[en] The monolayer Al₂O₃:Ag thin films were prepared by magnetron sputtering. The microstructure and optical properties of thin film after annealing at 700 °C in air were characterized by transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and spectrophotometer. It revealed that the particle shape, size, and distribution across the film were greatly changed before and after annealing. The surface plasmon resonance absorption and thermal stability of the film were found to be strongly dependent on the film thickness, which was believed to be associated with the evolution process of particle diffusion, agglomeration, and evaporation during annealing at high temperature. When the film thickness was smaller than 90 nm, the film SPR absorption can be attenuated until extinct with increasing annealing time due to the evaporation of Ag particles. While the film thickness was larger than 120 nm, the absorption can keep constant even after annealing for 64 h due to the agglomeration of Ag particles. On the base of film thickness results, the multilayer Al₂O₃:Ag solar selective thin films were prepared and the thermal stability test illustrated that the solar selectivity of multilayer films with absorbing layer thickness larger than 120 nm did not degrade after annealing at 500 °C for 70 h in air. It can be concluded that film thickness is an important factor to control the thermal stability of Al₂O₃:Ag thin films as high-temperature solar selective absorbers.

[en] Through infiltration of ZrO₂ sol into SiO₂ columnar thin films, the linear birefringence of SiO₂ columnar thin films is greatly enhanced. Field emission scanning electron microscopy, atomic force microscopy, particle size analysis and UV-vis-NIR spectrophotometry are employed to characterize the morphology, pore size, particle size distribution and optical properties of the thin films and ZrO₂ sol, respectively. The results indicate that the as-deposited SiO₂ thin films are porous with a tilted-columnar structure and low refractive index. The pore size increases with deposition angle and is larger than the size distribution of ZrO₂ sol. After filling with ZrO₂ sol, the polarization splitting is enlarged. Due to the loose columnar structure, it decreases with an increase in the deposition angle. The maximum increment in transmission difference (ΔT) is about ten times larger than that of as-deposited thin film. Infiltrating ZrO₂ sol into SiO₂ columnar thin films is an effective method to improve the linear birefringence of SiO₂ columnar thin films.

[en] Poly (vinyl alcohol) (PVA) and poly (vinyl pyrrolidone) (PVP) nanofibers embedding Ag nanoparticles (5-18 nm) have been prepared successfully by electrospinning at room temperature. Scanning electron microscope (SEM), X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), Fourier transform IR spectra (FTIR), and Raman scattering were used to characterize the structure and properties of Ag nanoparticle-embedded PVA and PVP nanofibers before and after heat treatment at different temperature. The antibacterial activity of Ag nanoparticle-embedded PVP nanofibers after heat treatment was also tested, which indicated that the biological activity of yeast cells was effectively inhibited by these Ag nanoparticle-embedded PVP nanofibers.

[en] Ag nanoparticle embedded NaYF₄:0.05Tb·xCe/PVP (PVP stands for poly(vinyl pyrrolidone)) composite nanofibers have been prepared by electrospinning. A field emission scanning electron microscope and x-ray diffraction have been utilized to characterize the size, morphology and structure of the as-prepared electrospun nanofibers. Obvious photoluminescence (PL) of NaYF₄:0.05Tb·0.05Ce/PVP electrospun nanofibers due to the efficient energy transfer from Ce³⁺ to Tb³⁺ ions is observed. The PL intensity of the electrospun nanofibers decreases gradually with the addition of Ag nanoparticles. No obvious surface plasmon resonance enhanced luminescence is observed. The reasons for the weakening of the emission intensity with the addition of Ag nanoparticles have also been discussed in this work.

