Phase Formation and Dielectric Characterization of the Bi 2 O 3 –TeO 2 System Prepared in an Oxygen Atmosphere

Solid‐state synthesis of compositions from the Bi 2 O 3 –TeO 2 system show that, under an oxygen atmosphere, Te 4+ oxidizes to Te 6+ and yields four room‐temperature stable compounds: Bi 2 Te 2 O 8 , Bi 2 TeO 6 , Bi 6 Te 2 O 15 , and new a compound with the nominal composition 7Bi 2 O 3 ·2TeO 2 . Dense ceramics can be prepared from all these compounds by sintering between 650° and 800°C under an oxygen atmosphere. The permittivity of these compounds varies from ∼30 to ∼54, the Q × f value from 1.100 to 41.000 GHz (∼5 GHz), and the temperature coefficient of resonant frequency from −43 to −144 ppm/K. Bi 6 Te 2 O 15 and 7Bi 2 O 3 ·2TeO 2 do not react with silver, and, therefore, they have the potential to be used for applications in low‐temperature cofired ceramic (LTCC) technology.