Cryomilling as environmentally friendly synthesis route to prepare nanomaterials

The milling of materials at cryogenic temperature has gained importance both in academic as well as the industrial community in the last two decades, primarily because of significant advantages this technique as compared to milling at room temperature; environmental friendly nature, cost-effectiveness, rapid grain refinement, less contamination, and large scale production capability of various nanomaterials. Scientifically, milling at cryo-temperature exhibits several distinct material related phenomena; suppression of recovery and recrystallization, predominant fractures over cold welding, significantly low oxidation, and contamination, leading to rapid grain refinement. Cryomilling has extensively been used to obtain finer scale powder of spices for the preservation of aroma, medicines for effective dissolution, or amorphization. It has been considered an environmentally friendly process as it utilizes benign liquid nitrogen or argon without discharging any toxic entity to the environment, making the process attractive and sustainable. The present review is intended to provide various scientific as well as technological aspects of cryomilling, environmental impact, and future direction.