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Electronic structures near the Fermi level of polymer/1T-LixTaS2 layered nanocomposites have been studied by tunnelling spectroscopy. Polymer/1T-LixTaS2 layered nanocomposites were synthesized by using the exfoliation–adsorption technique. Single crystals of 1T-TaS2 were used as host materials. Poly(ethylene oxide) (PEO) and poly(ethylenimine) (PEI) with different molecular weights were adopted as guest intercalants. Powder x-ray diffraction patterns showed that all samples of the polymer/1T-LixTaS2 layered nanocomposites contain organic polymer between all individual 1T-TaS2 sheets. Although 1T-TaS2 single crystal is well known to show quite unique temperature dependences of the resistivity due to the charge density wave (CDW), the resistivities of all polymer/1T-LixTaS2 nanocomposites showed semiconductor-like temperature dependences. The tunnelling spectra of polymer/1T-LixTaS2 nanocomposites revealed that the CDW gap disappears in the density of states near the Fermi level of polymer/1T-LixTaS2 nanocomposites and their electronic structures show a metallic behaviour.

High-performance optical devices with a figure accuracy of sub-micrometer level and a surface roughness of atomic level are required to collect and/or to focus a neutron on a sample without scattering loss. To fabricate a high-performance neutron focusing supermirror, a two-stage numerically controlled local wet etching technique combined ion beam sputter deposition was developed. By applying this technique, a plano-elliptical substrate made of synthesized quartz glass with a figure accuracy of less than 0.5 μm was fabricated, and its surface was deposited with NiC/Ti multilayers by ion beam sputtering to produce an m=4 supermirror. The focusing performance of the supermirror was evaluated at the SUIREN of JRR-3M, and a focusing gain of 6 in peak intensity was achieved compared with a nonfocused direct beam.

We have developed a 1-dimensional elliptic mirror combining a supermirror coated with ion-beam sputtering and precise elliptic surface figured with the numerically-controlled local wet etching process. In this study, NiC/Ti supermirror (m = 4) was deposited on a precisely figured surface of synthesized quartz glass over 90 mm × 40 mm. Wideband neutrons of λ > 3.64A were focused with focal spot size down to 0.25 mm, peak intensity gain up to 6 without significant diffuse scattering. Time-of-flight measurements suggest that wideband neutrons are effectively focused to the focal point.

We have measured the Cu 2p and O 1s X-ray photoemission spectra of the high-T c superconductors Nd2-x Ce x CuO4-y and La2-x Sr x CuO4, and the copper oxides CuO and Cu2O. The Cu 2p spectra of superconductors show features similar to those of CuO with divalent Cu ions. For Nd2-x Ce x CuO4-y , the intensity ratio of the satellite to the main peaks decreases with increasing Ce content. The O 1s spectra exhibit a single-peaked structure and are insensitive to whether either electron or hole is doped.

Superconducting polycrystalline BaPb1-x Bi x O3 thin film is attempted in the switching of microwave energy of 2.8 GHz. The film is installed in a TE111 mode cylindrical cavity made of copper and immersed in liquid helium. Transition from super- to normal-conducting states is made by a pulse current through the film of the order of 108 A/m2. The microwave energy stored in the cavity is extracted in the short time of 60 ns. The observed output powers are compared with numerical analysis and the possibility of improving the switching characteristics is discussed.