[en] The antimony doped tin oxide (SnO₂:Sb) (ATO) thin films were prepared by oblique angle electron beam evaporation technique. X-ray diffraction, field emission scanning electron microscopy, UV-vis-NIR spectrophotometer and four-point probe resistor were employed to characterize the structure, morphology, optical and electrical properties. The results show that oblique angle deposition ATO thin films with tilted columns structure are anisotropic. The in-plane birefringence of optical anisotropy is up to 0.035 at α = 70 deg., which means that it is suitable as wave plate and polarizer. The electrical anisotropy of sheet resistance shows that the sheet resistance parallel to the deposition plane is larger than that perpendicular to the deposition plane and it can be changed from 900 Ω/□ to 3500 Ω/□ for deposition angle from 40 deg. to 85 deg., which means that the sheet resistance can be effectively tuned by changing the deposition angle. Additionally, the sandwich structure of SiO₂ buffer layer plus normal ATO films and oblique angle deposition ATO films can reduce the resistance, which can balance the optical and electrical anisotropy. It is suggested that oblique angle deposition ATO thin films can be used as transparent conductive thin films in solar cell, anti-foggy windows and multifunctional carrier in liquid crystal display.

[en] Graphical abstract: Combining codeposition and short time post annealing, VO₂ (M) with high quality and excellent phase transition performance is obtained. After mixing the VO₂ powder with acrylic resin, the composite films deposited on glass show superior visible transmission and solar modulation, which can be used as an excellent candidate of low cost smart window in energy saving field. - Highlights: • The VO₂ powder obtained by short time thermolysis method is high purity and crystallinity with superior phase transition performance. • The maximum decreasing efficiency of phase transition temperature is about −30 K/at% with w = 0.4 at%. • After mixing VO₂ powder with acrylic resin, the maximal visible transmission of the composite films is 48% and the transmission modulation at 2000 nm is 37.3% with phase transition temperature of 66.2 °C. • Though the phase transition performance is weakened by tungsten doping, the film prepared by 1.3 at% tungsten doped VO₂ still show superior transmission modulation about 26.4%, which means that it is a potential candidate as smart windows. - Abstract: VO₂ powder with superior phase transition performance was prepared by convenient thermolysis method. The results illustrated that VO₂ powder show high purity and crystallinity. VO₂ particles are transformed from cluster to quasi-sphere with the increase of annealing temperature. The DSC analysis proves that VO₂ show superior phase transition performance around 68 °C. The phase transition temperature can be reduced to 33.5 °C by 1.8 at% tungsten doping. The maximum decreasing efficiency of phase transition temperature is about −30 K/at% with w = 0.4 at%. After mixing VO₂ powder with acrylic resin, the maximal visible transmission of the composite thin films on glass is 48% and the transmission modulation at 2000 nm is 37.3% with phase transition temperature of 66.2 °C. Though the phase transition performance is weakened by tungsten doping, the film prepared by 1.3 at% tungsten doped VO₂ still show superior transmission modulation about 26.4% at 2000 nm, which means that it is a potential candidate as smart windows

[en] Highlights: • Via solvent–thermal and pyrolysis method, VO_2 (M) powder was synthesized in air. • Aiding by grinding, VO_2 (M) nanoparticles with the size of 22 nm were obtained. • The VO_2 films show great thermochromic properties with T_l_u_m = 62.1% and ΔT_s_o_l = 12.4%. • The haze is down to 1.9%, which is superior with films prepared by other methods. - Abstract: In this paper, high crystallinity and pure phase VO_2 (M) powder is synthesized by a novel and facile method. Aiding by additional manual grinding and etching process, 22 nm high-quality VO_2 (M) nanoparticles can be obtained. The structure and properties of the VO_2 (M) particles were characterized by X-ray diffraction analysis, transmission electron microscopy, differential scanning calorimetry and UV–vis–NIR spectrophotometer. After mixing VO_2 (M) nanoparticles with transparent polymer, thin films prepared by grinded VO_2 nanoparticles show excellent thermochromic properties. The solar modulation ability is up to 12.4% with luminous transmittance of 62.7%. Moreover, The haze of films prepared by grinded VO_2 (M) nanoparticles is down to 1.9%, which is far less than that of films prepared by original VO_2 (Haze = 8.5%) and etched VO_2 particles (Haze = 4.6%). Dramatical improvement of thermochromic property and definition indicate that it is a promising method to prepare large-scale VO_2 nanoparticles and cost-effective smart window

