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Cathode ray tube glass waste was used to produce glass foams by a powder sintering route. The glass waste powder was mixed with small amounts (5 and 8 wt%) of coal fly ash, which acted as foaming agent, and the compacts of the mixed powders were heated at different sintering temperatures in the range 600–800 °C for various dwell times (30–120 min). The effect of the different processing conditions on the microstructural characteristics (porosity, pore size and pore size distribution), mechanical resistance and thermal conductivity of the produced foams was investigated. The volume of pores tended to increase with sintering temperature and time, and glass foams (with a porosity higher than 50 %) were only achieved after sintering at 750 °C. The average pore size increased with sintering temperature and dwell time, and pore growth was particularly accentuated at 800 °C, where coalescence of the pores occurred, with a consequent decrease in compressive strength. Selected combinations of the sintering temperature, dwell time and foaming agent led to glass foams with a satisfactory microstructural homogeneity, which exhibited mechanical strength and thermal conductivity values similar to commercial foams used as thermal insulating materials. © 2016, Springer Science+Business Media New York.

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Metal nanoparticles are of great interest for light trapping in photovoltaics. They are usually incorporated in the rear electrode of solar cells, providing strong light scattering at their surface plasmon resonances. In most cases, the nanoparticles are self-assembled by solid-state dewetting over a transparent conductive oxide (TCO) layer incorporated in the cell's rear electrode. Up to now, this process has been optimized mainly by tuning the thermal annealing parameters responsible for dewetting, or the thickness of the precursor metallic layer; but little attention has been paid to the influence of the underlying TCO layer properties on the morphology of the nanoparticles formed, which is the focus of the present article. This work investigates Ag nanoparticles structures produced on distinct surfaces by a simple, fast and highly reproducible method employing rapid thermal annealing. The results indicate that both the thermal conductivity and surface roughness of the TCO layer play a determinant role on the morphology of the nanostructures formed. This is of particular relevance, since we show in the study performed that the parasitic absorption of these Ag nanostructures is reduced, while the scattering is enhanced when the Ag nanostructures are formed on TCO layers with the highest conductivity and the lowest surface roughness (∼1 nm). These results unveil novel possibilities for the improvement of plasmonic nanostructures fabricated by thermal dewetting, via the careful adjustment of the physical properties of the underlying surface. © 2016 American Chemical Society.

Abstract Due to the introduction of distributed renewable energy technologies with variable resource availability, the need of flexible electrical systems is evident. In general, flexibility is achieved from the supply side and often using carbon intensive energy generators. Therefore, improving the flexibility of the electrical system by taking advantage of renewable energy generation capacities and demand response measures in buildings is of major importance for a sustainable development. Control systems to implement these demand response measures need to quantify the flexibility of the respective buildings. Having this into consideration, this paper aims at presenting a literature review on methodologies to quantify the energy flexibility of buildings.