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Nakai, Tomoaki*; Kobune, Masafumi*; Nagamoto, Takeru*; Kikuchi, Takeyuki*; Yoneda, Yasuhiro
Transactions of the Materials Research Society of Japan, 41(3), p.251 - 254, 2016/09
Solid solutions of NaNbO and KNbO
are the candidate for non-Pb piezoelectric materials. It is difficult to obtain dense ceramics owing to the difference of their calcination temperature. We developed the malic acid complex method to obtain the (Na
K
Li
)NbO
to obtain a high-quality ceramics sample. It was found that (Na
K
Li
)NbO
lies complicated phase boundaries; one is the structural phase boundary between NaNbO
and KNbO
, the other is that between (Na,K)NbO
mixture and LiNbO
, which is a sintering additive.
Yoneda, Yasuhiro; Nagamoto, Takeru*; Nakai, Tomoaki*; Kobune, Masafumi*
Transactions of the Materials Research Society of Japan, 41(2), p.197 - 200, 2016/06
BiNa
TiO
(BNT) has been investigated as a lead-free piezoelectric material. We have already performed structure analysis of BNT. The average structure of BNT with low-temperature synthesis is a rhombohedral structure and it becomes a monoclinic structure as the synthesized temperature increases. Our local structure analysis indicated that the
-site atoms of Bi and Na displaced toward different position depending on the lattice expansion and construction. We synthesized BNT crystals with various substitution and performed local structure analysis to examine the hypothesis. The local structure analysis revealed that the substitution effect on BNT can be explained by our hypothesis.
Yoneda, Yasuhiro; Nagamoto, Takeru*; Nagata, Hajime*; Kobune, Masafumi*
no journal, ,
BiNa
TiO
(BNT) is a candidate for lead-free piezoelectric material having a perovskite-type structure. The crystal structure of BNT was believed to be rhombohedral. Recently, BNT grown by high-temperature synthesis was reported to be monoclinic. We have synthesized Bi
Na
TiO
crystal in the high temperature condition so as to apply the Rietveld method for average structure refinement and the atomic pair-distribution function (PDF) technique for local structure refinement. The Bragg peaks can be reproduced by assuming a monoclinic structure, while the local structure can be reproduced by assuming a rhombohedral crystal structure.