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Abstract: Single-phase β-FeSi2 thin films have been grown on quartz substrates using femtosecond laser deposition (800nm, 50fs, 1KHz) under gas pressure of 3.0×10−4 Pa. X-ray diffraction (XRD) and field-emission scanning electron microscopy (SEM) were used to determine the structural properties and surface images of the films. Typical XRD patterns of the film showed that no other diffraction peak except β-FeSi2 was found. The SEM results indicated that the films were composed of well-distributed grains, in the range 50–150nm in diameter. In addition, normal incidence spectral transmittance and reflectance data suggested that the β-FeSi2 film has a direct energy gap of about 0.85eV. The thickness of the layer and the refractive index of the film were determined by performed calculation in the wavelength range 1.9–2.7μm. Furthermore, the Raman spectra of the films were also discussed. [Copyright &y& Elsevier]

Different thickness of Na 2/3 Ni 1/4 Mn 3/4 O 2 thin films were deposited on stainless steel substrates by pulsed laser deposition technique. X-ray diffraction and field-emission scanning electron microscope results reveal that the thin film with highly preferred c-axis orientation is composed of homogeneous nano-sized grains. The charge/discharge tests indicate that the 0.55 μm thick film demonstrates a high initial discharge capacity of 175.3 mAhg −1 and a retention of 91% after 30 cycles at a current density of 13 mAg −1 . Furthermore, as the current density increases from 13 to 130 mAg −1 , about 89% of its initial discharge capacity can be maintained, exhibiting excellent rate capability. These superior electrochemical properties would promote Na 2/3 Ni 1/4 Mn 3/4 O 2 thin film to be a promising cathode material for sodium-ion micro-batteries. [ABSTRACT FROM AUTHOR]

Aluminium oxide (Al2O3)-modified LiNi0.5Mn1.5O4 (LNMO) thin-film electrodes were prepared by pulsed laser deposition and effects of surface modification on interfacial reactions of LNMO were studied. The modification by Al2O3 was carried out successively after the deposition of LNMO thin-film. Field-emission Scanning Electron Microscope results show that Al2O3 disperses uniformly in nano-scale on the film electrodes. Charge/discharge behavior of the batteries under a high cutoff voltage of 4.9V vs. Li is highly improved by using Al2O3 modification, especially at elevated temperature. The electrochemical properties of LNMO thin-film electrodes are also affected by the thickness of coating. It is found that 20nm thick Al2O3 coating layer improves thermal stability most obviously among them. At 55°C, 84.1% of its initial capacity at 1C-rate can be retained after 100 cycles, and as the rate increases from 0.2 to 10C the reversible capacity can still maintain 80.7mAhg−1, which are greatly improved compared to pristine, 6 and 40nm thick Al2O3 modified samples. [ABSTRACT FROM AUTHOR]

Highlights: [•] Well-crystallized and high-stabilized spinel LNMO film cathode with excess of lithium was synthesized on stainless steel substrates by pulsed laser deposition technique. [•] The discharge capacity of the sample deposited at 750°C decreases slightly to 116.8mAhg−1 at 0.5C after 100 cycles with a stable Coulombic efficiency of 98%. [•] It also exhibits excellent rate capability. As the rates increase to 5 and 10C, about 95.4 and 92.3% of its initial capacity at 0.2C can be retained. [ABSTRACT FROM AUTHOR]

Abstract: CuO nanocrystalline thin films are deposited on quartz substrates by pulsed laser deposition. The grown single-phase CuO films are characterized by X-ray diffraction, X-ray photoelectron spectrometer and transmission electron microscopy. The optical nonlinearity of CuO films is investigated by the Z-scan method under a high-repetition-rate (HRR) femtosecond laser (800nm, 50fs, 80MHz). The CuO nanocrystalline films are found to be good optical limiters with a limiting threshold of 0.3GW/cm2 and a damage threshold of 1.65GW/cm2. The possible mechanisms of the optical limiting are also proposed. [Copyright &y& Elsevier]

Abstract: By performing Z-scan method with a femtosecond laser (800nm, 50fs, 1kHz), we investigated the third-order optical nonlinearities of a cuprous oxide (Cu2O) film. Single-phase Cu2O film deposited on a quartz substrate was obtained using the pulsed laser deposition technique. The structure properties, surface morphology and optical transmission spectrum were characterized by X-ray diffraction, scanning electron microscopy and double beam spectrophotometer, respectively. The Z-scan results show that the Cu2O film exhibits large nonlinear refractive index, n2 =3×10−3 cm2/GW, while the two-photon absorption coefficient, α 2 =40cm/GW, is relatively small. It implies that the Cu2O film is a promising candidate for nonlinear photonic devices. [Copyright &y& Elsevier]

By controlling the oxygen pressure, single-phase CuO and CuO thin films have been obtained on quartz substrates using a pulsed laser deposition technique. The structure properties and linear optical absorption of the films were characterized by X-ray diffraction and UV-VIS spectroscopy. By performing z-scan measurements using a femtosecond laser (800 nm, 50 fs), the real and imaginary parts of the third-order nonlinear susceptibility, Re χ and Im χ, of the films were determined. Both CuO and CuO films exhibited large optical nonlinearities, which is comparable to those in some representative semiconductor films such as ZnO and GaN films using femtosecond laser excitation. Compared with CuO films, the CuO films showed larger third-order nonlinear optical effects under off-resonance excitation. Furthermore, the mechanisms of the optical nonlinearities in CuO and CuO films are explained in the main text. It was suggested that the reasons of the difference in their nonlinear refractive effects may be related to the different electronic structure in CuO and CuO materials. [ABSTRACT FROM AUTHOR]

