High pressure discharge lamp

A free high pressure sodium vapor discharge lamp comprising:

• a vessel having a discharge space formed therein;
• end members hermetically sealing the vessel;
• electrical leads extending through the end members;
• electrodes disposed at the ends of the electric leads extending through the end members;
• the discharge space including sodium, a starting gas;
• and
• said vessel comprised of a ceramic including the following dopant in parts per million:
• 50≦MgO≦1500
• 100≦HfO2≦1500
• 0≦ZrO2≦700
• 0≦Y2O3≦300
• 0≦Sc2O3≦1000
• 0≦Dy2O3≦1000
• 0≦Tb2O3≦1000
• with the proviso that at least 5 ppm Sc2O3, Dy2O3, Tb2O3, or mixtures thereof is included.

An arc tube comprised of a ceramic material including the following dopants in parts per million:

• 50≦MgO≦1500
• 100≦HfO2≦1500
• 0≦ZrO2≦700
• 0≦Y2O3≦300
• 0≦Sc2O3≦1000
• 0≦Dy2O3≦1000
• 0≦Tb2O3≦1000
• with the proviso that at least 5 ppm Sc2O3, Dy2O3, Tb2O3, or mixtures thereof is included.

An arc discharge vessel having electrodes disposed therein, a fill within the discharge vessel wherein the arc discharge vessel consists essentially of alumina including the following dopants in parts per million:

• 50≦MgO≦1500
• 100≦HfO2≦1500
• 0≦Y2O3≦300
• 0≦Sc2O3≦1000
• 0≦Dy2O3≦1000
• 0≦Tb2O3≦1000
• with the proviso that at least 5 ppm Sc2O3, Dy2O3, Tb2O3, or mixtures thereof is included.