Armin Konrad

Examination of the Binding Mechanism of Mercury in Fluorescent Lamp Coatings

ABSTRACT The mercury consumption during the operation of fluorescent lamps is not entirely understood. There are no publications that have reported in which chemical state the mercury is bound in alumina precoats. In the present study, alumina precoat lamps without a phosphor coating were built and seasoned for up to 8400 h. Parts from the seasoned lamps were analyzed using X-ray photoelectron spectroscopy (XPS) und thermal desorption mass spectrometry (TDMS). It could be shown that the state of the chemical binding of the mercury atoms changes with seasoning time. It appears that mercury is deposited in a zero-valent binding state that changes to an HgO-like binding state with increased seasoning time of the lamp.

Modelling of the mercury loss in fluorescent lamps under the influence of metal oxide coatings

The mercury transport and loss mechanisms in the metal oxide coatings of mercury low pressure discharge fluorescent lamps have been investigated. An existing model based on a ballistic process is discussed in the context of experimental mercury loss data. Two different approaches to the modeling of the mercury loss have been developed. The first one is based on mercury transition rates between the plasma, the coating, and the glass without specifying the underlying physical processes. The second one is based on a transport process driven by diffusion and a binding process of mercury reacting to mercury oxide inside the layers. Moreover, we extended the diffusion based model to handle multi-component coatings. All approaches are applied to describe mercury loss experiments under the influence of an Al 2 O 3 coating.