Nickel borides particle sizes

In this system the average particle size depends on the BH4 Ni " ratio, the nickel salt concentration and the size of the inner water core of the reversed micelle. A BH4" Ni ratio of three gives the smallest size catalyst particles. Lower ratios lead to the formation of larger particles while higher ratios have no further effect on particle size. Micelles with smaller water cores produce smaller catalyst particles. The effect of nickel salt concentration on particle size is complex the smallest particles are formed with a concentration of 5x10"2M. Fig. 12.3 shows the relationship between the micelle composition, nickel salt concentration and the nickel boride particle size. For any given preparation the catalyst particles are essentially uniformly sized with only a 0.5 run distribution. ... 

Figure 14 shows the dependence of the nickel boride particle size on the water content in the microemulsion and on the Ni(Il) ion concentration. The average size of the particles decreases with decreasing size of the inner water core (decreasing water content), while... 

Monodispersed, 2- to 6-nm-dia- Particles, formed from their metal salts by meter nickel boride, cobalt boride, NaBH4 reduction, were used as catalysts, nickel-cobalt boride, and iron Micellar core size controlled particle sizes... 

Monodisperse colloidal nickel boride and cobalt boride particles are synthesized by reducing, with NaBH4, the metallic ions solubilized in the water cores of the microemulsions. The NaBH4/MCl2 ratio was held equal to 3, because larger particles were obtained for a lower value, the particle size remaining constant above that ratio [2-4]. 

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