Great research efforts to investigate the glass-forming ability (GFA) in alloys have been made, leading to an observation that a pinpoint composition produces the best glass-forming characteristics. The reason for this observation is still unknown, limiting the development of bulk metallic glasses (MGs) with a relatively large size. In this work, systematic experimental measurements coupled with calculations were performed to address this issue using the NiNb binary alloy system. It is found that the atomic-level packing efficiency and the clusters-level regularity parameters strongly contribute to their GFA. In particular, the best glass former found in a pinpoint composition possesses the local maximum of the atomic-packing efficiency and the highest degree of the cluster regularity. This work provides an understanding of GFA from atomic and cluster levels and will shed light on the development of more MGs with relatively large critical casting sizes.

Indentation tests are used to determine the hardness of a material, e.g., Rockwell, Vickers, or Knoop. The indentation process is empirically observed in the laboratory during these tests; the mechanics of indentation is insufficiently understood. We have performed first molecular dynamics computer simulations of indentation resistance of polymers with a chain structure similar to that of high density polyethylene (HDPE). A coarse grain model of HDPE is used to simulate how the interconnected segments respond to an external force imposed by an indenter. Results include the time-dependent measurement of penetration depth, recovery depth, and recovery percentage, with respect to indenter force, indenter size, and indentation time parameters. The simulations provide results that are inaccessible experimentally, including continuous evolution of the pertinent tribological parameters during the entire indentation process.

Interfacial reactions at 100 and 150 °C in the Sn–20.48 at.% In–3.05 at.% Ag (Sn–20.0 wt% In–2.8 wt% Ag)/Ni couples are studied. Three unusual phenomena are observed. First, liquation is found in Sn–20.48 at.% In–3.05 at.% Ag (Sn–In–Ag)/Ni couples that are reacted at 150 °C, which is lower than the melting points of both the solder and the Ni substrate. In addition to the Ni3Sn4 phase, liquid phase is formed in the reaction layer. Second, the liquid phase disappears and isothermal solidification occurs when there is prolonged isothermal heat treatment at 150 °C. The results are similar to those for transient liquid phase bonding. Third, the thickness of the reaction layer in Sn–In–Ag/Ni couples that are reacted for 1440 h at 150 °C is 40 times thicker than that of those reacted at 100 °C. The reaction mechanisms for these three unusual phenomena: liquation, isothermal solidification, and an extraordinary increase in the reaction rate for only 50 °C difference in temperature are elaborated and are related to each other.

A novel combination of low-field magnetic alignment (MA) and templated grain growth (TGG) was used to fabricate highly textured diamagnetic 0.72Pb(Mg1/3Nb2/3)O3–0.28PbTiO3 (0.72PMN–0.28PT) ceramics. Samples were produced by nonaqueous slip casting of PMN–PT slurries, in which diamagnetic plate-like 0.4(Na1/2Bi1/2)TiO3–0.6PbTiO3 (0.4NBT–0.6PT) template particles were aligned by dynamic MA in a 2.2-T permanent magnet array. Template alignment improved as slurry viscosity increased, with a 32-vol% solid loading (a viscosity of ∼0.1 Pa s at 0.1 s−1) giving optimal texture quality (7.85° FWHM, f = 92 vol%) after sintering and TGG. Alignment was stable for more than 3 h during slip casting, allowing fabrication of ∼1-cm thick textured ceramics with high piezoelectric response (d33 = 1222 pC/N). The success of dynamic MA at low magnetic field (2.2 T) is attributed to an increase in driving force for alignment of large (5–10 μm) template particles relative to the randomizing effect of Brownian motion (i.e., thermal energy kBT).

The fabrication methods and the basic properties of the metal-oxide nanostructures referred as nanowires are presented and reviewed in this paper, with particular emphasis to the electrical and optical properties and their useful implementation for chemical and biochemical sensing. The field of chemical sensors has benefited by the wealth of highly crystalline nanostructures produced by physical and chemical methods. Large variation in bulk electrical conductivity, structural stability upon high temperature operation, high degree of crystalline ordering, large impact of point defects and surface states have unveiled the potential for the sensing field and have opened up new perspectives of application and for the realization of novel device architectures. This paper will summarize various techniques for preparation and characterization; then, the growth mechanisms and working principles will be discussed. Finally, the challenges that this field is currently facing are presented to signify the perspectives of expansion.

