4 shows the results of TG-DTA analysis for the mixture after milling at 700 rpm in the planetary ball mill for 1 hr. In the TG curve, the weight loss detected is
from H2O and CO2that evaporate to the air. The DTA curve shows an endothermic
peak at about 100
o
C, indicating that H2O was evaporated. Moreover, the DTA curve
have exothermic peaks between 400-600
o
C, indicating the chemical reaction between
reactant mixture occurs in this range. On the other hand, furnace heating method
needs a high temperature, about 1000
o
C, to synthesis zirconia [13]. DTA results of
zirconia produced with using conventional methods, such as, sol-gel, hydrothermal [8,
11-12] show an exothermic peak at the same temperature as the mechanochemical
method. However, the furnace heating method and conventional methods have
disadvantages, for example the need for several operational steps, many chemical
reagents, high temperature and long times to synthesis zirconia powder [7].