Even though the crystal structure of lead telluride (PbTe) has been extensively studied for many years, we discovered that the structure has a strong tendency to form Pb-depleted disks on {001} planes. These disks are around 2–5 nm in diameter and less than 0.5 nm in thickness, with a volume density of around 9 × 1017 cm−3, resulting in lattice strain fields (3–20 nm) on both sides of the disks along their normal directions. Moreover, such disks were also observed in Pb-rich Pb1.3Te, Pb-deficient PbTe1.3, and thallium (Tl)-doped Tl0.01Pb0.99Te and Tl0.02Pb0.98Te crystals. Because of the effects of diffraction contrast imaging by transmission electron microscopy and orientations of the crystals, these native lattice strain fields were incorrectly recognized as precipitates or nanoinclusions in PbTe-based materials. This discovery provides new insight into the formation mechanism of the precipitates or nanoinclusions in PbTe-based materials.

Welded joints of P92 steel subjected to creep testing at 650 °C and 70 MPa were investigated. Type IV cracking was observed in the fine-grained heat-affected zone (FGHAZ) of the welded joints by optical microscopy. It was found that with varying creep times, the number of creep voids increased at an accelerating rate and the maximum number of voids was formed in the FGHAZ. Scanning electron microscopy observations revealed that precipitates were formed in the interior of creep voids, suggesting that the nucleation of the creep voids is related to the precipitates. These creep voids then connected with each other, isolated the grain from the matrix, and formed zigzag microcracks, leading to type IV cracking. New coarse carbides—the Laves phase and Cr7C3—were precipitated during creep. These carbides can deteriorate the creep strength and stimulate the nucleation of creep voids in the FGHAZ.

Ni- and Cu-free Zr–Al–Co–Ag bulk metallic glasses (BMGs) with diameters up to 20 mm were synthesized by copper mold casting. The effects of Ag alloying on the superior glass-forming ability (GFA) of Zr–Al–Co–Ag alloys were studied based on the localized atomic structure and crystallization behavior. High-energy synchrotron radiation x-ray diffraction result reveals that Ag addition in Zr–Al–Co system results in a more homogeneous local atomic structure, which could be an origin for the improved GFA of the Zr–Al–Co–Ag alloy. Crystallization products of the Zr–Al–Co–Ag glassy alloy are more complex than those of the Zr–Al–Co glassy alloy. The Zr–Al–Co–Ag BMGs free from highly toxic elements Ni and Cu exhibited a combination of superior GFA, high compressive fracture strength over 2000 MPa, low Young’s modulus of 93 to 94 GPa, and good corrosion resistance in phosphate-buffered solution (PBS), inspiring their potential biomedical applications.

Iodine-doped CdS (I-CdS) with controllable morphologies, pure hexagonal phase, and enhanced photocatalytic activity was synthesized via a mild hydrothermal process with polyvinylpyrrolidone-iodine (PVP-I) acting as the template-directing reagent and iodine source. The morphologies of the as-prepared samples could be adjusted from irregular cone-shaped particles to uneven microspheres, further to smooth microspheres, while the crystal phases were also transformed from mixed cubic and hexagonal phases to pure hexagonal phase upon increasing the molar ratio of PVP-I to Cd2+ from 0 to 2. The iodine doping could result in red shift of the absorption edges and band gap narrowing of the I-CdS samples. Importantly, a critical point of 0.5 of molar ratio of PVP-I to Cd2+ for iodine doping was found to be necessary for obtaining a pure hexagonal phase that facilitates the improving of photocatalytic activity on the degradation of Rhodamine B in aqueous solution under visible light irradiation.

To detect the relatively strong scattering signals of the Raman scattering and the x-ray diffraction (XRD) from CdS and those from the CdS/CdTe interface, an inverted CdTe solar cell structure was prepared and a 35-nm-thick CdS film was deposited on the surface of a CdTe solar cell structure. The Raman and high-resolution XRD scattering spectra allowed us to qualitatively study the interdiffusion and its related reactions at the CdS/CdTe interface. Interdiffusion began to occur at a relatively low temperature of about 350 °C, which coincided with the CdS phase transformation from cubic to hexagonal phase. Substantial interdiffusion of S and Te occurred after heat treatment at a temperature of 550 °C, resulting in formation of S-rich and Te-rich CdSxTe1−x alloy at the CdS/CdTe interface, with S and Te atomic concentration of ∼9% and 11% diffused into the CdTe and the CdS films, respectively.

