Sublimation study of BiBr₃

Abstract

Steady-state sublimation vapour pressures of anhydrous bismuth tribromide have been measured by the continuous gravimetric Knudsen-effusion method from 369.3 to 478.8 K. Additional effusion measurements have also been made from 435.4 to 478.6 K by the torsion—effusion method. Based on a correlation of Δ_sub H ⁰₂₉₈ and Δ_sub S ⁰₂₉₈ , a recommended p(T) equation has been obtained for BiBr₃(s)

$$\alpha - {\rm B}i{\rm B}r_3 :log{\text{ }}p = - C\alpha /T - 12.294log{\text{ }}T + 5.79112 \times 10^{ - 3} {\text{ }}T + 47.173$$

with Cα=(Δ _subH ⁰₂₉₈ +20.6168)/1.9146×10^-2

$$\beta - {\rm B}i{\rm B}r_3 :log{\text{ }}p = - C\beta /T - 23.251log{\text{ }}T + 1.0492 \times 10^{ - 2} {\text{ }}T + 77.116$$

with Cβ=(Δ _subH ⁰₂₉₈ +46.2642)/1.9146×10^-2 where p is in Pa, T in Kelvin, Δ _sub H ⁰₂₉₈ in kJ mol⁻¹. Condensation coefficients and their temperature dependence have been derived from the effusion measurements.