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Abstract: This paper reports that the ultrasonic methods can be used to accurately characterize forged reactor vessels. The Charpy V-notch impact tests were conducted on the respective specimens with three different types of heat history. Various test results including fracture appearance transition temperature (FATT) were obtained. A pulse-echo method with longitudinal waves was used to measure attenuation and velocity of ultrasonic wave. The velocity was measured repeatedly nine times on each specimen. The attenuation coefficient of the ultrasonic wave changed with heat treatment temperature and conditions (as-quenched, tempered, PWHT). The fracture appearance transition temperature can be predicted using the ultrasonic characteristics. [Copyright &y& Elsevier]

The combined structural refinement using X-ray and neutron powder diffraction data was carried out to determine the crystal system and to get the structural information of Bi4Ti3O12. Of the two crystal systems, monoclinic and orthorhombic, the monoclinic system was more suitable than the orthorhombic one as a crystal system of Bi4Ti3O12 at room temperature. The final weighted R-factor, Rwp, on the all data was 7.02% (Rwp=15.03% and 4.97% for X-ray and neutron powder diffraction data, respectively) and the goodness-of-fit indicator, S (=Rwp/Re), was 1.16. The structural parameters of Bi4Ti3O12, such as lattice parameters, atomic coordinates and isotropic thermal parameters, were successfully determined on the basis of the monoclinic crystal system. The lattice parameters obtained from the combined structural refinement were a=5.4483(1) A˚, b=5.4092(1) A˚ and c=32.8111(4) A˚. The remnant polarization (Pr) of Bi4Ti3O12, 2Pr, showed 19.24 μC/cm2. [Copyright &y& Elsevier]

The structural refinement of SnO2 thin film prepared by PECVD was performed by the Rietveld method using X-ray diffraction data. The agreement between calculated and observed patterns was not satisfactory, which was attributed to the preferred orientation effect. The effect of preferred orientation was corrected by three kinds of approaches: a March–Dollase function, a pole density distribution using an inverse pole figure and a generalized spherical harmonic function. Of these methods, the approach using the generalized spherical harmonic function was the most effective than the other two approaches. The final residual weighted R-factor, Rwp, was converged 7.92%. The lattice parameters were a=b=4.7357(2) and c=3.1937(2). Other structural parameters were well in accordance with those of SnO2 powder. [Copyright &y& Elsevier]

The Rietveld refinement for the highly textured copper (Cu) sheet, which was prepared by a cold rolling process, was carried out by both the X-ray diffraction data of the normal direction in the sample orientation and the pole figure data of three reflections: (111), (200) and (220). The agreement between calculated and observed patterns was not satisfactory due to the textured effect of the copper sheet. The Rietveld refinement for the copper sheet could be done successfully by applying the pole density of each reflection obtained from the corresponding inverse pole figure to the X-ray diffraction data for the normal direction. The final R-weighted pattern, Rwp, was 12.99% and the goodness-of-fit indicator, S, was 3.68. This approach, based on the pole density distribution of each reflection, may be an alternative technique to do the Rietveld refinement for strongly textured polycrystalline samples where simple or semiempirical functions do not sufficiently describe the textured effect. [Copyright &y& Elsevier]

Abstract: Nanoindentation has been used to gain insight into the elastic/plastic contact responses of material at very small scales. The Oliver and Pharr''s analysis (W.C. Oliver and G.M. Pharr, J. Mater. Res. 7 (1992) 1564) on the nanoindentation curve, however, can be meaningless when plastically deformed material piles around the indented points. This study suggests a measuring methodology of the real contact area enlarged by the material pile-up and its corresponding mechanical properties; the pile-up corrected contact area can be calculated inversely from the reduced modulus formulation with input information of the independently determined Young''s modulus based on the Hertzian loading analysis. This contact correction relaxed overestimates in the elastic modulus and hardness interpreted from the nanoindentation curve and yielded actual mechanical properties comparable to the literature values of a (100) tungsten monocrystal. In addition, theoretically estimated upheaval amount of the contact boundary in this study was nearly consistent with the average pile-up height measured from an atomic-force microscope. [Copyright &y& Elsevier]

Abstract: Potassium titanate (K2O·nTiO2, n =4 or 6) nanostructures were prepared by a sol-gel method. The growth of potassium tetratitanate (K2Ti4O9) and potassium hexatitanate (K2Ti6O13) nanorods was obtainable in a range of Ti(OC2H5)4/CH3OK molar ratio from 1 to 2 and heating temperature from 800 °C to 950 °C with different morphologies and size distributions of the products. The role of pre-crystallized K2O phase on the growth behavior of K2O·nTiO2 (n =4 or 6) nanostructures was demonstrated by structural and morphological observation. [Copyright &y& Elsevier]

A co-precipitation process using transition metal hydrates was used to prepare a mixture of M(OH) 2 and MO(OH) (M=Ni 0.5 Co 0.2 Mn 0.3 ). This powder consisted of dense, quasi-spherical particles each composed of plate-like particles of ca. 250 nm across. By increasing the temperature, M(OH) 2 was made to transform into MO(OH) at ca. 220 °C, then into M 3 O 4 at ca. 330 °C. Moreover, the M 3 O 4 phase persisted without further reaction until 700 °C. During these phase transitions, the mixed-metal (M) in M(OH) 2 , MO(OH) and M 3 O 4 retained disordered cation distributions at the same crystallographic sites of their host lattices without appearance of any phases related to Ni, Co and Mn. The MO(OH) phase appeared owing to exposure to air. M(OH) 2 at room temerature had the lattice parameters ( a = b =2.9991(2) Å and c =8.5892(2) Å) with space group ( P6 3 /mmc ). [ABSTRACT FROM AUTHOR]

Abstract: ZnO nanowires (ZNWs) were synthesized on Co-coated Si wafer via a carbon thermal reduction vapor transport method. Scanning electron microscopy, X-ray diffraction and transmission electron microscopy investigations show that these ZNWs present a high-quality single-crystalline hexagonal structure. Field emission (FE) characteristics of the ZNWs film were measured. A low turn-on voltage for driving a current density of 0.1 μA/cm2 is about 3.9 V/μm. The field enhancement factor was determined to be ∼1180 for ZNWs film. Exposure of H2 during FE causes a permanent increase in the FE current and a decrease in the turn-on field. Also, the field enhancement factor γ was finally increased from 1180±20 to 1510±20 after FE saturation. [Copyright &y& Elsevier]