Alumina-based ceramic composition

摘要

A sintered alumina-based ceramic body exhibiting excellent electrical characteristics, in particular, excellent dielectric power factor and a temperature coefficient of a resonant frequency, which consists essentially of 0.01 to 7 parts by weight of Ta2O5 admixed with 100 parts by weight of an expanded Al2O3-SnO2-TiO2 ternary base composition (by molar fraction) of: -Al2O3 SnO2 TiO2 -0.925 0.055 0.020 -0.625 0.285 0.090 -0.625 0.0245 0.3505 -0.925 0.010 0.065 - Dielectric power factor tan delta of 10x10-5 or below and temperature coefficient (Tf) of the resonance frequency from -28 to +14 ppm/ DEG C. Tf=0 is achieved at a preferred range. An alumina-based ceramic sintered body having a compositional range within a triangular range defined by sequentially connecting the points P, Q and R in the following compositional table of the Al2O3-SnO2-TiO2 ternary system, expressed in terms of the molar fraction: -Al2O3 SnO2 TiO2 -P 0.95 0.025 0.025 -Q 0.70 0.225 0.075 -R 0.70 0.075 0.225 - can provide the same dielectric power factor but with a temperature coefficient tau epsilon of the dielectric constant from -40 to +40 ppm/ DEG C. within 1 MHz to 7 GHz.