Patent ID: 8772188

Claim:
A glass-ceramic having at least two crystal phases, wherein at least one crystal phase has a positive temperature dependence of the resonance frequency τ f , at least one crystal phase has a negative temperature dependence of the resonance frequency τ f and the glass-ceramic has a resulting temperature dependence of the resonance frequency τ f of 0+/−20 ppm/K, and wherein the glass-ceramic has at least the following constituents (in mol % on an oxide basis): SiO 2 5-50 Al 2 O 3 0-20 B 2 O 3 0-25 BaO 0-25 TiO 2 10-60 RE 2 O 3 5-45, where Ba can be partly replaced by Sr, Ca, and Mg, where RE is lanthanum, another lanthanide or yttrium and where Ti can be partly replaced by Zr, Hf, Y, Nb, V, Ta, Mn, and Cr.