Classification of stacking faults and their stepwise elimination during the disorder$\rightarrow$ order transformation of nickel hydroxide

Ramesha, TN and Kamath, Vishnu P and Shivakumara, C (2006) Classification of stacking faults and their stepwise elimination during the disorder$\rightarrow$ order transformation of nickel hydroxide. In: Acta Crystallographica Section B, 62 (4). pp. 530-536.

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Abstract

Nickel hydroxide samples obtained by strong alkali precipitation are replete with stacking faults. The local structures of the stacking faults resemble the stacking patterns of different polytypic modifications that are theoretically possible among the layered hydroxides. This resemblance becomes a basis for the classification of stacking faults into different types. Each type of stacking fault produces a characteristic non-uniform broadening of peaks in the X-ray powder diffraction pattern of nickel hydroxide. DIFFaX simulations aid the classification and quantification of stacking faults. Hydrothermal treatment of a poorly ordered nickel hydroxide slurry at different temperatures (338-473 K) and different durations (5-48 h) shows that the stacking faults are removed in a stepwise manner. The as-precipitated sample has 17-20% stacking faults of the $3R_2$ variety, which evolve into the $2H_2$ type at 413 K. The $2H_2$ stacking faults persist up to 443 K. The stacking faults are completely removed only at 473 K. At this temperature an ordered ${\beta}-Ni(OH)_2$ phase is observed.

Item Type:	Journal Article
Publication:	Acta Crystallographica Section B
Additional Information:	Copyright of this article belongs to Blackwell.
Keywords:	Nickel hydroxide;Stacking faults;Polytypes;Hydrothermal treatment.
Department/Centre:	Division of Chemical Sciences > Solid State & Structural Chemistry Unit
Date Deposited:	13 Sep 2006
Last Modified:	19 Sep 2010 04:19
URI:	http://eprints.iisc.ac.in/id/eprint/3529

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