Thermoluminescence (TL) and radioluminescence (RL) are reported over the temperature range 25–673 K from MgSiO4:Tb and MgSiO4:Eu. The dominant signals arise from the transitions within the Rare Earth (RE) dopants, with limited intensity from intrinsic or host defect sites. The Tb and Eu ions distort the lattice and alter the stability of the TL sites and the peak TL temperature scales with the Tb and Eu ion size. The larger Eu ions stabilize the trapped charges more than for the Tb, and so the Eu TL peak temperatures are ∼20% higher. There are further size effects linked to the TL driven by the volume of the upper state orbitals of the rare earth transitions. For Eu the temperatures of the TL peaks are wavelength dependent since higher excited states couple to distant traps via more extensive orbits. The same pattern of peak temperature data is encoded in RL during heating. The data imply that there are sites in which the rare earth and charge stabilizing defects are closely associated within the host lattice, and the stability of the entire complex is linked to the lattice distortions from inclusions of impurities.

Mechanical properties are of fundamental importance in materials science and engineering, and have been playing a great role in various materials applications in the human history. Measurements of mechanical properties of 2-dimensional (2D) materials, however, are particularly challenging. Although various types of 2D materials have been intensively explored in recent years, the investigation of their mechanical properties lags much behind that of other properties, leading to lots of open questions and challenges in this research field. In this review, we first introduce the nanoindentation technique with atomic force microscopy to measure the elastic properties of graphene and 2D transition metal dichalcogenides. Then we review the effect of defects on mechanical properties of 2D materials, including studies on naturally defective chemical-vapor-deposited and intentionally defective 2D materials. Lastly, we introduce a nano-electromechanical device, resonators, built on the basis of the excellent mechanical properties of 2D materials.

Single-walled carbon nanotube (SWNT) and conductive polymer composite were studied as a potential electrode candidate for plastic electronic devices such as organic light-emitting diodes (OLEDs) and solar cells. A novel conductive polymer, poly(2,7–9,9(di(oxy-2,5,8-trioxadecane))fluorene) (PFO), was synthesized and characterized as a surfactant to disperse SWNTs in solutions. The ethylene oxide (EO) side chain of rigid PFO backbone acts as a template to wrap around SWNTs in solution. Up to 0.02% (by weight) of SWNTs are stabilized and well separated in the solution phase. The carbon nanotube can be dispersed in solutions for over 4 mo. Transmission electron microscopy (TEM) images of solvent cast film suggest highly uniformed SWNT distribution incorporated in the conductive polymer matrix. Transmittance characterization shows the film is as transparent as indium tin oxide conducting glass. Conductivity measurement shows SWNTs can effectively inject charges into the PFO polymer matrix at low voltage. The current versus voltage profile of the SWNT/PFO composite film (2% SWNT in PFO by weight) shows that the majority current conducting is carried by SWNTs.

In this study, resistive switching (RS), polarization switching, and charge distribution under DC bias in undoped ZnO thin films are studied by applying scanning probe microscopy (SPM) techniques on the same location. The techniques include Piezoresponce Force Microscopy, Kelvin Probe Force Microscopy, and Conductive Atomic Force Microscopy. The effects of oxygen partial pressure during the film deposition are also investigated. The results show that high resistance state (HRS) is accompanied by the polarization switching and charges storage. By comparing the SPMs results from the same location, it is found that the oxygen partial pressure during film deposition is an important factor over the holes injection during the poling processes in the HRS. On the other hand, the low resistance state (LRS) may be dominated by the electrons injection. Based on these findings, the energy band diagrams in the Pt-tip/ZnO-film/Pt-bottom-electrode structure with the applications of the external biases are illustrated schematically. This study also proposes a more persuasive mechanism of RS in ZnO films.

The microstructures, high-temperature mechanical properties, and fracture behavior of Mg–Gd–Y–Zr alloy components produced by low-pressure sand casting with different Gd and Zr contents, have been investigated. The ultimate tensile strength (UTS), tensile yield strength, and total elongation (EL) were measured within the 25–300 °C range. At the same temperatures, the UTS and yield strength (YS) of the T6 treated Mg–xGd–3Y–0.5Zr alloys increased with Gd content increasing from 9 to 11%, which was attributed to the improvement of precipitation strengthening. Increasing the Zr content from 0.3 to 0.5% leads to dramatic decrease in grain size and improved tensile properties of T6 treated Mg–10Gd–3Y–yZr alloys which is considered to be due to grain-boundary strengthening. With the increase of tensile temperature, both UTS and YS of the T6 treated Mg–xGd–3Y–yZr alloys initially increase and then decrease. The β′ precipitates provide important strengthening sources in experimental alloys, especially at elevated temperatures. The Mg–10Gd–3Y–0.5Zr alloy shows good combination of strength and EL within the 25–300 °C range.

