In this work, pure yttrium aluminum garnet was obtained by the partial chemical method at the low temperature. In this approach, alpha-alumina nanoparticle, yttrium nitrate, urea, and tetraethyl orthosilicate (TEOS) were used as Al3+, Y3+, precipitation agent, and both dispersant and phase formation assistant agents, respectively. The results showed that TEOS molecules as a dispersant agent caused the less agglomeration of the alumina-yttria core-shell structure with a diameter of 200-300 nm, as compared to particles obtained without using TEOS molecules. Furthermore, by using 0.5 and 1 wt% of TEOS, the YAG formation temperature was decreased from 1400 degrees C to 1200 degrees C through the liquid-phase diffusion mechanism. Thus, in this case, the TEOS molecules acted as phase formation assistant agent for the constitution of YAG phases.