An n-body Cu–Zr–Ti potential is constructed and applied to evaluate a glass-forming composition range (GFR) of the Cu–Zr–Ti ternary system by molecular dynamics simulations using a solid-solution model, which is formed via random substitution of solvent atoms by a certain number of solute atoms. It is found that the GFR of the Cu–Zr–Ti ternary system is located within an approximate distorted quadrilateral composition region, in which the solid solutions are unstable and spontaneously collapse to form amorphous phases. The compositions of the four vertexes of the distorted quadrilateral are determined to be Cu22Zr78Ti0, Cu24Zr0Ti76, Cu56Zr0Ti44, and Cu72Zr28Ti0, respectively. In addition, the simulation results are in good agreement with the experimental observations and compatible with some empirical rules.

The kinetics of hydrogen in preparing amorphous boron carbide (a-B5C:H) thin films was studied. The hydrogen concentration of a-B5C:H thin films formed by plasma-enhanced chemical vapor deposition (PECVD) from a single-source precursor (o-B10C2H12) is ∼35–50 at.% as determined by nuclear reaction analysis. The hydrogen concentration of the a-B5C:H thin films is an exponential function of the precursor flux during the deposition. After annealing, the hydrogen concentration in the a-B5C:H thin films decreases with the increasing annealing temperature. The kinetics of hydrogen removal during annealing is controlled predominantly by its dissociation from PECVD radicals in the a-B5C:H thin films. The activation energy of about 0.14 eV is related to hydrogen dissociation from B–H bonds, but higher activation energy (∼0.44 eV) is required to strip the hydrogen atoms from C–H bonds in the thin films.

An ecofriendly process has been successfully developed to synthesize the polycrystalline silver nanopolyhedrons with a high yield at large scale. By using tannic acid in the presence of poly (vinyl pyrrolidone) (PVP), high quality silver nanopolyhedrons were obtained in an aqueous one-pot reaction without any templates or auxiliaries. The film made from the silver nanostructures exhibits an electrical conductivity higher than 104 S/cm on both rigid and flexible substrates. The supreme mechanical strength of this silver film recommends its wide application in printing and flexible electronics.

A multitarget sputtering method was applied to embed Au nanoparticles in TiO2 thin films (Au/TiO2 films) with a high concentration of Au particles (19–41 at%). The absolute values of imaginary part of the third-order nonlinear susceptibility, |Im [χ(3)]|, of the Au/TiO2 films, exhibited a peak around the localized surface plasmon resonance absorption peak (around 660 nm), and the maximum value was estimated to be 3.6 × 10−7 esu measured by the femtosecond Z-scan technique. The figure of merit, |Im [χ(3)]|/α, (α is the absorption coefficient of the film at the corresponding wavelength of the measurement) of the film was calculated to be 1.4 × 10−12 esu·cm, which was larger than that of the Au/SiO2 film. This is mainly due to the local field enhancement.

Tungsten nanoparticles (W-NPs) with average sizes ranging between 30 and 80 nm were prepared by thermolytic decomposition of tungsten hexacarbonyl in presence of a mixture of surfactants, oleic acid and oleyl amine. Fourier transform infrared spectroscopy and x-ray photoelectron spectroscopy (XPS) results reveal that the surfactants oleic acid and oleyl amine bonded to the surface of W-NP through their functional groups, which in turn render stability to the nanopowders with respect to coarsening or aggregation. XPS results also confirm that carbon is present only at the surface of the W-NPs. The as-synthesized W-NPs were amorphous, and on heat treatment at 600 °C for 1 h, the amorphous powders transform into a body-centered cubic crystalline form (α-W).

Near-infrared quantum cutting involving the conversion of one visible photon into two near-infrared photons was demonstrated in Ca0.99−xYbxWO4: Tb0.01 phosphors. From the analysis of the refinement of x-ray diffraction patterns, the suitable concentration range of Yb3+ in Ca0.99WO4: 0.01Tb3+ was determined to be 0–20%. By investigating their luminescent spectra and decay lifetimes, second-order downconversion from Tb3+ to Yb3+ were proved and the possible quantum cutting mechanism was proposed. Quantum efficiency related to Yb3+ concentration was calculated and the maximum efficiency was reached at 140.4%. Because the energy of Yb3 + 2F7/2 → 2F5/2 transition matches well with the band gap of the crystalline Si, the Ca0.99−xYbxWO4: Tb0.01 phosphors could be potentially applied in silicon-based solar cells.