The piezoelectric properties of the NKNT ceramics were enhanced by aging in air for a period of time owing to the compensation of oxygen vacancies.

This paper reports the enhanced piezoelectric properties in [(Na0.535K0.480)0.966Li0.058] (Nb0.90Ta0.10)O3 ceramics sintered at 1075–1120 °C. Because of morphotropic phase boundary-like behavior achieved by altering the sintering temperature from 1090 to 1105 °C, the piezoelectric coefficient is enhanced to 268 pC/N, the highest value reported for the LiTaO3-doped (Na,K)NbO3 ceramics. The corresponding Curie temperature and remanent polarization reached 445 °C and 11.5 μC cm−2, respectively.

n-Type Bi2Te3 thermoelectric materials were prepared by spark plasma sintering (SPS) using mechanically alloyed powders, and fine-grained Bi2Te3 bulks with preferred grain orientation have been fabricated by SPS as a hot-forging process. The effects of orientation degree and hot-forging temperature on thermoelectric properties were investigated. The electrical resistivity was reduced by increasing orientation degree, the Seebeck coefficient was increased by raising hot-forging temperature, and consequently the power factor was significantly increased from 2.1 mW/mK2, measured at 423 K, before hot-forging to 3.1 mW/mK2 after hot-forging at 733 K. The maximum ZT value after hot-forging at 733 K reached 1.18 measured at 423 K. This value was 20% higher than that before hot-forging, although the corresponding thermal conductivity was a little increased after hot-forging. The bending strength was greatly enhanced from 62 MPa to 120 MPa after the hot-forging.n-Type Bi2Te3 thermoelectric materials were prepared by spark plasma sintering (SPS) using mechanically alloyed powders, and fine-grained Bi2Te3 bulks with preferred grain orientation have been fabricated by SPS as a hot-forging process. The orientation degree of the (0 0 l) c-planes was increased from 0.12 for the sample before hot-forging to 0.45 and 0.67 for the samples hot-forged at 673 K and 733 K, respectively. The effects of orientation degree and hot-forging temperature on the thermoelectric and mechanical properties were investigated.

Bismuth sulfide powders were synthesized by mechanical alloying (MA) and then consolidated by spark plasma sintering (SPS) technique. In order to improve the electrical transport properties of bismuth sulfides, the carrier concentration was optimized by modifying chemical composition of sulfur through producing sulfur vacancies, and the carrier mobility was enhanced by a two-step SPS as a hot-forging process through increasing grain orientation. The electrical resistivity of bismuth sulfides was reduced to 10−4 from 10−2 Ω m by optimizing sulfur content, and further lowered by hot-forging, whereby the power factor was significantly increased from 91 to 254 μW/mK2. The hot-forged Bi2S2.90 sample showed the highest ZT=0.11 (at 523 K), which is higher than the reported value. The present work revealed that bismuth sulfide compounds as a promising candidate of thermoelectric materials can be synthesized by a simple process.Electrical properties of bismuth sulfides were improved by optimizing carrier concentration through modifying compositions of sulfur and enhancing carrier mobility through SPSed hot-forging. The ZT value of 0.11 was obtained, which is the maximum reported so far .