The joint of dissimilar metals between Mo2FeB2-based cermets and 316L stainless steel was welded by gas tungsten arc welding with no fillers. The weldability was investigated by plate rigid restraint cracking test and transverse rupture strength was measured by the three-point bending test. Microstructure of the weld joint was studied with scanning electron microscope, energy-dispersive spectrometer, X-ray diffractometer and differential scanning calorimeter, etc. Corrosion behavior was investigated by the potentiodynamic polarization test. Results revealed that weld solidification cracking susceptibility existed in the fusion zone. Coarse irregular complex ternary boride phase (M3B2) and hypoeutectic microstructure were formed in weld metal (WM). In heat affected zone (HAZ), a small number of M3B2 grains dissolved into the γ-Fe based binder, with growth and coalescence of the remaining M3B2 grains. Microhardness of HAZ increased slightly and WM presented the highest microhardness in the whole joint. Besides, potentiodynamic polarization test showed that WM had a better corrosion resistance than Mo2FeB2-based cermets, which can be attributed to the higher Cr content and relatively homogenous Mo distribution.

A novel sort of cellular titanium foam with the porosity of 86–90% and the main-pore size of 0.5–3.0 mm was successfully prepared. Such foam exhibited a compressive curve showing three regimes: the initial elasticity, the middle zigzag plateau, and the final “densification.” This “densification” presented a course that the broken pieces continually accumulated in those pores which were unbroken or not entirely broken. The fracture morphology suggested that the compressive failure was typically brittle for this titanium foam. The electromagnetic shielding performance was investigated in the radio wave frequency range (0.3–3000 MHz) for this foam, which showed an evident effectiveness with a good performance at low frequencies. On the whole, the effectiveness would be superior while the porosity of the sample was relatively small. It could be inferred that the present foam samples would perform their electromagnetic shielding mainly by the reflection loss mechanism in the low-frequency range, and give priority to the absorption loss mechanism at the upper-frequencies.

Novel 1–1.5 μm BiOCl0.5Br0.5 composite microspheres were prepared by coprecipitation method, then calcined at different temperatures. The BiOCl0.5Br0.5 samples before and after calcination were characterized by powder x-ray diffraction, thermogravimetric analysis, N2-physical adsorption, scanning electron microscopy, Fourier transformed infrared spectroscopy, and UV-Vis diffuse reflectance spectroscopy. The photocatalytic activity of the samples was evaluated by photocatalytic degradation of Rhodamine B under visible light irradiation. The results showed that the thermostability of BiOCl0.5Br0.5 composite microspheres is lower than BiOCl and higher than BiOBr. Heat treatment at low 500 °C could obviously improve the crystallinity of BiOCl0.5Br0.5 microspheres, resulting in a significant increase in activity. BiOCl0.5Br0.5 microspheres calcined at 450 °C displayed the highest activity and stability. At elevated temperature calcination (600–800 °C), phase transition occurred over BiOCl0.5Br0.5. Br element was gradually lost and new phase of Bi24O31Br10 appeared. High temperature calcination did not change the morphology of BiOCl0.5Br0.5, but the surface area and surface OH groups decreased, which resulted in a large decrease in activity.

Nanometer-sized fibers are recently getting increased attention in heterogeneous catalysis due to the superior transport properties and effective dispersion they offer. A key challenge in this application is creation of nanofibers with internal open porosity that can provide larger accessible catalytic surface and easier mass transport into the fibers. The synthesis of potassium doped iron/aluminum oxides ceramic nanofibers with mesoporous structure is presented herein. Uniform fiber mats were prepared by electrospinning (ES) using two different precursors: an aqueous solution of metal nitrates and an organic solution of metal acetylacetonates. The organic precursors gave rise to a promising mesoporous structure with fibers diameter mainly in the 300–400 nm range. Precursor viscosity was used as a stability indicator and its influence on the ES process was studied. Collection efficiency of as high as 90% was achieved. The increased understanding in fiber morphological evolution can open new possibilities in heterogeneous catalysis.

