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)
H(SO)
}
{ND)D(SO)} system; Ferroelectricity in (NH)H(SO)大坂 俊雄*; 巻田 泰治*; 下司 和男
Journal of the Physical Society of Japan, 49(2), p.593 - 598, 1980/00
被引用回数：33 パーセンタイル：85.63(Physics, Multidisciplinary)(NH)H(SO)とその重水素置換化合物(ND)D(SO)との混晶系の相転移を誘電測定によって調べ、常圧に於ける相図を完成した。重水素置換率90%以上の結晶では、軽水素塩にみられない強誘電相が出現する。又、重水素置換の相転移に対する効果と、すでに報告した静水圧の効果との間に著るしい相関があることが見出された。
)(SO)下司 和男
Journal of the Physical Society of Japan, 41(4), p.1437 - 1438, 1976/04
被引用回数：408kbarまでの圧力領域における誘電性の測定によって(NH)H(SO)の二つの高圧相(V?相、V??相)が強誘電性を示すことを見出した。1気圧で-25
C付近に極大をもつ誘電率の巾広いピークは、圧力の増加と共に高さを増す。この誘電率の極大が発散する圧力値(~5.1kbar)より僅に低い圧力(~4.9kbar)から強誘電性高圧相(V?相)が安定化される。ロッシェル塩-アンモニウム・ロッシェル塩系にみられる類似の現象との比較が行なわれた。
の局所構造解析米田 安宏; 尾原 幸治*; 永田 肇*
no journal, ,
非鉛圧電体材料のエンドメンバーとして有力なニオブ酸カリウム(KNbO)の局所構造解析を高エネルギー放射光X線を用いて行った。ペロブスカイト酸化物強誘電体では、従来変位型相転移と考えられていたBaTiO, PbTiO, NaNbOなどにおいて、秩序-無秩序型のコンポーネントが見出されている。そこで、KNbOにおいても局所構造解析を広範囲な温度領域で行うことによって、秩序-無秩序型のコンポーネントを見出すことを試みた。KNbOの最低温相は菱面体晶構造であるが、この菱面体歪は3度の相転移を経た立方晶相においても存在することがわかった。
斉藤 淳一; 武末 尚久*; 木場 知将*; 工藤 淳貴*; 松尾 直樹*
no journal, ,
In general, piezoelectrics show their highest performance if they are single crystals. However, many of the growth procedures are time-consuming and unpractical, which results in our choice of the sintered polycrystal ceramics for practical use. This general situation causes trade-off between the performance and the effort of process, which motivated us to develop a simple process to obtain the highly-oriented dense integration of piezoelectric single-crystal nanoparticles. Intuitibely saying, the expected process can be realized by using cube- or rectangular-shaped particles, because their plane-to-plane contacts allow their crystallographically oriented ordering to include quite a little space among them. Such the particle is called nanocube, and there have been found the several kinds so far. For this work, the most adequate nanocube is of barium titanate (BT); therefore, we decided to choose BT nanocubes as the model system and exploit a shape of real dices as imitations of the nanocubes for a first trial experiment of this work. In this experiment, dices are mechanically agitated or pressed in soft mediums such as polyvinyl alcohol, and continuous monitoring of the dices are done during the mechanical operations. The results will be presented in the meeting.
斉藤 淳一; 木場 知将*; 工藤 淳貴*; 松尾 直樹*; 武末 尚久*
no journal, ,
We fabricated nanocube crystals of barium titanate by hydrothermal synthesis and also solvothermal, according to the methods of prior studies. Each particle is the single crystal and has the well-known conventional crystal structure, which was confirmed by TEM and X-ray diffraction. Currently, we are trying to build the oriented dense assemblage by mechanical operations such as stirring the particles in a small container, based on the previous imitation experiment with real dices stirred in a cylinder. How our praticles are crystallographically oriented and ordered were confirmed by X-ray diffraction in various conditions of the operations. The result will be presented in the meeting.
斉藤 淳一; 工藤 淳貴*; 木場 知将*; 松尾 直樹*; 武末 尚久*
no journal, ,
We synthesized single-crystal nancubes of barium titanate (BT), known as a typical perovskite ferroelectrics, by hydrothermal synthesis and also solvothermal. Typical forms of the nanocubes are given. The next stage of this fabrication includes integration and solid-solutionaizing BT nanocubes with other similar substances; the former is expected to provide large spontaneous electric polarization of the single-crystal level, and the latter gigantic piezoelectric response, called morphotropic phase boundary effect; we have already been working on the former, so we subsequently decided to work on the latter. In this work, we try the same synthesis methods involving zirconia or zirconium complex for a zirconium substitute to titanium. The obtained substance will be investigated by TEM, X-ray diffraction, and dielectric measurements. The result will be presented in the meeting.
斉藤 淳一; 松尾 直樹*; 木場 知将*; 工藤 淳貴*; 武末 尚久*
no journal, ,
We synthesized single-crystal nancubes of barium titanate (BT), known as a typical perovskite ferroelectrics, by hydrothermal synthesis and also solvothermal; our pressed and sintered sample shows typical temperature dependence of capacitance of BT. The next stage of this fabrication includes crystallographically highly oriented dense integration and solid-solutionaizing BT nanocubes with other similar substances; the former is expected to provide large spontaneous electric polarization of the single-crystal level, and the latter gigantic piezoelectric response, called morphotropic phase boundary effect. We have already been working on the former by mechanical agitation, e.g. stirring the nanocubes in a small container; we obtained typical data of X-ray diffraction of BT and found a tendency for our nanocubes to be oriented therefore, we subsequently decided to work on the latter. In this work, we try the same synthesis methods involving zirconia or zirconium complex for a zirconium substitute to titanium and also calcium hydroxide for calcium to barium. Conventionally sintered polycrystal samples of this system are known to show high performances as piezoelectrics, so it is possible that our integrations show the higher performance than the conventional samples. The obtained substance will be investigated by TEM, X-ray diffraction, and dielectric measurements. The result will be presented in the meeting.
-Bi(Mg,Ti)O固溶体のX線PDF解析米田 安宏; 和田 智志*
no journal, ,
BiFeOは有用な強誘電体であるが、強誘電相の菱面体晶構造が大きく歪むため、分極を反転させることは容易ではなく、さまざまな添加剤を添加して誘電特性を改善する試みがなされている。添加剤としてBaTiOとBi(Mg
Ti)Oを選択し、放射光を用いて構造解析を行った。BiFeOは菱面体晶構造で、BaTiOは正方晶構造である。Bi(MgTi)Oは、反強誘電性の斜方晶構造を持ち、BiFeOとBaTiOを結合するバッファーとして機能することが期待されている。ミクロからマクロへと構造が平均化する過程が明らかになり、また、温度によって様々な変化が見られた。このような構造の柔軟性により、BiFeOの大きな歪みが軽減され、分極が可能になると考えられる。
