FE-SEM observation of chains of nanohillocks in SrTiO3 and Nb-doped SrTiO3 surfaces irradiated with swift heavy ions

高速重イオン (SHI) がセラミックスに真上から入射すると、SHI 一つに対してヒロック (ナノメートルサイズの隆起物) が一つ表面に形成される。一方で近年、SHI がチタン酸ストロンチウム (SrTiO3) や酸化チタン (TiO2)の表面をかするように入射した場合、表面にはイオンの飛跡に沿って連続的に複数個のヒロックが形成されると報告がある。これらは原子間力顕微鏡 (AFM) を用いて観察されており、観察結果には AFM のプローブ寸法由来の測定誤差を含んでいる。本研究では、ヒロックのサイズより十分小さい分解能 (1.5 nm) を有し、非接触で観察可能な電界放出形走査電子顕微鏡 (FE-SEM) を用いて連続ヒロックを観察する手法を検討した。本発表では連続ヒロックのFE-SEM観察結果とともに、新しい連続ヒロックの形状変化メカニズムを提案する

Ion species discrimination method by linear energy transfer measurement in Fujifilm BAS-SR Imaging Plate

We have developed a novel discrimination methodology to identify ions in multispecies beams with similar charge to mass ratios but different atomic numbers. After an initial separation by charge-to-mass ratio using co-linear electric and magnetic fields, individual ions can be discriminated by considering the Linear Energy Transfer and non-linear detector response of ions irradiating stimulable phosphor plate (Fujifilm imaging plate), by comparison with Monte-Carlo calculation. We apply the method to energetic multispecies laser-driven ion beams and use it to identify silver ions produced by the interaction between a high contrast, high intensity laser pulse and a sub-m silver foil target. We also show that this method can be used to calibrate imaging plate for arbitrary ion species without requiring individual calibration

Gallium-effect in a lead-free solder for silver-sheathed superconducting tape

Solder joints of silver-sheathed superconducting tapes are promising for various commercial applications. In this research, Pb, Ga, and Ga-doped lead-free Sn–Ag–Cu solders are used to study the gallium effect for the low joint resistivity with silver-sheathed DI-BISCCO type H tapes. In Ga-doped Sn–Ag–Cu solder, a smooth interfacial Ag _2 Ga layer is uniformly formed on the Ag-sheath surface. As a result, the solder joint achieved a very low joint resistivity of 16 nΩcm ^2 at 40 K. The present gallium-doped lead-free solder can also be applied to general soldering use with Ag materials