Abstract
Ceramics in the system Al2O3-SrTiO3 are studied with a view to obtain microwave dielectrics with dielectric constant of about 10, a near zero temperature coefficient of resonant frequency (TCF) and high quality factor. Compositions having formula (1 − x)Al2O3-xSrTiO3 with x = 0.01 to 0.08 (by weight fraction) are prepared and characterized. The major phases in the sintered samples are Al2O3, SrTiO3 and SrAl12O19. Changes in the lattice parameters of Al2O3 and SrTiO3 with composition indicate some solid solution formation. The highest sintered density (95 to 96%) is obtained for the composition 5 wt% SrTiO 3 . The dielectric constant remains nearly unchanged. The Q for disc resonator decreases from ∼ 2078 to ∼927 with increasing SrTiO3 content. The TCF varies from −43 to 11.3 with increasing SrTiO3 from 1 wt% to 8 wt%. Thus it appears feasible to design compositions in this system with near zero TCF, high Q · f and a low dielectric constant.
Published Version
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