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.
Failure analysis for poor solderability of Au surface of PCB
Nonwetting is one of the common problems and is always rejected in electronic assemblies. ENIG pads of a PCBA exhibited nonwetting after lead-free reflow soldering. With the aid of stereomicroscope, SEM&EDS and XRF, a series of analysis was performed. And after visual inspection, surface and cross section analysis, thickness measurement and solderability test, it can be inferred that oxidation of plating surface was the main reason for nonwetting, and corrosion in Ni plating caused an adverse impact on solderalibity.