AlN ultrafine powders were synthesized at low temperature by Carbothermal Reduction Nitride (CRN) route from a sol-gel precursor by using aluminum nitrate

glucose and calcium nitrate as raw materials. The influence of Ca-compound on the phase transformation behavior of the precursors

as well as the particle size and morphology of synthesized AlN powders

were investigated. X-ray diffraction patterns showed that Ca-compound reacted with alumina powder and resulted in aluminate phase of CaAl4O7

Ca3Al10O18

CaAl2O4 and Ca12Al14O33. Those aluminate phases formed liquid during the nitradation process

which promoted the transformation of Al2O3 to AlN and vaporized at high temperature. Compared to the approach without additive

the use of Ca-compound addition reduced the synthesis temperature of AlN from 1500 ℃ to 1400 ℃. SEM photographs showed that AlN powders synthesized with Ca-compound addition were larger than those without Ca addition

and high doping of Ca-compound lead to the growth of AlN powders. With [Ca]/[Al] of 0.0262

the particle sizes of AlN powders synthesized at 1350 ℃ were 60-80 nm. When the nitradation temperature was increased to 1400 ℃

the single AlN with the particle sizes of 100-180 nm was obtained.