Zum Kristallisations- und Schmelzverhalten von Auripigment und den strukturanalogen Verbindungen Claudetit und Arsenselenid

Solid State Studies on Synthetic and Natural Crystalline Arsenic(III) Sulfide, As2S3 (Orpiment): New Data for an Old Compound

“…As far as the temperature of fusion of natural as well as synthetic orpiment is concerned, it can be seen in Table that experimental T fus values found in the literature scatter within 577−599 K. Cernosek et al reported a DSC melting curve in which the melting temperature (580 K) virtually hits the temperature for point b in Figure . However, these authors, as well as Voigt and Jacob, mentioned onset temperatures (596 and 599 K, respectively) close to the temperature for point c in Figure . Thus, the discrepancy between the data in Table and the data in Table might be related to how the melting temperature is determined.…”

“…However, production of synthetic crystalline samples through direct synthesis from the elements usually yields a vitreous solid that is notoriously difficult to crystallize, even after seeding the melt. 1 Nevertheless, crystals had already been obtained by annealing the glass for 12 days at 573 K 2 or 7 days at 568 K, 3 while transport through the vapor phase under a temperature gradient is known to produce heterogeneous mixtures made of realgar As 2 S 2 and orpiment crystals together with a glassy deposit. 4 As 2 S 3 is an important material for physical (semiconducting, optical) applications and, because it is an excellent glass former, basic thermodynamic properties (melting point, heat of fusion, etc.)…”

“…The naturally occurring crystalline arsenic(III) sulfide, As 2 S 3 , has been known from antiquity as orpiment. However, production of synthetic crystalline samples through direct synthesis from the elements usually yields a vitreous solid that is notoriously difficult to crystallize, even after seeding the melt . Nevertheless, crystals had already been obtained by annealing the glass for 12 days at 573 K or 7 days at 568 K, while transport through the vapor phase under a temperature gradient is known to produce heterogeneous mixtures made of realgar As 2 S 2 and orpiment crystals together with a glassy deposit …”