*7.1.1 Mechanical milling*

Mechanical milling is a method of placing elements in a high-power mill with or without a medium (wet and dry milling) to reduce the particle size of the element. The rolling ball transfers its kinetic energy to the milled elements, resulting in the size reduction of the elements to nanoscale dimensions [29, 35–41]. This energy transfer depends on various factors such as the type of mill, packing of balls, milling speed, type of milling (wet or dry), duration, and milling temperature. This method is more reliable than traditional methods it can be used for both wet and dry materials and large-scale synthesis of nanomaterials due to their inexpensiveness.
