| Summary: | 碩士 === 國立成功大學 === 材料科學(工程)學系 === 86 === Partial decomposition of SrxBa1-xNb2O6 powder due to ball
milling effect has been investigated. The X-ray diffraction(XRD)
measuments showed that except SBN 30&40, the other compositions
of SBN have partially decomposed and the higher the ratio of Sr/
Ba, the more amount it decomposes. This phenomena was considered
to be caused by the strain energy due to the ball milling.
The relationship between partial decompositon and abnormal grain
growth was studied. The comparisons of the SBN60 samples were
sintered at 1300oC w/o pre-treatment after ball milling and, in
which abnormal grain growth occurred in the samples without pre-
treatment but not in the pre-treated samples. Further
examination of the microstructures using TEM indicated that
liquid phase might develop during sintering. XRD measuments
showed the decomposed phase remaining for sample heated at
1300oC but not in pre-treated samples. Therefore, it is
suggested that the development of the liquid phase might be due
to the nonstoichiometric decomposed phase via the effect of ball
milling. The grain growth kinetics of SBN50 at 1275oC time
has the form of G4-G04=Kt fitted by the experimental data.
However, grain growth of SBN60 was not obviously at 1275oC until
48h.After 48h, the abnormally large grain were observed in
SBN60.It was suggested that this abnormal grain growth was due
to the anisotropy of the grain boundary mobility. Finally,
The dielectric behavior of SBN50&60 were studied. The equivalent
circuit was used to fit the frequency dependent dielectric
behavior and describe the relaxation behavior.
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