Abstract: The Au/TiO2 composite films have been fabricated using the pulsed laser deposition technique. The optical transmission spectra of the films were investigated in the range from 300 to 900nm and the surface plasmon resonance peaks were observed varying from 550nm to 650nm. The optical nonlinearities of the as-deposited and annealed samples were investigated by the Z-scan method using a high-repetition-rate femtosecond laser. It was found that, for the as-deposited samples, the sign of nonlinear absorption coefficients (β) changed from negative to positive with increasing Au concentration. However, for all the annealed samples, the sign of β was found to be negative. The nonlinear responses induced by the cumulative thermal effects were suggested to contribute to this phenomenon. [Copyright &y& Elsevier]

Abstract: Titanium dioxide (TiO2) films have been fabricated on fused quartz and Si(001) substrates by pulsed laser deposition technique and the single-phase anatase and rutile films were obtained under the optimal conditions. The surface images and optical transmission spectra were investigated by scanning electron microscopy and double beam spectrophotometer, respectively. The values of optical band-gap and linear refractive index of the anatase and rutile films were determined. The optical nonlinearities of the films were measured by Z-scan method using a femtosecond laser (50 fs) at the wavelength of 800 nm. Through the open-aperture and closed-aperture Z-scan measurements, the real and imaginary parts of the third-order nonlinear optical susceptibility were calculated and the results show that the anatase phase TiO2 films exhibit larger nonlinear refractive effects compared with rutile phase. The figure of merit, T, defined by T = βλ/n 2, was calculated to be 0.8 for anatase films, meeting the requirement of T <1 and showing potential applications in all-optical switching devices. [Copyright &y& Elsevier]

Abstract: In this work we investigate the third-order optical nonlinearities in CuO films by Z-scan method using a femtosecond laser (800 nm, 50 fs, 200 Hz). Single-phase CuO thin films have been obtained using pulsed laser deposition technique. The structure properties, surface image, optical transmittance and reflectance of the films were characterized by X-ray diffraction, Raman spectroscopy, scanning electron microscopy and UV–vis spectroscopy. The Z-scan results show that laser-deposited CuO films exhibit large nonlinear refractive coefficient, n 2 =−3.96×10−17 m2/W, and nonlinear absorption coefficient, β =−1.69×10−10 m/W, respectively. [Copyright &y& Elsevier]

Abstract: Anatase phase TiO2 films have been grown on fused silica substrate by pulsed laser deposition technique at substrate temperature of 750°C under the oxygen pressure of 5Pa. From the transmission spectra, the optical band gap and linear refractive index of the TiO2 films were determined. The third-order optical nonlinearities of the films were measured by Z-scan method using a femtosecond laser (50fs) at the wavelength of 800nm. The real and imaginary parts of third-order nonlinear susceptibility χ (3) were determined to be −7.1×10−11esu and −4.42×10−12esu, respectively. The figure of merit, T, defined by , was calculated to be 0.8, which meets the requirement of all-optical switching devices. The results show that the anatase TiO2 films have great potential applications for nonlinear optical devices. [Copyright &y& Elsevier]

Abstract: Copper oxide, Cu2O and CuO, thin films have been synthesized on Si (100) substrates using pulsed laser deposition method. The influences of substrate temperature and oxygen pressure on the structural properties of copper oxide films were discussed. The X-ray diffraction results show that the structure of the films changes from Cu2O to CuO phase with the increasing of the oxygen pressure. It is also found that the (200) and (111) preferred Cu2O films can be modified by changing substrate temperature. The formation of Cu2O and CuO films are further identified by Fourier transform infrared spectroscopy. For the Cu2O films, X-ray photoelectron spectroscopic studies indicate the presence of CuO on the surface. In addition, the optical gaps of Cu2O and CuO films have been determined by measuring the transmittance and reflectance spectra. [Copyright &y& Elsevier]

Abstract: Zinc oxide (ZnO) thin films have been grown on Si (100) substrates using a femto-second pulsed laser deposition (fsPLD) technique. The effects of substrate temperature and laser energy on the structural, surface morphological and optical properties of the films are discussed. The X-ray diffraction results show that the films are highly c-axis oriented when grown at 80°C and (103)-oriented at 500°C. In the laser energy range of 1.0mJ–2.0mJ, the c-axis orientation increases and the mean grain size decreases for the films deposited at 80°C. The field emission scanning electron microscopy indicates that the films have a typical hexagonal structure. The optical transmissivity results show that the transmittance increases with the increasing substrate temperature. In addition, the photoluminescence spectra excited with 325nm light at room temperature are studied. The structural properties of ZnO films grown using nanosecond (KrF) laser are also discussed. [Copyright &y& Elsevier]

Abstract: Titanium dioxide thin films have been synthesized on Si (100) substrates using pulsed laser deposition method (KrF: 248 nm, 20 ns, 5 Hz). The emission spectra of the plasma induced by ablating TiO2 target in the oxygen or argon ambient gas were analyzed. The influences of substrate temperature and ambient gas pressure on the structural properties of TiO2 films were discussed. The X-ray diffraction results show that the films deposited at 750 °C are (004)-oriented anatase phase and (110)-oriented rutile phase under the oxygen and argon pressure of 5 Pa, respectively. The scanning electron microscopy images indicate that the TiO2 films have a uniform and smooth surface and are composed of nanocrystal grains. The pure anatase and rutile phase TiO2 films are further proved by Raman spectromicroscopy. In addition, the optical transmission spectra and Fourier Transform infrared spectroscopy of the films were also studied. [Copyright &y& Elsevier]