| 1. A ceramic substrate composition comprising a glass represented by aB2O3-bRe2O3-cZnO in which Re is a rare earth element which is at least one element selected from the group consisting of lanthanum and
neodymium and the molar amounts a+b+c=1; and wherein the molar amounts (a, b, and c) fall within a region defined in a ternary
composition diagram by Point A (0.4, 0.595, 0.005), Point B (0.4, 0.25, 0.35), Point C (0.52, 0.01, 0.47), Point D (0.9, 0.005,
0.095), and Point E (0.9, 0.09, 0.01) or on the lines connection the Points, and further comprising at least one of (a) at
least one oxide selected from the group consisting of aluminum oxide and titanium oxide in an amount of 50% or less by weight
of the total amount, (b) a mixed oxide ceramic material including at least one crystal phase selected from the group consisting
of ReBO3, Re3BO6, Re(B2O3)3 and ReB3O6, (c) a crystallization glass that can precipitate at least one crystal phase selected from the group consisting of ReBO3, Re3BO6, Re(B2O3)3 and ReB3O6 and (d) a crystallization glass that can precipitate at least one crystal phase selected from the group consisting of ReBO3, Re3BO6, Re(B2O3)3 and ReB3O6 and, in addition to the rare earth oxide of the glass, a rare earth oxide comprising Re2O3.
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