A Novel Method of Synthesis of Nanostructured Aluminum Nitride Through Sol‐Gel Route by In Situ Generation of Nitrogen

Abstract

Nanostructured Aluminum Nitride ( AlN ) has been prepared by carbothermal reduction followed by nitridation ( CTRN ) of alumina gel over a temperature range 1200°C–1350°C and time period of 30 min to 3 h. Before heat treatment the gel is repeatedly evacuated and purged with ammonia. The nanopores of the gel are filled with ammonia which acts as a source of in situ nitrogen at heat‐treatment temperature. Dextrose also decomposes at the reduction temperature and generates ultrafine carbon. The stability diagram of the carbon saturated Al – N – O system is constructed and it shows that extremely low partial pressure of oxygen is required for the stability of AlN . The ultrafine carbon as well as hydrogen from the cracking of ammonia is not sufficient to create the extremely low partial pressure of oxygen required for the stabilization of AlN . So the sample is heat treated in charcoal boat in nitrogen atmosphere to achieve an extremely low partial pressure of oxygen required for the formation of AlN . The material has been characterized through XRD , FESEM , and HRTEM analyses. The spherical particle size of AlN is obtained ∼21 nm.