Microwave assisted solution combustion synthesis of nanocrystalline
yttria has been reported [15,16] but calcinations at higher
temperatures was required to be done. Earlier we reported citrate
nitrate gel combustion synthesis of Nd:Yttria nanopowders, with
polyhedral particle morphology, in microwave oven with supply
of oxygen without high temperature calcinations [17]. Many researchers
have successfully exploited the advantages of solution
combustion using fuel mixtures for the synthesis of single/multicomponent
oxide nanoparticles [18–21] the present work novel
mixed fuel microwave combustion approach is being used for direct
synthesis of phase pure Nd:Y2O3 nanopowders without high temperature
calcinations. The required amounts of urea and L-alanine
for complete combustion were calculated using the basic principles
of propellant chemistry [11]. Effect of sulfate ion on morphology
and size was also explored. Synthesis was carried out by taking
the advantage of microwave, for energy efficient and rapid volumetric
heating and mixed fuel for highly exothermic reaction. Present
process led to direct formation of nearly spherical particles on
sulfate addition, which is expected to be highly sinterable. Furnace
combustion was carried out for comparison with microwave
combustion.