Mo-Ni-O powders

It was later shown for the Mo-Ni-O powder electrodeposition [33] that this mechanism is only partially correct and that amraig metallic Ni and Mo, the M0O3 phase is also electrodeposited. Taking into account that NiO, M0O3, and MoNid phases were detected in as-deposited samples by TEM, it was obvious that the mechanism of alloy electrodeposition similar to the one presented by Eqs. (7.16, 7.17, 7.18, and 7.19) could be applied for the formation of MoNid phase only, since it assumed complete reduction of both metal ions. By the analogy with the mechanism proposed by Podlaha and Landolt [28-30], it was suggested that the MoNid phase could be formed by the following mechanism [34] ... 

The Mo-Ni-O powders were electrodeposited from two supporting electrolytes, as in the case of Co-Ni system 1 M NHjCl-fO. M NH4OH and 1 M (NH4)2S04 -f 0.7 M NH4OH, with the pH of the solutions being 9.0. 

Morphology of Mo-Ni-O Powders Electrodeposited from Chloride-Containing Electrolytes... 

Fig. 8.27 Typical agglomerates for the Mo-Ni-O powders electrodeposited at the Ni/Mo = 1/0.5. (a) Agglomerates of the size in the range of about 2-50 pm, (b) Top view of sharp edges at the surfaces of agglomerates (Reprinted from Ref. [1] with kind permission from Springer)...

It should be emphasized here that most of the phases detected in the recrystallized electrodeposited Mo-Ni-O powders [14, 15] (MoNi4 and M0O3) were also found in as-electrodeposited Mo-Ni-O powders, indicating their formation during the process of alloy electrodeposition. 

Jovic VD, Jovic BM, Lacnjevac U, Brankovic G, Bernik S, Recnik A (2010) An attempt to predict the mechanism of Mo-Ni-O powders electrodepositimi from the results of their TEM... 

Morphology, Chemical, and Phase Composition of Electrodeposited Co-Ni, Fe-Ni, and Mo-Ni-O Powders... 

Fig. 5.52 Typical crystals for samples 1—(a), 2—(b), and 3—(c), detected after annealing of corresponding Mo-Ni-O powders at 600°C for 2 h (Reprinted from [121] with the permission of Elsevier.)...

To define temperatures of recrystallization and solid state reaction in the investigated Mo-Ni-O powders, stepwise annealing for 2 h in nitrogen atmosphere was performed (1) at 300°C, (2) at 400°C, (3) at... 

The TEM analysis was performed on two Mo-Ni-O powders Ni-rich (Ni/Mo = 1/0.3) and Mo-rich (Ni/Mo = 1/3) powders. The common characteristic of both powders is the presence of amorphous and crystalline particles. 

After these findings it is much easier to understand the process of solid state reaction that is supposed to take place during the annealing of these powders [121,122]. The formation of NiMo04 phase should be the consequence of the reaction between NiO and M0O3 in the solid state, which takes place at a temperature of about 600°C [150, 158, 159] and is more pronounced in the Ni-rich Mo-Ni-O powder [122]. 

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