3. Results
Figure 1 shows XRD from samples heated 3 h at different temperatures (before water washing). After heating for 3 h at 500°–650°C, NaCl, CaCO3, and m-ZrO2 were identified as the main phases, along with small amounts of Na2CO3, but CaZrO3 was not detected. CaZrO3 peaks began to appear at 700°C. With increasing temperature from 700° to 1000°C, the CaZrO3 peak height increased, whereas m-ZrO2 and CaCO3 peak heights decreased significantly. Na2CO3 peak heights decreased slightly, whereas NaCl peak heights were almost unchanged. Small amounts of CaO-stabilized ZrO2 were detected after heating for 3 h at 900°–1000°C. On further increasing the temperature to 1050°C, other phases such as m-ZrO2 and CaO-stabilized ZrO2 disappeared, and only CaZrO3 and NaCl were detected