Cation substitution for the Ba2+ and Ti4+ sites in the BaTiO3 structure was attempted in low-fired glass-ceramics derived from glass powders that have perovskite phase compositions corresponding to (BaTiO3 : REAlO3) = 9:1 and 8:2 (RE = La, Nd and Sm) to control the Curie temperature (7C) of the ferroelectric glass-ceramics. The La3+-substituted (9:1) sample heated at 950°C for 24 h showed a broadened εr-temperature relationship with substantial lowering in Tc to ∼-55°C. The Ba:La ratio in the perovskite particles was estimated to be in the range of 4:1-6.7:1, whereas very little A13+ was incorporated into the same particles. It was found that the Tc of the glass-ceramics fabricated in our serial study could be adjusted by A-site cation substitution in BaTiO3. Tailored glass-ceramic samples with room temperature εr of 200-300 and Tc of around 0&C had good microwave tunability of 30-40% under dc bias voltage of 10-50kV/cm. The high tuning sensitivity of the low-fired glassceramics was confirmed by comparative examination of the dielectric properties of well-crystallized ceramics and thin films.
|Japanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers
|Published - 2005 9月 22
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