Synthesis of aluminium nitride under 2.45 GHz microwave irradiation

Aluminium nitride (AlN) is a functional ceramic which has several properties, and it is applied to substrate materials and fillers for packaging materials of electronic devices. Microwave heating has characteristics such as internal heating, rapid heating and selective heating, so it is useful for synthesis of ceramics. In this work, spherical AlN particles were synthesised by carbothermal reduction and nitridation of Al2O3 under 2.45 GHz microwave irradiation. The mixture of spherical Al2O3 particles and carbon was used as the starting materials. Carbon absorbed microwaves selectively, and the starting materials were heated rapidly in flowing nitrogen gas. Al2O3 was converted to AlN in a short time; and finally, polycrystalline spherical AlN particles were successfully formed. They retained particle diameters of spherical Al2O3 particles used as the starting material.