[en] We have reported a low-cost and fast formation of highly efficient Er centers in ZnO thin films. As a high sensitivity tool for the detection of trace of Er dopant in ZnO film, spectroscopic ellipsometry is employed to disclose the systematic interrelationship of the crystallinity, dielectric function and optical band structure. Pure ZnO thin film shows very sharp band structure. The films with 0.05 at.% Er dopant, annealed at 600 °C and 800 °C, exhibit the similar tendency where the dopant level appears at the band tail. The band structure of the films with 0.05 at.% Er dopant, annealed at 400 °C, is very close to that of pure ZnO. While the samples annealed at 1000 °C are on the verge of amorphousness, and the flat curve of photon energy dependent ε_i(E) is observed. The strain effect caused by the formation of ErO₆ pseudo-octahedron structure greatly affects the value of dielectric constants. Therefore, SE analyses reveal significant effect of Er doping and annealing temperatures on the modification of optical band structure, dielectric property and optically active center in ZnO films. - Highlights: ► ZnO:Er films are prepared by a sol–gel spin coating method. ► Complex refractive index and optical band gaps of ZnO:Er films are provided. ► Ellipsometric analyses reveal significant effect of Er light-doping into ZnO

[en] Highlights: • Hierarchical micro-nanostructure of transition metal oxide was designed. • MOF-derived nanoporous Co₃O₄ was obtained. • Electrospinning technique was used to construct the nanoporous structure. • The Co₃O₄ as supercapacitor electrodes shows high specific capacitance. -- Abstract: The design and synthesis of hierarchical micro-nano structures of transition metal oxides have played an essential role in the supercapacitor field. In this work, in situ three-dimensional construction of nanoporous cobalt oxide (Co₃O₄) has been derived from the metal-organic framework (MOF) distributed evenly in electrospun polyacrylonitrile nanofibers. Due to large specific surface area and network architectures, the as-synthesized Co₃O₄ electrode notably presents a high specific capacitance of 970 F/g at a current density of 1 A/g. Besides, the as-obtained electrode exhibits a high energy density of 54.6 Wh/kg at a power density of 360.6 W/kg and maintains a capacitance retention of 77.5% after 5000 cycles at 6 A/g. Therefore, this method paves a way to produce the nanoporous MOF-derived Co₃O₄ network architecture as advanced electrodes materials, which shows an application potential for the energy storage industry.

[en] This paper describes a solution-based route to synthesize vanadium dioxide (VO₂) thermochromic thin films on glass substrate by spin-coating technology followed by nitrogen-annealing with vanadium pentoxide (V₂O₅) and oxalic acid (H₂C₂O₄) as source material, which is fairly economical and practical. Surface morphologies indicate that the films obtained by this method are homogeneous and particulate, irregular prisms emerge as the annealing temperatures increase. X-ray diffractions show that films annealed at relatively low temperature are pure monoclinic phase with a preferred orientation of (011). NaV₄O₇ and NaV₆O₁₅ form along with raising the heating temperatures. VO₂ films obtained exhibit excellent visible transparency and switching property at near-infrared wavelengths across the metal–semiconductor transition. Transmittance change at λ = 2000 nm of VO₂ thin film annealed at 450 °C attains as high as 41.5% and its solar modulation efficiency reaches up to 8.8%. The W-doped VO₂ film at a doping level of 1 at.% exhibits a thermochromic switch at 37 °C with a narrow hysteresis, which will greatly favor the practical application of VO₂-based smart windows. - Highlights: ► Vanadium dioxide thermochromic film was prepared via a solution-based deposition. ► Tungsten doping reduced the phase transition temperature to 37 °C. ► Tungsten doping narrowed the transmittance hysteresis loop. ► Our results will propel the application to vanadium dioxide-based smart windows