| Popis: |
The characteristics of the Ba(Mg1/3Ta2/3)O3, BMT, powders prepared from chemical routes were compared with that of the BMT powders prepared from mixed-oxide routes. The formation of secondary phase, which usually occurs during the calcination of mixed-oxide derived BMT powders, has been pronouncedly suppressed for the BMT powders prepared using chemically-derived routes. Among the chemical processes utilized for preparing the BMT powders, hydrolysis of alkoxides results in powders with the best crystallization behavior. Pure perovskite phase can be obtained by calcining the hydrolyzed alkoxides at 1150 °C (4 h). All the BMT materials prepared from chemically-derived powders possess lower sintered density, finer grain size than these prepared from mixed-oxide derived powders. However, the chemically-derived BMT materials exhibit larger Q×f (880,000 GHz) and smaller dielectric constant (K=18) than the mixed-oxide derived materials (Q×f=556,000 GHz, and K=30). |
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