Rare Metals

The manganite perovskite polycrystal samples of (La1−x Dy x )2/3Sr1/3MnO3 (x = 0, 0.1, 0.2, 0.35, and 0.5) doped with Dy were prepared by solid state reaction in atmosphere to measure their X-ray diffraction (XRD) patterns, scanning electric microscope (SEM) images, infrared absorption spectra, and microwave electromagnetic properties. The displacement of the XRD peaks of the samples was found, and the 2ϑ increases from 0.05° to 0.5°. The grains of undoped La2/3Sr1/3MnO3 not only have the greatest size, but also the most regular shape. The size of the grains decreases as the Dy doping content increases from 0 to 0.5. The infrared absorption spectra of all samples were measured at room temperature. An absorption peak corresponding to the stretching vibration mode of Mn-O bonds appears within the range of 591–629 cm−1. The absorption peak shifts from a higher frequency to a lower one with the decrease of the average ionic radius of A-site. The frequency dependence of microwave-absorbing properties, imaginary components of the complex magnetic permeability μ″ and dielectric permeability ε″ for all samples was measured at room temperature from 8 to 13 GHz. The results show that the loss of microwave absorption can be attributed to both the magnetic and electric losses. The increase of Dy content not only enhances the microwave absorption but also causes the displacement of the absorption peaks.

The vacuum electromagnetic induction nitriding technology was applied to prepare a gradient nitrided layer on the surface of a Ti6Al4V alloy, which possesses TiN and α-Ti (N) phases. Moreover, transmission electron microscopy was conducted to confirm the presence of numerous high-density stacking faults caused by TiN and Ti2N phases distributed on the surface of the alloy, along with a large number of basal stacking faults inside. A high-density stacking fault led to serious distortion of lattice fringes. Lattice and numerous edge dislocations caused by defects were observed in the subsurface layer. For the surface layer, the Vickers hardness reached HV0.25 1211.30 and the residual compressive stress increased, while the nano-hardness increased to 14.07 from 5.31 GPa in the substrate. The micrometre scratch test results indicated that the plasticity and hardness of the nitrided layer changed in a gradient. The 50-μm effective hardened layer depth and surface compressive stress of the Ti6Al4V alloy were enhanced by the stacking faults.

The hot compression behaviors of W-50%Cu composite were investigated at the strain rate range from 0.01 to 5.00 s−1 and the temperature range from 850 to 1000 °C on Gleeble-1500D hot simulator. The results show that the flow stress during hot compression of W-50%Cu composite is strongly affected by the compression temperature and the strain rate. Moreover, the flow stress decreases with the raising deforming temperature, and increases with the increasing strain rate. The flow stress of the W-50%Cu composite at high temperature can be expressed by Arrhenius model, and the values of structural factor A, stress scale parameter α, stress index n and hot deformation activation Q are 3.18 × 109 s−1, 0.0133 MPa−1, 6.27393 and 239.442 kJ/mol, respectively.

The daily life of people in the intelligent age is inseparable from electronic device, and a number of bacteria on touch screens are increasingly threatening the health of users. Herein, a photocatalytic TiO2/Ag thin film was synthesized on a glass by atomic layer deposition and subsequent in situ reduction. Ultraviolet–visible (UV-Vis) spectra showed that this film can harvest the simulated solar light more efficiently than that of pristine TiO2. The antibacterial tests in vitro showed that the antibacterial efficiency of the TiO2/Ag film against S. aureus and E. coli was 98.2% and 98.6%, under visible light irradiation for 5 min. The underlying mechanism was that the in-situ reduction of Ag on the surface of TiO2 reduced the bandgap of TiO2 from 3.44 to 2.61 eV due to the formation of Schottky heterojunction at the interface between TiO2 and Ag. Thus, TiO2/Ag can generate more reactive oxygen species for bacterial inactivation on the surface of electronic screens. More importantly, the TiO2/Ag film had great biocompatibility with/without light irradiation. The platform not only provides a more convenient choice for the traditional antibacterial mode but also has limitless possibilities for application in the field of billions of touch screens.

In this paper, thermoluminescence (TL) properties of rare earth Tb3+-doped α-Sr2P2O7 were examined after β-irradiation and photoluminescence (PL) properties of samples were examined for proper excitation. All the samples were synthesized by high-temperature combustion method. The X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy characterization confirms the formation of pure α-phase with crystallized in orthorhombic structure of samples. The PL emission spectra of all samples exhibit characteristic green emission peaks of Tb3+ where the peak at 545 nm has the highest emission intensity for Tb3+ concentration of 5.0 mol%. The TL glow curves of β-irradiated Tb3+-doped α-Sr2P2O7 phosphors were recorded at different heating rates of 2, 4, and 6 K·s−1. TL curves of all sample exhibit combination of two peaks: peak at 420 K shifts toward higher temperature, while peak at 525 K remains unaffected with the increase in Tb3+ concentration as well as fading effect. The activation energy and kinetic parameters of the samples were evaluated using thermoluminescence peak shape method.