Growth and structure analysis of tungsten oxide nanorods using environmental transmission electron microscopy
The WO3 nanorods were fabricated in environmental transmission electron microscopy (ETEM) by simply heating it in oxygen atmosphere. Altough, WO3 nanorod showed high crystalline, but the stacking fault existed in nanorod. Furthermore, the nanorod was grown on tungsten wire through slit of oxide layer on it.
The Growth Mechanism of a-Fe 2O 3 Ellipsoidal Particles in Solution
Abstract The mechanism of formation of ellipsoidal hematite (α-Fe 2 O 3 ) particles, obtained by homogeneous precipitation from ferric salt solutions under different experimental conditions, is reported. Monocrystalline ellipsoidal particles having an axial ratio of 6, precipitated by aging FeCl 3 solutions in the presence of small amounts of phosphate anions, are formed by an ordered aggregation of smaller ellipsoids. The nature of the forces involved in this process and the role played by phosphate anions are discussed. Ellipsoidal hematite particles (axial ratio 1.65) obtained by aging Fe(NO 3 ) 3 acidic (HNO 3 ) solutions were found to contain a certain amount (≈8%) of goethite (α-FeOOH) in the particle core. A formation mechanism involving the heterogeneous nucleation of hematite on initially precipitated goethite cores is suggested.
Crystallography of Impurity Adsorption on Copper Surfaces
The object of the investigation was to determine the sites at which impurity adsorption occurs on crystalline surfaces. This was done by measuring the variation of surface free energy (γ) with orientation (θ). A relation between the torque [τ=(∂γ/∂θ)μ], chemical potential (μ), surface excess (Γ), and orientation is derived: (∂τ/∂μ)θ = — (∂Γ/∂θ)μ. Methods for determining surface torques by measuring dihedral angles at grooves where twin boundaries and grain boundaries intersect surfaces are discussed.Measurements were made of relative torques τ/γ on copper surfaces for the range of oxygen pressures from 10−22 to 10−13 atm at 1000°C using water—hydrogen mixtures. Increasing po2 was found to increase the magnitude of the torque on the (111) and (100) orientations. This indicates preferential adsorption at a range of orientations on the smooth, low‐index (100) and (111) surfaces rather than on stepped surfaces of orientations different from the low‐index orientations.A calculation based on a simple model of t...