Play and folklore

This issue of Play and Folklore has a special focus on children’s outdoor play. We hear many stories about the constraints placed on children’s play by adults – the growing number of ‘bannings’ include handstands, cartwheels, throwing things, playing with sticks, digging holes and rough-and-tumble play. Even simply touching each other is forbidden in some schools. In this issue we bring a more positive perspective on play by highlighting some of the ways in which children are being encouraged and assisted to explore, experiment, be adventurous and make their own fun

Lewis Acid Activated Olefin Metathesis Catalysts

Since its discovery, catalytic olefin metathesis has been used as a powerful tool for the synthesis of a variety of molecules. Over the last 20 years research in this area has received enormous attention in the development of new catalysts and applications. The vast majority of the ruthenium based catalysts developed have been modifications to the Grubbs Catalyst type architecture. The research presented herein focuses on the development of new olefin metathesis catalysts bearing tridentate, dianionic ligands and their activation with Lewis acids. Complexes [(PPhPh.D

The \u27Cat and Mouse\u27

Reports of the death of children’s games in school playgrounds are greatly exaggerated, finds Judy McKinty

Characterisation of beta-FeSi2 fabricated by ion beam assisted deposition.

beta-FeSi2 has been shown to have a minimum direct band gap of 0.87 eV, which leads to the opportunity of Si based opto-electronics. One of the many applications that beta-FeSi2 has been linked with is solar cells. Its proposed suitability for solar cell applications originates from a large absorption coefficient above the fundamental edge (105 cm-1), predicted solar cell efficiencies as high as 23% and photoelectric properties with a quantum efficiency of 32%. Ion beam assisted deposition represent a technique that is suitable for producing low cost material over large areas, thus making it suitable for solar cell fabrication. The work reported here represents an in-depth optical characterisation of the effects of fabrication and post-fabrication processing on ion beam assisted deposited FeSi layers on Si substrates. Two different sets of substrates have been investigated; the first were deposited with layers of Fe and Si in the ratios between (40%:60%) and (29%:71%), and the second were deposited in stoichiometric ratios (1:2). A range of post-fabrication processes have been investigated, these have included studying the effects of annealing time (10 minutes to 18 hours) and temperature (100°C to 900°C) on the band gap and defects underneath the fundamental absorption edge. A study of the effect of annealing regime on the measurement temperature dependency of the band gap was also completed. The results have shown that annealing temperature has a stronger effect on the band gap rather than annealing time, while both affect the absorption underneath the fundamental edge. Optical evidence for the formation of beta-FeSi2 was found for annealing temperatures as low as 425°C. Increasing the annealing temperature/time also results in structural changes in the material, which are dependent on the as-deposited composition of the FeSi layer. beta-FeSi2/Si(n-type) solar cell devices have been fabricating, showing rectifying I-V characteristics, and a photo-voltage spectral response that indicated two distinct regions; 0.72 eV to 1.1 eV and 1.1 eV and above

Characterisation of beta-FeSi2 fabricated by ion beam assisted deposition.

beta-FeSi2 has been shown to have a minimum direct band gap of 0.87 eV, which leads to the opportunity of Si based opto-electronics. One of the many applications that beta-FeSi2 has been linked with is solar cells. Its proposed suitability for solar cell applications originates from a large absorption coefficient above the fundamental edge (105 cm-1), predicted solar cell efficiencies as high as 23% and photoelectric properties with a quantum efficiency of 32%. Ion beam assisted deposition represent a technique that is suitable for producing low cost material over large areas, thus making it suitable for solar cell fabrication. The work reported here represents an in-depth optical characterisation of the effects of fabrication and post-fabrication processing on ion beam assisted deposited FeSi layers on Si substrates. Two different sets of substrates have been investigated; the first were deposited with layers of Fe and Si in the ratios between (40%:60%) and (29%:71%), and the second were deposited in stoichiometric ratios (1:2). A range of post-fabrication processes have been investigated, these have included studying the effects of annealing time (10 minutes to 18 hours) and temperature (100°C to 900°C) on the band gap and defects underneath the fundamental absorption edge. A study of the effect of annealing regime on the measurement temperature dependency of the band gap was also completed. The results have shown that annealing temperature has a stronger effect on the band gap rather than annealing time, while both affect the absorption underneath the fundamental edge. Optical evidence for the formation of beta-FeSi2 was found for annealing temperatures as low as 425°C. Increasing the annealing temperature/time also results in structural changes in the material, which are dependent on the as-deposited composition of the FeSi layer. beta-FeSi2/Si(n-type) solar cell devices have been fabricating, showing rectifying I-V characteristics, and a photo-voltage spectral response that indicated two distinct regions; 0.72 eV to 1.1 eV and 1.1 eV and above

Characterisation of #beta#-FeSi_2 fabricated by ion beam assisted deposition

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