Solution process has become a promising method to synthesize
nanoparticles at relatively low temperature (80–100 C)
with a simple apparatus compared with solid-state reaction
method and/or hydrothermal method [19,20]. Recently, the
importance of solution process is getting higher since this
method enable to obtain large volume of metal oxides
economically at low temperature. However, this method is not
frequently used to prepare multi-component metal oxides
because of the deficiency of understandings concerning reactivity
between metal oxides in solutions at low temperature and
reaction mechanism during homogeneous nucleation process
with different metals.