Temperature-induced control over phase selection among hydroxides of nickel |
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Authors: | T N Ramesh P Vishnu Kamath |
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Affiliation: | (1) Department of Chemistry, Central College, Bangalore University, Bangalore, 560 001, India |
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Abstract: | While at low (4°C) temperatures, addition of ammonia to aqueous metal nitrate solutions induces the precipitation of α-nickel hydroxide and at high (25–65°C) temperatures, β-Ni(OH)2 is formed. The crystallinity of the product improves at higher temperatures of precipitation and the product obtained at
65°C is devoid of various disorders such as stacking faults, turbostraticity and interstratification. This provides a simple
and efficient alternative to the hydrothermal synthesis of crystalline β-Ni(OH)2. The temperature induced control over phase selection provides direct experimental evidence for the metastability of α-nickel hydroxide. Crystalline β-Ni(OH)2 is, however, a poor electrode material for alkaline secondary cells and exhibits a capacity of only 75 ± 10 mAh/g, against
the theoretically expected 289 mAh/g. |
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Keywords: | Nickel hydroxide crystallinity disorder ammonia precipitation |
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