Formaldehyde (HCHO) is widely used in construction, wood processing, furniture, textile, and carpeting industries. However, it is highly toxic. It strongly irritates human eyes and nose, and is a carcinogen. In this paper, the effects of gas concentration and operating temperature on the sensing properties of the nano-SnO2 flat-type coplanar gas sensor arrays to formaldehyde were studied. The results revealed that the nano-SnO2 flat-type coplanar gas sensor arrays exhibited good sensitivity such as a fast response, short recovery time, and low detection limit. In addition, the adsorption and surface reactions of formaldehyde on SnO2 films were also studied by in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) at 200–300 °C. Molecularly adsorbed formaldehyde, formate, dioxymethylene, polyoxymethylene, H2O, and CO2 surface species were formed during formaldehyde adsorption at 200–300 °C. Moreover, a possible mechanism of the reaction process was given.

Doping of a heteroatom such as nitrogen in carbon nanomaterials provides a means to tailor their electronic properties and chemical reactivities. In this article, we present simple methods to synthesize carbon quantum dots (CQDs) with high nitrogen doping content (18–22%), involving the reaction of glucose in the presence of urea under hydrothermal conditions or by microwave irradiation. The N-doped carbon quantum dots (N-CQDs) show high aqueous solubility and tunable photoluminescence (PL). Interaction of N-CQDs with exfoliated graphene or dimethylaniline quenches PL. Interaction of N-doped as well as undoped C-dots with electron-donating tetrathiafulvalene and electron-withdrawing tetracyanoethylene has been examined. The intense blue PL of CQDs has been exploited to produce white light by mixing the CQDs with yellow light emitting ZnO nanoparticles or graphene oxide. The N-doped CQDs exhibit superior photocatalytic activity compared to pristine CQDs.

The liquid impingement erosion behavior of a zirconium-based bulk metallic glass (BMG), Zr44Ti11Cu10Ni10Be25, was evaluated in this study. For comparison, commonly used hydroturbine steel was evaluated under the same test conditions. BMG demonstrated more than four times higher resistance against cavitation erosion compared with hydroturbine steel. The unusually high erosion resistance for BMG is attributed to its uniform amorphous structure with no grain boundaries, higher hardness, and ability to accommodate strain through localized shear bands.

New experimental methods have been developed to optimize the accuracy and precision of the measured phase angle in nanoindentation experiments on viscoelastic materials performed with a Berkovich indenter. Measurements conducted in fused silica and sapphire form the basis of a new instrument calibration. Experimental verification of the new calibration and an enhanced test method is demonstrated in polycarbonate (PC) and polymethyl methacrylate (PMMA). In comparison to the standard continuous stiffness measurement (CSM) technique, the new calibration and test method reduces the measurement error in the phase angle of PC from 1900% to 10% and from 135% to 10% in PMMA. Scatter in phase angle measured by the new test method is nearly 10 times less than the level observed using the standard CSM technique. The effect of time dependent deformation on the measured phase angle is also documented. The experimental observations and results are applicable to a variety of dynamic nanoindentation test methods.

In suspensions of magnetic nanoparticles in appropriate carrier liquids—commonly called ferrofluids—an external magnetic field can control the fluid properties such as viscosity. This article provides an overview of the properties and general makeup of ferrofluids, as well as classical fluid dynamics. Some of the applications of ferrofluids are also described.

Access to affordable and reliable energy has been a cornerstone of the world’s increasing prosperity and economic growth since the beginning of the Industrial Revolution. Our use of energy in the 21st century must also be sustainable. This article provides a techno-economic snapshot of the current energy landscape and identifies several research and development opportunities and challenges, especially where they relate to materials science and engineering, to create the foundation for this new industrial revolution.

New strategies for materials fabrication are of fundamental importance in theadvancement of science and technology. Nanocrystals, especially with ananisotropic shape such as cubic, are candidates for building blocks for newbottom-up approaches to materials assembly, yielding a functional architecture.Such materials also receive attention because of their intrinsic size-dependentproperties and resulting applications. Here, we report synthesis andcharacteristics of BaTiO3 and SrTiO3 nanocubes and theordered assemblies as ferroelectric supracrystals. BaTiO3 andSrTiO3 nanocubes with narrow size distributions were obtained inan aqueous process. BaTiO3 films made up of ordered nanocubeassemblies were fabricated on various substrates by evaporation-inducedself-assembly method. Regardless of the substrate, the nanocubes exhibited {100}orientations and a high degree of face-to-face ordering, which remained evenafter heat treatment at 850 °C. Piezoresponse force microscopy wascarried out on the supracrsytal films to obtain plots of thed33 piezoelectric coefficient against the polingfield, and ferroelectric hysteresis curves were shown.