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Maskless Lithography
Published in Bruce W. Smith, Kazuaki Suzuki, Microlithography, 2020
Lanthanum hexaboride is frequently used as a thermionic emitter by forming it into a pointed rod and heating its tip indirectly using a combination of thermal radiation and electron bombardment [7]. At a tip temperature of 1600 °C and a beam energy of 12 keV, Broers reported a brightness of over 105 Acm−2 sr−1 and a lifetime of the order of 1000 h. This represents an increase in longevity of a factor of two orders of magnitude over a tungsten filament working at the same brightness. This is accounted for by the comparatively low operating temperature, which helps to reduce evaporation. Two factors allow lanthanum hexaboride to be operated at a lower temperature than tungsten. The first is its comparatively low work function (approximately 2.7 eV as opposed to 4.5 eV). The second, and probably more important, factor is that the curvature of the tip of the lanthanum hexaboride rod is about 10 µm, whereas that of the emitting area of a bent tungsten wire is an order of magnitude greater. As a result, the electric field in the vicinity of the lanthanum hexaboride emitter is much greater, and the effects of space charge are much less pronounced.
Electron Sources
Published in Peter E. J. Flewitt, Robert K. Wild, Physical Methods for Materials Characterisation, 2017
Peter E. J. Flewitt, Robert K. Wild
The most direct way to improve the source brightness is to reduce the work function ϕ. Lanthanum hexaboride, LaB6, has a value for Φ of 2.7 eV compared with 4.5 eV for conventional tungsten. Table 5.2 compares the relative brightness achievable for various modifications of tungsten filaments and the LaB6. The LaB6 source provides a very substantial brightness increase over the normal thermionic sources and is stable for long periods. Field emitters offer a further increase of at least 1000-fold in brightness compared with tungsten but require an ultra-high-vacuum (UHV) system (Table 5.2). As shown in Figure 5.6, a high field in the region of the cathode enhances electron emission because of the reduced height of the potential barrier (Joy 1974). At large fields, the barrier is narrow and electrons can pass through even at room temperature. Contrary to expectation, although the field emission source provides the highest brightness, it is not suitable or appropriate for all applications.
Lanthanum hexaboride coated D-shaped fibre for Q-switched pulse generation
Published in Journal of Modern Optics, 2022
S. Omar, B. Musa, N. Ahmed, Z. Jusoh, H. A. Rahman, A. H. A. Rosol, R. Apsari, S.W. Harun
Lanthanum hexaboride (LaB6) is a ceramic material with a high melting temperature of 2210°C and one of the highest electron emissivity. It has been widely used in developing hot cathodes [16]. Recently, LaB6 was reported for application as a solar absorber material due to its excellent optical properties [17]. More recently, we have demonstrated a Q-switched and mode-locked pulse generation using a LaB6 thin film, which was placed between two fibre ferrules as a SA [18]. In this paper, we report on the deployment of LaB6-coated D-shape fibre as a novel SA for the generation of Q-switched laser. This alternative approach is expected to improve the interaction between light and LaB6 material as well as to increase the damage threshold of the SA. The D-shape fibre was first prepared by the polishing wheel technique at the insertion loss of 1 dB. The LaB6 powder was dispersed in polyvinyl alcohol liquid and then deposited onto the D-shape fibre by the drop-casting technique. A robust Q-switched pulse has been obtained with the integration of LaB6-coated D-shape fibre in the erbium-doped fibre laser (EDFL) cavity. It attained the maximum pulse energy of 73.94 nJ, which is significantly higher compared to that of the previous work [18].
Hexakis(dimethylsulfoxide-O)-cobalt(II) hexatungstate, [Co(C2H6OS)6][W6O19]: synthesis from aqueous dimethylsulfoxide solution, crystal structure determination, FT-IR and Raman spectroscopy analysis, and surface micromorphology
Published in Journal of Coordination Chemistry, 2018
Olena Yu. Poimanova, Serhii V. Radio, Anna O. Medvid, Olena A. Kretova, Katerina Ye. Bilousova, Vyacheslav N. Baumer, Grigorii M. Arzumanian, Nelya V. Doroshkevich, Victor T. Panyushkin
Studies of the surface morphology of salt sample by scanning (raster) electron microscopy and X-ray microanalysis were carried out using a complex analytical scanning electron microscope JSM 6490 LV (JEOL) and energy-dispersive X-ray spectrometer INCA PentaFETx3 (OXFORD Instruments). Imaging of samples deposited on a conductive graphite tape was carried out in two modes: backscattered electron imaging (BEI) mode for the elemental analysis of phases constituting the samples; and secondary electron imaging (SEI) mode for the study of surface of obtained salts. The cathode material was lanthanum hexaboride (LaB6). The accelerating voltage – 10–20 kV.