Katsumi Handa

Development of a multilayer Fresnel zone plate for high-energy synchrotron radiation X-rays by DC sputtering deposition

Hard X-ray microscopy with high spatial resolution (<or=0.1 microm) using a high-energy and high-brilliance X-ray microprobe is expected to be a promising technology for various types of analysis, imaging etc. in materials science, biology and medicine. A multilayer Fresnel zone plate (FZP) could be a promising approach to focusing optics in the high-energy X-ray region (>or=20 keV) because a large thickness (aspect ratio) can be available. Various types of multilayer FZPs have been fabricated by DC sputtering deposition. Their focusing characteristics have been evaluated at the high-brilliance undulator beamline BL47XU of SPring-8. An optical system using a Cu/Al multilayer FZP (with an outermost zone width of 0.25 microm) as the focusing optics fabricated by the optimum deposition condition with precise film (zone) thickness control has attained an almost diffraction-limited microbeam of 0.3-0.35 microm at 8.9 keV. A line-and-space resolution test pattern has been observed: fine structures up to 0.2 microm were clearly observed in the measured image. This FZP has been working since 1995, keeping good focusing characteristics. It can be said from these results that a spatial resolution better than 0.1 microm in the high-energy X-ray region is in prospect by the development of a multilayer FZP with a narrower outermost zone width in the near future.

Application of Lithium Metal Electrodes to All-Solid-State Lithium Secondary Batteries Using Li3 PO 4 ­ Li2 S ­ SiS2 Glass

The Li 3 PO 4 -Li 2 S-SiS 2 glass electrolyte exhibited instability against a Li metal electrode in the charge-discharge cycle using a LiCoO 2 positive electrode. The interface products between the Li electrode and the glass electrolyte were investigated by Si and S-K edge near-edge X-ray absorption fine structure analyses. It was suggested that Li 2 S and Si coordinated to three sulfur atoms formed after charge-discharge cycles. This side reaction could be suppressed by modifying the surface of Li metal by N 2 gas, leading to improvement of the charge-discharge property compared to unmodified Li electrode. The operating voltage attained to about 4 V in the modified Li/Li 3 PO 4 -Li 2 S-SiS 2 glass electrolyte/LiCoO 2 cell, which was comparable to Li-ion battery using a liquid electrolyte.

Fabrication of a hard x-ray sputtered-sliced Fresnel phase zone plate

A Fresnel phase zone plate for hard x ray was fabricated by physical vapor deposition alternating transparent and opaque layers onto a fine gold wire core 47 μm in diameter. The zone plate, which is comprised of 25 pairs of alternating Ag and C layers, is designed to operate with a focal length of 124 mm for a parallel beam at 8.1 keV. The thickness of the zone plate is less than 10 μm and is capable of operating as a phase zone plate. Using the brilliant monochromatized x-ray beam from the TRISTAN Main Ring, with an undulator, the minimum focal spot size attained for the first order focal beam was 0.5 μmφ. The light collecting efficiency was determined to be near 11%.

Short-range structure of alkaline-earth borate glasses by pulsed neutron diffraction and molecular dynamics simulation

Abstract The structure of vitreous MO· n B 2 O 3 (M=Ca and Ba; n =2, 3 and 4) has been studied by pulsed neutron diffraction measurement with the help of molecular dynamics (MD) simulation. The first and second peaks assigned to the nearest-neighbor B–O and O–O correlations, respectively, in the obtained total pair distribution functions shifted little with increasing MO content, while the asymmetry of the first peak increased significantly with MO content; these results are different from those for potassium borate glasses. It was inferred that the BO 3 and BO 4 units are better defined in these alkaline-earth borate glasses than those in the potassium borate glasses. Both the full-width at half maximum (FWHM) of the first peak and the average co-ordination number of O around B clearly increased as MO content increased which is the same behavior with alkali borate glasses. The fraction of four-co-ordinated B showed a larger deviation from x /(1− x ) for CaO–B 2 O 3 glasses than that for BaO–B 2 O 3 glasses which shows a different dependence of the deviation on cation size from that in alkali borate glasses, and is in good agreement with the results from MD simulation.

