Calorimetric measurements of the glass transition are presented for metallic glasses, B203, and organic polymers with cooling and heating rates ranging over more than three orders of magnitude. Fits of the onset temperatures of the glass transition to a Vogel-Fulcher-type equation give divergence temperatures significantly above the values obtained for Vogel-Fulcher fits to the viscosity. The width of the glass transition extrapolates to a sharp step transition at a finite heating and cooling rate, which is close to the range where the data were taken. The results suggest that the glass transition becomes independent of the experimental time scale in a regime that may be accessible to measurements.

Macroporous hexagonal WO 3 (h-WO 3 ) films were obtained at 400 °C from a sol containing tungstic acid with organically modified silane as a template. Asymmetric electrochromic devices based on the macroporous h-WO 3 layer were constructed. XRD and micro-Raman studies of the intercalation/ deintercalation of lithium into the h-WO 3 layer of the device as a function of the applied voltages were performed. In h-WO 3 , Li + can be intercalated into three potential sites: trigonal cavity (TC), hexagonal window (HW), and four-coordinated square window (SW). XRD measurements show systematic changes in the lattice parameter, which was associated with the amount of Li intercalated into the h-WO 3 layer. Correspondingly, Raman spectroscopy shows that at 1.0 V Li + completely fill TC and partially fill HW sites. For potentials g1.5 V, Li + are inserted into the SW, as evidenced from the vanishing of the ν(O-W-O) Raman modes. The reversible characteristics of the device from optical measurements and Raman spectra demonstrated that the coloration process in the electrochromic device is mainly due to the Li + that occupy HW and SW sites of the h-WO 3 . Optical measurements performed as a function of applied potentials, show excellent contrasts between colored and bleached states and qualifies the macroporous h-WO 3 -based device for smart window applications.

We have carried out intensity fluctuation spectroscopy measurements using coherent x rays to study the dynamics of critical fluctuations in a binary alloy at equilibrium.An intense coherent hard x-ray beam, produced from an undulator source, was scattered from a single crystal of Fe3Al held at l l l temperatures near the B2 DO& order--disorder transition. A speckle pattern was observed at the (; -, -, ) superlattice reAection. Below T, it was essentially static, while above T, it Auctuated in time. The behavior of the normalized time correlation function is consistent with predictions of theory.

We investigate the calorimetric liquid-glass transition by performing simulations of a binary Lennard-Jones mixture in one through four dimensions. Starting at a high temperature, the systems are cooled to T = 0 and heated back to the ergodic liquid state at constant rates. Glass transitions are observed in two, three and four dimensions as a hysteresis between the cooling and heating curves. This hysteresis appears in the energy and pressure diagrams, and the scanning rate dependence of the area and height of the hysteresis can be described using power laws. The one-dimensional system does not experience a glass transition but its specific heat curve resembles the shape of the D≥2 results in the supercooled liquid regime above the glass transition. As D increases, the radial distribution functions reflect reduced geometric constraints. Nearest neighbor distances become smaller with increasing D due to interactions between nearest and next-nearest neighbors. Simulation data for the glasses are compared with crystal and melting data obtained with a Lennard-Jones system with only one type of particle and we find that with increasing D crystallization becomes increasingly more difficult.

Porous orthorhombic tungsten oxide (o-WO 3 ) thin films, stabilized by nanocrystalline anatase TiO 2 , are obtained by a sol-gel based two stage dip coating method and subsequent annealing at 600 C. An Organically Modified Silicate (ORMOSIL) based templating strategy is adopted to achieve porosity. An asymmetric electrochromic device is constructed based on this porous o-WO 3 layer. The intercalation/deintercalation of lithium ions into/from the o-WO 3 layer of the device as a function of applied coloration/bleaching voltages have been studied. XRD measurements show systematic changes in the lattice parameters associated with structural phase transitions from o-WO 3 to tetragonal Li x WO 3 (t-Li x WO 3 ) and a tendency to form cubic Li x WO 3 (c-Li x WO 3 ). These phase transitions, induced by the Li ions, are reversible, and the specific phase obtained depends on the quantity of intercalated/ deintercalated Li. Raman spectroscopy data show the formation of t-Li x WO 3 for an applied potential of 1.0 V and the tendency of the system to transform to c-Li x WO 3 for higher coloration potentials. Optical measurements show excellent contrasts between colored and bleached states. An alternate photochromic device was constructed by sensitizing the o-WO 3 layer with a ruthenium based dye. The nanocrystalline anatase TiO 2 in the o-WO 3 layer has led to an enhanced photochromic optical transmittance contrast of $51% in the near IR region. The combination of the photochromic and electrochromic properties of the synthesised o-WO 3 layer stabilized by nanocrystalline anatase TiO 2 opens up new vista for its application in energysaving smart windows.

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Recent developments in the synthesis of transition metal oxides in the form of porous thin films have opened up opportunities in the construction of electrochromic devices with enhanced properties. In this paper, synthesis, characterization and electrochromic applications of porous WO3thin films with different nanocrystalline phases, such as hexagonal, monoclinic, and orthorhombic, are presented. Asymmetric electrochromic devices have been constructed based on these porous WO3thin films. XRD measurements of the intercalation/deintercalation of Li+into/from the WO3layer of the device as a function of applied coloration/bleaching voltages show systematic changes in the lattice parameters associated with structural phase transitions in LixWO3. Micro-Raman studies show systematic crystalline phase changes in the spectra of WO3layers during Li+ion intercalation and deintercalation, which agree with the XRD data. These devices exhibit interesting optical modulation (up to ~70%) due to intercalation/deintercalation of Li ions into/from the WO3layer of the devices as a function of applied coloration/bleaching voltages. The obtained optical modulation of the electrochromic devices indicates that, they are suitable for applications in electrochromic smart windows.

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