Crystallized glass, substrate for magnetic disc, magnetic disc and method of producing crystallized glass

摘要

A crystallized glass has a main crystal phase of alpha-quartz (SiO2) and lithium disilicate (Li2.2SiO2) and has a thermal expansion coefficient of (90~130)x10-7/K at -50° C.~70° C. The crystallized glass mentioned above, has a following chemical composition; 70 wt %<=SiO2<=80 wt %, 5 wt %<=Al2O3<=9 wt %, 7 wt %<=Li2O<=10 wt %, 1 wt %<=P2O5<=3 wt %, 0 wt %<=K2O<=3 wt %, 0 wt %<=CaO<=3 wt %, 0 wt %<=BaO<=4 wt %, 0 wt %<=ZnO<=4 wt %, 0 wt %<=Sb2O3<=1 wt %, 0 wt %<=ZrO2<=6 wt %, 0 wt %<=Nb2O5<=6 wt %, 0 wt %<=SnO2<=4 wt %, 0 wt %<=MoO3<=3 wt %, 0.7 wt %<=(Nb2O5+SnO2+MoO3)<=6 wt %.