Formation of nanoflowers: Au and Ni silicide cores surrounded by SiO x branches.

This work reports the formation of nanoflowers after annealing of Au/Ni bilayers deposited on SiO2/Si substrates. The cores of the nanoflowers consist of segregated Ni silicide and Au parts and are surrounded by SiO x branches. The SiO2 decomposition is activated at 1050 °C in a reducing atmosphere, and it can be enhanced more by Au compared to Ni. SiO gas from the decomposition of SiO2 and the active oxidation of Si is the source of Si for the growth of the SiO x branches of the nanoflowers. The concentration of SiO gas around the decomposition cavities is inhomogeneously distributed. Closer to the cavity border, the concentration of the Si sources is higher, and SiO x branches grow faster. Hence, nanoflowers present shorter and shorter branches as they are getting away from the border. However, such inhomogeneous SiO gas concentration is weakened in the sample with the highest Au concentration due to the strong ability of Au to enhance SiO2 decomposition, and nanoflowers with less difference in their branches can be observed across the whole sample.

Formation of nanocrystalline γ-ZrH in Zr-Nb alloy: Crystal structure and twinning.

In the present work, the lattice parameter and the twins of γ-ZrH hydride in Zr-2.5Nb-1Si were characterized using high resolution electron microscopy. The lattice parameters of γ-ZrH (P42/mmc, Zr2H2 unit cell) is determined to be a = 0.336 nm, c = 0.508 nm. Twinning γ-ZrH hydride ({011}<01̅1> type) is for the first time reported in zirconium alloys, whose orientation relationship with α-Zr is [100]γ-twins // [12̅10]α and (011)γ-twins // (0002)α. The formation process of γ-ZrH twins is also discussed based on a 'grow-in' mechanism during the transformation from α-Zr to γ-ZrH hydride.

Dual-pump Kerr Micro-cavity Optical Frequency Comb with varying FSR spacing.

In this paper, we demonstrate a novel dual-pump approach to generate robust optical frequency comb with varying free spectral range (FSR) spacing in a CMOS-compatible high-Q micro-ring resonator (MRR). The frequency spacing of the comb can be tuned by an integer number FSR of the MRR freely in our dual-pump scheme. The dual pumps are self-oscillated in the laser cavity loop and their wavelengths can be tuned flexibly by programming the tunable filter embedded in the cavity. By tuning the pump wavelength, broadband OFC with the bandwidth of >180 nm and the frequency-spacing varying from 6 to 46-fold FSRs is realized at a low pump power. This approach could find potential and practical applications in many areas, such as optical metrology, optical communication, and signal processing systems, for its excellent flexibility and robustness.