Borosilicate glass

Borosilicate glass consists from 80 %  SiO2, 10% B2O3 and around 10% from additional minerals as Al2O3, K2O, CaO, MgO.

Borosilicate glass became popular under the brand names "Duran" by the inventor Otto Schott and  "Pyrex" by Corning Glass since 1915.

Boronsilicate glass has extreme thermal and chemical stability. It therefore is extensively applied tor chemical laboratory apparatus.

It is also applied for plasma chambers of Low pressure plasma systems, if the stability of stainless steel chambers against etching prozesses is not sufficient or if microwave plasma stimulation requires transparent chamber walls.

Plasma Chamber
The Plasma Chamber of the Low pressure Plasma system "Bell Jar" is made of borosilicate glass