•Na2/3Ni1/4Mn3/4O2 thin films were prepared by pulsed laser deposition.•The thin film shows highly preferred c-axis orientation and is composed of homogeneous nano-sized grains.•Na2/3Ni1/4Mn3/4O2 thin film cathodes exhibit excellent cycling performance and rate capability.Different thickness of Na2/3Ni1/4Mn3/4O2 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 Na2/3Ni1/4Mn3/4O2 thin film to be a promising cathode material for sodium-ion micro-batteries.

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 4.9 V 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 20 nm 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 10 C the reversible capacity can still maintain 80.7mAhg−1, which are greatly improved compared to pristine, 6 and 40 nm thick Al2O3 modified samples.

•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 116.8 mAh g−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.Lithium secondary batteries using LiNi0.5Mn1.5O4 films as a cathode material were prepared by pulsed laser deposition on stainless steel substrates. X-ray diffraction and Field-emission Scanning Electron Microscope results show that the film deposited at 750 °C exhibits good crystallinity with well-defined grains structure. Charge/discharge behavior of the batteries under a high cutoff voltage of 4.9 V vs. Li was highly improved by using Li-rich samples, which exhibits larger specific capacity and higher rate capability. Especially, when the substrate temperature increases to 750 °C, the reversible capacity maintains 116.8 mAh g−1 after 100 cycles at 0.5C, and the Coulombic efficiency is almost a constant value of 98%. It also exhibits excellent rate capability, as the rates increase to 5 and 10C, and about 95.4% and 92.3% of its initial capacity at 0.2C can be retained.Lithium secondary batteries using LiNi0.5Mn1.5O4 (LNMO) films as a cathode material were prepared by pulsed laser deposition on stainless steel substrates. X-ray diffraction and Field-emission Scanning Electron Microscope results show that the film deposited at 750 °C exhibits good crystallinity with well-defined grains structure. As shown in the results of X-ray photoelectron spectroscopy, the average oxidation state of Mn is increased gradually with rising substrate temperature, besides, small amounts of Fe ions can also be seen on the surface of the samples, which can affect the electrochemical properties of the samples. Charge/discharge behavior of the batteries under a high cutoff voltage of 4.9 V vs. Li was highly improved by using Li-rich samples. Excess of lithium in these samples can combine with the impurities to obtain various Li–Fe modified LNMO thin films at high annealing temperature, which exhibit larger specific capacity and higher rate capability. Especially, when the substrate temperature increases to 750 °C, the reversible capacity maintains 116.8 mAh g (1 after 100 cycles at 0.5C, and the Coulombic efficiency is nearly a constant value 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. The rate capability of the samples can be shown as follows (Li-rich Sample A (550 °C), B (650 °C), and C (750 °C); Stoichiometric Sample D (750 °C)).

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 (800 nm, 50 fs, 80 MHz). The CuO nanocrystalline films are found to be good optical limiters with a limiting threshold of 0.3 GW/cm2 and a damage threshold of 1.65 GW/cm2. The possible mechanisms of the optical limiting are also proposed.Highlights► Single-phase CuO nanocrystalline thin films are fabricated by pulsed laser deposition. ► Optical limiting effect of CuO films has been observed by the Z-scan method under a high-repetition-rate (HRR) femtosecond laser (800 nm, 50 fs, 80 MHz). ► The CuO nanocrystalline films are good optical limiters with a limiting threshold of 0.3 GW/cm2 and a damage threshold of 1.65 GW/cm2.

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 900 nm and the surface plasmon resonance peaks were observed varying from 550 nm to 650 nm. 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.

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 5 Pa. 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 (50 fs) at the wavelength of 800 nm. 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 T=βλ/n2T=βλ/n2, 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.

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.

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, n2 = − 3.96 × 10− 17 m2/W, and nonlinear absorption coefficient, β = − 1.69 × 10− 10 m/W, respectively.

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 1.0 mJ–2.0 mJ, 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 325 nm light at room temperature are studied. The structural properties of ZnO films grown using nanosecond (KrF) laser are also discussed.

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/n2, was calculated to be 0.8 for anatase films, meeting the requirement of T < 1 and showing potential applications in all-optical switching devices.

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.