An atom probe field ion microscopy survey of several bulk metallic glasses including the zirconium-based glasses Z r 1 i 3 4 6 2 s s , 7 5 7 , 5 1 0 2 7 . 5 4 . ~ . ~ . ~ ~ ~ . Z ~ , ~ N ~ , A ~ ~ O C U ~ , ~ N ~ I Z , ~ , and Zr ,,,, T ~ , A ~ , , C U ~ ~ , , N ~ , ~ , ~ , together with two non-zirconium-based glasses Ti3,Zr,,Cu4,NiS, and Mg,,Cu,,Y,,, is presented. Non random distribution of s...

The varying degrees of configurational disorder in metallic glasses are investigated quantitatively by molecular dynamics studies. A parameter, the quasi-nearest atom, is used to characterize the configurational disorder in metallic glasses. Our observations suggest configurational disorder play a role in structural heterogeneity, plasticity and dynamic relaxations in metallic glasses. The broa...

We have studied the third order optical nonlinearities of Ge-As-Se-based glasses. The glasses have high melting and glass transition temperatures that offer the potential for integration with traditional compound oxide glasses into highly nonlinear, high-index-contrast fibers. We used z-scan and femtosecond pump-probe techniques to measure the nonlinear refractive index and two-photon absorptio...

Glasses have liquid-like structure, but exhibit solid-like properties. A central question concerns the relation between the structure and mechanical properties of glasses, but structural changes remain difficult to resolve. We use a novel combination of rheology and x-ray scattering to resolve structural changes in colloidal glasses and link them directly to their mechanical behavior. By combin...

Reaction order in Bi-doped oxide glasses depends on the optical basicity of the glass host. Red and NIR photoluminescence (PL) bands result from Bi(2+) and Bin clusters, respectively. Very similar centers are present in Bi- and Pb-doped oxide and chalcogenide glasses. Bi-implanted and Bi melt-doped chalcogenide glasses display new PL bands, indicating that new Bi centers are formed. Bi-related ...

A long-sought goal in metallic glasses is to impart ductility without conceding their strength and elastic limit. The rational design of tough metallic glasses, however, remains challenging because of the inability of existing theories to capture the correlation between plasticity, composition and processing for a wide range of glass-forming alloys. Here we propose a phenomenological criterion ...

We describe and demonstrate a pair of diopter-adjustable eyeglasses aimed to correct presbyopia; the glasses provide a tunable optical power in the whole surface of the lens cell, eliminating the optical distortion typical of bifocal/trifocal or progressive glasses. The wearer can actively control the optical power by a simple sliding gesture on the bridge of the glasses, so that presbyopic vis...

A paramount challenge in materials science is to design damage-tolerant glasses. Poisson's ratio is commonly used as a criterion to gauge the brittle-ductile transition in glasses. However, our data, as well as results in the literature, are in conflict with the concept of Poisson's ratio serving as a universal parameter for fracture energy. Here, we identify the electronic structure fingerprin...

The water content in seven glass samples from the K/T boundary on Haiti was determined by micro-infrared spectrometry. These glasses are thought to result from impact melting associated with the K/T boundary impact, although this interpretation is not unanimous. The results of the water determinations, 0.013-0.021 wt% H20, show that the Haiti glasses are water-poor. This is a common characteris...

The atomic structure of the Au 6×6 on Si(111) phase has been determined using direct methods and surface X-ray diffraction data. This surface structure is very complicated, with 14 independent gold atoms, relaxations in 24 independent silicon sites and three partially occupied gold sites. In one sense the structure can be described as microdomains of the parent E3×E3 Au on Si(111) structure. A ...