Erik Boonekamp

LITHIUM TRAPPING AT EXCESS OXYGEN IN SPUTTER-DEPOSITED A-WO3 FILMS

The initial stages of electrochemical intercalation of lithium in sputter-deposited tungsten oxide thin films were studied. The as-deposited films show a substantial irreversible uptake of lithium without an electrochromic effect. This trapping of lithium is associated with the presence of excess oxygen in the film. The experimental results are consistent with a reaction of lithium and interstitial oxygen to form a neutral Li2−Oi complex. Our findings are relevant for the manufacture of electrochromic devices, and the electrochemical titration method used may be applied to probe excess oxygen in other oxidic films as well.

Sol-gel coatings for optical and dielectric applications

Publisher Summary This chapter discusses the advantages and disadvantages of sol–gel deposition compared with some other deposition methods. A brief history of sol–gel chemistry in relation to some important application areas is presented in the chapter in addition to the different ways to produce a colored sol–gel layer. Thin films can be deposited using various techniques. A broad distribution distinguishes between deposition from the vapor phase and from the liquid phase. The most important application of sol–gel processes is the manufacture of optical coatings, especially on glass: coatings on cathode ray tubes (CRTs), lenses, mirrors (especially laser mirrors), and eyeglasses. A wide range of coatings can be made using sol–gel chemistry. Many of them, such as hybrid materials, cannot be made by any other route. For other materials, sol–gel offers an alternative that is attractive for large-scale production because of its flexibility.

LED solution for E14 candle lamp

On a short to medium term, energy efficient retrofit LED products can offer an attractive solution for traditional lamps replacement in existing fixtures. To comply with user expectations, LED retrofit lamps should not only have the same mechanical interface to fit (socket and shape), but also have the similar light effect as the lamps they replace. The decorative lighting segment shows the best conditions to meet these requirements on short term. In 2008, Philips Lighting Shanghai started with the development of an LED candle lamp for the replacement of a 15W Candle shape (B35 E14) incandescent bulb, which is used in e.g. chandeliers. In this decorative application the main objective is not to generate as much light as possible, but the application requires the lamp to have a comparable look and, primarily, the same light effect as the incandescent candle lamp. This effect can be described as sparkling light, and it has to be directed sufficiently downwards (i.e., in the direction of the base of the lamp). These requirements leave very limited room for optics, electronics, mechanics and thermal design to play with in the small outline of this lamp. The main voltage AC LED concept is chosen to save the space for driver electronics. However the size of the AC LED is relatively big, which makes the optical design challenging. Several optical solutions to achieve the required light effect, to improve the optical efficiency, and to simplify the system are discussed. A novel prismatic lens has been developed which is capable of transforming the Lambertian light emission from typical high power LEDs into a butter-fly intensity distribution with the desired sparkling light effect. Thanks to this lens no reflecting chamber is needed, which improves the optical efficiency up to 70%, while maintaining the compact feature of the original optics. Together with advanced driver solution and thermal solution, the resulting LED candle lamp operates at 230V, consumes 1.8W, and delivers about 55 lm at 3000K with the requested radiation pattern and sparkle effect. Some field tests were done with positive feedback.