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Effects of CaTiO 3 and SrTiO 3 Additions on the Microstructure and Microwave Dielectric Properties of Ultra‐Low‐Fire TeO 2 Ceramics
Author(s) -
Wang SeaFue,
Huang ChiYuen,
Liu YenLing
Publication year - 2010
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1551-2916.2010.03826.x
Subject(s) - materials science , microstructure , ceramic , eutectic system , dielectric , raman spectroscopy , sintering , mineralogy , microwave , analytical chemistry (journal) , composite material , chemistry , optics , optoelectronics , physics , quantum mechanics , chromatography
In this study, microwave dielectric ceramics of TeO 2 with various amounts of CaTiO 3 and SrTiO 3 were prepared. The densification, microstructural evolution, and dielectric properties of the ultra‐low‐fire ceramic composites were characterized. Three phases including TeO 2 , TiTe 3 O 8 , and CaTe 2 O 5 or SrTe 2 O 5 were observed in the CaTiO 3 ‐ or SrTiO 3 ‐added TeO 2 system. Eutectic reactions of the CaTe 2 O 5 –TeO 2 and SrTe 2 O 5 –TeO 2 systems occurred at 650° and 590°C, respectively, enhancing the densification through liquid‐phase sintering. The X‐ray diffraction observations were confirmed as the Raman spectra located at 450–520 and 780–820 cm −1 corresponded, respectively, to TiTe 3 O 8 and CaTe 2 O 5 or SrTe 2 O 5 . The densification temperatures of TeO 2 –CaTiO 3 ceramics ranged from 630° to 670°C depending on the CaTiO 3 content, while all TeO 2 –SrTiO 3 ceramics were densified at 610°C. TeO 2 –10 wt% CaTiO 3 and TeO 2 –15 wt% SrTiO 3 ceramics were found to sustain best performance in CaTe 2 O 5 –TeO 2 and SrTe 2 O 5 –TeO 2 systems. They showed the following major microwave dielectric properties: ɛ r ≈28.6, Q × f ≈15 600 GHz, and τ f ≈−3.24 ppm/°C, and ɛ r ≈28.7, Q × f ≈12 400 GHz, and τ f ≈−3.81 ppm/°C, respectively.