Enthalpies of high-temperature phase transitions and fusion in lanthanum oxide (La2O3) were directly measured for the first time. Three samples were prepared by laser melting, sealed in tungsten crucibles, and heated in a differential thermal analyzer calibrated by melting Al2O3. Transformation enthalpy of La2O3 from A to H phase is 23 ± 5 kJ/mol at 2046 ± 5 °C and from H to X phase is 17 ± 5 kJ/mol at 2114 ± 5 °C. Lanthanum oxide melts at 2301 ± 10 °C, with enthalpy of fusion of 78 ± 10 kJ/mol.

Tin dioxide (SnO2) is an important base material for a variety of gas sensors and catalysts. However, there is a lack of experimental data on the energetics of SnO2 surfaces and their water adsorption. In this work, the surface energies of anhydrous and hydrated SnO2 nanoparticles were measured by combining high-temperature oxide melt solution calorimetry and water adsorption calorimetry. The SnO2 nanoparticles were synthesized through oxidation of metallic tin using nitric acid followed by heat treatment at different temperatures to achieve surface areas ranging from 4000 to 10,000 m2·mol−1(25–65 m2·g−1). The enthalpy of the anhydrous surface is 1.72 ± 0.01 J·m−2, and that of the hydrated surface is 1.49 ± 0.01 J·m−2. The integral heat of water adsorption is −75 kJ·mol−1, with a chemisorbed maximum coverage of ∼5 H2O·nm−2. SnO2 has a lower surface energy and less exothermic enthalpy of water adsorption than the isostructural TiO2 (rutile) reported previously. This comparison suggests that the excellent sensing properties of SnO2 may be a consequence of its relatively low affinity for surface H2O molecules that compete with other gases for adsorption.

Microstructural and electrical properties of Gd-doped CeO2 (GDC; Ce0.9Gd0.1O1.95) thin films prepared by pulsed laser deposition as an electrolyte in solid-oxide fuel cells (SOFCs) were investigated. The GDC thin films were prepared on various substrates including single-crystal yttria-stabilized zirconia (YSZ) and magnesium oxide (MgO) substrates. The GDC thin-film electrolytes with different grain sizes and grain morphologies were prepared by varying the deposition parameters, such as substrate temperature, oxygen partial pressure, target repetition rate, and laser ablation energy. The microstructural properties of these films were examined using X-ray diffraction (XRD), transmission electron microscopy (TEM), and atomic force microscopy (AFM). Alternating-current (AC) and direct-current (DC) electrical measurements through in-plane method show that the electrical property of the GDC thin film strongly depends on grain size, e.g., the total conductivity of the films deposited at 700 °C (7.3 × 10−3 S/cm) is about 20 times higher than the ones deposited at room temperature (3.6 × 10−4 S/cm) at the measurement temperature of 600 °C.

Nickel oxide–polypyrrole (NiO–PPy) composites for lithium-ion batteries were prepared by a chemical polymerization method with sodium p-toluenesulfonate as the dopant, Triton-X as the surfactant, and FeCl3 as the oxidant. The new composite material was characterized by Raman spectroscopy, thermogravimetric analysis, scanning electron microscopy, and field-emission scanning electron microscopy. Nanosize conducting PPy particles with a cauliflower-like morphology were uniformly coated onto the surface of the NiO powder. The electrochemical results were improved for the NiO–PPy composite compared with the pristine NiO. After 30 cycles, the capacities of the NiO and the NiO–PPy composite were about 119 and 436 mAh·g−1, respectively, indicating that the electrochemical performance of the composite was significantly improved.

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.

Ti–Si–C–N thin films were deposited onto WC-Co substrates by industrial scale arc evaporation from Ti3SiC2 compound cathodes in N2 gas. Microstructure and hardness were found to be highly dependent on the wide range of film compositions attained, comprising up to 12 at.% Si and 16 at.% C. Nonreactive deposition yielded films consisting of understoichiometric TiCx, Ti, and silicide phases with high (27 GPa) hardness. At a nitrogen pressure of 0.25–0.5 Pa, below that required for N saturation, superhard, 45–50 GPa, (Ti,Si)(C,N) films with a nanocrystalline feathered structure were formed. Films grown above 2 Pa displayed crystalline phases of more pronounced nitride character, but with C and Si segregated to grain boundaries to form weak grain boundary phases. In abundance of N, the combined presence of Si and C disturbs cubic phase growth severely and compromises the mechanical strength of the films.

Transparent and high preferential c-axis-oriented ZnO thin films doped with SiO2 have been prepared by sol–gel method using zinc nitrate and tetraethylorthosilicate as precursors, absolute ethanol as solvent, and diethanolamine as sol stabilizer. Thin film deposition was performed by spin coating technique at a spinning speed of 2000 rpm/sec on glass substrate followed by calcinations at 500 °C. The structural characteristics of the samples were analyzed by x-ray diffractometer and atomic force microscope. The optical properties were studied by an ultraviolet–visible spectrophotometer. The results show that all the prepared ZnO thin films have a compact hexagonal wurtzite structure. With the change in the amount of SiO2 dopants, the intensity of (002) peak, particle size, surface root mean square roughness, thickness, transmittance, absorbance, and the optical band gap of the ZnO–SiO2 thin films were changed as well.

