ハイドロタルサイト型層状化合物 Al_2Li(OH)_6(NiCl_4)_<1/2> の酸化及び還元雰囲気中での加熱変化

概要

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A hydrotalcite-type (HT) layered double hydroxide Al_2Li(OH)_6(NiCl_4)_<1/2> was synthesized by an ionic exchange of Al_2Li(OH)_6NO_3 and its thermal changes under oxidizing and reducing atmospheres were investigated. The synthesized NiCl-<2->_4 type HT compound was found to have a hexagonal cell with a=5.10 and c=23.08 Å . From the observed interlayer spacing, the NiCl^<2->_4 anions in the inter:layers considerably form a planar square structure. Since the ion exchange was not complete, the amount of NiCl^<2->_4 anions in the interlayers was rather low and a fair amount of NO^-_3 and/or Cl^- anions remained in the interlayers. The intercalation of NiCl^<2->_4 anions influenced the thermal stability of the HT compound and its decomposition temperature increased to about 70℃ compared with that of NO^-_3 type HT compound. By firing under an oxidizing atmosphere, the Ni component which formed from the decomposition of NiCl^<2->_4 anions was incorporated with LiAl_5O_8, which then formed from the decomposition of the HT compound. On the other hand, Ni metal particles were also found in the samples fired under a reducing atmosphere. Two different types of Ni metal particles were found in the samples: (1) very uniform and fine particles with an average particle size of 4 nm and (2) fine particles with submicron meter in size. They were dispersed in the matrix of LiAl_5O_8 and formed nanocomposites.
日本粘土学会の論文
1996-07-26