A novel approach to synthesis of nanosize MgAl2O4 spinel powder through sol–gel citrate technique and subsequent heat treatment

The influence of heat-treatment atmosphere during the synthesis of nanosized MgAl2O4 spinel powder employing the sol-gel citrate route was investigated. Based on BET measurement of specific surface area, crystallite size, simultaneous thermal analysis, and microscopic observation, it was clarified that the argon atmosphere used for heat treatment of the precursor reduced the particle size of the synthesised ceramic powders significantly. Compared with heat treatment in an air atmosphere, the carbonaceous material remaining from citrates had an important role in hindering the particle sintering. The slower heat generation in an argon atmosphere created a chance to achieve a nanocrystalline MgAl2O4 spinel powder with crystallite size in the range 5-7 nm. The argon treatment solved the problem of sudden heat generation in the sol-gel citrate method to synthesise nanosized MgAl2O4 spinel particles in the range of 20-100 nm.