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Gallium (Ga) helps solubilize rare-earth ions in chalcogenide glasses, but has been found to form the dominant crystallizing selenide phase in bulk glass in our previous work. Here, the crystallization behavior is compared of as-annealed 0-3000 ppmw Dy 3+ -doped Ge-As-Ga-Se glasses with different Ga levels: Ge 16.5 As (19 -x) Ga x Se 64.5 (at.%), for x = 3 and 10, named Ga 3 and Ga 10 glass series, respectively. X-ray diffraction and high-resolution transmission electron microscopy are employed to examine crystals in the bulk of the as-prepared glasses, and the crystalline phase is proved to be the same: Ge-modified, face centered cubic a-Ga 2 Se 3 . Light scattering of polished glass samples is monitored using Fourier transform spectroscopy. When Ga is decreased from 10 to 3 at.%, the bulk crystallization is dramatically reduced and the optical scattering loss decreases. Surface defects, with a rough topology observed for both series of as-prepared chalcogenide glasses, are demonstrated to comprise Dy, Si, and [O]. For the first time, evidence for the proposed nucleation agent Dy 2 O 3 is found inside the bulk of as-prepared glass. This is an important result because rare-earth ions bound in a high phonon-energy oxide local environment are, as a consequence, inactive mid-infrared fluorophores because they undergo preferential nonradiative decay of excited states.

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Hydrophobic metallic coatings have attracted increasing interest in the recent years due to their excellent mechanical durability. But the wetting behavior and hydrophobic mechanism of metallic coatings are far from clear. In this work, Ni-Cu-P ternary coatings with hierarchical structure were prepared on 304 stainless steel by electrodeposition method. The surface morphologies, phase compositions, and wetting behavior were studied systemically. Timedependent wetting behaviour of Ni-Cu-P coatings had been clearly observed, and the surface of the as-deposited coatings changed from hydrophilic state to hydrophobic state after aging in ambient air. The related surface wetting mechanism was investigated with the assistance of plasma cleaning to study the possible surface adsorption contributing to the time-dependent wetting behavior. The variations of the surface species were analyzed using X-ray photoelectron spectroscopy (XPS), showing the composition change of both carbon and the oxygen. The atomic ratio of hydrocarbon on the Ni-Cu-P coating first increased from 78.7 % to 86.5 % when stored in ambient air and then decreased from 82.3 % to 65.9 % after the plasma cleaning treatment; while the variation of oxygen content was an opposite trend. The results indicated that the observed time-dependent wettability was a combined result of the adsorption of airborne hydrocarbon and the change of lattice oxygen on the coating surface.