1. Li-silicate glass-ceramics comprising a pentavalent metal oxide selected from NbO, TaOi mixtures thereof, and includes less than 2.0 wt.% KO.2. Glass ceramic according to Claim. 1 except lithium silicate glass ceramic, which includes at least 6.1 wt.% ZrO.3. Glass ceramic according to Claim. 1 or 2, with the exception of glass ceramic, which includes at least 8.5 wt.% Transition metal oxide selected from the group consisting of yttrium oxides, oxides of transition metals having atomic number 41-79 and mixtures of these oksidov.4. Glass ceramic according to Claim. 1 or 2, which comprises less than 1.0, particularly less than 05 wt.%, And preferably less than 0.1 wt.% CO, and most preferably is substantially free KO.5. Glass ceramic according to Claim. 1 or 2, which comprises less than 1.0, particularly less than 05 wt.%, And preferably less than 0.1 wt.% NaO, and most preferably is substantially free NaO.6. Glass ceramic according to Claim. 1 or 2, which comprises at least 2.0 and in particular at least 2.1 wt.% NbOili TaO.7. Glass ceramic according to Claim. 1 or 2, which comprises less than 0.1 wt.% LaO, and preferably is substantially free of LaO.8. Glass ceramic according to Claim. 1 or 2 which includes a pentavalent metal oxide or mixtures thereof in an amount of 0,1-8,2 in particular 1,5-8,0 and preferably 2,0-5,0 weight .%.9. Glass ceramic according to Claim. 1 or 2, which contains lithium metasilicate as the main crystalline phase, and in particular, contains more than 5% by volume, preferably greater than 10 volume% and particularly preferably more than 15% by volume litiya.10 metasilicate crystals. Glass ceramic according to claim1. Литиево-силикатная стеклокерамика, включающая в себя оксид пятивалентного металла, выбранный из Nb2O5, Ta2O5 и смесей таковых, и включающая в себя менее 2,0 масс.% К2О.2. Стеклокерамика по п. 1, за исключением литиево-силикатной стеклокерамики, которая включает в себя, по меньшей мере, 6,1 масс.% ZrO2.3. Стеклокерамика по п.
