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Updated: Jun 12, 2026

Chemical Precipitation Method for the Synthesis of Nb2O5 Modified Bulk Nickel Catalysts with High Specific Surface Area
Published on: February 19, 2018
Synthesis and properties of well-crystallized layered rare-earth hydroxide nitrates from homogeneous precipitation
Fengxia Geng1, Yoshitaka Matsushita, Renzhi Ma
1International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan.
Abstract:
We report the synthesis and characteristics of a rare-earth based layered family, Ln(8)(OH)(20)(NO(3))(4) x nH(2)O with Ln = Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, and Y, synthesized through homogeneous precipitation of Ln(NO(3))(3) x xH(2)O with hexamethylenetetramine. The products were uniform and of high crystallinity. Their morphology gradually changed from elongated hexagon (Sm, Eu, Gd) and hexagon (Tb, Dy) to rhombus (Ho, Er, Tm). Selected area electron diffraction revealed that the in-plane structure resembled that of the chloride counterpart, Ln(8)(OH)(20)Cl(4) x mH(2)O. Unit cell dimensions of the host layer, a and b, decreased with contracting size of lanthanide ions, whereas no such trend was observed for the interlamellar distance, c/2, which is dominated by hydration degree. Stability of the samples with temperature and relative humidity (RH) was examined. At high temperature or low RHs, hydrated water molecules could be removed, which afforded a phase with a basal decrease of approximately 0.6 A. The transition was reversible as revealed by an in situ powder X-ray diffraction study, but a RH hysteresis exists. The reversibility increased with an increase in atomic number or layer charge density. Nitrate anions of both phases could be quantitatively exchanged by other anions under ambient conditions.
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