Process for producing a blank, and a blank

A method for producing a dental molded part, the method comprising the steps of:

• producing a molten mass with a composition (in % by weight):
• SiO2 46.0-72.0;
• Li2O 10.0-25.0;
• ZrO2 6.5-14.0;
• P2O5 1.0-10.0;
• Al2O3 0.1-8.0;
• K2O 0.1-5.0;
• CeO2 0.1-4.0;
• B2O3 0.0-4.0;
• Na2O 0.0-4.0;
• Tb4O7 0.0-2.5;
• and
• 0.0 to 4.0 of at least one additive,
• producing a glass frit by atomizing the molten mass and quenching the molten mass in a medium,
• generating glass powder particles from the glass frit with a grain size distribution d90<80 μm,
• crystallizing lithium silicate crystals with a volume fraction between 10% and 90% by a first thermal treatment of either the glass frit or the glass powder particles in a first temperature range at a temperature T1 with 500° C.≦T1≦750° C. for a duration t1 with 5 min≦t1≦120 min, whereby, glass-ceramic powder particles with a grain size distribution d90≦80 μm are produced from a heat-treated glass frit,
• pressing the glass-ceramic powder particles to form a blank,
• machining the blank by milling to produce a pre-form part corresponding to the dental molded part, taking into consideration the shrinkage characteristics of the blank, and
• sintering the pre-form part at a temperature T2 with 800° C.≦T2≦1050° C. for a duration t2 with 5 min≦t2≦60 min.