[en] The authors studied the vacancy type defects of the HgCdTe crystals by using positron annihilation time technique. Samples grown by Te solution method accommodate a large amount of Hg vacancies, no matter what kind of conducting type (n type or p type) they are. By suitable annealing process the as-grown p-type samples can be turned into n-type, and the trapping of the positrons decreased (the positron annihilation time decreases by 14-17 ps). If the samples are annealed at higher temperature, the positron annihilation time will increase. This indicates that the Hg vacancies are increased. The bulk time of the positron annihilation in HgCdTe the authors obtained in this experiment is 272 ps. According to the positron annihilation time and the electric parameters of the samples, the authors obtain the appropriate annealing temperature is 180-220 degree C

[en] We have reported the growth of p-type As-doped ZnO nanorod (NR) arrays and their electrical and electroluminescence (EL) properties. Well-directed ZnO NR arrays were grown on the Si substrate. The GaAs wafer was employed as an arsenic resource. Thermal anneal was performed to diffuse an As element into a ZnO NR. The As content increased with the increase in annealing time and temperature, which was measured utilizing energy dispersive x-ray spectroscopy in transmission electron microscopy (TEM). When enough As was doped, ZnO NR arrays began to show p-type behaviour and formed good p-n heterojunctions with the n-type Si substrate. The high-resolution TEM (HRTEM) was employed to measure the lattice structure change in the ZnO NR before and after As doping. The ultraviolet EL spectrum of the n-Si/p-ZnO NR arrays' light emitting diode device was measured at room temperature and a peak at a wavelength of about 380 nm was observed in the spectrum

[en] Optical transient absorption spectra of Ag-BaO thin film were detected in the wavelength range from 450 to 800 nm by the pump supercontinuum-probe technique with 130 fs time resolution. The optical ultrafast relaxation, in which the electrons near the Fermi level of silver nanoparticles were excited to non-equilibrium state and then returned to equilibrium state, was observed. The decay times were exponentially fitted and varied from 4 to 0.67 ps depending on the probe wavelength. The peak unoccupied state, X₄', of electrons in silver was estimated to locate at 1.47 eV above the Fermi level. (author)

[en] We present a theoretical study of spin transport in a series of organometallic iron-cyclopentadienyl, Fe_nCp_n+1, multidecker clusters sandwiched between either gold or platinum electrodes. Ab initio modeling is performed by combining the non-equilibrium Green's function formalism with spin density functional theory. Due to the intrinsic bonding nature, the low-bias conductance of the Fe_nCp_n+1 clusters contacted to gold electrodes is relatively small even for strong cluster-electrode coupling. However, a nearly 100% spin polarization of the transmitted electrons can be achieved for the Fe_nCp_n+1 (n>2) clusters. In contrast, the Fe_nCp_n+1 (n>2) clusters attached to platinum electrodes through Pt adatoms not only can act as nearly perfect spin filters but also show a much larger transmission around the Fermi level, demonstrating their promising applications in future molecular spintronics.

[en] Wide-coverage near infrared (NIR) phosphor-converted LEDs possess promising potential for practical applications, but little is developed towards the efficient and wide-coverage NIR phosphors. Here, we report the single-component lanthanide (Ln${}^{3+}$) ions doped Cs${}_2$M (In${}_{0.95}$Sb${}_{0.05}$)Cl${}_6$ (M=alkali metal) nanocrystals (NCs), exhibiting emission from 850 to 1650 nm with high photoluminescence quantum yield of 20.3 %, which is accomplished by shaping the multiple metal halide octahedra of double perovskite via the simple alkali metal substitution. From Judd-Ofelt theoretical calculation and spectroscopic investigations, the shaping of metal halide octahedra in Cs${}_2$M (In${}_{1-<!--\; ???\; -->x}$Sb${}_x$)Cl${}_6$ NCs can break the forbidden of f-f transition of Ln${}^{3+}$, thus increasing their radiative transition rates and simultaneously boosting the energy transfer efficiency from host to Ln${}^{3+}$. Finally, the wide-coverage NIR LEDs based on Sm${}^{3+}$, Nd${}^{3+}$, Er${}^{3+}$-tridoped Cs${}_2$K${}_{0.5}$Rb${}_{0.5}$(In${}_{0.95}$Sb${}_{0.05}$)Cl${}_6$ NCs are fabricated and employed in the multiplex gas sensing and night-vision application. (© 2023 Wiley‐VCH GmbH)

[en] Graphical abstract: A thermal annealing procedure was described for fine modifying the photonic bandgap properties of colloidal photonic crystals, which were self-assembled from vinyl-functionalized silica spheres by a gravity sedimentation process. Highlights: → We described a thermal annealing procedure for fine modifying the photonic bandgap properties of colloidal photonic crystals. → The position of its stop band had more than 25% blue shift by annealing the sample from 60 to 600 deg. C. → The annealing temperature and the Bragg peak values have a linear relationship in the 120-440 deg. C range. → The effects provide a simple and controllable method for modifying the photonic bandgap properties of colloidal photonic crystals. - Abstract: A thermal annealing procedure for fine modifying the photonic bandgap properties of colloidal photonic crystals was described. The colloidal photonic crystals were assembled from monodisperse vinyl functionalized silica spheres by a gravity sedimentation process. The samples diffract light following Bragg's law combined with Snell's law. By annealing the sample at temperatures in the range of 60-600 deg. C, the position of its stop band shifted from 943 to 706 nm. It had more than 25% blue shift. In addition, the annealing temperature and the Bragg peak values have a linear relationship in the 120-440 deg. C range. Fourier transform infrared (FT-IR) spectra and thermo-gravimetric analysis (TGA) curves of vinyl functionalized silica spheres confirmed the above results. The effects provide a simple and controllable method for modifying the photonic bandgap properties of colloidal photonic crystals.

[en] Oxygen redox in Li-rich oxides may boost the energy density of lithium-ion batteries by incorporating oxygen chemistry in solid cathodes. However, oxygen redox in the bulk usually entangles with voltage hysteresis and oxygen release, resulting in a prolonged controversy in literature on oxygen transformation. Here, we report spectroscopic evidence of peroxo species formed and confined in silicate cathodes amid oxygen redox at high voltage, accompanied by Co${}^{2+}$/Co${}^{3+}$ redox dominant at low voltage. First-principles calculations reveal that localized electrons on dangling oxygen drive the O-O dimerization. The covalence between the binding cation and the O-O dimer determines the degree of electron transfer in oxygen transformation. Dimerization induces irreversible structural distortion and slow kinetics. But peroxo formation can minimize the voltage drop and volume expansion in cumulative cationic and anionic redox. These findings offer insights into oxygen redox in the bulk for the rational design of high-energy-density cathodes. (© 2021 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH)