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Microwave Properties of Ba 2 Ti 9 O 20 Doped with Zirconium and Tin Oxides
Author(s) -
Lin WenYi,
Speyer Robert F.,
Hackenberger Wesley S.,
Shrout Thomas R.
Publication year - 1999
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.1151-2916.1999.tb01897.x
Subject(s) - dopant , materials science , zirconium , tin , microstructure , doping , analytical chemistry (journal) , phase (matter) , temperature coefficient , volatilisation , chemical engineering , mineralogy , inorganic chemistry , metallurgy , chemistry , composite material , organic chemistry , optoelectronics , engineering
The effects of solid‐solution additives, their concentration, and the thermal processing schedule on the microstructure evolution and microwave properties of Ba 2 Ti 9 O 20 were studied. The solubility of tin in Ba 2 Ti 9 O 20 was higher than that of zirconium. Both elements facilitated the formation of phase‐pure Ba 2 Ti 9 O 20 resonators. Ba 2 Ti 9 O 20 formed most easily with low dopant concentrations (0.82 mol%) (most impressively for ZrO 2 substitutions). Extended heat treatment (16 h versus 6 h at a temperature of 1390°C) resulted in volatilization of the grain‐boundary liquid phase, which leads to more‐porous resonators that have correspondingly lower permittivities. Increasing the dopant concentration resulted in minor increases in the quality factor; doping with zirconium led to slightly higher values (a maximum of 13900 at a frequency of 3 GHz). Increasing the measurement temperature degraded the quality factor (most precipitously for BaTi 4 O 9 ). The temperature coefficient decreased as the ZrO 2 substitution increased but was largely unaffected by the SnO 2 concentration. Excess TiO 2 in a batch with no other dopants demonstrated degraded microwave properties.