Hard X-ray Microbeam Experiment at the Tristan Main Ring Test Beamline of the KEK

A hard X-ray microbeam with zone-plate optics has been tested at the MR-BW-TL beamline on the Tristan main ring of the KEK, and preliminary experiments on scanning microscopy have also been performed. A sputtered-sliced Fresnel zone plate with an Au core and Ag/C multilayer is used as an X-ray focusing device. The outermost zone width of the zone plate is 0.25 microm. A focused spot size of approximately 0.5 mum has been achieved at an X-ray energy of 8.54 keV. In a scanning X-ray microscopy experiment, test patterns with submicrometer fine structure have been clearly resolved.

X-ray microbeam with sputtered-sliced Fresnel zone plate at SPring-8 undulator beamline

Abstract A hard X-ray microbeam created from a sputtered-sliced Fresnel zone plate has been tested at SPring-8 undulator beamline. Focusing properties are evaluated in the X-ray wavelength regions of 0.15– 1.5 A . The measured focal beam size is about 0.6 μm at an X-ray wavelength of 1.4 A . In a scanning microscopy experiment, resolution-test-patterns with 0.2 μm structure are resolved at an X-ray wavelength of 0.45 A .

X-ray diffraction study on the short-range structure of K2O–TeO2 glasses and melts

Abstract The short-range structure of K 2 O–9TeO 2 and K 2 O–4TeO 2 in amorphous states such as glass and melt has been investigated by X-ray diffraction (XRD) and semi-empirical molecular orbital calculation (AM1-MOPAC method). The structure of amorphous alkali tellurites consisted of the TeO 4 trigonal bipyramids (tbp) and the TeO 3 trigonal pyramids (tp). Confirmed in the present work is that the TeO 4 trigonal bipyramids characteristics of TeO 2 -based glasses transform into TeO 3 trigonal pyramids with increasing modifier K 2 O content and a rise of temperature. The usage of XRD and MOPAC enabled us to comprehend in some details what to happen in phase transition from glasses to melts.

Glass Formation in the MoO3-La2O3-Nd2O3 System

Novel low melting glasses in the MoO3-La2O3-Nd2O3 system were obtained at different cooling rates (102 K/s and 104-105 K/s). Characterization of the amorphous samples was made by differential thermal analysis (DTA) and X-ray absorption fine structure (XAFS) method. According to DTA data of the glass samples, the glass transition temperatures are at 325-330 0C, the crystallization started above 410 0C and the melting temperatures are at 660-720 0C. A structural model of glasses was suggested on the basis of XAFS and IR investigations. It was shown that the predominant structural units in the amorphous network of glasses containing 90 -80 mol% MoO3 are MoO6 groups. The appearance of MoO4 groups deteriorates the glass formation ability.

Suppression of Corrugated Boundaries in Multilayer Fresnel Zone Plate for Hard X-Ray Synchrotron Radiation Using Cylindrical Slit

Corrugated zone roughness of a circular Cu/Al multilayer Fresnel zone plate (FZP) was successfully suppressed. Such a zone corrugation was often observed in the concentric multilayers prepared using a conventional sputtering apparatus. The zone corrugation is a consequence of the oblique component of the deposition flux (i.e. shadowing effect). We therefore set a cylindrical slit (a linear slit on the surface of a stainless steel cylindrical shield) between the target and the substrate in order to eliminate the oblique flux. As a result, the zone corrugation was not observed using a scanning ion microscope (SIM).

Structure of K2O–TeO2 Glasses

The structure at room temperature and structural change from room temperature to the temperature above melting point (Tm) of K2O-TeO2 glasses were studied by the use of XAFS spectroscopy, high-temperature Raman spectroscopy, high-temperature XRD and X-ray RDF (Radial Distribution Function). XAFS spectroscopy has indicated that K2O-TeO2 glasses consist of both TeO4 trigonal bipyramid (tbp) units and TeO3 trigonal pyramid (tp) units , and high-temperature Raman results have indicated that TeO4tbp units convert to TeO3tp units with the increase of temperature and by the addition of K2O in the K2O-TeO2 glasses. The high-temperature XRD and X-ray RDF results were in good agreement with the results of the high-temperature Raman spectroscopy. Furthermore, the XAFS spectroscopy has shown that potassium ions have a similar local structure in all K2O-TeO2 glasses studied.