Abstract: An infrared lamp with a closed-off enveloping tube which encloses an emission source joined with contacts for a power supply in the form of a carbon ribbon which, extending in a direction of a long axis of the enveloping tube, determines an irradiation length of the infrared lamp in the sense of a higher irradiation output. The carbon ribbon has a length which is larger than the irradiation length by a factor of at least 1.5. With a procedure for heating a material to be processed using the infrared lamp, which makes possible short processing times in connection with a simultaneous high degree of energy efficiency, the infrared lamp may be operated such that its maximum emission lies within a wavelength range from 1.8 &mgr;m to 2.9 &mgr;m, and such that its power output comes to at least 15 Watts per cm3 of the volume enclosed by the enveloping tube over the irradiation length.

Abstract: A silica glass crucible is disclosed comprising an aluminum-doped inner wall layer. An aluminum-doped layer can be formed on an outer wall portion. The inner layer is non-homogeneously doped with aluminum to promote silica crystallization. The non-homogeneous silica grain mixture contains aluminum and can be aluminum-doped and aluminum-free silica grains or, alternatively, aluminum-coated coarse quartz grain.