This work presented a study on the improvement of laser surface treatment on rolling contact fatigue resistance of gray cast iron. Sample surface covered with carbon powder was coupled with localized treatment by high-energy laser beam—a process defined as “laser cladding (LC).” With this method, the optimum precoating thickness was experimentally studied. Compared to the region treated by laser remelting, the crystal in LC region was finer, more compact, and uniform. Mechanical property testing showed not only high micro-hardness of LC region, but also improved tensile and compressive resistance of treated material. Fatigue wear tests and thorough analysis of fatigue detects suggested that LC treatment significantly improved fatigue wear resistance (FWR). Improved FWR was likely facilitated by delayed initiation and propagation of cracks, as well as the reduction of contact stress on substrate. Additionally, formations of fatigue defects on sample surface were thoroughly discussed.

Two kinds of heavy-alloying β-type TiAl-based alloys Ti44Al6Nb1.0Cr2.0V (A1) and Ti44Al6Nb1.0Cr2.0V0.15Y0.1B (A2) are newly designed. They are prepared by vacuum consumable melting (VCM) and cold crucible directional solidification (CCDS). Via the theoretical analysis and tentative experiment, five alternative heat treatment (HT) schedules are proposed and studied that the corresponding microstructure and room temperature (RT) tensile property are investigated, and finally the optimized HT schedules are acquired. After HT5 (heat preservation in β phase region and at 1290 °C, and then ladder cooling), A2 alloy cast by VCM exhibits a better tensile property with average elongation of 1.20%. For the two CCDS ingots, after HT3 (mainly annealing at 1280 °C), B2 phase and (B2 + γ) blocky morphology are reduced, the columnar grains and small angle lamellas are reserved, and the tensile property also has a moderate improvement.

Experimental observations have shown that carbon nanotubes (CNTs)/Al nanocomposites with high level ordered nanolaminates exhibit greatly improved plasticity. The increased plasticity is mainly attributed to enhanced dislocation storage capability and two-dimensional alignment of the reinforcement. Here a theoretical model is proposed with interactions between aligned CNTs and grain boundary dislocations emitted from a crack tip taken into consideration to investigate crack blunting and fracture toughness in nanocrytalline metal matrix composites (MMCs). The critical shear stress for emission of first dislocation from intersections between a long, flat crack and aligned CNTs is quantitatively characterized. The final equilibrium positions and maximum numbers of emitted dislocations for different orientation angles and microstructures of aligned reinforcement are evaluated. In addition, the dependence of enhanced fracture toughness on effective gliding distance of emitted dislocations is also determined. The results show that the existence of aligned CNTs can lead to an increase of critical crack intensity factor by 77% than that in dislocation free case under certain conditions. The model may provide a basis understanding of ductility in aligned CNTs-reinforced nanocrystalline MMCs on respective of emission and motion of dislocations.

Hematite (α-Fe2O3) photoanodes are widely studied as candidates for water splitting photoelectrochemical (PEC) cells. To speed up the development of high efficiency hematite photoanodes, systematic investigations of the effect of material properties such as dopants and microstructure on PEC properties that determine the photoanode performance are crucial. Toward this end, this work presents a route for reproducible fabrication of thin film hematite photoanodes with reproducible microstructure and PEC properties. Hematite thin (50 nm) films are deposited by pulsed laser deposition from a Ti-doped (1 cation%) Fe2O3 target onto cleaned transparent conducting substrates (fluorinated tin oxide, FTO, coated glass substrates). Special attention is paid to rigorous cleaning of the substrates prior to the hematite deposition, which is found to be crucial for achieving highly reproducible results. Specimens prepared by this route display homogenous conformal coating with very little spread in PEC properties between different specimens, meeting the necessary prerequisite for systematic investigation of hematite photoanodes.

Two-dimensional (2D) materials, such as graphene, hexagonal boron nitride, and molybdenum sulfide (MoS2), have attracted considerable interest from the academia and industry because of their extraordinary properties. With the remarkable development of transmission electron microscope (TEM), nanolabs can be established inside the TEM to simulate a real environment by introducing external fields, such as electron irradiation, thermal excitation, electrical field, and mechanical force, into the system. In consequence, besides static structural characterization, in situ TEM can also realize dynamic observation of the evolution in structures and properties of 2D materials. This extension promises an enormous potential for manipulating and engineering 2D materials at the atomic scale with desired structures and properties for future applications. In this study, we review the recent progress of in situ electron microscopy studies of 2D materials, including atomic resolution characterization, in situ growth, nanofabrication, and property characterization.