Nickel aluminate spinels were prepared by solid‐state reaction. Their lattice parameters (a0) changed with preparation temperature, which was explained by cation distribution, vacancies formation, and cation entrance. When the preparation temperature increased from 1100° to 1200°C, a0 decreased with temperature as the result of the uptake of Al2O3. After 1200°C, a0 increased to temperature, which was attributed to some Ni2+ exchange with tetrahedral sites and some vacancies occupancy by Ni2+ and Al3+.
The single crystal NiAl 2 O 4 was prepared by a solid-state reaction. The change of its cation distribution with temperature was calculated by a modified thermodynamic equation by including a new parameter d, which is a characteristic of nonconfiguration entropy. The calculated results showed that the degree of inversion for NiAl 2 O 4 decreases with temperature, although the temperature dependence of cation distribution is very weak. This result was supported by X-ray diffraction measurement.
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