Sintering behavior of combusted iron powder in a packed bed reactor with nitrogen and hydrogen

Sintering behavior of micron-sized combusted iron powder is studied in a packed bed reactor,at various temperatures under inert(nitrogen)and reducing(hydrogen)conditions.Compression tests are subsequently used to quantify the degree of sintering.A sintering model,based on the formation of a solid bridge through solid state surface diffusion of iron atoms,matches the experimental results.Sintering of combusted iron occurs at temperatures≥575°C in both nitrogen and hydrogen atmospheres and increases exponentially with temperature.The observed decrease in reduction rate at high temperatures is not caused by the sintering process but by the formation of wüstite as an intermediate species,leading to the formation of a dense iron layer.Iron whiskers form at high temperatures(≥700°C)in combination with low reduction rates(≤25 vol%H2),leading to the production of sub-micron fines.

MoO_(x) and V_(2)O_(x) as hole and electron transport layers through functionalized intercalation in normal and inverted organic optoelectronic devices

To achieve fabrication and cost competitiveness in organic optoelectronic devices that include organic solar cells(OSCs)and organic light-emitting diodes(OLEDs),it is desirable to have one type of material that can simultaneously function as both the electron and hole transport layers(ETLs and HTLs)of the organic devices in all device architectures(i.e.,normal and inverted architectures).We address this issue by proposing and demonstrating Cs-intercalated metal oxides(with various Cs mole ratios)as both the ETL and HTL of an organic optoelectronic device with normal and inverted device architectures.Our results demonstrate that the new approach works well for widely used transition metal oxides of molybdenum oxide(MoOx)and vanadium oxide(V_(2)O_(x)).Moreover,the Cs-intercalated metaloxide-based ETL and HTL can be easily formed under the conditions of a room temperature,water-free and solution-based process.These conditions favor practical applications of OSCs and OLEDs.Notably,with the analyses of the Kelvin Probe System,our approach of Cs-intercalated metal oxides with a wide mole ratio range of transition metals(Mo or V)/Cs from 1:0 to 1:0.75 can offer significant and continuous work function tuning as large as 1.31 eV for functioning as both an ETL and HTL.Consequently,our method of intercalated metal oxides can contribute to the emerging large-scale and low-cost organic optoelectronic devices.