| Budget Amount *help |
¥3,800,000 (Direct Cost: ¥3,500,000、Indirect Cost: ¥300,000)
Fiscal Year 2007: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000)
Fiscal Year 2006: ¥2,500,000 (Direct Cost: ¥2,500,000)
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| Research Abstract |
The recent rapid expansion of telecommunication systems demand dielectric substances with high dielectric constant whose temperature dependence is flat and low loss. Some kinds of niobates such as Ba_5Nb_4O_<15>, Sr_2Nb_2O_7 and LiNbO_3 have recently attracted much attention because of excellent dielectric properties and lead-free materials potentially applicable in microwave communication.
In this work, to design and form excellent dielectric substamces, we synthesized niobate hybrid nano-particles from the novel double-metal alkoxides with controlled chemical composition including Nb, Ba, Sr, Li and/or Na. Thus, nano-particles of Ba_5Nb_4O_<15>, Sr_2Nb_2O_7 , LiNbO_3 , NaNbO_3 and their hybrids were synthesized. The effects of alkoxyl group of the alkoxide precursors on the products were also examined. Structural characterization of the specimens were carried out with TEM, EDS and XRD to clarify formation process, crystallization, substitution limit of ions, elemental distribution and consolidation. The optimum consolidation conditions by spark-plasma-sintering, i.e., heating rate, temperature and time, were elucidated for niobate nano-particles
Dense these niobate ceramics consisting of fine microstructures were obtained by the combination of using double metal alkoxides as the precursor for synthesis of the niobates and applying the controlled spark-plasma-sintering process. The measured permittivity showed higher values and flat dependence on temperature compared with those of the conventionally synthesized and sintered ceramics, due probably to its designed composition, fine microstructures and higher density
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