In this work, one PVA/ZnO:Fe sample and five PVA/ZnO:Fe/ZnS nanocomposites with varying Fe doping concentrations were successfully synthesized via a chemical precipitation method using polyvinyl alcohol (PVA) as the capping agent. The structural, morphological, compositional, and optical properties of the synthesized samples were investigated using X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Energy-Dispersive X-ray analysis (EDAX), Transmission Electron Microscopy (TEM), UV-visible Spectroscopy, Photoluminescence (PL) Spectroscopy and Fourier Transform Infrared (FTIR) Spectroscopy. The characterization results confirmed the successful formation of the PVA/ZnO:Fe and PVA/ZnO:Fe/ZnS nanocomposites and demonstrated that Fe doping significantly influences their structural and optical properties. The photocatalytic performance of the synthesized nanocomposites was evaluated through the visible-light-driven degradation of methyl orange (MO). The results revealed that the incorporation of the ZnS shell, together with appropriate Fe doping, markedly enhanced the photocatalytic activity compared with PVA/ZnO:Fe. The optimum nanocomposite exhibited a maximum degradation efficiency of 95.97
The electro-optical properties of all inorganic vacancy-ordered perovskites In2MI6 (M = Ti, Zr, Hf, and Ce) are inspected using Density Functional Theory (DFT), within the FP-LAPW scheme using the modified Becke Johnson (mBJ) method as implemented in the WIEN2k electronic structure package. The computed energy band gaps of In2TiI6, In2ZrI6, In2HfI6, and In2CeI6 are 1.03, 1.97, 2.50, and 1.04 eV, respectively. Electronic structure analysis discloses pronounced hybridization between the In-5s and the I-5p states in the valence bands. Optical analysis indicates that In2TiI6 and In2CeI6 exhibit enhanced optical absorption in infrared, visible and ultraviolet wavelength ranges, while In2ZrI6 and In2HfI6 primarily absorb in the visible and ultraviolet ranges. Among the investigated compounds, In2CeI6 exhibits the lowest reflectivity. All materials show relatively high refractive indices, indicating strong light–matter interaction. These findings suggest that In2MI6 perovskites may be favorable candidates for photovoltaic devices and ultraviolet photodetectors.
The influence of low concentrations of gadolinium (Gd) on the dielectric and optical characteristics of layered ferroelectric semiconductor TlInS2 is analyzed. A series of TlIn1 − xGdxS2 single crystals (x = 0, 0.001, and 0.005) was synthesized and grown by directional solidification (Bridgman–Stockbarger) from pre-synthesized polycrystals. Phase/structure identification was performed by X-ray diffraction. Dielectric measurements were carried out at room temperature over 20 Hz–1 MHz to determine the complex dielectric permittivity ε*(f) and the AC conductivity σac(f). Optical absorption was measured at 100–300 K, and the direct optical band gap was determined using the Tauc method. The results show that Gd doping leads to a redshift of the TlInS2 band gap by approximately 70 meV at 100 K for x = 0.005 and increases the real and imaginary parts of ε*(f) at a fixed frequency, with the effect being most pronounced in the low-frequency region. Doping also increases σac and modifies the frequency power-law behavior (σac ∼ f s). At high frequencies, a regime with s ≈ 0.8–typical of hopping transport via localized states near the Fermi level–is observed. In addition, the optical band gap decreases relative to undoped TlInS2. Within the hopping-conductivity model, we estimated localized-state parameters (density of states NF, average hopping time τ, hopping distance R, and energy spread ΔE), finding an approximately threefold increase in NF at x = 0.005 and about fivefold decrease in ΔE compared with the undoped sample. These results are attributed to the simultaneous enhancement of interfacial/space-charge polarization at low frequencies and an increased density of defect- and impurity-induced localized states in the band gap.
The ZnO:Er3+ is synthesized using a combination of the solid-state reaction method and a water bath heating process. The effect of Er3+ concentration and annealing temperature on the structure, morphology and optical properties of the samples is studied. X-ray diffraction (XRD) and scanning electron microscopy (SEM) studies show that the ZnO:Er nanoparticles have a hexagonal wurtzite structure with a spherical-like morphology, and the particle size of the sample with 3
Negative electron affinity (NEA) InGaAs photocathodes are essential for near-infrared (NIR) vacuum detection, yet they suffer from a fundamental trade-off between quantum efficiency (QE) and operational stability. Conventional Cs/O activation offers excellent stability but limited NIR response, while Cs/NF3 activation boosts NIR QE at the cost of rapid degradation. Here, we propose and systematically investigate a Cs-O-NF3 hybrid activation strategy to break this dilemma in laminated composite InGaAs photocathodes incorporating a distributed Bragg reflector. Through 24-hour continuous photocurrent decay measurements, in-situ spectral response tracking, and ex-situ XPS/UPS surface analyses, we benchmark four activation protocols (n ≥ 3 samples each). The Cs-O-NF3 hybrid activation not only achieves a 1064 nm QE of approximately 0.84