Effects of tungsten (W) addition to the electroless Ni(P) under bump metallization (UBM) on the solder joint reliability were investigated by preparing Ni–xW–5P and Ni–xW–9P films. Characteristics of the NiWP films, interfacial reaction with Sn–3.5Ag solder, and the impact resistance of solder joints was investigated by conducting differential scanning calorimetry, x-ray diffraction, scanning electron microscopy, transmission electron microscopy (TEM), and drop tests. Tungsten increased the thermal stability of the film and raised the crystallization temperature, but the crystallinity decreased with the W content in the film. The drop impact resistance of the Sn–3.5Ag/Ni–xW–9P joints was improved remarkably with the W content in the UBM, which was a direct consequence of the elimination of Ni3Sn4 spalling from the UBM. Additions of W up to 16 wt.% did not suppress intermetallic compound (IMC) spalling completely, but 22 wt.% W did up to 4 reflows, which increased the number of drops to failure (Nf) from 50 to over 300. TEM study showed the presence of an amorphous (Ni,W)3P layer between Ni3Sn4 and the original Ni–22W–9P UBM.

Microstructural investigation and thermodynamic simulation were carried out to study precipitation during the solidification of AZ31 Mg alloy containing up to 1wt% Sr. Increasing Sr content from 0.01 to 1 wt% led to the formation of an Al–Sr line compound (Al4Sr) and to the suppression of Al–Mg precipitate (β-Mg17Al12). Transmission electron microscopic (TEM) investigation and energy dispersive spectroscopic analysis on extracted precipitates revealed Mg and Zn solubility in the Al4Sr particles. It is shown that Sr content also affects the precipitation of Al–Mn precipitates. Thermodynamic calculations predict that the increase in Sr content limits the Al–Mn reaction and the precipitation of Al–Mn precipitates with low Al/Mn ratio. Microstructural investigations determined the presence of two Al–Mn precipitates (Al8Mn5 and AlMn), either in the form of large dendritic plates or small nano-scale particles in the Mg matrix. It has been calculated by the thermodynamic model and confirmed by TEM that by increasing the Sr content, solubility of Al solid decreases whereas the level of Mn increases slightly.

The microstructure characteristics of nanocrystalline magnesium-based alloy processed by cryomilling and spark plasma sintering were investigated. The as-received and cryomilled powders and the consolidated bulk material were characterized by scanning and transmission electron microscopies, x-ray diffraction, and electron dispersive spectroscopy techniques. The cryomilled powders resulted in an average grain size of 25 nm. After spark plasma sintering, a bimodal grain size distribution with coarse grains around 500 nm and fine grains of 52 nm, which is one of the smallest grain sizes reported in bulk nanostructured Mg alloys, was found. Our results suggest this novel process as a viable method to provide new opportunities for the development of nanostructured Mg-based alloys.

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.

Electropulsing-induced evolution of texture during recrystallization of Fe–3%Si alloy strip was studied using electron backscattered diffraction and x-ray diffraction techniques. Under electropulsing, various textures occurred during several seconds of recrystallization in the alloy. The Goss texture (G-texture) with high energy storage developed with increasing misorientation distribution of the low-angle grain boundaries. The mechanism of the electropulsing-induced G-texture evolution was discussed from the point of view of electropulsing dynamics.

In this work, elastic properties of Mg-based bulk metallic glasses (BMGs) with different chemical compositions were investigated. By compositional tuning in the quaternary Mg–Cu–Ag–Y alloys, the Poisson’s ratio ν of 0.332 is achieved at Mg56Cu21Ag14Y9 BMG, in excess of the previously suggested critical value (ν = 0.31–0.32) for the brittle-to-tough transition in metallic glasses. With the properties of the constituent elements, the predicted values of the bulk modulus B and shear modulus μ of Mg-based BMGs are 8% and 10% greater than the measured value, respectively. Notch toughness KQ of the ten investigated Mg-based BMGs varies between 3.6 and 8.2 MPa√m. Intrinsic brittleness of Mg glass is associated with its tiny plastic zone size (in micrometer scale) and weak resistance to crack propagation. The toughness variations are lack of significant correlation with the ν or μ. Among the investigated alloys, the Mg59.5Cu22.9Ag6.6Gd11 BMG manifests a good combination of improved toughness and high glass-forming ability.

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.

A comprehensive investigation has been made of the solidification of nitrogen-atomized Al86Ni6Y4.5Co2La1.5, using focused ion beam, transmission electron microscopy, and other analytical means. Face-centered cubic Al2Y was identified to be the leading crystalline phase rather than crystalline Al. A new orthorhombic-structured phase was identified in partially or fully crystallized powder particles. Apart from oxygen, nitrogen was also found to be associated with the leading crystalline phase Al2Y in which nitrogen exists as substitutional Nx−. These findings facilitate the basis for understanding the unique aspects of the Al86Ni6Y4.5Co2La1.5 bulk metallic glass, including its powder preparation by gas atomization.

Controlling the grain size and morphology of cast cobalt-based components is important for optimizing a component’s in-service properties. This work investigates the role of boron on the grain size of binary cobalt–boron alloys by application of contemporary grain refinement theory. Boron solute is found to refine the width of the columnar grains but fails to promote the columnar to equiaxed transition. The lack of equiaxed grains is attributed to the thermal solidification conditions and a lack of potent nucleant particles. The refinement of the columnar grains with boron solute may be due to a growth restriction mechanism.