Mechanical alloying, synthesis using

The use of mechanical milling is also a suitable method for powder preparation. The feature of this procedure is to obtain powders of small crystallite size of a few nanometers with a high concentration of lattice defects. There are many mechanochemical studies on the synthesis of alloys, solid solutions, nanophasc materials, and intermetallic compounds. Of course, the mechanical alloying also has been applied to prepare mixed oxides containing cerium oxide to enhance catalysis, such as CeOj-TbO, CeOj-HfOj, Ce02 Zr02-Mn0, and CeOt ... 

The application of mechanical alloying to the synthesis of rare-earth permanent magnets was first demonstrated by the work of Schultz and co-workers (Schultz et al. 1987). Subsequently, the magnetic properties of a number of rare-earth-transition-metal compounds synthesized by the mechanical alloying of elemental powders, mechanical milling of intermetallic compounds, or by mechanochemical reaction, using oxide and halide precursors, have been studied. 

Initial studies on electrocatalysis for fuel cell application using amorphous alloys were related to the oxygen evolution reaction (OER) [131,132], Ni-based amorphous alloys have a significant contribution to the development of materials for application in fuel cells due to their high stability in alkaline medium, relative low overpotential, low cost, and high corrosion resistance. The synthesis of the alloys is relatively simple. The catalyst can be obtained via the mechanical alloy technique, where the metallic elements are placed in a planetary ball mill for several hours, at the desired ratio. An important observation is that the as-synthesized catalyst does not display significant catalytic activity as compared to the crystalline material. An acid treatment with HE or HF-HNO3 is required for activation of the material surface [133,134],... 

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