The cracking efficiency of a catalytic double-oven arsenic dimer source has been studied by modulated beam mass spectrometry and the catalytic activity of several materials investigated through the cracking of the tetramer molecules produced from crystalline arsenic with a pyrolytic boron nitride (pBN) oven. The catalytic activity decreases as follows: Pt, Pt-Rh>Re>Ta>Mo, W-Re>graphite>pBN. Platinum and its alloys with rhodium react with arsenic above 500 °C giving definite compounds and therefore cannot be used as a catalyst. A 95% conversion efficiency is obtained with rhenium around 700 °C, a temperature which is more than 300 °C lower than the temperature required with graphite for an equivalent efficiency. Such a decrease of the operating temperature of the cracker cell is of great practical interest because of the reduction of the arsenic flux contamination by outgassing impurities.
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Barski et al. (1987) studied this question.
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