Recent Surface Studies Using Biassed Secondary Electron Imaging

The growth and surface diffusion of Cs on Si(100) and Ag on Fe(110) have been studied using biassed secondary electron imaging (b-SEI) and Auger electron spectroscopy (AES). The b-SEI technique was found capable of detecting Cs on the Si surface with a 0.5% ML sensitivity. Unusual diffusion profiles containing linear sections were obtained for coverages (θ) \u3c 1/2 ML. The general form of these profiles were reproduced using a 2-phase model, where Cs chains act as sources of mobile adatoms, in conjunction with a diffusion coefficient of the form D ~ θ (1- Cθ). This form of D, obtained from Boltzmann-Matano analysis, is consistent with diffusion theory including strongly repulsive Cs-Cs interactions. An adatom diffusion energy, Ed, = 0.47 ± 0.05 eV was found to be consistent with measurements of the diffusion coefficient made in the temperature range 333 ≤ T ≤ 363K. The growth mode for Ag on Fe(110) was determined by AES and b-SEI to be Stranski-Krastanov, with islands growing on top of two intermediate layers. Diffusion experiments conducted on finite Ag patches show that following annealing, adatoms dissociate from the islands and second monolayer and contribute to the observed expansion of the first monolayer. The diffusion results also indicate that while islands are still present, there is a competition between adatoms entering and leaving the second monolayer

Characterization of Mn-Doped PIN-PMN-PT Single Crystal Grown by Continuous-Feeding Bridgman Method

Mn-doped Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 (Mn:PIN-PMN-PT) single crystals are attractive piezoelectric materials owing to their high mechanical quality factor. However, the single crystal boules grown by the conventional Bridgman method show compositional variation along the growth direction. In particular, the Mn content exhibits large variation due to its severe segregation. To improve the compositional uniformity, we applied the continuous-feeding Bridgman method to the growth of a Mn:PIN-PMN-PT single crystal boule. Then, the composition and property distributions of the boule along the growth direction were evaluated. The results showed that excellent composition and property uniformity were carried out over 80mm in boule length. The ranges of the electromechanical coupling coefficient (k33) and the piezoelectric coefficient (d33) were 0.931–0.934 and 1352–1517 pC/N, respectively. The ranges of the mechanical quality factor (Qm31) and the depolarization field (Ed) were 417–535 and 785–859 V/mm, respectively. The Qm31 and the Ed values were higher than those of the non-doped PIN-PMN-PT single crystals. The continuous-feeding Bridgman method is therefore an effective technique for improving the uniformity of the Mn content. As a result, the Mn:PIN-PMN-PT single crystal grown by the continuous-feeding Bridgman method possesses excellent property uniformity with characteristics suitable for high power piezoelectric applications

Association between Combined Structure Function Index and Glaucoma Severity

The aim of this study was to investigate the relationship between combined structure function index (CSFI) and standard automated perimetry (SAP) parameters such as mean deviation (MD) and visual field index (VFI) in open-angle glaucoma (OAG). We retrospectively reviewed medical records from September 2009 to July 2015, which included 195 eyes of 195 patients with OAG or normal-tension glaucoma who underwent SAP and optical coherence tomography on the same day (male: female, 128 : 67; mean age, 61.4 ± 11.3 years; mean spherical equivalent, −2.39 ± 2.3 D). We divided participants into three stages based on MD value: early, MD > −6 dB; middle, −6 dB ≥ MD ≥ −12 dB; and advanced, MD < 12 dB. We then evaluated correlations between CSFI and SAP parameters in each stage using Pearson’s correlation coefficient. Mean CSFI (%), mean MD (dB), and VFI (%) in each stage were early (22.4, −2.13, and 94.0); middle (47.9, −8.78, and 75.4); and advanced (68.3, −17.32, and 49.0), respectively. Correlations between CSFI and whole, early, middle, and advanced MD were −0.88 (p<0.001), −0.68, −0.24, and −0.76, respectively. Correlations between CSFI and whole, early, middle, and advanced VFI were −0.86 (p<0.001), −0.59, −0.20, and −0.83, respectively. Consistency between CSFI and SAP indices in middle-stage glaucoma was low