Effect of Temperature on the Layered Structure of Hydrotalcite-like Mg and Al Layered Double Hydroxides by Means of in situ High Temperature Powder X-ray Diffraction

Eiji KANEZAKI

doi:10.1380/jsssj.19.288

ハイドロタルサイト様Mg/Al層状複水酸化物の高温その場測定粉末XRD法による層構造の温度変化

金崎英二

著者情報

ジャーナルフリー

1998 年 19 巻 5 号 p. 288-293

DOI https://doi.org/10.1380/jsssj.19.288

詳細

発行日: 1998/05/10 受付日: 1997/09/29 J-STAGE公開日: 2009/08/07 受理日: 1997/11/13 早期公開日: - 改訂日: -
訂正情報
訂正日: 2009/08/07 訂正理由: - 訂正箇所: 論文抄録訂正内容: Wrong : Mg/Al-layered double hydroxide with interlayer carbonate (Mg/Al/CO₃-LDH) is synthesized with atomic ratio Mg/Al=2, 3 or 4. In situ high temperature powder X-ray diffraction (in situ HTXRD) patterns of Mg/Al/CO₃-LDH reveal that the solid phase having hydrotalcite-like layered structure (Phase I) is unstable when the temperature of the solid sample is elevated. Immediately after Phase I disappears, another solid phase (Phase II) grows and becomes predominant. In the direction of c-axis, Phase II has the basal spacing d=0.659 nm which is smaller than that of Phase I. Mixed solids of MgO and a spinel (MgAl₂O₄) are observed after Phase II degrades. Two endothermic peaks both of which are associated with weight loss appear below 400° in the result of differential thermal analysis/thermal gravimetry (DTA/TG). Phase II is formed at the endotherm of lower temperature and degrades at that of higher temperature. Phase II is unstable at room temperature and transits to an amorphous phase slowly after days of storage in a dry condition. It is observed that a very small part of this amorphous phase transits to Phase I in the same dry condition. Solid state chemistry of the synthetic Mg/Al/CO₃-LDH is investigated by means of in situ HTXRD, DTA/TG and X-ray photoelectron spectroscopy (XPS).
Right : Mg/Al-layered double hydroxide with interlayer carbonate (Mg/Al/CO₃-LDH) is synthesized with atomic ratio Mg/Al=2, 3 or 4. In situ high temperature powder X-ray diffraction (in situ HTXRD) patterns of Mg/Al/CO₃-LDH reveal that the solid phase having hydrotalcite-like layered structure (Phase I) is unstable when the temperature of the solid sample is elevated. Immediately after Phase I disappears, another solid phase (Phase II) grows and becomes predominant. In the direction of c-axis, Phase II has the basal spacing d=0.659 nm which is smaller than that of Phase I. Mixed solids of MgO and a spinel (MgAl₂O₄) are observed after Phase II degrades. Two endothermic peaks both of which are associated with weight loss appear below 400° in the result of differential thermal analysis/thermal gravimetry (DTA/TG). Phase II is formed at the endotherm of lower temperature and degrades at that of higher temperature. Phase II is unstable at room temperature and transits to an amorphous phase slowly after days of storage in a dry condition. It is observed that a very small part of this amorphous phase transits to Phase I in the same dry condition. Solid state chemistry of the synthetic Mg/Al/CO₃-LDH is investigated by means of in situ HTXRD, DTA/TG and X-ray photoelectron spectroscopy (XPS).

抄録

Mg/Al-layered double hydroxide with interlayer carbonate (Mg/Al/CO₃-LDH) is synthesized with atomic ratio Mg/Al=2, 3 or 4. In situ high temperature powder X-ray diffraction (in situ HTXRD) patterns of Mg/Al/CO₃-LDH reveal that the solid phase having hydrotalcite-like layered structure (Phase I) is unstable when the temperature of the solid sample is elevated. Immediately after Phase I disappears, another solid phase (Phase II) grows and becomes predominant. In the direction of c-axis, Phase II has the basal spacing d=0.659 nm which is smaller than that of Phase I. Mixed solids of MgO and a spinel (MgAl₂O₄) are observed after Phase II degrades. Two endothermic peaks both of which are associated with weight loss appear below 400° in the result of differential thermal analysis/thermal gravimetry (DTA/TG). Phase II is formed at the endotherm of lower temperature and degrades at that of higher temperature. Phase II is unstable at room temperature and transits to an amorphous phase slowly after days of storage in a dry condition. It is observed that a very small part of this amorphous phase transits to Phase I in the same dry condition. Solid state chemistry of the synthetic Mg/Al/CO₃-LDH is investigated by means of in situ HTXRD, DTA/TG and X-ray photoelectron spectroscopy (XPS).

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