Pure amorphous solids are traditionally considered to set the lower bound of thermal conductivity due to their disordered atomic structure that impedes vibrational energy transport. However, the lower limits for thermal conductivity in heterogeneous amorphous solids and the physical mechanisms underlying these limits remain unclear. Here, we use equilibrium molecular dynamics to show that an am...

On compressing low-density amorphous ice (LDA) at 125 K up to 1.6 GPa two distinct density steps accompanied by heat evolution are observable in pressure-density curves. Samples recovered to 77 K and 1 bar after the first and second step show the X-ray diffraction pattern of high-density amorphous ice (HDA) and veryHDA (VHDA), respectively. The compression of the once formed HDA takes place lin...

BACKGROUND The in-depth understanding of the enzymatic hydrolysis of cellulose with heterogeneous morphology (that is, crystalline versus amorphous) may help develop better cellulase cocktail mixtures and biomass pretreatment, wherein cost-effective release of soluble sugars from solid cellulosic materials remains the largest obstacle to the economic viability of second generation biorefineries...

The experimental conditions were optimized for the synthesis of amorphous SiO2 particles by the reaction of neutralization of sodium silicate solution with H2SO4 solution. Amorphous SiO2 particles were characterized by XRD, FT-IR, FE-SEM, EDS and microelectrophoresis. The amorphous peak was located at 2θ = 21.8 in the XRD pattern. Primary SiO2 particles were ~ 15 to ~ 30 nm in size and they agg...

Ice sheets play a more important role in the global silicon cycle than previously appreciated. Input of dissolved and amorphous particulate silica into natural waters stimulates the growth of diatoms. Here we measure dissolved and amorphous silica in Greenland Ice Sheet meltwaters and icebergs, demonstrating the potential for high ice sheet export. Our dissolved and amorphous silica flux is 0.2...

Using a masked hydrogen plasma treatment to spatially control the crystallization of amorphous silicon to polycrystalline silicon in desired areas, amorphous and polycrystalline silicon thin-film transistors (TFTs) with good performance have been integrated in a single film of silicon without laser processing. Both transistors are top gate and shared all process steps. The polycrystalline silic...

Selective exposure of a hydrogenated amorphous silicon ~a-Si:H! film to a room-temperature hydrogen plasma using a patterned masking layer and a subsequent anneal at 600 °C, results in patterned polycrystalline and amorphous silicon regions. However, most of the hydrogen in the amorphous silicon is lost, leading to severe degradation in its properties. In this letter, we report the rehydrogenat...

X-ray powder diffraction (XRD) in combination with the Rietveld method was used to evaluate the proportion of crystalline and amorphous (glassy) phases in fly ashes produced in pulverized-coalcombustion (PCC) power plants. The quantification of amorphous phases through the Rietveld method is most usually carried out i) by using an internal standard or ii) by using a poorly-crystalline phase to ...