Time and temperature dependence of phosphorus vapor pressure as measured by a pressure-balanced, sealed-ampoule technique

For some commercial red P currently available, the vapor pressure values given by the supplier´s data sheets are much different from those of K.J. Bachmann and E. Buehler (1974). During the synthesis of InP in sealed fused silica ampoules, explosions often occur when the vapor pressure estimated from the P reservoir temperature and the Bachmann-Buehler data is well below the breaking strength of the ampoule. To avoid such problems, the authors are balancing the P pressure inside the sealed synthesis ampoule with high-pressure Ar gas in a steel pressure vessel. Balancing is accomplished with the aid of a transducer that senses the difference between the P and Ar pressures. Unexpectedly rapid changes in P pressure with reservoir temperature have been observed during synthesis runs employing this procedure. A study of the time and temperature dependence of P vapor pressure that utilizes the pressure balancing apparatus and technique developed for InP synthesis is described.<>