In the present work we report on the synthesis of dense, highly transparent and conductive polycrystalline ZnO films on amorphous glass substrates using low temperature hydrothermal route. Among other characterization methods we have applied the FEGSEM/EBSD analyses in order to determine the texture of the obtained oriented ZnO films. Because of small size of the ZnO crystals the EBSD technique was modified and optimized for achieving the analytical resolution in submicrometer range, which allowed us to confidently determine the orientation of ZnO grains smaller than 1 um. From the recorded EBSD crystal orientation image maps we have defined the orientations of the individual ZnO crystals. From corresponding pole figures we found that ZnO films have prominent texture in crystallographic c-axis direction, i.e. that the ZnO crystals have their basal {0001}-planes oriented within ± 3 deg with respect to the substrate surface.
COBISS.SI-ID: 25764903
In this article we report on the advanced microstructural characterization and compositional analyses of submicrometer-sized reaction phases in modified Nd-Fe-B sintered magnets doped with terbium. Using a grain-boundary diffusion process (GBDP) the Tb reacts with matrix Nd2Fe14B grains and consequently core-shell structures are formed at the surface of original matrix grains with shell thickness from a few tens of nanometers up to a few micrometers. Such structures were investigated using a high-resolution FEGSEM scanning electron microscopy and energy-dispersive (EDS) and wavelength-dispersive (WDS) X-ray spectroscopies. In order to achieve submicrometer analytical resolution two methods were applied: (i) WDS with measurements of the common Nd-L, Fe-K and Tb-L spectral lines and (ii) low-voltage EDS, analyzing the “atypical” low-energy Nd-M, Tb-M and Fe-L lines with dedicated standardization procedure. The Monte Carlo calculations confirmed that in both cases an enhanced, submicrometer lateral analytical resolution was achieved, i.e. 0.4 um with the WDS and only 0.15 um with the EDS. The quantification of spectroscopic measurements was performed using modern matrix correction XPP and with standards specially prepared for those analyses. Quantitative analyses confirmed that the reaction phase (NdxTb1–x)2Fe14B is formed after the diffusion of Tb with the equilibrium concentration of Tb being equal to x=0.5, i.e., with the atomic ratio of Nd/Tb equal to 1/1. We also found that a relatively sharp Tb concentration gradient from the shell to the core occurs within a length of ≈ 0.5 um, while the Fe concentration remains unchanged. In terms of magnetic properties, the Tb-doping significantly increased coercivity by ≈ 30 % while the remanence remained at the same value as in the undoped Nd-Fe-B.
COBISS.SI-ID: 25799207
In this paper we describe the study of twin-boundary formation of Japanese twins in quartz using several microscopy methods: OM, SEM and TEM. Our contribution to this work was focused on the implementation of FEGSEM microscopy and analytical electron backscatter difraction method – EBSD, which were applied for the determination of crystallographic orientations of quartz-crystal regions near twin-boundary. When analyzing quartz in electron microscopes it is important to take into account that this material is very sensitive to local heating caused by discrete, focused electron point-beam analysis, as it is the case of the EBSD analysis. Consequently, crystal structure disappears locally and transforms into amorphous one from which the EBSD patterns cannot be generated. This problem was solved using precise optimization of the experimental parameters of the FEGSEM and the EBSD system. From the obtained electron diffraction patterns we were able to determine accurate crystallographic orientation of quartz specimen and the position of twin-boundary across the crystal. On the base of unit cell orientation measurements we have directly confirmed that the twin-boundary angle is equal to 84 deg, which corresponds to Japanese twins in quartz.
COBISS.SI-ID: 25756455