Physical and optical properties of sol-gel nano-silver doped silica film on glass substrate as a function of heat-treatment temperature

Nano-silver doped silica films were deposited on glass slides using a sol-gel process and heat-treated at different temperatures. The films were characterized by ultraviolet-visible spectroscopy, x-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), Rutherford backscattering spectrometry (RBS), and transmission electron microscopy for their optical, chemical, and structural properties. The absorption peak of silver colloids (wavelength from 400 to 460 nm) was present and a blueshift and intensity reduction of the absorption peak was observed during heat-treatment. Particle size reduction and surface morphology changes in the films were observed by AFM as a function of varying heat treatment temperatures. Silver nanoparticles were formed through spontaneous reduction of silver ions. The oxidation of silver occurs during heat-treatment, causing a reduction of absorption intensity. An interdiffusion between the Ag in the film and Na in the substrate glass was observed by XPS and RBS. Sodium in the coating likely increased the stability of silver oxide at high temperature treated samples

Technical solutions for adaptation of housing for elderly persons with physical disabilities and cognitive impairment

International audienceLimousin is characterized as the oldest region of France with a mean age of 43 years in 2005, five years more than the national average. The part of the population of more than 75 years old is more important in Limousin (about 11 %) than at the national level (7.2 %). At now, there are in France 850 000 dependent persons of more than 60 years and they will be more than a million in 15 years. There are approximately 400 000 places in nursing homes, and eight French out of ten wish to live at home as long as possible. Preservation at home clearly appears as a real challenge of public health. The adaptation of housing constitutes an actual opportunity for the help to the preservation at home. The aging is accompanied by the appearance of gradual physical and psychological fragilities. The objective of our study has been to identify the physical and mental specificities of the elderly to take into account for an adequate adaptation of the housing environment. Declining abilities with age may be severe handicaps. The main options available to recover the person's living initial conditions focus on the development of suitable prostheses and several adaptations of home or furniture equipments. For the elderly people, the functional abilities reduction concerns mainly the sensory capabilities, the capacity of thermoregulation, the motor capabilities with a high risk of falling, the capacity of arousal and alertness. In our study, all these capabilities are taken into account in detail to derive specific and useful parameters to be applied for home environment adaptation. We give basic technical solutions for each of the potential disability. All these solutions are based upon ergonomics principles applied of the house furniture, of the floor and of the rooms disposal within the house. Thanks to home automation equipments, technical aspects can be added and applied to security, light and thermal comfort management that can help to preserve elders at home. The study is made in association with Habilim, a Real estate developer who acts for the comfort and the quality of life of residential buildings in particular for elderly and disabled people. The study is driven in parallel in cooperation with the gerontology service of the University Hospital of Limoges and researchers in the field of ICT and technologies for elderly and disabled people

Homojunction silicon solar cells doping by ion implantation

International audienceProduction costs and energy efficiency are the main priorities for the photovoltaic (PV) industry (COP21 conclusions). To lower costs and increase efficiency, we are proposing to reduce the number of processing steps involved in the manufacture of N-type Passivated Rear Totally Diffused (PERT) silicon solar cells. Replacing the conventional thermal diffusion doping steps by ion implantation followed by thermal annealing allows reducing the number of steps from 7 to 3 while maintaining similar efficiency. This alternative approach was investigated in the present work. Beamline and plasma immersion ion implantation (BLII and PIII) methods were used to insert n-(phosphorus) and p-type (boron) dopants into the Si substrate. With higher throughput and lower costs, PIII is a better candidate for the photovoltaic industry, compared to BL. However, the optimization of the plasma conditions is demanding and more complex than the beamline approach. Subsequent annealing was performed on selected samples to activate the dopants on both sides of the solar cell. Two annealing methods were investigated soak and spike thermal annealing. Best performing solar cells, showing a PV efficiency of about 20%, was obtained using spike annealing with adapted ion implantation conditions

L'énergie à découvert

L'énergie est devenue une question vitale pour les sociétés, le citoyen, l'humanité tout entière. Sujet scientifique, économique, politique et écologique majeur, elle suscite des débats, parfois violents, sur les choix à faire aujourd'hui et leurs conséquences pour l'avenir des hommes et de la planète. Mais, alors que se tient le grand débat national sur la transition énergétique, comment se forger une opinion objective sans connaître les données scientifiques les plus complètes sur les potentiels et les limites de chaque source d'énergie ? Ce livre les met enfin à la disposition du public. L'énergie, qu'est-ce que c'est ? Quelles sont les grandes lois physiques qui la gouvernent ? Comment la produire, la transporter, la stocker ? Le solaire, la biomasse, l'éolien, l'hydraulique sont-ils des solutions alternatives suffisantes ? Et quelle part leur réserver à l'avenir ? Les nombreux articles de ce livre (près de 130) proposent au citoyen des outils pour se faire une opinion face à ces questions. Physiciens, chimistes, biologistes, géophysiciens, environnementalistes, géographes, économistes, y précisent, chiffres et schémas à l'appui, la place respective des énergies fossiles, du nucléaire et des énergies renouvelables. Au-delà, ils expliquent quelles sont les perspectives offertes par la science sur le mix énergétique, le problème du stockage, l'amélioration de nos usages de l'énergie, ses impacts environnementaux et sanitaires